Rhinoceros - Ontario Local Schools

Rhinoceros - Ontario Local Schools
®
Rhinoceros
modeling tools for designers
Training Manual
Level 2
RH50-TM-L2-Jan-2015
Rhinoceros v5.0, Level 2, Training Manual
Updated 1/28/2015 by: Pascal Golay, Jerry Hambly, Mary Fugier
Technical Review: Lambertus Oosterveen
© Robert McNeel & Associates 2014
All Rights Reserved.
Printed in USA
Copyright © by Robert McNeel & Associates
Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted
without fee provided that copies are not made or distributed for profit or commercial advantage. To copy
otherwise, to republish, to post on servers, or to redistribute to lists requires prior specific permission.
Request permission to republish from Publications, Robert McNeel & Associates, 3670 Woodland Park Avenue
North, Seattle, WA 98103; FAX (206) 545-7321; e-mail [email protected]
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Table of Contents
PART I: Getting Started ..................................................... 5
Curve fairing to control surface quality ........................... 98
1 Introduction ..................................................................... 1
8 Use background bitmaps ........................................... 103
Duration ........................................................................... 1
9 An approach to modeling ........................................... 111
Prerequisites: ................................................................... 1
10 ................................................. Applying 2-D graphics 121
Course Objectives............................................................ 1
Make a model from a 2-D drawing ............................... 126
Schedule A: 3 Classroom Days ................................... 3
11 ......................................................... Surface analysis
Schedule B: 6 Half Days (On-line Training) ................. 3
12 .................................................................... Sculpting 137
131
PART II: Interface Customization ...................................... 7
Tools to help in control point editing ............................. 137
2 Customizing Rhino ......................................................... 9
Gumball ................................................................... 137
The toolbar layout ............................................................ 9
DragMode ................................................................ 137
Rules for commands in buttons ................................. 15
Nudge ...................................................................... 138
Command aliases .......................................................... 18
SetPt ........................................................................ 138
Macro editor ................................................................... 19
InsertKnot ................................................................ 138
Shortcut keys ................................................................. 20
InsertControlPoint .................................................... 138
Plug-ins .......................................................................... 21
13 ....................................................... Deformation tools 145
Scripting ......................................................................... 24
Template files................................................................. 25
Deforming objects ........................................................ 145
14 .........................................................................Blocks 151
PART III: Advanced Modeling Techniques ..................... 31
Instances and definitions .............................................. 151
3 NURBS topology ........................................................... 33
Defining blocks ........................................................ 151
4 Curve creation and continuity ..................................... 37
Insertion points ........................................................ 151
Curve degree ................................................................. 37
Embedded and linked blocks ................................... 151
Curve and surface continuity.......................................... 39
Layers and blocks ........................................................ 151
Curve continuity and curvature graph ............................ 40
Editing blocks ............................................................... 152
Advanced techniques for controlling continuity .............. 49
15 ......................................................... Troubleshooting 155
5 Surface continuity ........................................................ 51
General strategy ........................................................... 155
Analyzing surface continuity........................................... 51
Start with a clean file .................................................... 155
Matching surface continuity............................................ 51
Guidelines for Repairing Files ...................................... 155
Add knots to control surface matching ........................... 55
16 ......................................................... Polygon meshes 159
Surfacing commands that pay attention to continuity ..... 58
Render meshes ............................................................ 159
Surface blend options .................................................... 69
Meshes for manufacturing ............................................ 159
Fillets, blends and corners ............................................. 70
Meshes from NURBS objects ....................................... 160
6 Modeling with history ................................................... 79
PART IV: Rendering ...................................................... 165
Activating history ............................................................ 80
17 ................................................................... Rendering 167
Why is history off by default?..................................... 80
Rendering properties .................................................... 169
Steps in the History chain .............................................. 81
Scene lighting ............................................................... 171
History enabled commands............................................ 82
Image and bump maps................................................. 173
History-related commands ............................................. 82
Decals .......................................................................... 174
7 Advanced surfacing techniques.................................. 85
Dome-shaped buttons .................................................... 85
Creased surfaces ........................................................... 91
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List of Exercises
Exercise 1—Trackball mouse (warm-up).............................. 5
Exercise 2—Customizing Rhino’s interface .......................... 9
Exercise 3—Topology ........................................................ 33
Exercise 4—Trimmed NURBS ........................................... 35
Exercise 5—Curve degree ................................................. 37
Exercise 6—Geometric continuity ...................................... 43
Exercise 7—Tangent continuity .......................................... 45
Exercise 8—Curvature continuity ....................................... 48
Exercise 9—Surface continuity and MatchSrf ..................... 51
Exercise 10—Continuity commands ................................... 58
Exercise 11—Patch options ............................................... 61
Exercise 12—Lofting .......................................................... 62
Exercise 13—Blends .......................................................... 63
Exercise 14—Blend options ............................................... 69
Exercise 15—Variable radius fillets .................................... 71
Exercise 16—Variable radius blends and chamfers ........... 72
Exercise 17—Fillet with patch ............................................ 73
Exercise 18—Soft corners .................................................. 73
Exercise 19—History introduction ...................................... 79
Exercise 20—Soft domed buttons ...................................... 85
Exercise 21—Surfaces with a crease ................................. 91
Exercise 22—Surfaces with a crease (Part 2) .................... 95
Exercise 23—Handset ...................................................... 103
Exercise 24—Cutout ........................................................ 111
Exercise 25—Importing an Adobe Illustrator file............... 121
Exercise 26—Flow the logo onto a freeform surface with
history........................................................................ 123
Exercise 27—Making a detergent bottle ........................... 126
Exercise 28—Surface analysis ......................................... 131
Exercise 29—Dashboard.................................................. 139
Exercise 30—Using cage editing to deform an object ...... 145
Exercise 31—Using other deformation tools .................... 148
Exercise 32—Block basics ............................................... 152
Exercise 33—Inserting files as blocks .............................. 153
Exercise 34—Troubleshooting ......................................... 157
Exercise 35—Meshing...................................................... 159
Exercise 36—Rhino rendering.......................................... 167
Exercise 37—Rendering a scene ..................................... 169
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PART I:
Getting Started
1 Introduction
This course guide accompanies the Level 2 training sessions in Rhinoceros. This course is designed for individuals
who will be using and/or supporting Rhino.
The course explores advanced techniques in modeling to help participants better understand how to apply Rhino’s
modeling tools in practical situations.
In class, you will receive information at an accelerated pace. For best results, practice at a Rhino workstation
between class sessions, and consult the Rhino Help system from the Help menu: Help Topics.
Duration
3 days
Prerequisites:
Completion of Level 1 training or equivalent, plus three months (minimum) experience using Rhino.
Course Objectives
In Level 2, you learn how to:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
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Customize toolbars and toolbar collections
Create simple macros
Use advanced object snaps
Use distance and angle constraints with object snaps
Construct and modify curves that will be used in surface building using control point editing methods
Evaluate curves using the curvature graph
Use a range of strategies to build surfaces
Rebuild surfaces and curves
Control surface curvature continuity
Create, manipulate, save and restore custom construction planes
Create surfaces and features using custom construction planes
Group objects
Visualize, evaluate, and analyze models utilizing shading features
Place text around an object or on a surface
Map planar curves to a surface
Create 3-D models from 2-D drawings and scanned images
Clean up imported files and export clean files
Use rendering tools
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CHAPTER 1
INTRODUCTION
Schedule A: 3 Classroom Days
Schedule B: 6 Half Days (On-line Training)
Day 1
Topic
Session 1
Topic
8-9:30AM
Introduction and warm up exercise.
9-10:45AM
Introduction and warm up exercise.
9:30AM-12PM
Interface and customization
11AM-12:30PM
Interface and customization
12-1PM
Lunch
Session 2
Topic
1-3PM
NURBS topology and curve degree
9-10:45AM
NURBS topology and curve degree
3-5PM
Curve and surface continuity
11AM-12:45PM
Curve and surface continuity
Day 2
Topic
Session 3
Topic
8-10AM
History, advanced surfacing and
CPlane tools
9-10:45AM
History, advanced surfacing and
CPlane tools
More CPlanes, mapping objects to
surfaces
11AM-12:45PM
More CPlanes, mapping objects to
surfaces
10AM-12PM
12-1PM
Lunch
1-3PM
Surface analysis
Session 4
Topic
3-5PM
Putting it all together—Scoop
exercise
9-10:45AM
Surface analysis
11AM-12:45PM
Putting it all together—Scoop
exercise
Session 5
Topic
9-10:45AM
More CPlanes, mapping objects to
surfaces
11AM-12:45PM
Surface analysis, direct surface
manipulation
Session 6
Topic
9-10:45AM
Blocks, troubleshooting, Meshing
11AM-12:45PM
Rendering (time allowing)
All Sessions
Questions:
12:45-1PM
End of Class
1:00PM
Day 3
Topic
8-10AM
More CPlanes, mapping objects to
surfaces
10AM-12PM
Surface analysis, direct surface
manipulation
12-1PM
Lunch
1-3PM
Blocks, troubleshooting, Meshing
3-5PM
Rendering (time allowing)
Class
schedules are
suggested.
Actual class
schedule will
be set by the
instructor.
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INTRODUCTION
Exercise 1—Trackball mouse (warm-up)
1
Begin a new model, save it as Trackball.3dm.
2
Model a trackball mouse on your own.
The dimensions are in millimeters. Use the dimensions as guides only.
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PART II:
Interface Customization
2 Customizing Rhino
This chapter discusses customizing Rhino’s interface with the following tools:
•
•
•
•
•
Toolbar layout
Macro Editor
Shortcut keys
Scripting
Template files
The toolbar layout
The toolbar layout is the arrangement of toolbars containing command buttons on the screen. The toolbar layout
is stored in a file with the .rui extension that you can open and save. Rui files contain command macros, icons in
three sizes, as well as tooltips and button text. Rhino comes with a default toolbar file and automatically saves the
active toolbar layout before closing unless the .rui file is read-only. You can create your own custom toolbar files
and save them for later use.
You can have more than one toolbar file open at a time. This allows greater flexibility to display toolbars for
particular tasks.
Rhino’s customization tools make it easy to create and modify toolbars and buttons. Adding to the flexibility is the
ability to combine commands into macros to accomplish tasks that are more complex. In addition to toolbar
customization, it is possible to set up command aliases and shortcut keys to accomplish tasks in Rhino.
Exercise 2—Customizing Rhino’s interface
In this exercise, we will create buttons, toolbars, macros, aliases, and shortcut keys that will be available to use
throughout the class.
To create a custom toolbar collection
There are times that the standard commands and buttons do not do exactly what you want. For example, Zoom
Extents will look at all of the objects in a model and then zoom to the extents of these objects. In this exercise,
we will open a model that has several objects including some light objects.
Let us say we want to use Zoom Extents to zoom to the objects, but we do not want the command to consider the
light objects. In this exercise, we will make a new toolbar with a button that will Zoom Extents while ignoring any
light objects in the model.
1
Open the model ZoomLights.3dm.
2
From the Tools menu, click Toolbar Layout.
This opens the Rhino Options dialog on the Toolbars page.
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Highlight the Default toolbar file.
4
On the Toolbars page click the File menu, click Save As.
5
Type Level 2 Training in the File name box and click Save.
CUSTOMIZING RHINO
A copy of the current default toolbar file is saved with the new name.
Toolbar files are saved with a .rui extension. You will use this new toolbar file to do some customization.
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In the Rhino Options dialog, on the Toolbars page, all the open toolbar files are listed along with a list of all
the individual toolbars for the selected toolbar file.
Check boxes show the current state of the toolbars. A checked box indicates that the toolbar is displayed.
To create a new toolbar
1
On the Toolbars page click the Edit menu, click New Toolbar.
2
In the Toolbar Properties dialog, name the toolbar Zoom, and click OK.
A new single button toolbar appears.
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Close the Rhino Options dialog.
Another way to work with toolbars is to use the title bar of a floating toolbar.
4
Right-click on the title bar of the new toolbar you created.
A popup list of toolbar options and commands displays.
To edit the new button
1
Hold down the Shift key and right-click the smiley face button in the new toolbar.
The Button Editor dialog appears with fields for commands for the left and right mouse buttons, as well as
for the tooltips.
2
In the Button Editor dialog, click Image only.
In the Text box, type Zoom No Lights.
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For the Left mouse button Tooltip, type
Zoom Extents except lights
For the Right mouse button Tooltip, type
Zoom Extents except lights all viewports.
4
In the Left mouse button Command box, type
! _SelNone _SelLight _Invert _Zoom _Selected _SelNone.
5
In the Right bouse button Command box, type
! _SelNone _SelLight _Invert _Zoom _All _Selected _SelNone.
Debug the new button
Combine above macro with SetRedrawOff/SetRedrawOn. This will make the macro run without flashing and
without too much info being reported to command history.
Your macro will work regardless of adding SetRedrawOff/SetRedrawOn. However, this is good practice to
make your macro work more elegantly.
1
In the Left mouse button Command box, type
! _SetRedrawOff _SelNone _SelLight _Invert _Zoom _Selected _SelNone _SetRedrawOn.
2
In the Right bouse button Command box, type
! _SetRedrawOff _SelNone _SelLight _Invert _Zoom _All _Selected _SelNone _SetRedrawOn.
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To change the bitmap image for the button
1
In the Button Editor dialog, click the
Edit... next to the button icon in the upper
right to open the Bitmap Editor.
The bitmap editor is a simple paint
program that allows editing of the icon
bitmap. It includes a grab function for
capturing icon-sized pieces of the screen,
and an import file function.
2
In the Edit Bitmap dialog, click the File
menu, click Import Bitmap to Fit, and
select the ZoomNoLights_32.bmp.
You can import any bitmap image. If the
bitmap is too large, it will be scaled to fit
as it is imported.
3
In the Edit Bitmap dialog, make any
changes to the picture, and click OK.
Double-click on the color swatches to the
right of the standard color bar to access
the Select Color dialog for more color
choices.
4
Click OK in the Select Color dialog.
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To change the bitmap image to use an alpha channel
Notice that the new button’s background color does not match the background color of the other buttons. We will
change the image background using an alpha channel, so that it matches the Windows 3D Objects color like the
other buttons.
1
Hold down the Shift key and right-click the
ZoomNoLights button.
2
In the Button Editor dialog, click Edit to
open the Bitmap Editor.
3
Left-click the upper right color swatch to the
right of the black color. Change the alpha
color number, labeled A, for the button color
from 255 to 1.
This will make the current paint color
transparent.
4
Change to the Fill tool, then right-click in
the background area of the button image.
5
Click OK in the Edit Bitmap dialog, and then
click OK in the Button Editor dialog.
The color matches the Windows 3D Objects
color.
To use the new button
1
Click the ZoomNoLights button.
2
Use the button to zoom the model two ways.
You will notice that it ignores the lights when doing a Zoom Extents.
Rules for commands in buttons
You can enter the commands or command combinations in the appropriate boxes, using these rules:
Item
Sample
Description
Space
!_Line
A space is interpreted as Enter.
Commands do not have spaces (for example, SelLight) but you must leave a space
between commands.
“‟
! (Exclamation mark)
If your command string refers to a file, toolbar, layer, object name, or directory for
which the path includes spaces, the path, toolbar name, or directory location must
be enclosed in double-quotes.
!-_circle
' (apostrophe)
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An ! (Exclamation mark) followed by a space is interpreted as Cancel. Generally, it is
best to begin a button command with an exclamation mark (!) if you want to cancel
any other command that may be running when you click the button.
View manipulation commands like Zoom can be run in the middle of other
commands. For example, you can zoom and pan while picking curves for a loft. An
'(apostrophe) prior to the command name indicates that the next command is a nest
able command.
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Sample
_ (underscore)
- (Hyphen)
Description
An underscore (_) runs a command as an English command name.
Rhino can be localized in many languages. The non-English versions will have
commands, prompts, command options, dialogs, menus, etc., translated into their
respective languages. English commands will not work in these versions. For macros
written in English to work on all computers (regardless of the language of Rhino), the
macros need to force Rhino to interpret all commands as English command names,
by using the underscore.
-_Sweep2
Pause
Commands with dialogs can be run at the command-line with command-line options.
To suppress the dialog and use command-line options, prefix the command name
with a hyphen (-).
User input and screen picks are allowed in a macro by putting the Pause command in
the macro. Commands that use dialogs, such as Revolve, do not accept input to the
dialogs from macros. Use the hyphen form of the command (-Revolve) to suppress
the dialog and control it entirely from a macro.
Note: These rules also apply to scripts run using the ReadCommandFile command and pasting text at the
command prompt. More sophisticated scripting is possible with the Rhino Script plug-in, but quite a lot can
be done with the basic commands and macro rules.
Some very useful commands for macros are SelLast, SelPrev, SelName, Group, SetGroupName, SelGroup, Invert,
SelAll, SelNone, ReadCommandFile, and SetWorkingDirectory.
To link a toolbar to a button
1
Shift+right-click the Zoom Extents button in the Standard toolbar.
2
In the Button Editor dialog, click in the Linked toolbar area, select Zoom from the list, and click OK.
Now the Zoom Extents button has a small black triangle in the lower right corner indicating it has a linked
toolbar.
3
Click and hold the Zoom Extents button to fly out your newly created single button toolbar.
If you close the Zoom toolbar you just created, you can always re-open it using the linked button.
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Try the new linked button.
To add a command to an existing button
1
Hold the Shift key and right-click the Move button on the Main toolbar.
2
In the Button Editor dialog, in the Right mouse button Command box, type
! _Move _Pause _Vertical
3
In the Button Editor dialog, in the Right mouse button Tooltip box, type Move Vertical.
This button will allow you to duplicate objects in the same location. We will use this command several times
during the class.
4
Select one of the objects in the model and right-click on the Move button.
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Move the selected object vertically from the construction plane.
Command aliases
The same commands and macros that are available for buttons are also available for command aliases. Command
aliases are like using shorthand in Rhino. They are commands and macros that are activated whenever commands
are allowed, but are often used as a keyboard shortcut followed by Enter, Spacebar or clicking the right mouse
button.
Use aliases for command sequences that you use often or frequently.
Note: When making aliases, use keys that are close to each other or repeat the same character 2 or 3 times, so
they will be easy to use.
To make a command alias
1
Open the model Aliases.3dm.
2
From the Tools menu, click Options.
3
In the Rhino Options dialog, on the Aliases page, you can add aliases and command strings or macros.
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Click New to make a new alias.
We will make aliases to mirror selected objects vertically and horizontally across the origin of the active
construction plane. These are handy when making symmetrical objects built centered on the origin.
5
In the Alias column, type mx.
In the Command Macro column, type ! _Mirror _Pause _XAxis
The alias is in the left column and the command string or macro is in the right column. The same rules apply
here as with the buttons. Aliases can be used within other aliases' macros or button macros.
6
Click New to make another new alias.
7
In the Alias column, type my.
In the Command Macro column, type ! _Mirror _Pause _YAxis.
To try the new aliases
Select some geometry and type mx or my and press Enter.
If no objects are pre-selected, the Pause in the script prompts you to select objects, and an Enter will
complete the selection set.
Macro editor
When making macros that are more complicated, it is good practice to use Rhino’s built-in macro editor. Macros
can be edited and run directly from the editor. This allows you to quickly test whether command options and
syntax are correct.
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To use the macro editor
In the following example we will make a mirror macro that allows you to mirror across the construction plane. We
will use the Macro Editor to build and test the macro before we add it to the Alias list.
1
From the Tools menu, click Command, then click Macro
Editor.
2
In the Macro Editor type
! _Mirror _Pause _3Point 0 1,0,0 0,1,0.
3
To test the macro, click the Run
Editor.
4
If the macro runs as expected, select the text and copy it to
the clipboard.
5
Open the Options dialog on the Alias page and make a new
alias mc. Paste the text from the Macro Editor into the Alias
command column.
6
Select some geometry and try the new alias out. Type mc and
press Enter.
icon in the Macro
To Export and Import Options
There are times when you might want to copy all or some of the options from one computer to another. An
example might be a desktop computer and a laptop computer. This is especially true for aliases, keyboard
shortcuts, and display modes. Rhino has commands that Export options to a file as well as Import options from a
file.
1
From the Tools menu, click Export Options.
2
In the Save As dialog, for the File Name, type Level2_Options.
The current options are saved to a file.
3
Now, delete one of the aliases you previously made.
4
From the Tools menu, click Import Options.
5
In the Import Options dialog, select the file you just saved.
6
For the Options to import, click Aliases, Appearance, or any other options you wish to import.
Check to see if the alias you deleted is back.
Shortcut keys
The same commands, command strings, and macros that you can use for buttons and aliases are also available
for keyboard shortcuts. Shortcuts are commands and macros that are activated by certain combinations of
function keys, Ctrl, Alt, and alphanumeric keys.
To make a shortcut key
1
From the Tools menu, click Options.
2
In the Rhino Options dialog, on the Keyboard page, you can add command strings or macros.
3
Click in the column next to the F4 to make a new shortcut.
4
Type _DisableObject snap _Toggle for the shortcut.
This shortcut will make it easy to toggle the state of running object snaps.
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Close the dialog and try it out.
There are several shortcut keys that already have commands assigned. The same rules apply here as with
the buttons and aliases.
Plug-ins
Plug-ins are programs that extend the functionality of Rhino. Plug-in classifications include:
Included plug-ins
Shipped and installed with Rhino. Some of these plug-ins are loaded, for example Rhino Render, Render
Development Kit, Rhino Toolbars and Menus, BoxEdit, etc. Others are installed, but not loaded. Most of these
plug-ins are Import/Export plug-ins. They are generally enabled and will get loaded when they are used for the
first time.
Rhino 5.0 Labs plug-ins
Experimental plug-ins developed in-house. These plug-ins are being considered for inclusion in future service
releases or the next version of Rhino. They are available for download from the Rhino 5.0 Labs Tools website.
McNeel plug-ins
Flamingo nXt, Penguin, Brazil (rendering) and Bongo (animation) are McNeel products that are available for
purchase.
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Third-party plug-ins
These are programs and utilities that are developed by third-party developers. Some of these are free, but
most are available for purchase. A few of the programs are stand-alone applications that work with Rhino, but
are not plug-ins. Generally, they add some specific capability to Rhino. For example RhinoCam is a CAM
application, VRay is a rendering application, RhinoGold is jewelry design software, etc. For more information
about these programs visit the Rhino Resources website.
To load a plug-in
For this example we have included a plug-in from the Rhino 5.0 labs page for you to install and use.
1
From the Tools menu, click Options.
2
Click Plug-ins.
A list of currently loaded and available plug-ins is displayed.
3
On the Plug-ins page, click Install.
4
In the Load Plug-In dialog, navigate to the Level 2/Models/Plug-ins folder, then, depending on which
version of Rhino 5.0 you’re running, click either RhinoPolyhedra_x64.rhp or RhinoPolyhedra_x86.rhp
(needed for 32-bit version of Rhino 5.0).
5
To run the command, type Polyhedron on the command-line.
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In the Polyhedron dialog, select one of the polyhedrons from the list, then click a center point and a radius
point.
To load a plug-in using drag and drop
1
Open a Windows Explorer window.
2
Navigate to the folder that has the plug-in you want to install.
3
Simply click and hold the plug-in file, drag it and drop it into the Rhino window.
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Scripting
Rhinoceros supports scripting using RhinoScript and Rhino.Python.
To script Rhino, you must have some programming skills. Fortunately, scripting is easy to learn and there are
materials available to help you get started.
For more information, go to the Developer Wiki. In addition, Rhino installs with Help for both scripting tools. See
the EditScript and EditPythonScript commands for details.
We will not cover how to write a script in this class, but we will learn how to run a script and apply it to a button.
The following script will list information about the current model.
To load a RhinoScript
1
From the Tools menu, click RhinoScript, then click Load.
2
In the Load Script File dialog, click Add.
3
In the Open dialog, select CurrentModelInfo.rvb, then
click Open.
Note: You may get a message that Rhino “Cannot find
the script file CurrentModelInfo.rvb.
If that happens you will need to include the full path to the
folder where the script file is located or add a search path
in the Files section of Rhino Options.
4
In the Load Script File dialog, highlight
CurrentModelInfo.rvb, then click Load.
5
Save the current model. If you do not have a saved version
of the model, no information is possible.
6
From the Tools menu, click RhinoScript, then click Run.
7
In the Run Script Subroutine dialog, click
CurrentModelInfo and then click OK.
A dialog describing the current information about this
model displays.
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To edit the script file
1
From the Tools menu, click RhinoScript, then click Edit.
2
On the Rhino Script Editor window, from the File menu, click Open.
3
On the Open dialog, select CurrentModelInfo.rvb, then click Open.
We will not be editing script files in this class. This exercise is to show how to access the editing feature if
needed.
4
Close the Rhino Script Editor window.
To make a button that will load or run a script
1
From the Tools menu, click Toolbar Layout.
2
In the Toolbars dialog, check the File toolbar then close the
dialog.
3
Right-click on the title bar of the File toolbar, then click New
Button from the popup menu.
4
In the Button Editor dialog, in the Left mouse button
Tooltip, type Current Model Information.
5
In the Right mouse button Tooltip, type
Load Current Model Information.
6
In the Text box, type Model Info.
7
In the Left mouse button Command box, type
! -_RunScript (CurrentModelInfo)
8
In the Right mouse button Command box, type
! -_LoadScript “CurrentModelInfo.rvb”
To add a custom bitmap
1
In the Button Editor dialog, click Edit.
2
In the Edit Bitmap dialog, from the File menu, click Import Bitmap, and Open the
CurrentModelInfo.bmp, then click Open.
3
In the Button Editor dialog, click OK.
4
Try the new button.
Template files
A template is a Rhino model file you can use to store basic settings. Templates include all the information that is
stored in a Rhino 3DM file: objects, blocks, layouts, grid settings, viewport layout, layers, units, tolerances, render
settings, dimension settings, notes, and any setting in document properties.
You can use the default templates that are installed with Rhino or save your own templates to base future models
on. You will likely want to have templates with specific characteristics needed for particular types of model
building.
The standard templates that come with Rhino have different viewport layouts or unit settings, but no geometry,
and default settings for everything else. Different projects may require other settings to be changed. You can have
templates with different settings for anything that can be saved in a model file, including render mesh, angle
tolerance, named layers, lights, and standard pre-built geometry and notes.
If you include notes in your template, they will show in the Open Template File dialog.
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The New command begins a new model with a template (optional). It will use the default template unless you
change it to one of the other templates or to any other Rhino model file.
To change the template that opens by default when Rhino starts up, choose New and select the template file you
would like to open when Rhino starts, then check the Use this file when Rhino starts box.
To create a template
1
Start a new model.
2
Select the Small Objects - Inches.3dm file as the template.
3
From the Render menu, click Current Renderer, and then click Rhino Render.
To set the Document Properties
1
From the File menu, click Properties.
2
In the Document Properties dialog, on the Grid page, change the Snap spacing to 0.1, the Minor grid
lines every to 0.1, the Major lines every to 10, and the Grid line count to 10.
3
On the Mesh page change the setting to Smooth & slower.
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4
On the Rhino Render page, check Use lights on layers that are off.
5
On the Units page, change the Angle tolerance to 0.5, click OK.
CUSTOMIZING RHINO
The end tangent normals will be determined by this setting.
To set up the layers
1
Open the Layers panel and rename Layer 05 to Spotlights, Layer 04 to Curves, Layer 03 to Surfaces, and
Default to Reference.
Make the Spotlights layer current.
Delete Layer 01 and Layer 02 layers.
2
Set up a spotlight so that it points at the origin and is approximately 45 degrees in the Top viewport and
tilted 45 degrees in the Front viewport.
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3
Use the my alias to mirror the light to make a second one.
4
To make the Curves layer the only visible layer, from the Edit menu, click Layers then click One Layer On.
Select the Curves layer.
To set save notes
1
From the Panel menu, click Notes.
Type the details about this template in the Notes panel.
2
From the File menu, click Save As Template.
Name the template Small Objects – Decimal Inches - 0.001.3dm.
This file with all of its settings is now available any time you start a new model.
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To set a default template
1
From the File menu, click New.
2
Select the template you want to use as the default template.
3
In the Open Template File dialog, check the Use this file when Rhino starts checkbox.
You should make custom templates for the kind of modeling that you do regularly to save set up time.
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PART III:
Advanced Modeling Techniques
3 NURBS topology
The underlying geometry of NURBS surfaces have a rectangular topology in UV, or parameter space. Rows of
surface points, and parameterization, are organized in two directions (U and V). These two directions are
crosswise to each other, at more or less 90 degrees on an ideal surface, though this is not always possible. This
structure is not always obvious when creating or manipulating a surface. Remembering this structure is useful in
deciding which strategies to use when creating or editing geometry.
Exercise 3—Topology
This exercise will demonstrate how NURBS topology is organized and discuss some special cases that need
consideration when creating or editing geometry.
1
Open the model Topology.3dm.
There are several surfaces visible on the
current layer.
2
Turn on the control points of the simple
rectangular plane on the left.
It has four control points, one at each corner—
this is a simple untrimmed planar surface that
shows the rectangular topology.
3
Now, turn on the control points of the curvier
surface.
There are many more points, but it is clear that they are arranged in a rectangular fashion.
1
Select the cylinder.
It appears as a continuous circular surface, but
it also has a rectangular boundary.
2
Use the ShowEdges command (Analyze menu:
Edge Tools > click Show Edges) to highlight the
surface edges.
Notice that there is a seam highlighted on the
cylinder. The seam that is highlighted
represents two edges of the rectangle, while
the other two edges are circular at the top and
the bottom. The rectangular topology is
present here, also.
3
Select the sphere.
It appears as a closed continuous object.
4
Use the ShowEdges command to highlight the
edges.
Notice that there is a seam highlighted on the
sphere. The highlighted seam represents two
edges of a rectangular NURBS surface, while
the other two edges are collapsed to a single
point at the poles. When all of the points of an
untrimmed edge are collapsed into a single
point, it is called a singularity.
The rectangular topology is present here, also, though very distorted.
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1
Turn on the Control Points for the sphere.
2
Zoom Target (View menu: Zoom > Zoom Target)
draw a select window very tight around one of the
poles of the sphere.
3
Select the point at one pole of the sphere and start
the Smooth (Transform menu: Smooth) command.
4
In the Smooth dialog, uncheck Smooth Z, then
click OK.
NURBS TOPOLOGY
A hole appears at the pole of the sphere. There’s
no longer a singularity at this pole of the sphere.
ShowEdges will highlight this as an edge as well.
5
Use the Home key to zoom back out.
This is the fastest way to step back through view changes.
To select points
1
Open the Select Points toolbar.
2
Select a single point at random on the sphere.
3
From the Select Points toolbar, click Select U.
An entire row of points is selected.
4
Clear the selection by clicking in an empty area and
select another point on the sphere.
5
From the Select Points toolbar, click Select V.
A row of points in the other direction of the
rectangle is selected. This arrangement into uand v-directions is always the case in NURBS
surfaces.
6
Try the other buttons in this toolbar on your own.
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NURBS TOPOLOGY
Exercise 4—Trimmed NURBS
1
Open the model Trimmed NURBS.3dm.
This surface has been trimmed out of a much
larger surface. The underlying four sided
surface data is still available after a surface
has been trimmed, but it is limited by the trim
curves (edges) on the surface.
2
Select the surface and turn on the control
points, then drag a few control points.
Control points can be manipulated on the trimmed part of the surface or the rest of the surface, but notice
that the trimming edges move around as the underlying surface changes. The trim curve always stays on
the surface.
3
Use the Undo command to undo the point manipulation.
To remove the trims from a surface
1
Start the Untrim (Surface menu: Surface Edit
Tools > Untrim) command.
2
Select the single edge of the trimmed surface.
The original underlying surface appears and
the trim boundary disappears.
3
Use the Undo command to return to the
previous trimmed surface.
To detach a trimming curve from a surface
1
Start the Untrim command with the
KeepTrimObjects option set to Yes (Surface
menu: Surface Edit Tools > Detach Trim).
2
Select the edge of the surface.
The original underlying surface appears. The
boundary edges are converted to curves,
which are no longer associated with the
surface.
3
Undo, to return to the previous trimmed
surface.
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To shrink a trimmed surface
1
Start the ShrinkTrimmedSrf command (Surface menu: Surface Edit Tools >
Shrink Trimmed Surface).
2
Select the surface and press Enter to end the command.
The underlying untrimmed surface is replaced by a one with a smaller range
that matches the old surface exactly in that range. You will see no visible
change in the trimmed surface. Only the underlying untrimmed surface is
altered.
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4 Curve creation and continuity
We will begin this part of the course by reviewing a few concepts and techniques related to NURBS curves that will
simplify the learning process during the rest of the class. Curve building techniques have a significant effect on the
surfaces that you build from them.
Curve degree
The degree of a curve refers to the highest degree polynomial in the equation for the curve. In practice, it relates
to the extent of the influence a single control point has over the length of the curve.
For higher degree curves, a control point has less local influence and a more broad influence over the entire
length of the curve. It also has higher internal continuity.
In the example below, the five curves have their control points at the same six points. Each curve has a different
degree. The degree can be set with the Degree option in the Curve command.
Exercise 5—Curve degree
1
Open the model Curve
Degree.3dm.
2
Use the Curve command (Curve
menu: Free-Form > Control Points)
with Degree set to 1, using the
Point object snap to snap to each
of the points.
3
Repeat the Curve command with
Degree set to 2.
4
Repeat the Curve command with
Degree set to 3.
5
Repeat the Curve command with
Degree set to 4.
6
Degree 1: Control points on curve—
no bending.
Degree 2: Control points off
curve.
Degree 3
Degree 4
Repeat the Curve command with Degree set to 5.
Degree 5
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Analyzing the curvature of a curve
1
Use the CurvatureGraph command (Analyze
menu: Curve > Curvature Graph On) to turn on the
curvature graph for one of the curves. Set the
DisplayScale to a number that shows the graph as
in the illustration—between 110-120 should work
well.
The graph indicates the curvature on the curve—
this is the inverse of the radius of curvature. The
smaller the radius of curvature at any point on
the curve, the larger the amount of curvature.
2
Turn on the control points for the
curve you have graphed and view the
curvature graph as you drag some
control points. Note the change in the
curvature hairs as you move points.
3
Repeat this process for each of the
curves. You can use the Curvature
Graph dialog buttons to remove or
add objects from the graph display.
Note:
• Degree 1 curves have no curvature and no graph displays.
• Degree 2 curves are internally continuous for tangency—the steps in the graph indicate this condition. Note
that only the graph is stepped not the curve.
• Degree 3 curves have continuous curvature—the graph will not show steps but may show hard peaks and
valleys. Again, the curve is not kinked at these places—the graph shows an abrupt but not discontinuous
change in curvature.
• In higher degree curves, higher levels of continuity are possible.
• For example, a Degree 4 curve is continuous in the rate of change of curvature—the graph doesn’t show any
hard peaks.
• A Degree 5 curve is continuous in the rate of change of the rate of change of curvature. The graph doesn’t
show any particular features for higher degree curves but it will tend to be smooth.
• Changing the degree of the curve to a higher degree with the ChangeDegree command with
Deformable=No will not improve the internal continuity, but lowering the degree will adversely affect the
continuity.
• Rebuilding a curve with the Rebuild command will change the internal continuity.
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Curve and surface continuity
Since creating a good surface so often depends upon the quality and continuity of the input curves, it is
worthwhile clarifying the concept of continuity among curves.
For most curve building and surface building purposes we can talk about four useful levels of continuity:
Not continuous
The curves or surfaces do not meet at
their end points or edges. Where there
is no continuity, the objects cannot be
joined.
Positional continuity (G0)
Curves meet at their end points,
surfaces meet at their edges.
Positional continuity means that there
is a kink at the point where two curves
meet. The curves can be joined in
Rhino into a single curve but there will
be a kink and the curve can still be
exploded into at least two sub-curves.
Similarly two surfaces may meet along a common edge but will show a kink or seam, a hard line between the
surfaces. For practical purposes, only the end points of a curve or the last rows of points along the edges of two
untrimmed surfaces need to match to determine G0 continuity.
Tangency continuity (G1)
Curves or surfaces meet and the
directions of the tangents at the
endpoints or edges is the same. You
should not see a crease or a sharp
edge.
Tangency is the direction of a curve at
any particular point along the curve
Where two curves meet at their endpoints the tangency condition between them is determined by the direction in
which the curves are each heading exactly at their endpoints. If the directions are collinear, then the curves are
considered tangent. There is no hard corner or kink where the two curves meet. This tangency direction is
controlled by the direction of the line between the end control point and the next control point on a curve.
In order for two curves to be tangent to one another, their endpoints must be coincident (G0) and the second
control point on each curve must lie on a line passing through the curve endpoints. A total of four control points,
two from each curve, must lie on this imaginary line.
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Curvature continuity (G2)
Curves or surfaces meet, their tangent
directions are the same and the radius
of curvature is the same for each at
the endpoint.
Curvature Continuity includes the above G0 and G1 conditions and adds the further requirement that the radius of
curvature be the same at the common endpoints of the two curves. Curvature continuity is the smoothest
condition over which the user has any direct control, although smoother relationships are possible.
For example, G3 continuity means that not only are the conditions for G2 continuity met, but also that the rate of
change of the curvature is the same on both curves or surfaces at the common end points or edges.
G4 means that the rate of change of the rate of change is the same. Rhino has tools to build such curves and
surfaces, but fewer tools for checking and verifying such continuity than for G0-G2.
G5+ has no visible evidence of more continuity.
Curve continuity and curvature graph
Rhino has two analysis commands that will help illustrate the difference between curvature and tangency. In the
following exercise, we will use the CurvatureGraph and the Curvature commands to gain a better
understanding of tangent and curvature continuity.
To show continuity with a curvature graph
1
Open the model Curvature_Tangency.3dm.
There are five sets of curves, divided into three groups.
One group has positional (G0) continuity at their common ends.
Group (a-c) has tangency (G1) continuity at
their common ends.
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Group (b- d) has curvature (G2) continuity at
their common endpoints.
2
Use Ctrl+A to select all of the curves. Then, turn on the Curvature Graph (Analyze
menu: Curve > Curvature Graph On) for the curves. Set the Display Scale in the
floating dialog to 100 for the moment. Change the scale if you cannot see the
curvature hair.
The depth of the graph at this setting shows, in model units, the amount of curvature
in the curve.
3
First, notice the top sets of curves (a-b). These have two straight lines and a curve in
between.
The lines do not show a curvature graph—they have no curvature.
The image just to the right shows what is
meant by the curvature not being
continuous—the sudden jump in the curvature
graph indicates a discontinuity in curvature.
Nevertheless the line-arc-line is smoothly
connected. The arc picks up the exact
*direction* of one line and then the next line
takes off at the exact direction of the arc at its
end.
On the other hand, the G2 curves (b) again
show no curvature on the lines, but the curve
joining the two straights is different from the
G1 case. This curve shows a graph that starts
out at zero—it comes to a point at the end of
the curve, then increases rapidly but
smoothly, then tails off again to zero at the
other end where it meets the other straight. It
is not a constant curvature curve and thus not
a constant radius curve. The graph does not
have a sudden jump in the curvature graph; it
goes smoothly from zero to its maximum.
The G1 middle curve is an
arc. It shows a constant
curvature graph as expected
because the curvature of an
arc never changes, just as
the radius never changes.
For the G2 middle curve,
the graph ramps up from
zero to some maximum
height along a curve and
then slopes back to zero,
matching the zero curvature
again on the other straight
line.
Thus, there is no discontinuity in curvature from the end of the straight line to end of the curve. The curve
starts and ends at zero curvature just like the lines have. So, the G2 case not only is the direction of the
curves the same at the endpoints, but the curvature is the same there as well—there is no jump in
curvature and the curves are considered G2 or curvature continuous.
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CURVE CREATION AND CONTINUITY
Next, look at the c and d curves.
These are also G1 and G2 but are not straight
lines so the graph shows up on all of the
curves.
Again, the G1 set shows a step up or down in
the graph at the common endpoints of the
curves. This time the curve is not a constant
arc—the graph shows that it increases in
curvature out towards the middle.
On G2 curves, the graph for the middle curve
shows the same height as the adjacent curves
at the common endpoints—there are no abrupt
steps in the graph.
The outer curve on the graph from one curve stays connected to the graph of the adjacent curve.
To show continuity with a curvature circle
1
Start the Curvature command (Analyze menu: Curvature circle) and select the
middle curve in set c.
The circle that appears on the curve indicates the radius of curvature at that
location—the circle that would result from the center and radius measured at
that point on the curve.
2
Drag the circle along the curve.
Notice that where the circle is the smallest, the graph shows the largest
amount of curvature. The curvature is the inverse of the radius at any point.
3
Click the MarkCurvature option on the command-line.
Slide the circle, snap to an endpoint of the curve, and click to place a
curvature circle.
4
Stop the command and restart it for the other curve sharing the endpoint just
picked.
Place a circle on this endpoint as well.
The two circles have greatly different radii. Again, this indicates a
discontinuity in curvature. These curves are G1 / tangent only, so the
curvature at the tangent meeting point is different for the two curves, and
that is where the curvature graph would take a jump.
5
Repeat the same procedure to get circles at the ends of the curves in set d.
Notice that this time the circles from each curve at the common endpoint are
the same radius. These curves are curvature continuous.
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6
CURVE CREATION AND CONTINUITY
Lastly, turn on the control points for the middle
curves in c and d. Select the “middle” control
point on either curve and move it around.
Notice that while the curvature graph changes
greatly, the continuity at each end with the
adjacent curves is not affected.
The G1 curve graphs stay stepped, though,
the size of the step changes.
The G2 curve graphs stay connected,
although there is a peak that forms there.
7 Look at the graphs for the G0 curves.
Notice that there is a gap in the graph—this
indicates that there is only G0 or positional
continuity.
The curvature circles, on the common
endpoints of these two curves, are not only
different radii, but they are also not tangent—
they cross each other. There is a discontinuity
in direction at the ends.
Exercise 6—Geometric continuity
1
Open the model Curve Continuity.3dm.
The two curves are clearly not tangent. Verify this with the continuity
checking command GCon.
2
Start the GCon command (Analyze menu: Curve > Geometric Continuity).
3
Click near the common ends (1 and 2) of each curve.
Rhino displays a message on the command-line indicating the curves are out
of tolerance—the endpoints of the two curves are not close enough to each
other to be considered the same.
Curve end difference = 0.030 millimeters
Radius of curvature difference = 126.531 millimeters
Curvature direction difference in degrees = 10.277
Tangent difference in degrees = 10.277
Curve ends are out of tolerance.
Often, imported curves are often "out of tolerance" and need this kind of
repair for accurate modeling.
To make the curves have position continuity
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1
Turn on the control points for both curves and zoom in on the common ends.
2
Turn on the Point object snap and drag one of the endpoints onto the other.
3
Repeat the GCon command.
The command-line message is different now:
Curve end difference = 0.000 millimeters
Radius of curvature difference = 126.771 millimeters
Curvature direction difference in degrees = 10.307
Tangent difference in degrees = 10.307
Curves are G0.
4
Undo the previous operation.
To make the curves have position continuity using Match
Rhino has a tool for making this adjustment automatically in the Match command.
1
To try this, start the Match command (Curve menu: Curve Edit Tools >
Match).
2
Pick near the common end of one of the curves.
3
Pick near the common end of the other curve.
By default, the curve you pick first will be the one that is modified to match
the other curve. You can make both curves change to an average of the two
by checking the Average Curves option in the following dialog.
4
In the Match Curve dialog, for Continuity
check Position, for Preserve other end
check Position, check Average Curves.
5
Repeat the GCon command.
The command-line message indicates:
Curve end difference = 0.000 millimeters
Radius of curvature difference = 126.708 millimeters
Curvature direction difference in degrees = 10.265
Tangent difference in degrees = 10.265
Curves are G0.
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Exercise 7—Tangent continuity
It is possible to establish a tangency (G1) condition between two curves by aligning the control points in a
particular way. The endpoints at one end of the curves must be coincident and these points in addition to the next
point on each curve must fall in a line with each other. This can be done automatically with the Match command,
although it is also easy to do by moving the control points using the normal Rhino transform commands.
We will use Move, SetPt, Rotate, Zoom Target, PointsOn (F10), PointsOff (F11) commands and the object
snaps End, Point, Along, Between and the Tab lock to move the points in various ways to achieve tangency.
First, we will create some aliases that will be used in this exercise.
To make Along and Between aliases
Along and Between are one-time object snaps that are available in the Tools menu under Object snaps. They
can be used only after a command has been started and apply to only one pick. We will create new aliases for
these object snaps.
1
In the Rhino Options dialog on the Aliases page,
click the New button
2
In the Alias column, type a.
In the Command macro column, type _Along.
3
In the Alias column type b.
4
In the Command macro column, type _Between.
5
Close the Rhino Options dialog.
To change the continuity by adjusting control points using Rotate and the Tab direction lock
The Tab direction lock locks the movement of the cursor when the Tab key is pressed. It can be used for moving
objects, dragging, or curve and line creation.
To activate Tab direction lock press and release the Tab when Rhino is asking for a location in space. The cursor
will be constrained to a line between its location in space at the time the Tab key is pressed and the location in
space of the last clicked point.
When the direction is locked, it can be released with another press and release of the Tab, and a new, corrected
direction set with yet another Tab press.
1
Turn on the control points for both curves.
2
Select the control point (1) second from the end
of one of the curves.
3
Start the Rotate command (Transform menu:
Rotate).
4
Using the Point object snap, select the common
endpoints (2) of the two curves for the Center
of rotation.
5
For the First reference point, snap to the
current location of the selected control point.
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6
For the Second reference point, make sure
the point object snap is still active. Hover the
cursor, but do not click, over the second point
(3) on the other curve. While the Point object
snap flag is visible on screen, indicating the
cursor is locked onto the control point, press
and release the Tab key. Do not click with the
mouse.
7
Bring the cursor back over to the other curve-notice that the position is constrained to a line
between the center of rotation and the second
point on the second curve; that is, the location
of the cursor when you hit the Tab key. You can
now click the mouse on the side opposite the
second curve.
CURVE CREATION AND CONTINUITY
During rotation, the Tab direction lock knows
to make the line from the center and not from
the first reference point.
The rotation endpoint will be exactly in line
with the center of rotation and the second
point on the second curve.
To change the continuity by adjusting control points using the Between object snap
1
Use the OneLayerOn command to turn on only
the 3D Curves layer.
2
Check the continuity of the curves with the
GCon command.
3
Turn on the control points for both curves.
4
Window select the common endpoints of both
curves (1).
5
Use the Move command (Transform menu:
Move) to move the points.
6
For the Point to move from snap to the same
point (1).
7
For the Point to move to, type b and press
Enter to use the Between object snap.
8
For the First point, snap to the second
point (2) on one curve.
9
For the Second point, snap to the second
point (3) on the other curve.
The common points are moved in-between the
two second points, aligning the four points.
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10 Check the continuity.
To change the continuity by adjusting control points using the Along object snap
1
Undo the previous operation.
2
Select the second point (3) on the curve on the
right.
3
Use the Move command (Transform menu:
Move) to move the point.
4
For the Point to move from, snap to the
selected point.
5
For the Point to move to, type A and press
Enter to use the Along object snap.
6
For the Start of tracking line, snap to the
second point (2) on the other curve.
7
For the End of tracking line, snap to the
common points (1).
The point tracks along a line that goes through
the two points, aligning the four points.
8
Click to place the point.
9
Check the continuity.
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To edit the curves without losing tangency continuity
With the Tab technique, we can adjust the meeting point of the curves, or the shape of either curve near the
meeting point, without losing the G1 continuity.
1
Window select the common endpoints or select
the second point on either curve.
Turn on the Point object snap and drag the
point(s) to the next one of the four critical
points.
2
When the Point object snap flag shows on the
screen, use the Tab direction lock by pressing
and releasing the Tab key without releasing the
mouse button.
3
Drag the point(s) and the tangency is
maintained since the drag direction is
constrained to the Tab direction lock line.
4
Release the left mouse button at any point to
place the point(s).
Note: To maintain G1 continuity make sure that any point manipulation of the critical four points takes place
along the line on which they all fall.
Once you have G1 continuity you can still edit the curves near their ends without losing continuity, using
the Tab direction lock.
This technique only works after tangency has been established.
Exercise 8—Curvature continuity
Adjusting points to establish curvature continuity is not as straightforward as for tangency. Curvature at the end
of a curve is determined by the position of the last three points on the curve, and their relationships to one
another are not as straightforward as it is for tangency.
To establish curvature or G2 continuity, the Match command is the only practical way in most cases.
To match the curves
1
Use the Match command (Curve menu: Curve
Edit Tools > Match) to match the magenta (1)
curve to the red (2) curve. Set Continuity to
Curvature, Preserve other end to Curvature,
and uncheck Average curves.
When you use Match with Curvature checked
on these particular curves, the third point on
the curve to be changed is constrained to a
position calculated by Rhino to establish the
desired continuity.
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The curve being changed is significantly
altered in shape.
Moving the third point by hand will break the
G2 continuity at the ends, though G1 will be
maintained
Advanced techniques for controlling continuity
There are two additional methods to edit curves while maintaining continuity in Rhino. (1) The EndBulge
command constrains points at the end to maintain continuity with the adjacent curve. (2) Adding knots will allow
more flexibility when changing the curve's shape.
To edit the curve with end bulge
1
Right-click on the Copy button to make a duplicate of the magenta curve and
then Lock it.
2
Start the EndBulge command (Edit menu: Adjust End Bulge).
3
Select the magenta curve.
Notice that there are more points displayed than were on the original curve.
The EndBulge command adds more control points to the curve if the curve
has less than the required control point count.
4
Select the third point, drag it, and click to place
the point, press Enter to end the command.
If the endpoint of the curve has G2 continuity
with another curve, the G2 continuity will be
preserved, because EndBulge preserves the
curvature at the endpoint of the curve.
Note: Adjusting control points will work to match curvature only in the simple case of matching to a straight line.
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To add a knot
Adding a knot or two to the curve will put more points near the end so that the third point can be nearer the end.
Knots are added to curves and surfaces with the InsertKnot command.
1
Undo your previous adjustments.
2
Start the InsertKnot command (Edit menu: Control Points > Insert
Knot).
3
Select the magenta curve.
4
Pick a location on the curve to add a knot in between the first two knot
markers.
In general, a curve or surface will tend to behave better in point editing
if new knots are placed midway between existing knots, thus
maintaining a uniform distribution.
Adding knots also results in added control points.
Knots and control points are not the same thing and the new control points will not be added at exactly the
new knot location.
The Automatic option automatically inserts a new knot in each span
exactly half way between existing knots.
If you only want to place knots in some of the spans, you should place
these individually by clicking on the desired locations along the curve.
Existing knots are highlighted in white.
5
Match the curves after inserting a
knot into the magenta curve.
Inserting knots closer to the end
of curves will change how much
Match changes the curve.
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5 Surface continuity
The continuity characteristics for curves can also be applied to surfaces. Instead of dealing with the endpoint,
second, and third points, entire rows of points at the edge, and the next two positions away from the edge are
involved. The tools for checking continuity between surfaces are different from the simple GCon command.
Analyzing surface continuity
Rhino takes advantage of the OpenGL display capability to create false color displays for checking curvature and
continuity within and between surfaces. These tools are located in the Analyze menu, under Surface. The tool,
which most directly measures G0-G2 continuity between surfaces, is the Zebra command. Zebra analysis
simulates reflection of a striped background on the surface.
Note: An OpenGL graphics accelerator card is not necessary to use these tools, although they may work faster
with OpenGL acceleration.
Matching surface continuity
The command used to establish G0, G1 or G2 continuity between surfaces is the MatchSrf command.
Match surface options
Option
Average surfaces
Description
Both surfaces are modified to an intermediate shape.
Refine match
Determines if the match results should be tested for accuracy and refined so
that the faces match to a specified tolerance.
Match edges by closest
points
The surface being changed is aligned to the edge it is being matched to by
pulling each edge point to the closest point on the other edge.
Preserve other end
If the surface does not have enough points its degree is raised (up to a
maximum of 5), until there are enough points.
Isocurve direction adjustment
Specifies the way the parameterization of the matched surfaces is determined.
Option
Automatic
Description
Evaluates the target edge, then uses Match target isocurve direction if it is
an untrimmed edge or Make perpendicular to target edge if it is a trimmed
edge.
Preserve isocurve direction
As closely as possible, keeps the existing isocurve directions the same as
they were in the surface before matching.
Match target isocurve
direction
Makes the isocurves of the surface that is being adjusted parallel to those of
the surface it matches.
Make perpendicular to
target edge
Makes the isocurves of the surface that is being adjusted perpendicular to
the edge being matched.
Exercise 9—Surface continuity and MatchSrf
The MatchSrf command takes surface edges as input and modifies one or both of the surfaces. You need to tell
the command exactly which edge to change and then which edge to match to the target surface. We will match
the white surface's edge to the green one first. Both the edge to change and the edge to match to are untrimmed
on these surfaces.
While MatchSrf is generally used to adjust surfaces that are fairly close to being at the desired continuity, this
example is somewhat exaggerated in order to clearly show the functionality and options.
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1
Open the model Surface Continuity.3dm.
2
Start the MatchSrf command (Surface menu: Surface Edit Tools >
Match).
3
Select the edge of the white surface on the edge nearest the green
surface.
4
Select the edge of the green surface near the same location as the
selection point on the white surface edge and press Enter.
5
In the Match Surface dialog, choose Position as the desired
Continuity, choose None for Preserve other end, uncheck Refine
match, and choose Automatic for Isocurve direction adjustment.
SURFACE CONTINUITY
Make sure all other check boxes are unchecked.
A shaded preview is automatically generated so you can see what the
result will be like.
6
Click OK.
The edge of the white surface is pulled over to match the edge of the
green one.
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To check the continuity with Zebra analysis
1
Check the surfaces with Zebra analysis tool
(Analyze menu: Surface > Zebra).
This command relies on an approximation of the
surface for its display information.
2
By default, the mesh generated by Zebra may be
too coarse to get a good analysis of the surfaces. If
the display shows very angular stripes rather than
smooth stripes on each surface, click the Adjust
mesh button on the Zebra dialog.
In general, the analysis mesh should be much finer than the normal shade and render mesh meshes.
It is a good habit to set these meshes the first time you use a surface analysis display mode in a model. This
setting is then saved in the file.
3
Use the detailed controls to set mesh parameters.
For this type of mesh, it is often easiest to zero out (disable) the Maximum angle setting and rely entirely on
the Minimum initial grid quads setting. This number can be quite high but may depend upon the geometry
involved.
In this example, a setting here of 5000 to 10000 will generate a very fine and accurate mesh.
4
The analysis can be further improved by joining the surfaces to be tested. Join the two surfaces.
This will force a refinement of the mesh along the joined edge and help the Zebra stripes act more
consistently.
There is no particular correlation between the stripes on one surface and the other except that they touch,
indicating G0 continuity.
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Undo the Join.
To match the surface to tangency
1
Use the MatchSrf command (Surface
menu: Surface Edit Tools > Match)
again with the Tangency option for
Continuity.
When you pick the edge to match
you will get direction arrows that
indicate which surface edge is being
selected. The surface that the
direction arrows are pointing toward
is the surface whose edge is
selected.
2
Check the surfaces with Zebra analysis.
Rotate the view to view along the seam.
The ends of the stripes on each surface meet the ends on the other
cleanly, though at an angle.
This indicates G1 continuity.
To match the surface to curvature
1
Use the MatchSrf command (Surface menu: Surface Edit Tools > Match)
with the Curvature option.
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SURFACE CONTINUITY
Check the surfaces with Zebra analysis.
The stripes now align themselves smoothly across the seam. Each stripe
connects smoothly to the counterpart on the other surface.
This indicates Curvature (G2) continuity.
Note: Doing these operations one after the other may yield different results than going straight to Curvature
without first using Position. This is because each operation changes the surface near the edge, so the
next operation has a different starting surface.
Add knots to control surface matching
As in matching curves, MatchSrf will sometimes distort the surfaces more than is acceptable in order to attain the
desired continuity. We will add knots to surfaces to limit the influence of the MatchSrf operation. The new second
and third rows of points will be closer to the edge of the surface.
Surfaces can also be adjusted with the EndBulge command.
To add a knot to a surface
1
Undo the previous operation.
2
Use the InsertKnot command (Edit menu: Control Points > Insert
Knot) to insert a row of knots near the end of the white surface.
When this command is used on a surface, it has more options. You
can choose to insert a row of knots in the U-direction, the V-direction,
or both. Choose Symmetrical to add knots at opposite ends of a
surface.
3
Use MatchSrf to curvature match the surface to the other.
Notice that the new matched surface is different from the old one.
To adjust the surface using end bulge
The EndBulge command lets you edit the shape of a surface without changing the tangent direction and the
curvature at the edge of the surface. This is useful when you need to alter the shape of a surface that has been
matched to another surface.
EndBulge allows you to move control points at a specified location on the surface. These points are constrained
along a path that keeps the direction and curvature from changing.
The surface can be adjusted equally along the entire selected edge or along a section of the edge. In the latter
case, the adjustment takes place at the specified point and tapers out to zero at either end of the range. Either
the start or endpoint of the range can be coincident with the point to adjust, thus forcing the range to be entirely
to one side of the adjustment point.
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Start the EndBulge command (Edit menu: Adjust End Bulge).
2
For the surface edge to adjust, pick the edge of the surface on the
right.
3
For the Point to edit, pick a point on the edge at which the actual
adjustment will be controlled.
SURFACE CONTINUITY
You can use object snaps and reference geometry to select a point with
precision.
4
For the Start of region to edit, pick
a point along the common edges to
define the region to be adjusted.
5
For the End of region to edit, pick
another point to define the region to
be adjusted.
To select a range at this point, slide
the cursor along the edge and click
at the beginning and endpoints of
the range. If the whole edge is to be
adjusted equally, simply press
Enter.
6
For the Point to adjust, select one of
the points that are displayed.
Rhino shows three points, of which
you are allowed to manipulate only
two. When you move the second
point, Rhino also moves the third
point that is not being directly
manipulated in order to maintain
the continuity. If you move the third
point it won’t change the second
point
7
Drag the point and click to adjust the
surface.
If maintaining the G2 curvature-matching condition at the edge is not needed, use the Continuity=Tangency
option to turn off one of the two points available for editing. Only G1 will be preserved.
8
Press Enter to end the command.
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To match an untrimmed surface to a trimmed surface
1
Start the MatchSrf command
(Surface menu: Surface Edit
Tools > Match).
2
Select the edge of the green
surface on the edge nearest the
blue surface.
The edge will not select and you
will see the following message
on the command-line:
Edge must be on the edge of a surface (not
a trimmed edge). Select untrimmed surface
edge to change ( MultipleMatches ).
3
Instead, select the untrimmed edge of the blue surface on the edge nearest the green surface.
4
Select the trimmed edge of the green surface near the same location as the selection point on the blue surface
edge.
5
In the Match Surface dialog,
choose Curvature as the desired
Continuity, choose None for
Preserve other end, check
Match edges by closest points,
and choose Automatic for
Isocurve direction adjustment.
Make sure all other check boxes
are unchecked.
A preview is automatically
generated so you can see what
the result will be like.
Notice that the blue surface does
not include the entire untrimmed
edge of the green surface. It
only extends as far as the
closest point from the original
surface.
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6
In the Match Surface dialog,
uncheck Match edges by closest
points, and check Refine match.
7
Change the Isocurve direction
adjustment and the Preserve
other end options to see what
happens to the matched surface.
When finished press OK.
SURFACE CONTINUITY
Surfacing commands that pay attention to continuity
Rhino has several commands that can build surfaces using the edges of other surfaces as input curves. They can
build the surfaces with G1 or G2 continuity to those neighboring surfaces. The commands are:
•
•
•
•
•
NetworkSrf
Sweep2
Patch (G1 only)
Loft (G1 only)
BlendSrf (G1 to G4)
The following exercises will provide a quick overview of these commands.
Exercise 10—Continuity commands
To create a surface from a network of curves
1
Open the model Continuity Commands.3dm.
On the Surfaces layer, two joined surfaces have been trimmed leaving
a gap. This gap needs to be closed up with continuity to the surrounding
surfaces.
2
Turn on the Network layer, if it is not already on, and make it current.
Several curves already in place define the required cross sections of the
surface.
3
Use the NetworkSrf command (Surface menu: Curve Network) to close
the hole with an untrimmed surface using the curves and the edges of the
surfaces as input curves.
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For the Select curves in network, select the four edges that border the
opening and the four curves inside the opening and press Enter.
Note that there is a maximum of four edge curves as input. You can also
specify the tolerances or maximum deviation of the surface from the
input curves.
By default, the edge tolerances are the same as the model's Absolute
Tolerance setting. The interior curves' tolerance is set 10 times looser
than that by default.
5
In the Surface From Curve
Network dialog, choose Curvature
continuity for all the edges, and click
OK.
The surface that is created has
curvature continuity on all four
edges.
6
Check the resulting surface with
Zebra analysis.
To make the surface with a two-rail sweep
1
Use the OneLayerOn command to
open the Surfaces layer by itself
again, and then click in the layers
panel of the status bar, and select the
Sweep2 layer.
2
Start the Sweep2 command (Surface
menu: Sweep 2 Rails) and select the
long surface edges as the rails.
3
Select one short edge, the crosssection curves, and the other short
edge as profiles.
4
Choose Curvature for both Rail
curve options.
Since the rails are surface edges,
the display labels the edges, and the
Sweep 2 Rails Options dialog
gives the option of maintaining
continuity at these edges.
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Click OK.
6
Check the resulting untrimmed
surface with Zebra analysis.
SURFACE CONTINUITY
To make a patch surface
The Patch command builds a trimmed surface, if the bounding curves form a closed loop. Patch can match
continuity to G1 if the bounding curves are edges. The Patch command:
•
•
•
•
1
Can use unlimited curves or points for input
Ignores noise of many control points
Is good for scanned data
Is good for reverse engineering
Turn on the Surfaces, and Patch
layers.
Turn all other layers off.
2
Start the Patch command (Surface
menu: Patch).
3
Select the edge curves and the
interior curves, and then press Enter.
4
In the Patch Surface Options
dialog, set the following options:
Set Sample point spacing to 1.0.
Set Stiffness to 1.
Set Surface U and V spans to 10.
Check Adjust tangency and
Automatic trim, and then click OK.
The nominal 3-D distance
between points sampled
from input curves
Rows and columns
The bigger the number, the
"stiffer" and more
rectangular and planar the
resulting surface will be
Takes the structure of a
selected surface
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Join the surfaces.
6
Use the ShowEdges command (Analyze menu:
Edge tools > Show Edges) to display naked edges.
SURFACE CONTINUITY
If there are naked edges between the new patch
surface and the existing polysurface the settings
may need to be refined.
7
Check the results with Zebra analysis.
Exercise 11—Patch options
To make a patch from an edge and points
Patch can use point objects as well as curves and surface edges as input. This exercise will use point and edge
inputs to demonstrate how the Stiffness setting works.
1
Open the model Patch Options.3dm.
2
Start the Patch command (Surface menu: Patch) and select the two point
objects and the top edge of the surface as input.
3
Check Adjust tangency and Automatic trim, set the Surface spans to
10 in each direction.
4
To get a good view of the two point objects, make the Front viewport the
active viewport and set it to a wireframe or ghosted view.
5
Set the Stiffness to 0.1 and click the Preview button.
With lower setting for stiffness, the surface fits through the points while maintaining tangency at the surface
edge. This can show abrupt changes or wrinkles in the surface.
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Set the Stiffness to 5 and click the
Preview button again.
With higher stiffness settings, the
patch surface is made stiffer and it
may not pass through the input
geometry. On the other hand, the
surface is less apt to show abrupt
changes or wrinkles, often making a
smoother and better surface.
With very high stiffness numbers,
the edges also may have a tendency
to pull away from the intended input
edges.
High stiffness number = the more
rectangular and planar the resulting
surface will be
Low stiffness number = the
smoother (fairer) the resulting
surface will be
More spans = greater density of
control points
Exercise 12—Lofting
To make a lofted surface
The Loft command also has built in options for surface continuity.
1
Open the model Loft.3dm.
2
Start the Loft command (Surface
menu: Loft).
3
Select the lower edge curve, the
curve, then the upper edge curved,
and press Enter.
When picking the curves, pick near
the same end of each curve. This
will insure that you do not get a
twist in the surface.
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In the Loft Options dialog, make
sure the Style is set to Normal, and
check the boxes for Match start
tangent and Match end tangent
are both checked. Press Enter when
done.
The new surface has G1 continuity
to the original surfaces.
5
SURFACE CONTINUITY
Style:
Loose—similar to control point
curve
Straight—similar to polyline
Normal/Tight—similar to
interpolated curve
Check the results with Zebra analysis.
Exercise 13—Blends
The next command that pays attention to continuity with adjoining surfaces is
BlendSrf.
The three blends in this file will serve to illustrate the basic features of the
BlendSrf command. The controls inside BlendSrf can be used to vary the
character of the blended shape.
To make a surface blend (BlendSrf 1)
In BlendSrf 1, we will create the transition between the trunk lid and side surfaces of the car body.
1
Open the model Blend.3dm.
2
Start the BlendSrf command (Surface menu: Blend Surface).
3
For the Select segment for first edge, select an edge along the red
polysurface of the car body as marked in the file.
Notice that only one surface edge segment is selected initially, but we
want to blend the full length of the gap between the white side surface
and the red surfaces.
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You can select the next edge segment by clicking on it, or by clicking on
Next at the command-line.
The edge from the adjacent surface is selected.
5
Press Enter to finish the selection for the first edge.
6
For the Select segment for second edge, select the top edge of the
white side surface at the end of the edge nearest your initial pick for the
first edge. Press Enter to finish edge selection.
The Adjust Surface Blend dialog with several controls appears.
Adjust Surface Blend dialog
The sliders refer to the two default shape curves at the ends of the
blend. Clicking the lock icon will force both sides of the blend to be
adjusted at the same time.
A button allows the user to add shape curves. These new shape
curves have adjustable handles on them exactly like the default
shape curves.
Note that while it is sometimes useful to add shape curves, you
should try to add as few as possible to achieve the shape you want.
Interpolation among the shape curves is better if they are not too
close together.
The radio buttons are for setting the continuity at each side of the
blend; the edges are labeled 1 and 2 in the viewport.
There are check boxes for further options. These options will be
discussed later in a separate exercise.
7
Uncheck the boxes for Same height and Planar sections. Make sure the continuity radio buttons are set to
Curvature.
There is a check box to show a preview of the blend surface.
In the viewport, you will notice a default pair of shape curves with
points. These points are called handles.
The number of handles available on the shape curves varies according to
the settings in the dialog.
For example, if the continuity is set to Curvature (bold) for both shape
curves 1 and 2, the curves will have six points (three for each curve).
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Try adjusting the handles on the shape curves. For example, at the rear
of the car, make the blend sharper by moving the handles out so that
they are crowded near the apex of the shape curve.
The handles can be adjusted interactively on each shape curve to
change the shape of the blend.
Moving the handles changes the shape on one side of one shape curve.
Pressing Shift while moving the handles forces both ends of the shape
curve to be adjusted together. This is useful in maintaining symmetry on
the blend shape.
Pressing Alt while adjusting handles rotates the handles and thus the
direction of the shape curve relative to the edge.
Moving the handle at an end of a shape curve changes the location of
the shape curve.
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Using the sliders in the dialog
changes all shape curves
together.
The top slider modifies all the
shape curves near the original
edge #1, and the lower slider
modifies all the shape curves
near the original edge #2.
9
Adjust the settings in the dialog
to the default value of 1.0, and
then press OK to make the
blend surface.
To make a surface blend (BlendSrf 2)
Next, we will blend between the roof rail and the side window.
1
Start the BlendSrf command (Surface menu: Blend Surface).
2
For the Select segment for first edge, select an edge along the rear
window of the car as marked in the file.
Notice that only a small part of the edge is selected. Although the
window is a single surface, the edges are split up into small pieces,
making it inconvenient to select all of them.
3
Use the All option on the command-line to force chaining the edge
fragments together.
Notice that the edge of the roof panel is also added, since the edges are
contiguous and tangent to one another.
Press Enter to finish the first edge selection.
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For the Select segment for second
edge, select the edge at the top of
the side window.
Notice the default shape curve
shows an S-shape at the lower end
of the blend area.
5
Press the Alt key while dragging the
handles to align the blend curve in a
more natural way.
To clean up the excess surfaces
To clean up the excess surfaces, we will trim the surfaces to each other. Since the intersections of the surfaces do
not go all the way to the edges of all of the surfaces, we can make intersection curves, join them, and then extend
them as needed on the surfaces.
1
Start the IntersectTwoSets command (Curve menu: Curve from
Objects > Intersection of Two Sets).
2
As the first set of objects to intersect, select the side window and the
roof blend surface you just completed. Press Enter.
3
As the second set of objects to intersect with the first set, select the
first blend surface you made. Press Enter.
4
Join the resulting curves.
5
Select the joined curve.
6
Start ExtendCrvOnSrf (Curve menu: Extend Curve > Curve on Surface)
and choose the lower blend surface as the surface to extend on.
7
Trim the bottom of the side window, the lower end of the roof rail blend,
and the side blend inside the roof and glass area.
To make a surface blend (BlendSrf 3)
Lastly, we will blend between the wheel arch and the side of the car.
1
Start the BlendSrf command
(Surface menu: Blend Surface).
2
For the Segment for first edge,
select an edge of the wheel arch
on the side of the car and Press
Enter.
3
For the Segment for second
edge, select the other edge of
the wheel arch.
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Change the continuity settings in
the dialog so that one edge has
Position continuity (G0) and the
other has Curvature continuity
(G2), and check the Preview
checkbox.
This will allow you to have a
hard edge at one of the edges.
5
Switch the continuity settings to
the opposite edges to change the
character of the blend.
You will probably have to rotate
the shape curves at both sides
of the wheel arch so that they
align with the bottom edge of
the side.
In this case, it is easier to do
this in the Front viewport.
6
Press the Alt key while dragging the
handles to align the blend curve to
the bottom edge of the side.
7
Press OK in the dialog to make the blend surface.
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Exercise 14—Blend options
To make a surface blend
In the following exercise, we will first make a surface blend that creates a self-intersecting surface. Then we will
use the surface blend options to correct the problem.
1
Open the model BlendSrf Options.3dm.
2
Start the BlendSrf command (Surface menu:
Blend Surface) and select the deeply curved edges
of the pair of surfaces marked 0.
3
In the dialog, make sure Same height
is not checked, and the bulge sliders
are set to 1.0, and then click OK.
4
Zoom in on the surface you just
created in the Top viewport.
Look closely at the middle of the
blend surface in this view using a
wireframe viewport. Notice the blend
has forced the surface to be selfintersecting in the middle. The
isocurves cross each other and make
a pinch or crease here.
Surface blend options
To avoid self-intersecting or pinched surfaces when creating a blend you can Adjust Blend Bulge sliders, use
Same height shapes, or use the Planar sections option.
In the following examples, we will look at each of these options.
To make a surface blend with options
1
Start the BlendSrf command and select the
edges of the pair of surfaces marked 1.
Adjust the sliders to make the bulge of the
surface less than 1. A number between 0.2
and 0.3 seems to work best.
The profiles of the cross sections at each end
of the blend as well as any you may add
between will update to preview the bulge.
Notice that the surface is not pinched in the
middle.
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Start the BlendSrf command and select the
edges of the pair of surfaces marked 2.
Change the Bulge to 0.5, but check Same
height shapes.
The Same height shapes option overrides
the tendency of the blend surface to get fatter
or deeper according to how far apart the
edges are. The height will be the same in the
center as it is at each end. This also has the
effect of making the sections of the blend
push out less and therefore not cross each
other out in the middle area.
3
Start the BlendSrf command and select the
edges of the pair of surfaces marked 3.
4
Pick the edges in the usual way.
Use the same bulge settings as the last pair of
surfaces.
5
Check Planar sections in the dialog and
uncheck Same height.
You are now asked to define which plane the
sections of the surface should be parallel to.
This is defined by clicking two points in any
viewport.
6
Click once anywhere in the Top viewport A then with Ortho on, click again in the
Top viewport B in the direction of the y-axis.
The resulting surface has its isocurves arranged parallel to the plane defined in
the Planar sections portion of the command. The isocurves do not intersect in
the middle of the surface since they are parallel the y-axis.
Fillets, blends and corners
In this exercise, we will discuss a variety of ways to fill holes and make transitions using the NetworkSrf, Loft,
Sweep1, Sweep2, Blend, Fillet and Patch commands.
While Rhino has automated functions for making fillets, several situations take manual techniques. In this section,
we will discuss making corners with different fillet radii, variable radius fillets and blends, and fillet transitions.
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Exercise 15—Variable radius fillets
To make a corner fillet with three different radii:
1
Open the model Corner Fillet.3dm.
2
Use the FilletEdge command (Solid
menu: Fillet Edge > Fillet Edge) to
fillet edge (1) with a radius of 5mm.
3
Use the FilletEdge command (Solid
menu: Fillet Edge > Fillet Edge) to
fillet edge (2) with a radius of 2mm,
and edge (3) with a radius of 3mm,
and the edge created by the previous
fillet with a radius of 2.5mm.
Note: Change the value for
CurrentRadius before selecting
the next edge.
4
Use the AddHandle option to add a
2.0 radius handle at the end of edge
2, and a 3.0 radius handle at the end
of edge 3.
5
Preview the results, and then press
Enter to make the fillet.
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SURFACE CONTINUITY
Exercise 16—Variable radius blends and chamfers
To make a variable radius blend
1
Open the model Sandal Sole.3dm.
2
Use the BlendEdge command (Solid menu: Fillet Edge > Blend Edge) to
make a variable radius blend on the bottom of the sole. Start with a
radius of 3mm.
3
Use the AddHandle option to add additional radii around the bottom of
the sole.
Add another 3mm radius to the front of the sole and then add a 7mm
radius to the instep on both sides.
4
Preview the blend and adjust the
handles as needed, and then press
Enter to make the blend.
To make an edge chamfer
1
Use the ChamferEdge command
(Solid menu: Fillet Edge > Chamfer
Edge) to make a 2mm chamfer
around the top edge of the sole.
This command, like the FilletEdge
command and the BlendEdge
command, allow for the addition of
handles with different values to
create a variable distance chamfer.
2
Preview the chamfer and make
adjustments as needed, then press
Enter to make the chamfer.
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Exercise 17—Fillet with patch
To make a six-way fillet using a patch
1
Open the model Fillet Edge.3dm.
2
Use the FilletEdge command (Solid menu: Fillet
Edge > Fillet Edge), with Radius=1, to fillet all
the joined edges at the same time.
3
Use the Patch command (Surface menu: Patch) to fill in the opening at the
center.
4
Select all six edges to define the patch.
5
In the Patch Options dialog, check Adjust Tangency and Automatic Trim.
Change the Surface U and V Spans to 10, and the Stiffness to 2.
Note: When the area to fill has more than four edges, the Patch command works better than the NetworkSrf
command.
Exercise 18—Soft corners
There are several ways to approach making a soft box shape like the illustration below.
In this exercise, we explore two different methods to make the
surfaces using the same underlying curves. Our design curves in this
example are all tangent arcs.
The first method will use the curves directly. For second method, we
will plan ahead and try to take into account the simple underlying
shapes suggested by the design curves.
The two approaches are different, but one is not inherently better or
contradictory to the other.
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SURFACE CONTINUITY
To make a rectangular shape with a curved top and soft corners (Part 1)
1
Open the model Soft Corners.3dm.
2
Use the Join command (Edit menu:
Join) to join the arcs that form the
base rectangular shape.
3
Change to the 03 Sweeps layer.
4
Use the Sweep1 command (Surface
menu: Sweep 1 Rail) to make the first
surface.
5
In the Sweep 1 Rail Options dialog,
check Closed sweep, then click OK.
6
Repeat the Sweep1 command to
make the second surface.
7
Pick the top edge of the surface you
just created, then select the crosssections in order, and press Enter.
8
In the Sweep 1 Rail Options dialog,
change the Style to Align with
surface, and then click OK.
This will insure tangent continuity
with the first surface.
9
Use the Patch command (Surface
menu: Patch) to fill in the opening at
the center.
10 Select the surfaces you made.
11 Start the EMap command (Analyze menu: Surface > Environment map).
Click Adjust mesh and refine the mesh in a similar way that you did for
the Zebra surface analysis command. Choose the Arches.png or Space
Needle.png from the drop-down list in the EMap Options dialog.
12 Tumble the view around.
Note the top surface has a pronounced X-shape in the pseudoreflections. The surface is not a clean interpretation of the original input
curves- there is this extra distortion across the top surface. So, even
though we have hit all the input curves, our surfaces are not necessarily
very nice.
To make a rectangular shape with a curved top and soft corners (Part 2)
This time, we will look at the input curves and make some judgments about the best way to construct the
surfaces.
One thing to keep in mind is that it is more important to make our primary surfaces have good curvature
characteristics, and less important for transitional surfaces.
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Primary surfaces will be the ones that define the overall shape. They tend to have relatively even curvature, and
less curvature than the transitions. Transition surfaces, as the term implies, provide transitions between the
primary shape surfaces. These surfaces tend to have higher curvature than the primary surfaces. Fillets and
blends, for example, are generally added as transition surfaces.
In this example, we have the four side surfaces and the top surface as primary surfaces. We will add the corners
afterwards as fillets. Since in our example the input curves are entirely made up of tangent arcs, we can define
the side and top surfaces as revolved surfaces. This type of surface is very exact and simple.
1
Change to the 02 Separate Curves
layer and turn all the other layers off.
2
Hide the fillet curve at each corner,
and the green cross-section curves.
3
Lock the red curves.
4
Use the Extend command (Curve
menu: Extend Curve) with an
ExtensionLength=10 to extend both
ends of the cyan curves and the top of
each black arc, press Enter to complete
the command.
Each arc is extended at each end using the existing arc radius.
The goal is to extend the arcs enough that they will intersect one another as in the illustration. The exact
amount is not critical.
5
Change to the 04 Surfaces layer.
6
Use the Revolve command (Surface
menu: Revolve) to make surfaces
from two adjacent extended vertical
curves.
7
Snap to the center of the base curve
to place the Start of revolve axis.
8
Press Enter to use CPlane z-axis
direction for the End of revolve
axis.
If you are in a Perspective viewport, this option will automatically set the axis vertical and save the trouble of
locating the second point.
1
Pick the Start angle as shown in the
image that is somewhere outside the
span of the desired final surface.
Make sure Ortho is not on at this
stage.
The goal is to make a surface that is
larger than will eventually be
needed to make the box, so the
exact starting and ending points are
not critical.
2
Pick another point for Revolution angle to create the vertical surface.
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3
Create an adjacent vertical surface in
the same way.
4
Use the MX and MY aliases you made on the first day to Mirror each of
the surfaces around the origin.
SURFACE CONTINUITY
To make the top surface
In this example, we will make the top surface by revolving one of the top curves around the center of the other
top curve. Since we will be working in the perspective view, it will be necessary to change the construction plane
for that viewport.
1
Use the Revolve command (Surface
menu: Revolve) to make the top
surface from the longer top arc.
2
Snap to the center of the shorter top
arc in the Right viewport to place the
Start of revolve axis.
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3
Press Enter to use CPlane z-axis
direction for the End of revolve
axis.
4
Pick the Start angle as shown.
5
Pick another point for Revolution
angle to create the top surface.
6
Use the CutPlane command (Surface
menu: Plane > Cutting Plane) to
make a cutting plane at the origin in
the z-axis.
SURFACE CONTINUITY
To make the surfaces into a solid
1
Use the CreateSolid command (Solid
menu: Create Solid) to join and trim
the surfaces into a closed solid.
2 Use the FilletEdge command (Solid
menu: Fillet Edge > Fillet Edge) to
fillet the edges. Set the
CurrentRadius to 15, select the four
vertical edges, and press Enter to
make the fillets.
3
Repeat the FilletEdge command to
fillet the top edges. Set the
CurrentRadius to 10, select the
eight top edges, and press Enter to
make the fillets.
The resulting surface is very clean
and smooth with no hard edges.
Note: You may notice a defect in a shaded viewport at one or more of the
corners. This is a render mesh related defect. There is nothing wrong
with the geometry.
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To fix the mesh
1
Use the Options command to change the mesh
settings.
2
On the Mesh page, change to a Custom mesh.
Use the settings on the right.
The visual defect goes away.
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6 Modeling with history
History allows editing or updating objects by editing the input geometry
that was used to create the objects. History is useful when there is a need
to edit the input of a command or when transformed copies of an object
need to stay matched to the original. Only certain commands support
history.
A list of commands in Rhino that support history is on page 82.
History is not the same as a “feature” or “parametric.” History information is saved in the Rhino *.3dm file.
A simple example would be the following:
Draw a circle.
Turn on Record History
and Array the circle.
Scale the original.
Watch the arrayed circles
update.
Exercise 19—History introduction
To make a lofted surface
1
Open the model
History_Intro.3dm.
2
Select the four cyan colored curves.
3
Start the Loft command (Surface
menu: Loft), select Normal style,
and click OK.
Loft the curves to generate a
smooth surface.
4
Turn on the control points and edit the surface.
Turning on surface control points allows the surface to be edited directly as always. However editing the
input curves does nothing to change the surface.
5
Undo or delete the loft.
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Activating history
History recording is off by default. It must be turned on before running a command to record history for that
command. The status of history recording is indicated on the Record History pane on the status bar. If the text
in this pane is bold, recording is active. Click the pane to change the status.
To record history for a particular command, click the Record History pane, and then start a command that pays
attention to history.
Why is history off by default?
• Unpredictable results. For example, if you Copy with history and make a change, all of the children start to
update.
• File size is larger with history enabled.
To make a lofted surface with history
1
Click in the Record History pane in
the status bar to make it bold and
active.
2
Select the four cyan colored curves.
3
Start the Loft command (Surface
menu: Loft), select Normal style,
click OK.
Notice the Record History pane is
no longer bold once a command has
run.
4
Select one of the input curves and
move it.
The loft surface updates to reflect
this new position.
5
Turn on control points of the input
curves.
6
Edit the points and the surface will
update.
7
Select the curves and Rebuild (Edit
menu: Rebuild) them to 10 points.
The lofted surface updates to reflect
this change as well. Changing
degree of the parent curves will also
change the degree of the child
surface in that direction.
8
Undo the three previous steps.
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Steps in the History chain
• The command must support History. A list of commands that support History is on the next page.
• History recording must be active when the command is actually run. By default, History recording is turned off
and must be activated each time a command is run for which the user wants to record history.
• History updating must be on. This is on by default. When it is on, edits to input objects are immediately
reflected in the updated output.
• History can be nested; for example, a curve can be projected onto a lofted surface, and the curve will follow
the changes to the lofted surface.
To project a curve onto a surface with history
This part of the exercise will demonstrate an example of nested history. We will be projecting the wheel cutout
curves onto the lofted surface.
1
First, we will change the CPlane for
the Perspective viewport. On the
CPlanes toolbar tab, click Set
CPlane World Right
.
2
Click in the Record History pane in
the status bar to make it active.
3
Use the Project command (Curve
menu: Curve from Object > Project)
to project the two wheel cutout
curves onto the lofted surface.
4
Set the CPlane back to World Top (CPlanes toolbar tab, Set CPlane
World Top).
5
Select one of the input curves for the loft. Modify it by:
•
Moving or scaling
•
Control point editing
Hint: Gumball can be helpful here.
The projected wheel cutout curves update to follow the surface.
Note: Any editing of the outputs will 'break' History and the connection between inputs and outputs will be lost.
Rhino will put up a warning box when this happens and the user can either Undo to restore the
connection, or continue editing and accept the break in History.
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History enabled commands
Transforms
Surfacing
Solid
Curve from object
Annotation
Point
Array
ArrayCrv
ArrayCrvOnSrf
ArrayPolar
ArraySrf
Bend (Copy option)
Copy
Orient (Copy option)
OrientCrvToEdge (Copy option)
OrientOnCrv (Copy option)
OrientOnSrf (Copy option)
Rotate (Copy option)
Scale (Copy option)
Mirror (Copy option)
Flow
FlowAlongSrf
ProjectToCPlane
RemapCPlane (Copy option)
Rotate (Copy option)
Rotate3D (Copy option)
Scale (Copy option)
Scale1D (Copy option)
Scale2D (Copy option)
ScaleByPlane (Copy option)
ScaleNU (Copy option)
SetPt
Shear
Stretch
Symmetry
Taper (Copy option)
Twist
EdgeSrf
ExtrudeCrv
ExtrudeCrvAlongCrv
ExtrudeCrvTapered
ExtrudeCrvToPoint
ExtrudeSrfToPoint
ExtrudeSrfAlongCrv
ExtrudeSrfTapered
Loft
NetworkSrf
OffsetSrf
Patch
PlanarSrf
RailRevolve
Revolve (Copy option)
Ribbon
Sweep1
Sweep2
TweenSurfaces
Pipe
Slab
ExtrudeSrf
ArcBlend
Blend
Crv2View
CSec
CrvThroughPolyline
CrvThroughPt
Helix (AroundCurve option)
Intersect
Offset
Project
Pull
Spiral (AroundCurve option)
TweenCurves
Dim
DimAligned
DimAngle
DimArea
DimCurveLength
DimDiameter
DimOrdinate
DimRadius
DimRotated
Hatch
Divide
History-related commands
History
HistoryPurge
SelObjectsWithHistory
SelChildren
History toolbar
SelParents
History Options
Inputs to a History-enabled command are called Parents in Rhino and the outputs are called Children.
Right-click the Record History pane to change the following options:
Always Record History
This option changes the default behavior so any eligible command will always record history. Use this option
with caution. In addition to unnecessarily increasing the file size, it can lead to unexpected behavior. To clear
history on particular objects or on all objects, use the HistoryPurge command.
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Update Children
Causes child objects to update each time the parent object changes. This increases the time it takes to update
complex objects. For very complex edits on the parent objects, turn off updating, make the changes, and then
turn Update Children on so that the update happens only once.
Lock Children
This option sets child objects to a locked state. Since directly editing the child objects breaks the connection to
the parent objects, locking the child objects prevents accidental editing. In addition, selecting child objects can
be cumbersome if they are in the same location as the parent objects. Locked child objects still update when
the parent objects are edited.
History Break Warning
This option displays a warning if an operation breaks the connection of a child object to its parent objects. The
Undo command will restore history.
Use the History command to control history recording, updating, locking, and warnings.
To change history options
1
Click on a curve to get the multi-select box.
If you edit the surface in any way, History for the object will break and
Rhino will warn you about this.
2
Select the surface and drag it. Rhino will warn you that dragging broke
history. Click OK.
Make sure to Undo after getting a “broken History” warning to restore
the connection between inputs and output.
3
Right-click in the Record History pane and check Lock Children.
This will make it impossible to edit a child in any way that will break
history, but you can select it to change its object properties or layer,
etc.
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7 Advanced surfacing techniques
There are an infinite number of complex and tricky surfacing problems. In this chapter, we will look at several
'tricks' that help in getting certain types of surfaces built cleanly. The goal, apart from showing you a few specific
techniques used in these examples, is to suggest ways in which the Rhino tools can be combined creatively to help
solve surfacing problems.
In this chapter, you will learn to make soft domed button shapes, creased surfaces, and how to use curve-fairing
techniques.
Dome-shaped buttons
The surfacing goal in this exercise is to create a dome on a shape like a cell
phone button where the top must conform to the general contour of the
surrounding surface but maintain its own shape as well. There are a number of
ways to approach this; we will look at three methods.
Exercise 20—Soft domed buttons
1
Open the model Button Domes.3dm.
The key to this exercise is defining a custom construction plane that represents the closest plane through the
area of the surface that you want to match. Once you get the construction plane established, there is a
variety of approaches available for building the surface.
There are several ways to define a construction plane. In this exercise, we will discuss four methods:
construction plane through three points, construction plane perpendicular to a curve, construction plane
tangent to a surface, and fitting a plane to an object.
2
Use OneLayerOn to turn on the Surfaces to Match layer to see the surface that determines the cut of the
button.
To create a custom construction plane using three points method
1
Start the CPlane command with the
3Point option (View menu: Set
CPlane > 3 Points).
2
In the Perspective viewport, using
the Near object snap, pick three
points on the edge of the trimmed
hole.
The construction plane now goes
through the three points. Notice the
construction plane origin is at the
first point.
3
Rotate the Perspective viewport to see the grid aligned with the trimmed hole.
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To create a custom construction plane perpendicular to a curve
With a line normal to a surface and a construction plane perpendicular to that normal line, you can define a
tangent construction plane at any given point on the surface
1
Start the CPlane command with the
Previous option (Viewport title rightclick menu: Set CPlane > Undo
CPlane Change).
2
Use the Line command with the
Normal option (Curve menu: Line >
Normal to Surface) to draw a line
normal to the underlying surface at a
point near the center of the trimmed
hole.
Set the command-line option for IgnoreTrims=Yes
trimmed hole in the surface.
3
Start the CPlane command with the
Curve option (View menu: Set
CPlane > Perpendicular to Curve).
4
Pick the normal.
5
Use the End object snap and pick the
end of the normal where it intersects
the surface.
so that the line can be drawn from a point inside the
The construction plane is set
perpendicular to the normal line.
To create a custom construction plane to a surface
This function sets the construction plane to match a surface. The placement is constrained so that the construction
plane is tangent to the surface at any given point on the surface. This works like the previous method without the
need to make the normal line.
1
Start the CPlane command with the
Previous option (Viewport title rightclick menu: Set CPlane > Undo
CPlane Change).
2
Delete the Normal line.
3
Start the CPlane command (View
menu: Set CPlane > Origin) with the
Surface option.
4
Pick the surface.
5
For the CPlane origin, change the
IgnoreTrims option to Yes, then
pick a point near the center of the
hole.
6
For the X axis direction, pick a point
in the direction of the long dimension
of the trim curve.
The construction plane is set
tangent to the surface at the origin.
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To create a construction plane fit through points
Using the PlaneThroughPt command to create a surface through a sample of extracted point objects will
generate a plane that best fits the points. The CPlane command with the Object option places a construction
plane with its origin on the center of the plane. This is a good choice in the case of the button in this file. There
are several curves from which the points can be extracted—the edge of the button itself, or from the trimmed hole
in the surrounding surface.
1
Start the CPlane command with the Previous option (Viewport title
right-click menu: Set CPlane > Undo CPlane Change).
2
Turn on the Surfaces and the Curves layer. Make the Curves layer the
current layer.
3
Start the DupEdge command (Curve menu > Curve from objects >
Duplicate edge) to duplicate the top edge of the button surface, press
Enter.
4
Copy the duplicated curve vertically
twice.
The vertical position of these curves
will determine the shape of the
button.
5
Use the Divide command (Curve
menu: Point Object > Divide curve by
> Number of segments) to mark off
the top copied curve with 50 points.
Set the command-line options to
Split=No and GroupOutput=Yes
6
Use SelLast to select the points just
created.
7
Use the PlaneThroughPt command
(Surface menu: Plane > Through
Points) with the selected points.
8
Press the Delete key to delete the
point objects that are still selected.
A rectangular plane is fit through
the selected points.
9
Use the CPlane command with the Object option (View menu: Set CPlane > To Object) to align the
construction plane with the plane.
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10 From the View menu, select Set CPlane, click Named CPlanes, then
click the SaveAs icon to save and name the custom construction plane
Button Top.
This will allow you to restore this custom construction plane at any
time.
11 Delete the surface you used to create the Button Top construction
plane.
To loft the button
1
Set the Surfaces layer as the current layer.
2
Use Loft to make the button.
3
Select the top edge of the surface and the two copied curves.
4
After selecting the curves, click Point on the command-line.
5
For the Loft endpoint, make sure the view that has the custom
construction plane is the current view, then type 0 (zero) and press
Enter.
The loft will end at a point in the middle of the plane, which is the origin
of the construction plane.
6
In the Loft Options dialog, under
Style, choose Loose, press OK.
With the Loose option, the
control points of the input curves
become the control points of the
resulting surface, as opposed to
the Normal option, in which the
lofted surface is interpolated
through the curves.
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7
Turn on control points on the lofted surface.
8
Select the next ring of points out from the
center.
ADVANCED SURFACING TECHNIQUES
Select one point and use SelV or SelU to
select the whole ring of points.
9
Use the SetPt command (Transform menu: Set
XYZ Coordinates) to set the points to the same
Z-elevation as the point in the center. Set the
radio button in the dialog to Align to CPlane.
Remember, this elevation is relative to the
current construction plane.
Note: You can use History when creating the loft, in which case the SetPt operation should be applied to the
topmost curve in the loft, not to the loft surface control points.
To use a patch surface to make the button
1
Use the DupEdge command to duplicate the top edge of the surface.
2
Move the duplicated curve in the World Z-direction a small amount.
3
Use Divide to mark off this curve with 50 points as before.
4
Use the PlaneThroughPt command with the selected points, and then
delete the points like the previous exercise.
5
Use the CPlane command with the Object option to set the construction
plane to the planar surface.
6
Make a circle or ellipse centered on the origin of the custom construction
plane.
7
Use the Patch command, selecting
the top edge of the button and the
ellipse or circle.
The surface is tangent to the edge
and concave on the top.
The size and vertical position of the
circle/ellipse will affect the shape of
the surface.
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Note: If you recorded History for the patch, you can select the ellipse and move it up and down or scale it in
two dimensions to modify the patch shape.
The Gumball control is perfect for making these adjustments. Make sure the Gumball alignment is set to
CPlane.
To use a rail revolve surface to make the button
1
Use the DupEdge command to duplicate the top edge of the surface.
2
Move the duplicated curve in the World Z-direction a small amount.
3
Set a CPlane to this curve using Divide and PlaneThroughPt as before.
4
Use Line with the Vertical option to
make a line of any convenient length
from the origin of the construction
plane down towards the button
surface.
5
Use the Extend command (Curve
menu: Extend Curve > By Line) to
extend the edge at the seam through
the rectangular surface.
6
Use the Intersect command (Curve
menu: Curve From Objects >
Intersection) to find the intersection
between the extended line and the
rectangular surface.
7
Use the Curve command to draw a
curve from the end of the normal
line, using the intersection point as
the middle control point, to the end
of the seam to use as a profile curve.
8
Start the RailRevolve command
(Surface menu: Rail Revolve). Set
the ScaleHeight option to Yes.
9
Select the curve you just created (1)
as the profile curve, the top edge of
the surface (2) as the path curve.
Select the upper end of the vertical
line (3) as one end of the revolve
axis and the lower end as the other
end of the revolve axis.
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10 RailRevolve does not pay attention
to continuity during the surface
creation so you will need to match
the new surface to the vertical sides
of the button for tangency or
curvature with the MatchSrf
command.
Creased surfaces
Often a surface needs to be built with a crease that may start at
a particular angle and change to another angle or diminish to
zero. The crease in the car body in the image is an example of
this. The following exercise covers two possible situations.
Exercise 21—Surfaces with a crease
The key to the following exercise is to get two surfaces that match with different continuity at each end. At one
end, we will match the surface with a 10-degree angle, and at the other end, we will match the surface with
tangency continuity. To accomplish this we will create a dummy surface at the correct angles and use this to
match the lower edge of the upper surface. When the dummy surface is deleted or hidden, the crease appears
between the two surfaces we want to keep.
1
Open the model Crease 01.3dm.
2
Turn on the Curve and Loft layers.
3
Make the Loft layer current.
4
Use the Loft command to make a surface from the three curves.
The Loft command remembers the settings across sessions. Make sure
the Loft style is set to Normal and Do not simplify.
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We are going to make a surface that
includes all the curves but has a crease
along the middle curve.
Use the middle curve to Split the
resulting surface into two pieces.
6
Use the ShrinkTrimmedSrf command
(Surface menu: Surface Edit Tools >
Shrink Trimmed Surface) on both
surfaces.
With a surface that results from a split
at an isocurve, shrinking it will allow the
edge to be an untrimmed edge because
the trim corresponds to the natural
untrimmed surface edge.
By trimming with a curve used in the
loft, the curve is in effect an isocurve.
You can also use the Isocurve option in
the Split command when the object to
be split is a single surface.
7
Hide the lower surface and turn off the Curve layer.
To create the dummy surface
We will change the top surface by matching it to a new dummy surface.
The dummy surface will be made from one or more line segments along the bottom edge of the top surface that
are set at varying angles to it.
To get a line that is not tangent but is at a given angle from tangent, the easiest method is to use the transform
tools to place the line tangent and then to rotate it by the desired increment.
1
Change to the Dummy Curve layer.
2
In the Top viewport, draw a line 20 units long.
3
Start the OrientCrvToEdge command
(Transform menu: Orient > Curve To
Edge).
4
For the Curve to orient, select the line.
5
For the Target surface edge, select the
lower edge of the surface.
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6
For the Pick target edge point, change the command-line option to Copy=Yes, and snap to an endpoint of
the edge.
7
For the Pick target edge point, snap to the other endpoint.
8
Press Enter.
The result should look like the images above.
9
In the Perspective viewport, use the
Viewport title right-click menu and
select Set CPlane > Perpendicular to
curve to set a construction plane
perpendicular to the lower edge of the
surface, snapping to the left end point of
the lower edge for the construction plane
origin.
Set up the rail line
1
Select the line segment at the left end and start the Rotate command. Set
the center of rotation at the origin of the new custom construction plane.
Rotate the segment 10 degrees.
The result should be like the image on the right.
2
Make the Dummy Surface layer current.
3
Use the Sweep1 command (Surface menu: Sweep 1 Rail) to create the
dummy surface.
4
Select the lower edge of the upper surface (1) as the rail and the two line
segments (2 & 3) as cross-section curves.
Make sure to use the surface edge and not the original input curve as the
rail for the sweep.
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In the Sweep 1 Rail Options
dialog, under Style, choose Align
with surface.
This option causes the sweep
surface to derive from the cross
section curves its angle relative to
the base surface at its edge. A
shape curve tangent to the base
surface will hold that tangency as
it sweeps along the edge, unless
another shape curve with a
different angle to the surface is
encountered, in which case there
will be a smooth transition from
one to the next
To match the surface to the dummy surface
1
Use the MatchSrf command to match the upper surface to the dummy
surface.
2
Select the lower edge of the upper surface.
3
Select the upper edge of the dummy
surface.
4
In the Match Surface dialog, choose
Tangency and check Match edges
by closest points.
This will keep distortion to a
minimum.
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Show the lower surface and hide the dummy surface.
6
Join the lower surface with the upper surface.
ADVANCED SURFACING TECHNIQUES
Because the surfaces are untrimmed, you have the option to merge the
surfaces back into one surface.
The crease fades smoothly from one end to the other of the polysurface. If
more control is needed over the angles of the crease, more segments can
be placed to create the dummy surface.
Exercise 22—Surfaces with a crease (Part 2)
In this exercise, there is no convenient relationship between the crease curve and the surface. While similar to
the other example, the upper surface is made with a two-rail sweep.
To create a crease with trimmed surfaces
1
Open the model Crease 02.3dm.
2
Use the Line command (Curve menu: Line > Single Line) to draw a single
line anywhere in the Top or Perspective viewport.
We will use this line to make a dummy surface.
3
Use the OrientCrvToEdge command (Transform menu: Orient > Curve
to Edge) to copy the curve for the dummy surface to the upper edge of
the lower surface.
4
Place a line at each end of the edge and somewhere in the middle of the
edge.
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5
Move each line segment by moving its
upper end to the lower end of the same
segment.
6
Use the CPlane command (View menu:
Set CPlane > Perpendicular to Curve) to
set the construction plane to align with
the line at the left of the surface.
7
Use the Rotate command (Transform menu: Rotate) to rotate the line 15
degrees as shown in the illustration on the right.
8
Repeat these steps for the line in the middle of the surface.
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To make the dummy surface
1
Use the Sweep1 command to create the dummy surface.
2
Select the upper edge of the lower surface as the rail and the three line
segments as cross-section curves. Use the Align with surface style for
the sweep.
3
Hide the original surface.
4
Use the Sweep2 command to make the upper surface.
Choose the upper edge of the dummy surface as a rail (1) and the long
curve at the top as the other rail (2).
Choose the curves at both ends as the cross-section curves (3) and (4).
5
In the Sweep 2 Rails Options
dialog, for the Rail continuity of
edge A, choose Tangency.
6
Delete the dummy surface.
7
Use Show or Show Selected
(Edit menu>Visibility>Show
selected) to show the original
lower surface.
8
Join the lower surface with the
upper surface.
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Curve fairing to control surface quality
Curves in Rhino can come from many sources, they can be:
•
•
•
•
Created in Rhino directly
Imported from digitized data
Imported from another application
Section curves generated from a mesh
It is important to understand that many of these curves need to be optimized for quality.
Fairing is a technique used to simplify curves while improving their curvature graphs and keeping their shape
within tolerance. It is especially important to fair curves that are generated from digitized data, intersections,
extracted isocurves, or curves from two views.
Generally, curves that are single-span curves work better for this process. A single span curve is a curve that has
one more control point than the degree. For examples a degree 3 curve with 4 control points, a degree 5 curve
with 6 control points, or a degree 7 curve with 8 control points.
To analyze a lofted surface with curvature analysis
1
Open the model Fair Curves.3dm.
2
Select the curves and use the Loft
command (Surface menu: Loft) with
Style set to Normal and Crosssection curve options set to Do not
simplify to make a surface.
The surface is very complex. It has
many more isocurves than are
needed to define the shape, because
the knot structures of the curves are
very different.
The surface also has compound
curvature.
3
Select the lofted surface and start the CurvatureAnalysis command (Analyze menu >
Surface>Curvature analysis).
This creates a so-called “False color” display using the same type of analysis meshes
as the Zebra command.
The amount of curvature is mapped to a range of colors allowing you to analyze for
areas of abruptly changing curvature or flat spots.
Choose Mean from the Style drop down.
This style is useful for showing discontinuities in the curvature—flat spots and dents.
The mean is between the two curvature circle values at each point, mapped to a color
value.
4
Push the AutoRange button.
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Click the Adjust Mesh button and adjust the Minimum initial grid
quads to have at least 5000 minimum grid quads to ensure a smooth
display of the color range.
Note the streaky and inconsistent colors on the surface. This indicates
abrupt changes in the surface.
6
Undo the loft.
To rebuild the curves
1
Change to the Tangency Direction
layer.
2
Use the Line command (Curve menu:
Line > Single Line) with the
Extension option, to make a line that
maintains the tangency direction of
an original curve from each end point
and coming back towards the curve,
any length.
Make the lines long enough to cross one another.
3
Change to Rebuilt Curves layer, and Lock the Tangency Direction
layer
4
Use the Rebuild command (Edit menu: Rebuild) to rebuild the curve.
Although there is a Rebuild option in the Loft command, rebuilding the
curves before lofting them gives you control over the degree of the
curves as well as the number of control points.
5
In the Rebuild Curve dialog, change the Degree to 5 and the Point
Count to 6 points. Uncheck Delete input, check Create new object on
current layer. Click the Preview button. Note how much the curves
deviate from the originals.
This makes the curves into single-span curves. Single-span curves are Bézier curves. A single-span curve is
a curve that has degree +1 control points. While this is not necessary to get high quality surfaces, it
produces predictable results.
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6
Lock the Original Curves layer. We
need to see these curves but we do
not want to be able to select them.
7
Select one of the rebuilt curves, and
turn on the Control points and
Curvature graph.
8
Fair the curve by adjusting points
until it matches the original curve
closely enough.
ADVANCED SURFACING TECHNIQUES
Start by moving the second point from each end of the rebuilt curve onto the tangent line. Use the Near
object snap to drag along the tangent line.
9
Check the curvature graph to make
sure the curve has smooth
transitions.
The curves are fair when the points
are adjusted so the rebuilt curves
match the original locked curves
closely, with good graphs.
10 Fair the other curves the same way.
Here are some things to keep in mind when adjusting the curves:
• If you want to keep the curve tangent direction consistent with the original curves, make sure the second
point from each curve stays on the green tangent direction line- only move these points with the Near
object snap pulling the point onto the line.
• The DragMode command, set to ControlPolygon will constrain point dragging to the curve control polygonyou can use this tool to keep the tangent directions constant.
• Where possible, when fairing a set of curves to be used as input to a single lofted surface, try to keep the
control point arrangement on each curve similar to the neighboring curves. This will help keep the surface
nicely aligned.
• When control point adjustment becomes difficult due to the small movements needed, try using the Nudge
keys to nudge the points by small amounts. See Help for more information about Nudge.
• You can also use the Gumball to move points. When fine-tuning with very small point movements needed,
you can set GumballDragStrength to something less than 100% to allow larger mouse movements to
make small changes in the point locations.
To use PointDeviation to visualize the deviation while you edit the curves
1
Make a Points layer and make it current.
2
Select all of the original curves and start the Divide command (Curve
menu: Point Object>Divide Curve by>Number of Points). Set the
Number of segments to 32 and GroupOutput=Yes.
3
Deselect all objects, and select the grouped points.
4
Start the PointDeviation command (Analyze menu: Surface>Point Set
Deviation), and at the Select curves, surfaces, and polysurfs to test
prompt, select the, roughly faired, rebuilt curves.
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When the Point/Surface Deviation dialog pops up,
set the numbers as follows:
Good point = 0.1
Bad point = 0.5
Ignore = 1.0
The display shows the deviation between the points
displayed on the original curves and the closest
locations to these on the rebuilt curves.
6
Lock the Points and the Original Curves layers.
7
Continue to modify the rebuilt curves
with the goal being that all points will
turn blue, as good points.
Note: If you close the dialog, you
lose the display and you need to
start over with PointDeviation.
To make a surface with fair curves
1
Loft the new curves.
The shape and quality of the surface
has very few isocurves but it is very
close to the shape of the first
surface.
2
Analyze the surface with CurvatureAnalysis.
Note the smooth transitions in the false color display, indicating smooth
curvature transitions in the surface.
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8 Use background bitmaps
This exercise describes the steps in creating a case for a small, hand held product, using bitmaps as templates. In
this exercise, we will focus on making curves from bitmap images and using fairing techniques on the curves
before making the surfaces.
We will begin by taking scanned sketches and placing them in three different viewports. The three hand-drawn
images need to be placed in their respective viewports and scaled appropriately so that they match each other.
You can align images more easily if they have been aligned and cropped so that they share the same length in
pixels. It helps to darken and slightly reduce the contrast of images that have a lot of bright white in them. This
allows a greater range of colors to be seen against them when tracing them in Rhino.
Exercise 23—Handset
1
Open the model Handset.3dm.
2
From the Tools menu, click Toolbar Layout.
3
In the Rhino Options dialog, on the Toolbars page, check Background Bitmap to open the toolbar, and
then close the dialog.
Use the toolbar buttons for the next part of the exercise.
The toolbar can also be accessed by flying out the Background Bitmap toolbar from the Viewport Layout
tab across the top.
4
It will make it easier in this exercise if you Split the Front viewport horizontally and make the lower view
the Bottom viewport. You can re-align the views like the illustration below.
5
In Rhino Options, on the View page, in the Viewport properties section, check Linked viewports.
This allows the viewports to stay aligned with each other when zooming and panning.
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To place background bitmaps
We will begin by making reference geometry to help in placing the bitmaps.
1
Make a horizontal line, from both
sides of the origin of the Top
viewport, 150 mm long.
2
Toggle the grid off in the viewports
that you are using to place the
bitmaps by pressing the F7 key.
This will make it much easier to see
the bitmap.
3
In the Front viewport, use the BackgroundBitmap command with the Place option (View menu:
Background Bitmap > Place) to place the HandsetElevation.bmp.
4
Use the BackgroundBitmap
command with the Align option
(View menu: Background Bitmap >
Align) to align the ends of the
handset to the line. The commandline prompts will tell you the steps to
follow.
The Align option shows blips at the
corners of the bitmap, so that it is
precise to use Point object snap to
specify them.
Pick two points on the bitmap—you can zoom way in to pick a point very accurately at this stage.
Pick the points at either extremity of the long shape. Next, you pick two points in space to which you would
like to have the image points just selected to correspond—snap to the endpoints of the 150 mm line.
5
Change to the Bottom viewport.
6
Use the same technique to place and align the HandsetBottom.bmp in
the Bottom viewport.
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Repeat these steps for the Top viewport.
To build the case
The most useful tool for tracing freeform curves is a control point curve.
Place the fewest number of points that will accurately describe the curve. Do not fall into the trap of trying to be
100% accurate with every point placement. With some experience you will be able to place about the right
number of points in about the right places and then point edit the curve into its final shape.
In this example, the 2-D curves can all be drawn quite accurately with a degree-3 curve using five or at most six
control points.
Remember to pay attention to the placement of the second points of the curves to maintain tangency across the
pointed end of the object.
1
In the Front viewport, trace two
curves to define the form of the case.
The front view curves describing the
top and bottom edges of the case
should extend on the right past the
form in the background image.
2
In the Bottom viewport, trace one
curve to define the form of the case.
Since the bottom view of the object
is symmetrical, you can make one
curve. Extend the curve past the
background image approximately
the same distance as you did with
the curves in the Front viewport.
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Draw the curve in the Front viewport
that defines the parting line
separating the top and bottom halves
of the case.
This curve is the front view of the
plan view’s edge curves. It should
be extended to the right the same
distance as the other edge curves.
4
Trim both bottom view and front
view form curves with a single cutting
plane or use the SetPt command to
set the points at the same plane.
5
In the Perspective viewport, select
the parting line curve and the outline
curve that you created in the Bottom
viewport.
6
Use the Crv2View command (Curve
menu: Curve From 2 Views) to create
a curve based on the selected curves.
A 3-D curve is created.
7
Hide or Lock the two original curves.
Now there are three curves.
8
Turn on the control points for the
curves.
Notice the number of control points
and the spacing. This is an example
of curves that need to be faired
before you can create a good
surface from them.
9
Fair the curves, using the same
technique as in the previous exercise.
10 Mirror the 3-D curve for the other
side.
The macros ! Mirror 0 1,0,0 and !
Mirror 0 0,1,0 are very useful for
accomplishing this quickly if they
are assigned to a command alias
and if the geometry is symmetrical
about the x- or y-axis.
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11 Loft the faired curves with the
Closed loft option checked.
Notice the quality of the surface and
how few isocurves there are.
A closed loft will have a seam.
To build the case (alternate technique 1)
1
Undo until your back to step 7 of
the previous part of the exercise.
2
Mirror the 3-D curve for the
other side.
3
Loft the curves, using the
Rebuild option to 18 points.
The isocurves all true up and
everything looks clean, but if
you look at the tip, it falls away
from the input curves.
The Rebuild option does not
sample more in areas of high
curvature but just divides the
curves up evenly.
To fair the surface
1
Hide the background bitmaps and set the viewport to wireframe.
2
Turn on surface points.
3
In the Top or Bottom viewport, move points on one side of the surface in
the y-direction to get the surface to match.
A few points moved should do it.
Now, how do we get the other side exactly the same?
4
Undo all the moves and instead of moving the points, select opposite
pairs of points and Scale1D in Y to move them symmetrically.
The base of the scale should be a middle point, use Ortho to keep the
scale axis true to Y.
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Show the Organic toolbar and use the Expand Y and Compress Y
nudge controls to do the same thing in small increments.
These buttons are macros of Scale1D using the origin as the scale origin.
6
Use similar techniques for adjusting points in the elevation view. Since the
points in this view are not symmetrical in the z-axis, do one side at a
time, moving rather than scaling the points.
Nudge keys or the Move in Z nudge controls in the Organic toolbar also
work.
To build the case using the CSec command (alternate technique 2)
The CSec command creates cross-section curves through profile curves.
1
Undo back to the four input curves.
2
Start the CSec command (Curve
menu > Cross section profiles).
3
Select the curves in order as if lofting
them, make sure the Closed option is
Yes, press Enter when done.
4
For the Start cross-section line, in
Front viewport, pick a point on either
side of the 4 curves.
5
For the End of cross-section line, use Ortho, and pick a point on the other side of the 4 curves.
6
Continue this process until you have 6-10 cross-section curves, evenly
spaced along the four curves.
Make sure to add one section snapping to the endpoints at the open end
of the set of curves.
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Window the section curves and the original long curves.
8
Start the NetworkSrf command (Surface menu > Curve Network) to
make the surface.
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9 An approach to modeling
A common question that users have when modeling, is “Where do I start?” In this section, we will discuss various
approaches to the modeling process.
There are two things to consider before your begin modeling: if reflections, fluid flow, air flow, or the ability to edit
using control points are important in the finished model, you will want to begin your models with geometry that
consists of cubic (degree 3) or quintic (degree 5) curves. If these are not important, you can use a combination of
linear (degree 1), quadratic (degree 2), cubic or quintic curves.
Start with simple shapes, the details can be added later. Begin by creating layers for the different parts. This will
help separate the parts for visualization, and help with matching the parts as you go.
We will review different products to try to determine which kind of surfaces are most important and some
approaches to modeling the product.
Exercise 24—Cutout
This exercise shows an approach to making a cutout surface that blends
smoothly and seamlessly into an existing curved surface. The new surface has
an arbitrary relationship to the existing surface so the general strategy can be
used in other cases.
For this exercise, we have created additional models for each stage of the
exercise. The models are for reference and include notes to explain the
procedure for the steps in that stage of the exercise. There will be a note at
each stage to indicate which model to open if needed.
1
Open the model Scoop.3dm.
2
Make the Cut-out Curves layer
current, turn on the Original
Surface layer, and turn off the
Completed Scoop layer.
3
In the Top viewport, select the
curves.
4
Start the Project command
(Curve menu: Curve From
Objects > Project).
5
Select the surface and press Enter.
The curves will be projected onto the surface.
6
Start the ExtendCrvOnSrf command
(Curve menu: Extend Curve > Curve
on Surface).
7
For the Curve to extend, select the
outer curve on the surface.
8
Select the surface.
The ends of the curve are extended
to the edge of the surface.
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Use the Trim command (Edit
menu: Trim) to trim the curves with
each other.
10 Join the three small curves into one.
11 Copy InPlace the surface and hide
the copy.
12 Use the joined curve to trim away the
part of the surface that is outside the
curve.
This leaves a small trapezoidal surface. This surface is a dummy that will be used to match to a new surface.
13 Use the ShrinkTrimmedSrf
command (Surface menu: Edit
Tools > Shrink Trimmed Surface) to
make this surface easier to see since
it will reset the isocurves to the new
surface size.
To make the curves for the floor of the scoop (Open Scoop 001.3dm if needed)
Next, we will make a surface for the bottom of the cutout. The cutout is rounded at one end, but we will build a
rectangular surface and trim it to be round at one end. This approach allows for a much lighter, more easily
controlled surface than trying hitting the edges exactly while building the surface.
In this part, we will make one curve with as few points as possible that shows the shape of the part that will
become the bottom of the scoop. When making the curve, try to look at it from various views while you work. Use
a degree 5 curve and six points for a very smooth curve. Check the curve with the curvature graph to get a nice
fair curve.
1
Use the Curve command to draw a
control point curve in the Front viewport.
On the Status bar, turn Planar mode on.
This will keep the curve in a single plane
for the moment.
Snap the first point of the curve to the
corner of the small dummy surface in
any convenient view. Then switch to the
Front viewport to continue drawing.
Draw the curve approximately tangent to the edge of the dummy surface and finish it lower, defining the
shape of the floor of the scoop.
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Adjust the curve with point editing to get
the right shape in the Top viewport.
Make sure to move the points only in
the y-direction (Ortho will help), so that
the shape in the Front viewport will not
be altered.
Make the curve approximate the
outermost of the original curves and
extend somewhat past the rounded end.
3
Use the Match command (Curve menu:
Curve Edit Tools > Match) to match the
curve with Curvature continuity to the
edge of the dummy surface.
Edit the curve further if needed but be
sure to use Match again if you have
moved any of the first three points in
the curve.
4
Copy the curve to the other edge.
5
Adjust the curves by moving the control
points until they look the way you want,
and then Match the curve to the edge of
the dummy surface.
If matching makes the curve distort too
much add a knot and try again. Using
the EndBulge command and further
point editing may be needed.
To create the floor surface of the scoop (Open Scoop 002.3dm if needed)
There are a few surfacing techniques that can be used to create the surface.
A 2-Rail Sweep would be one
obvious choice, using the new
curves as rails and the edge of the
dummy surface as the cross section.
The advantage of this is that other
cross-sections can be used to define
the floor shape if desired.
Since the rails are G2 to the dummy
surface (Matched in the last
sequence of steps), the surface will
be very close to G2 to the dummy
surface when created.
The MatchSrf command could fix
any discontinuity, if needed. This is
a good way to go and you may wish
to try it now.
2-Rail Sweep using the new curves
as rails and the surface edge as the
cross-section.
2-Rail Sweep using the new curves
as rails and the surface edge as the
cross-section with the simple sweep
option checked.
Another approach is to make a lofted surface between the two curves. The surface will need adjustment to match
to the dummy surface and will provide the opportunity to explore some options in the MatchSrf command so we
will outline this method below.
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Use the Loft command (Surface
menu: Loft) to create the surface
between the two curves.
Because the lofted surface is flat,
there will be a slight gap at the
edge of the dummy surface.
2
Use the MatchSrf command (Surface
menu: Surface Edit Tools > Match) to
match the lofted surface to the edge
of the dummy surface for curvature.
Use the Preview button to see how
the match will look.
You may notice that the matched
surface pulls around quite
drastically to be perpendicular to
the target edge.
If so, change the Isocurve adjustment from Automatic to Preserve
isocurve direction, and try the Preview again. The surface should
now match with much less distortion.
3
Use the Zebra command (Analyze menu: Surface > Zebra) to check the
continuity of the two surfaces.
To make the sides of the cutout (Open Scoop 003.3dm if needed)
To make the sides of the cutout, we will extrude the projected outline with 10 degrees of draft and trim it with the
lofted surface.
1
Select the outer projected curve.
2
Use the ExtrudeCrvTapered command (Surface menu: Extrude curve >
Tapered) to extrude the inner projected curve. Change the DraftAngle to
10. Pull the surface until it fully intersects with the bottom surface, but no
more, and pick.
If you extrude the surface too far, you might get a polysurface instead
of a single surface.
If this happens try to extrude again, but do not pull so far.
If you cannot pull it far enough to penetrate the floor without making a
polysurface, extrude it a short distance instead.
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Use the ExtendSrf command (Surface menu: Extend Surface) to extend
it through the floor surface.
The extruded surface is a very dense surface.
4
Use the FitSrf command (Surface menu: Surface Edit Tools > Refit to
Tolerance) to simplify the surface.
A Fitting tolerance of 0.001 with DeleteInput=Yes, ReTrim=Yes,
UDegree=3, and VDegree=3 should work well.
To create the fillets
Now the surfaces are ready to be filleted.
1
Show the main surface and Hide the dummy surface.
2
Use the FilletSrf command (Surface menu: Fillet Surface) with a
Radius=5, Extend=No, and Trim=No to make the fillets between the
bottom surface and the sides.
3
For the first surface to fillet, pick the bottom surface.
4
Pick the side surface near the same spot.
5
Repeat this for the side surface and the original surface.
The two fillets cross each other. We will trim them both back to their
intersection points.
Where you pick matters.
Trimming the fillet surfaces (Open Scoop 004.3dm if needed)
Both of the fillet surfaces are tangent to the tapered side of the scoop. Where the fillets cross they are tangent to
each other.
If we trim the ends of the fillets to a plane, then the resulting trimmed edges will be tangent to each other.
Trimming these surfaces will be helpful when creating the final surfaces that blend the fillets out between the
scoop and main surfaces.
To create the plane, first make circles with the AroundCurve option around one edge of the fillet surfaces, then
make planar surfaces from the circles.
1
Select the fillets and use the Invert
Hide button in the Visibility toolbar
to isolate them.
2
Start the Circle command, and use
the AroundCurve option. Set the
Int object snap only.
The AroundCurve option forces
the Circle command to look for
curves, including edge curves, to
draw the circle around.
3
Click on the upper edge of the lower surface and snap to the intersection point.
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4
Draw the circle out well past the
width of the fillet surfaces.
5
Use the PlanarSrf command
(Surface menu: Planar Curves) to
create a circular surface at the
intersection point.
6
Repeat these steps for the other
intersection.
7
Trim the fillets to the surfaces.
AN APPROACH TO MODELING
Trimming the sides of the scoop
You can use the trimmed fillets to trim back the side surface of the scoop.
1
Use ShowSelected to show the tapered side surface.
2
Use the fillet surfaces as trimming objects to trim the excess from the side
surface.
It is often much faster to trim with curves than to use surfaces,
especially if the surfaces are tangent to the object to be trimmed, as is
the case with fillets.
Duplicate the two edges that are in contact with the side surface to use
as trimming objects if you have a problem.
Trimming the main and floor surfaces (Open Scoop 005.3dm if needed)
The next task is to extend the edges of the fillets so that the main surface and the floor surface can be trimmed
back. The inner, or lower, edge of the lower fillet will be extended off the end of the floor surface and the outer, or
upper, edge of the upper fillet will be extended off past the end of the opening of the scoop as well. The extended
curves will be projected onto the respective surfaces and used to trim them.
1
In the Top viewport, use the Extend
command with the Type=Smooth
option to extend both bottom ends of
the lower fillet edge past the front of
the floor surface.
2
Use these curves, still in the Top
viewport, to Trim the outer edges
from the floor surface.
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Use Extend to extend the outer
edges of the upper fillet past the end
of the floor surface.
Note that in the Perspective
viewport these extended curves are
off in space at their outer ends.
4
ShowSelected the main surface if it
is hidden.
5
Project the curves onto the main
surface from the Top viewport.
6
ShowSelected or turn on the layer
for the original curves and Project
the line segment onto the main
surface.
7
Trim the projected curves with one
another so that they form a closed
loop.
8
Use the closed curves to Trim a hole
in the main surface.
Set up the curves to create the surfaces (Open Scoop 006.3dm if needed).
We are now nearly ready to create the surfaces. As you can see there are nice rectangular gaps in the surfaces,
we just need to arrange the curves and edges surrounding the gaps for use in making a 2-Rail Sweep or a surface
from a Curve Network. Because one end of each open rectangle is bounded by the two tangent fillet edges, we
need to create a single curve there to use as input. We will duplicate the four edges and join them into two sshaped curves. The other end of each rectangle is bounded by a portion of the end of the hole in the main surface.
We will split up that long edge into segments that correspond exactly to the ends of the rectangular openings.
1
Use DupEdge to create curves at the
trimmed edges of the fillets.
2
Join these four edges into two
curves.
3
Use the SplitEdge command
(Analyze menu: Edge Tools > Split
Edge) and the End object snap to
split the straight edge on the trimmed
hole in the main surface to the end
points of the floor surface's edge.
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AN APPROACH TO MODELING
Use the SplitEdge command to split
the long edges at the endpoints of the
fillet edges.
This will help NetworkSrf find a
solution more quickly.
5
Use the Sweep2 command with Rail continuity=Tangency or the
NetworkSrf command to create the last two surfaces.
The surfaces start with the s-shaped curves that you duplicated and end
with a flat line at the split edges.
6
(Open Scoop 006.3dm if needed)
Join the cutout surfaces and then
trim a hole at the bottom.
7
Mirror and Trim to get the other
scoop.
Extra cross section curves
Open Scoop 007.3dm, if needed.
Use Sweep2 or NetworkSrf to close the
holes. Filling the larger of the two holes
may benefit from extra cross section
curves. To add cross-sections, use the
Blend command to make tangent curves
approximately one-third and two-thirds of
the way along the edges of the opening.
Use these curves as additional input for a
network surface.
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1
Start the BlendCrv command (Curve
menu: Blend Curves > Adjustable
Curve Blend).
2
At the command-line, select the Edges
option. Set the Continuity=Tangency.
3
For the Select surface edge to blend,
click approximately one-third of the way
along one of the long edges of the
rectangular opening.
4
For the other Select surface edge to
blend, click on the edge opposite the
first one.
AN APPROACH TO MODELING
The blend curve will be placed across
the opening and a dialog will open.
5
In the Adjust Curve Blend dialog, set
the Continuity to Tangency for both
ends.
6
Make a second curve the same way
about two-thirds of the way along the
same edges.
7
Use the NetworkSrf command to
create the surface.
Remember to include the new curves
in the selection.
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10 Applying 2-D graphics
Often you are asked to take an existing design from a 2-D graphics package and include it as part of a Rhino
model.
In the following two exercises, we will move and position the graphic onto the model.
Exercise 25—Importing an Adobe Illustrator file
In this exercise, we will make a custom construction plane, import an Illustrator file, and place a logo on some
surfaces.
1
Open the model Air Cleaner.3dm.
2
In Rhino Options, Modeling Aids, set the Construction planes to use
Standard construction planes.
The following techniques will not work if the construction planes are set
to use Universal construction planes.
To import a file
1
Start the Import command (File menu: Import).
2
Change the Files of type to Adobe Illustrator (*.ai), and choose the
AirOne_Logo.ai to import.
3
In the AI Import Options dialog, click OK.
The logo curves appear at the origin of the Top
construction plane, are selected, and on the Default
layer.
Tip: If curves are not planar, use the
ProjectToCPlane command (Transform menu:
Project to CPlane).
4
While the imported geometry is still selected, use the Group command to
group the various curves together. This makes it much easier to select all
of the curves and not leave any behind in the following transform steps.
5
Start the Layer command.
6
Turn off the Logo layer in the Layer panel.
7
Right-click on the Logo layer, then click Copy Objects to Layer to
make a copy of the logo on the Logo layer.
We will use this copy later for another part of the exercise.
8
Turn off all the layers except Default and Top Surface.
To create the custom construction plane
We need to set a construction plane to the flat surface. The CPlane command will allow us to do this but the X
and Y directions of the new custom construction plane will be mapped to the u- and v-directions of the target
surface respectively. The Dir command will tell you how the u- and v-direction are pointing on the surface, and
allow you to change the directions of each.
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Select the flat disc shaped surface,
then from the Analyze menu, select
Direction (Analyze menu:
Direction).
This displays the current surface
normal direction and the U/V
directions. It is important to know
the u- and v-directions of the
surface.
The white arrows show the surface normals. A cursor with a red and green arrow appears when you move
over the selected surface.
The red arrow indicates the U direction and the green arrow indicates the V direction.
2
At the command-line, notice the options for changing the directions of the surface. You can click on these to
change the surface directions. The cursor and surface normals will update accordingly.
When all changes are made, press Enter to accept.
The goal is to have the U and V as in the second image.
In this way, the new construction plane will map to the surface
accordingly and the geometry can be mapped to the construction plane
predictably.
3
In the Perspective viewport, use the CPlane command with the Object
option (View menu: Set CPlane > To Object) or (Viewport title right-click
menu: Set CPlane > To Object) to set the construction plane to the
surface.
The x- and y-axes are parallel to the u- and v-directions of the surface
as you set them in the previous step.
4
You may want to save the new construction plane with the
NamedCPlane command (Viewport title right-click menu: Set CPlane >
Named CPlanes) to make it easy to retrieve later step.
To map the logo curves to the new construction plane
The command we will use to move the logo to the flat disk shaped surface uses the position of the object relative
to a construction plane.
1
Select the curves in the Top viewport. Make sure the Top viewport is
active, then start the RemapCPlane command (Transform menu:
Orient > Remap To CPlane).
This command depends upon the active construction planes at each
stage, so it is important to pick in the correct viewports.
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Click in the Perspective viewport with the custom CPlane.
You could use the Copy=Yes option in this command so that a copy is
remapped instead of the original.
The logo is positioned in the same relative position on the custom
construction plane as it was in the active viewport.
3
Rotate, Move, or Scale the logo to a new position.
For an accurate view of the surface and the curves, you may want to
use the Plan command in the Perspective viewport. This sets the view
to a parallel projection looking straight on at the plane.
4
Use the ExtrudeCrv command (Solid
menu: Extrude Planar Curve >
Straight) with the BothSides option
to make the text 3-D. The extrusion
distance should be 1 mm.
5
Use the BooleanDifference
command (Solid menu: Difference) to
recess the text into the surface.
Exercise 26—Flow the logo onto a freeform surface with history
In this part of the exercise, we will use the copy of the logo that is on the Logo layer and position it on the cutout
surface. This surface is not flat so we will use a different transform tool, Flow along Surface, to move it and
bend it along the surface. Flow along Surface morphs objects from a source surface to a target surface. It uses
the UV of the surfaces to determine how it flows. It is important that the source and target surfaces have the
same relative UV direction.
To make the base surface
1
Start the Layer command and make the Cutout layer the current
layer. Then, turn off all the layers except Cutout and Logo.
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2
Use the BoundingBox command (Analyze menu: Bounding box) to
make a rectangle around the logo.
3
Use the PlanarSrf command (Surface menu: Planar Curves) to make a
surface from the bounding box.
APPLYING 2-D GRAPHICS
To flow the logo curves onto the cutout surface
1
Use the Dir command to check the UV directions of the cutout surface.
2
Use the Dir command to adjust the UV directions of the base surface to
match the direction of the cutout surface.
3
In the status bar, make sure Record History is on.
If the text is not bold, click in the pane to turn on history recording.
4
Use the FlowAlongSrf command (Transform menu: Flow along Surface)
to move the logo onto the cutout surface.
Notice that the curve does not fit the surface.
5
Turn on the control points on the base surface and move them to make
the surface a little larger in all dimensions.
Since history was on when flowing the curve, any adjustment to the
base surface changes the way the curve fits on the cutout surface.
6
Use the ChangeDegree command (Edit menu: Change Degree) to
change the base surface to degree 3 in both the U and the V direction.
7
Adjust the control points further to fine tune the way the curve fits on the
cutout surface.
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To raise the logo lettering and flow it onto the cutout surface
1
Use the ExtrudeCrv command with the BothSides option to make the
text 3-D. The extrusion distance should be 1 mm.
2
Use the FlowAlongSrf command to move the solid logo onto the cutout
surface. Use the new base surface.
History is not needed this time, since all the needed adjustments were
already done on the base surface.
3
Use the BooleanUnion
command to join the logo with
the cutout surface.
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Make a model from a 2-D drawing
One of the more difficult modeling tasks in modeling is to interpret a set of 2-D
views into a 3-D model. Very often, the drawings are precise in some areas
and inexact in areas where complex surface transitions must take place in
three dimensions.
It is best to consult directly with the designer to clarify difficult areas, but this
is not always possible. Usually there are discrepancies between the views.
If there is no physical model available as reference, some decisions must be
made along the way about the best way to interpret the control drawing. For
example, you will have to consider which view to consider the most accurate
for a given feature.
In the following exercise, we will explore some strategies to create a blowmolded plastic bottle from a set of 2-D drawings. In this exercise, we have a
control drawing showing three views of the bottle. It is roughly dimensioned,
but we need to hold to the designer’s curves wherever possible.
We will only have time to finish the first stage of this model in class. We will
complete the bottle surfaces, but the details will be left out. Included in the
models folder is a finished bottle for your review.
Control drawing
Exercise 27—Making a detergent bottle
To group the parts
1
Open the model Detergent Bottle.3dm.
2
In the Top viewport, window select the objects that make the top view
(lower left) including the dimensions of the 2-D drawing.
3
Use the Group command to group the selected objects (Edit menu:
Groups > Group).
4
Repeat the previous steps to group the objects for the front view (upper
left) and the right view (upper right).
Each of the views is a separate group of objects.
To orient the Top view
1
Select the top view group.
2
Use the ChangeLayer command (Edit menu: Layers > Change Object
Layer) to change the layer to the 2D Template Top layer.
3
In the Top viewport, use the Move command to move the center of the
circles to 0,0.
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To orient the Front view
1
Select the front view group.
2
Use the ChangeLayer command to change the layer to the 2D Template
Front layer.
3
In the Top viewport, use the Move command to move the intersection of
the centerline and the horizontal line at the bottom to 0,0.
4
While the front view group is still selected, start the RemapCPlane
command (Transform menu: Orient > Remap to CPlane) in the Top
viewport.
5
Click in the Front viewport.
The view is oriented in 3-D space.
To orient the Right view
1
In the Top or Perspective viewport, select the right view group.
2
Use the ChangeLayer command to change the layer to the 3D Template
Right layer.
3
In the Top viewport, use the Move command to move the intersection of
the centerline and the horizontal line at the bottom to 0,0.
4
Use RemapCPlane to map the right view curves to the Right construction
plane.
The view is oriented in 3-D space.
Frequently 2-D curves for design control drawings will not be as carefully constructed as you like for making
accurate geometry. Before building 3-D geometry from the 2-D curves, check the curves and correct any errors
that can be found.
To create the 3-D curves
The inset part of the bottle will be cut into the surface later. For the moment, we just need to build the outer
surfaces. The fillets at the top and bottom indicated in the curves can be left out of the initial surface building and
added in as a separate operation. We will need to extend or redraw the edge curves to bypass the fillets and meet
at hard corners before making the surfaces.
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Several surfacing tools could be used to build the initial surfaces: A 2-Rail Sweep or a Surface from Network
of Curves are the obvious choices.
Network surfaces do not pay any attention to the curve structure, only the shape. All curves are refit and the
resulting surface has its own point structure.
Other commands including the Sweep tools, lofting and edge surfaces do pay attention to the curve structure in at
least one direction. In these cases, it often pays to use matched curves as cross sections. The choice of surfacing
tools may well determine the way in which the actual input curves are created.
1
Select the groups you made in the previous step, use the Ungroup command
(Edit menu: Groups > Ungroup) to ungroup them.
2
Select the curves from each 2-D template view that define the outer surface
and Copy them to the 3D Curves layer.
Since the bottle is symmetrical on both sides of the X-axis, you will only
need to copy the curves on one side. They will be mirrored later.
3
Use the OneLayerOn command (Edit menu: Layers > One Layer On) to set
the 3D Curves layer.
4
Move the curve defining the top surface of
the bottle to the same height as the top of
the vertical curves.
Use SetPt or Move with the Vertical option
in the Perspective viewport.
5
The vertical curves now can be extended past the fillet curves so that they
meet the top and bottom curves exactly on the endpoints of these curves.
One way is to extend the vertical curves using Extend with
Type = Smooth. Snap to the End or Quad points of the top curve and the
base curve at the bottom.
Extending the curves in this way will add complexity to the curves. If it is
important to keep the curves simple and well matched, it may be better
instead to adjust the points on the existing curves to extend them.
6
Undo the Extend operation, and instead point edit the curves directly.
You can make a duplicate set of curves and edit one of each leaving the
original in place as a template.
7
Mirror the base, top and side curve visible from the right view to the other
side.
The result should be a set of 8 curves that define the surface.
Most of these curves are essentially the original curves from the 2-D
drawings but rearranged in 3-D.
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Join the base curves and the top
curves into a closed loop.
The curves are set up for a surface
from a curve network or a two-rail
sweep.
To make a surface for the bottle with a sweep
From the drawing these are the only curves we have available to define the shape, so we will use these curves
directly to create the surface.
1
Change to the Surfaces layer.
2
Window select the curves, and try
Sweep2 to make a surface then
Shade the viewport.
Notice the shape gets severely out
of control at the rounded side of the
bottle.
3
Move this surface to the side for the
moment.
While it is possible to rearrange or
add curves to make the Sweep2
work better, it is worth checking
how a surface from a Curve
Network will work with the same
set of curves.
4
Select all of the curves, again, then
use the NetworkSrf command to
create the surface.
The NetworkSrf command handles this set of curves much more gracefully.
On your own
Make the inset surface and the handle.
Fillet the edges where indicated in the 2-D drawing.
Included in the model directory is a finished bottle, Finished Detergent bottle.3dm,
for your review.
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11 Surface analysis
Rhino has several tools to help you visually evaluate surface quality. In this exercise, we will use curve and
surface analysis tools to help build clean, simple surfaces with good continuity.
Some models require more attention to continuity, primarily, because it will show when manufactured. For
example, a blow-molded bottle will not show slight inconsistencies in the surface, but a car panel will.
Exercise 28—Surface analysis
The file, Surface Analysis.3dm, has a set of curves you will recognize from the previous exercise. Our task in
the current exercise is to make curves that can create cleaner, simpler surfaces with good continuity. We will
make use of the CurvatureGraph, Zebra, and CurvatureAnalysis to make sure we set things up for the best
results. Lastly, we will compare the surface analysis results in this file with the surface analysis results in the
previous exercise.
To evaluate the curves
First, let us look at the curvature graphs of the top and the bottom curves. These curves have a nice enough
shape, but there is room for improvement from a surfacing continuity perspective.
1
Select the top and bottom curves.
2
Start the CurvatureGraph command (Analyze menu: Curve > Curvature
Graph On) and set the Display scale to a value of 120.
The graph tells us that both curves are tangent continuous but have
curvature discontinuities in a couple of locations.
Assuming we want the surfaces we build from these curves to have curvature
continuity throughout, we will be better off modifying these curves before
creating the surfaces.
If we decide ahead of time what the surface arrangement will be, that will
help us understand how to draw clean new curves.
Building a surface that has consistent curvature as a single surface is good
modeling practice. Looking at the bottom curve, we can see two areas that
are good candidates for creating the surfaces, so we will start there. There is
an area of high curvature at the front (1) and a relatively flat stretch in the
middle with a rapidly increasing curvature at the handle side (2). The top
curve is smoother overall, but has similar corresponding regions of curvature.
By examining the current curves, we can identify two curves to build at the
top and bottom. The white vertical curve intersects the top and bottom
curves at the curvature discontinuity of the top curve, which is a modified
circle, and on an abrupt change in curvature on the lower curve. This
intersection is where we will start and end our modified curves.
To build the modified curves
1
Using the current curves as a reference, draw
four new curves of degree five with six points.
The goal is to redraw the top and bottom
curves in two parts each.
Keep in mind what you know about continuity,
CurvatureGraph, tangent directions, and
EndBulge.
Try to keep the control point locations even
and progressive.
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Analyze your curves with the CurvatureGraph command.
Try to get the graph clean with minimal, abrupt changes, while at the same
time match the original curve shapes as closely as possible.
They cannot be exactly the same as the originals if they are to have better
continuity, but it should be possible to get close.
To make the surfaces for the bottle from edge curves
There are four, single-span, curves that define each
area for the surfaces. In this part of the exercise we
will use the EdgeSrf command (Surface menu:
Edge curves) to create the surfaces. This command
is one that uses the input curve structure to create
the surface. It works best if the curves on opposite
sides of the rectangle match each other. The
resulting surface will be simpler.
Since we have taken care to meet this criterion, all
of the vertical curves are degree 3 with four points,
and the curves we just made are degree five with
six points, the resulting surfaces will share this
structure.
1
Select four curves that define one of the
surfaces.
2
Start the EdgeSrf command (Surface menu:
Edge curves).
3
Repeat steps 1 and 2 for the other surface.
4
Check the surfaces with the Zebra command.
The zebra stripes have a nice even flow but the surfaces are clearly not
tangent at the vertical edge.
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To match the surfaces for the bottle with MatchSrf
1
Use the MatchSrf command (Surface menu: Surface Edit Tools > Match) to
match the surfaces for Curvature. Try matching in both directions, and with or
without Average surfaces set.
In this case, the results are good no matter how the match is made, but it is
worth looking at the control points on the surfaces in each case.
Matching the larger surface to the smaller one, without Average, results in a
more erratic control point arrangement on the larger surface than any other
combination, particularly the second row from the top. Other considerations
being equal, the best choice is the surface with the most regular, even control
point arrangement.
2
Check the surfaces with the Zebra command.
The zebra stripes have a nice even flow with no discontinuity at the common
edge.
To match the surfaces for the bottle with Symmetry
In this section, we will make the other half of the bottle using the Symmetry command with Record History
turned on. Symmetry mirrors curves and surfaces, makes the mirrored half tangent to the original, and with
History recording active, when the original object is edited, the mirrored half updates to match the original.
1
Select the larger surface.
2
Use the Symmetry command (Transform menu: Symmetry) to mirror the surface
across the x-axis. Make sure Record History is on.
3
For the Select curve end or surface edge, select the edge of the surface (1).
4
For the Start of symmetry plane, type 0 and press Enter.
5
For the End of symmetry plane, use Ortho to pick a point along the x-axis.
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Repeat this process for the other surface.
If you edit either original surface, the mirrored part will update to match.
7
Check the surfaces with the Zebra command.
The zebra stripes have a nice even flow with no
discontinuity at the common edge.
To analyze the matched surfaces
At this point, we will use the Curvature Analysis tool to evaluate the matched surfaces. This can be useful in
locating areas of extreme curvature, but may force the display to ignore more subtle changes. In any case, the
display on each of these simple surfaces should be very smooth and clean.
1
Hide all curves to get a good view of the transitions between surfaces.
2
Select all of the surfaces and turn on Curvature Analysis display (Analyze
menu: Surface > Curvature Analysis).
Set the style to Gaussian, and click Auto Range. Make sure you have a
fine analysis mesh for a good visual evaluation. Click back and forth
between Auto range and Max range.
Auto Range attempts to find a range of color that will ignore extremes in
curvature, while Max Range will map the maximum curvature to red and
the minimum to blue.
The numbers are for Curvature, which is, 1/radius.
The goal when matching is to maintain as even and gradual a curvature display as possible, while meeting
the continuity requirements.
Notice the edges that have been matched appear to have a smooth color transition.
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To analyze and compare different surfacing techniques
Next, we will make another surface for comparison.
1
Copy the curves to one side.
2
Mirror and Join the top and base curves on the x-axis.
3
Mirror the vertical side curve on x-axis to make a set of curves
suitable for a surface form a curve network.
4
Use NetworkSrf to make a surface from these curves. Select the
new surface and Add it to the Curvature Analysis display.
The denser network surface (2) has a less clean appearance in
this display. The simple surfaces (1) still look cleaner at this
point.
Since the color change is mapped across the entire range
shown, it is important to remember that the Auto Range setting
indicates a very narrow range of curvature and that the actual
differences may be small even though the color change is great.
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12 Sculpting
Designers can build a relatively undefined surface and then use a variety of transform and analysis tools to sculpt
a surface in 3-D space in an intuitive and direct manner—design “as you go.”
Place curves approximately. The curves should be
edited copies of a single original if possible.
This ensures that they will be compatible when lofted,
and create the simplest, most easily edited surface.
Start with the big changes and then make the detailed
changes.
Use the IncrementalSave command to make copies
of the model as you progress.
In the following exercise, we have created four curves
for you to use. They describe a very simple dashboard
from which to start your design. An added steering
wheel, on a locked layer, is to help you get a sense of
scale and positioning of any elements you might wish
to add.
Tools to help in control point editing
Move Control Points by dragging, using the Move, Rotate, or Scale commands or other Transform
commands.
Dragging, of course, is the most fluid and interactive way to edit the shape. However, there may be situations
where the construction plane constraint for point movement is less than optimal. Here are some tools that can
help with control point editing:
Gumball
Gumball works very well with control points. It is convenient to be able to switch easily among the various
gumball orientation modes. Opening the Gumball toolbar will help.
When Gumball orientation is set to Align to Object, the blue axis orients itself to the surface normal for a
selected control point. By dragging the blue arrow, the control point moves in the local surface normal direction.
The red axis aligns to the surface U direction. Make fine adjustments by setting the Gumball drag strength to
something less than 100%.
DragMode
DragMode lets you override the current construction plane constraints in several ways.
Command-line options
World
This constrains dragging as if the CPlane were always World Top. This is rarely used.
CPlane
The default constraint in Rhino. Dragging takes place parallel to the active CPlane.
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View
Dragging takes place parallel to the current viewport. This can be useful in some oblique views.
UVN
Dragged surface control points with Ortho on (Shift key) are constrained to the surface u- and v-directions
and with the Ctrl key are constrained to the surface normal direction. Curve points are constrained to the
curve tangent and with Ctrl to the curve normal direction. For this exercise, this is most useful drag mode.
ControlPolygon
This mode constrains dragged curve and surface control points to the control polygon. In the case of multiple
selected points, each moves along its own control polygon. This is an excellent tool for keeping points well
organized in rows and columns.
As with the Gumball, having the DragMode toolbar open makes it easy to switch among modes while point
editing. Notice the cursor changes to reflect the current drag mode. In general, you will probably find it easier
to switch the Gumball off when dragging points using the special drag mode options.
MoveUVN
This tool opens a dialog box that allows you to move control points in increments according to a user set scale.
The point movement can be along the U, V, and N (Normal) directions. In addition, there are smoothing tools
in this dialog. These are very useful for smoothing out bunched or irregular control points to achieve a more
regular grid.
Nudge
Use the arrow keys with Alt, Alt+Shift and Alt+Ctrl to move points in small increments. Note the settings in the
(Options > Modeling aids > Nudge page) allow you to set the Nudge constraints similarly to some of the
DragMode settings mentioned above.
Tip: You can use the knowledge gained in the User Interface portion of this course to create macros that make it
easy to swap among the nudge modes.
SetPt
This allows you to true up points or rows of points in one, two, or all three dimensions.
Use any or all of the above tools to manipulate the surface points individually and in groups. Keep in mind the
point selection tools: SelU, SelV and others in the Select Points toolbar.
You will see that with a relatively sparse set of control points, as we have on this starting surface, the edits you
make tend to be large ones that affect the shape broadly. It is likely that you run out of control quickly.
In this case, you will find that you need have more localized control to add smaller details. You can add control by
increasing the density of the control points. There are two similar tools for this:
InsertKnot
Inserts one or more knots, and rows of control points. Surface points are rearranged so that the shape of the
surface does not change. In other words, except in special cases, the new points are not added at the same
location as the new knot.
InsertControlPoint
Allows you to place the row of points where you want them to be, however the mechanism for adding these points
does nothing to ensure that the shape of the surface stays the same. Generally, the shape will change.
Both InsertKnot and InsertControlPoint have advantages, but when you are making heavily curved and
sculpted surfaces, InsertKnot may be the safer choice since it does not change the shape of the surface.
Some considerations when inserting knots
Insert as few knots as you can to get the control you need. Add more later if needed. Keep the surface as
simple as possible while getting the control you need.
Where possible, insert knots so that they are as evenly spaced as possible. Try to place them halfway between
existing knots.
Command-line options
Automatic
Adds knots halfway between existing knots to maintain as uniform a structure as possible. It increases the
knot density of a curve or surface, and thus the control point density as well, while maintaining an even
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knot distribution, which makes point editing more predictable than with unevenly spaced knots. Be careful
with this option, as it adds a knot between each pair of existing knots, so a surface can become very dense
in structure very quickly.
MidPoints
Places markers halfway between the existing knots/knot lines that can act as guides for inserting knots
midway between existing knots. Use the Point object snap to place new knots at these markers.
Note: It is easy to get to a point where there are too many control points and you simply lose control of the
shape. Therefore, it is a good idea, to use IncrementalSave before adding complexity to the object. This
will allow you to go back to a simpler model without starting over if things get out of hand.
Exercise 29—Dashboard
1
Open the model Dash.3dm.
2
Loft the four curves together with the
Loose option from the dropdown list.
Using the Loose style creates the
simplest possible geometry and is
essential to creating a surface with
this technique. The surface will not
touch the interior curves of the loft
with this option, but it should be
very smooth and clean looking.
3
Turn on the control points.
If you also turn on points for the input curves, you will see that the point
structure of the surface exactly matches that of the four curves.
4
Turn off the Curves layer.
You can do at this point to sculpt the shape. The most obvious one is
simply to move the surface control points around, so let us start there.
As mentioned, Rhino has several powerful tools to help in control point
editing.
To edit and sculpt the surface
1
Turn on the points for the surface,
with Gumball off for the moment.
2
Window select the three control
points that are just to the right of the
steering column centerline.
3
Use the SetPt command (Transform
menu: Set XYZ Coordinates) to align
the groups of points in the x direction
in Top or Front snapping to the
centerline.
Notice that when the points are selected, there is a red and a green line extending from the selected pointsthis indicates the positive u- and v-directions.
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4
Use this information with the point
selection tools NextU, NextV,
PrevU, or PrevV to shift the selection
to the left or right to the next row of
points. SetPt these points to the
corresponding edge, left and right, of
the steering wheel.
5
Use Gumball to drag the lowest three
points near the steering wheel down
to accent the shape.
SCULPTING
The shape may not be symmetrical compared to the steering wheel.
6
Select the points nearest the top edge
of the steering wheel and set them all
to the same Z using SetPt.
7
Now, let us add some definition to the
dash in the area of the steering
wheel. Set the DragMode to
ControlPolygon, and drag three of
the points up very close to their
neighbors.
The shape of the surface changes only slightly. It is still very soft, and there are no more points available to
continue to edit there.
8
Use the InsertKnot command (Edit
menu: Control Points > Insert Knot)
to add a row of points in the V
direction.
The surface currently has no interior
knots so use the Automatic option
once to add a single knot.
Now, with the extra points you can
continue to slide points along the
control polygon to sharpen up the
surface in this area.
9
Use the IncrementalSave command (File menu: Incremental Save) before going on to the next step.
10 Another way to tweak the shape is to
set the point weight of some of the
points on the surface. For example,
select the three middle points that are
at the apex of the now sharply curved
area we have been editing. Start the
Weight command (Edit menu:
Control Points > Edit Weight).
Increase the weight of the points
to 2.
Higher weight points, relative to neighboring points, tend to pull the surface toward them. Lower weight
points cause the surface to fall away from the control points.
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To add and manipulate knots
Try inserting knots in either direction, using the Midpoints=Yes setting to be able to snap to span midpoints.
Insert some knows with Midpoint=No to insert knots close to existing ones to allow more local control.
1
Use the IncrementalSave command (File menu: Incremental Save)
before going on to the next step.
2
Use InsertKnot, Midpoints=Yes, to insert some knots in the U
direction. Snap to midpoints to keep knot spacing even.
Notice how the control point arrangement changes with each knot
inserted. You may want to true up some rows of points in X using SetPt
to keep the rows and columns organized.
3
Explore different shapes and design ideas using all of the tools mentioned
above.
4
Select some points that are out of
alignment. Start the MoveUVN
command (Transform menu:
MoveUVN). Use the Smooth sliders to
smooth some of the points that are
out of alignment.
5
Move some points to the right of the steering wheel closer to it to make
the shape more symmetrical about the steering wheel.
Where possible, try to keep the control point arrangement even and
progressive. As you might expect, there tend to be more control points
in areas that have been edited and shaped the most.
6
Add some more knots in the area of
the top of the steering wheel.
If you crowd a few knots in this
area, you can pull out a localized
feature that fades smoothly into the
surrounding surface.
To make the offset surface
When you are satisfied with the overall shape of the surface, you can add details to make a more finished object.
The surface can be offset and trimmed as in the first illustration.
Best results are obtained when the surface has at least degree 3 in both directions. Check this with Object
Properties.
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Note: Offsetting surfaces generally results in a surface of one step lower in internal continuity. Surfaces that are
only G1 internally may result in surfaces that have G0 continuity; that is, they may have a kink in them.
Although Rhino allows these surfaces, this can lead to problems downstream.
For this reason, if you intend to offset surfaces, it is best where possible to create the initial surface from
degree 3 or higher curves. These surfaces have at least G2 continuity so that offsetting them will result in
at least G1 continuous surfaces. Changing the degree of a surface that has been created from degree-2
curves to at least degree 3 in both directions is not sufficient to ensure a G2 surface. Simply changing the
degree after the fact does not improve internal continuity.
1
Change to the Cutting Curves layer.
2
Draw a curve that represents where
you want to split the surface.
3
Use the Offset command (Curve
menu: Offset Curve) to make a
duplicate of the curve offset by onehalf (0.50) inch.
4
Use the Trim command (Edit menu:
Trim) to trim the surface between the
curves.
5
Use the OffsetSrf command (Surface
menu: Offset Surface) to offset the
back surface by one-fourth (0.25)
inch.
6
Delete the original surface.
7
Use the BlendSrf command (Surface
menu: Blend Surface) to blend
between the two surfaces. Set edge 1
to Curvature (G2) and edge 2 to
Position (G0).
One of the things we are trying to
show here is a quick way to make a
“tucked” upholstery type transition.
Adjust the BlendSrf sliders so the
cross-section looks like the example
on the left.
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SCULPTING
Add details if time allows.
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13 Deformation tools
Deformation tools allow you to deform meshes, lines, surfaces, polysurfaces, and solids without worrying about
the integrity of the object.
Start the deformation commands from the Transform menu, or from the
Deformation Tools toolbar:
Icon
Command
Description
FlowAlongSrf
Morphs objects from a source surface to a target surface.
Splop
Copies, rotates, scales, and wraps objects on a surface, like pottery sprigging or appliqué.
OrientOnSrf
Moves or copies and rotates objects on a surface using the surface's normal direction for
orientation.
Maelstrom
Deforms objects in a spiral.
Stretch
Scales selected areas of an object in one direction.
Twist
Deforms objects by rotating them around an axis.
Bend
Deforms objects by bending along a spine arc.
Taper
Deforms objects toward or away from a specified axis.
Flow
Re-aligns an object or group of objects from a base curve to a target curve.
CageEdit
Deforms objects smoothly using one-, two-, and three-dimensional cages.
Cage
Creates a box-shaped cage object to be used with the CageEdit command to deform other
objects.
ReleaseFromCage
Removes selected objects from the influence of a control object set up by the Cage or
CageEdit command.
Deforming objects
Exercise 30—Using cage editing to deform an object
To deform an object with CageEdit
1
Open the model CageEdit_Mug.3dm.
2
Open the Cage toolbar.
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3
Start the CageEdit command (Transform menu: Cage Editing > Cage Edit
or Cage toolbar) and select the mug as the captive object.
4
For the control object, choose BoundingBox and then World.
5
Specify four cage points and degree 3 in each direction.
DEFORMATION TOOLS
The degree can be set up to degree 9. The point count must be greater
than the degree value in each direction.
6
For the Region to edit, choose Global.
The deformation of captive objects will take place throughout 3-D space
and will not end at the edges of the cage. This setting is important if
some of the captive objects are outside of the cage.
7
Move the control points on the top of the cage vertically to deform the
mug.
Cage points can be moved, dragged, scaled, sheared, rotated, bent, etc.
To limit the region to edit
To deform the handle only, a cage object is needed around the just the handle.
1
Use ReleaseFromCage (Cage toolbar) the mug from the cage object.
Delete the cage.
2
Start the Cage command and create a freestanding cage object.
3
Move the cage into place and Scale it before attaching it to the mug
4
Start the CageEdit command.
5
For the Select captive object, select the mug.
6
For the Select control object, select the pre-positioned cage object.
7
For the Region to edit, choose Local and set a Falloff distance to 5.
This tells Rhino that the distortion of the cage will affect only the region inside the cage, plus a smooth falloff
effective over 5 units moving out from the cage itself.
8
Move the two right-most vertical rows of cage points slightly to the right
in the Front viewport to increase the size of the handle.
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To CageEdit with a surface from the object
While it is possible to use any curve or surface as a control object in CageEdit, there are many cases where the
most intuitive solution is to use a curve or surface that is already part of the object.
The CageEdit command lets you select a surface, including a surface from the captive object, to use as control
object.
1
Open the model Salad_Cage.3dm.
2
Select the salad fork and start CageEdit.
3
For the Control object, click on the top surface of the fork.
A copy of the surface is extracted from the object and turned into a
control object.
4
Accept the defaults for the
subsequent options.
5
When the control points are on, move
the five points nearest the end
vertically.
This gives the fork a little more
bend to the front of the fork.
6
Undo.
To CageEdit with a curve from the object
A curve can also be used as a control object. In many cases, it makes sense to use a curve that already has the
same basic shape as the object. You can draw such a curve or extract an isocurve from the object itself and use
this as the control.
1
Re-open the model Salad_Cage.3dm without saving.
The red curve is an extracted isocurve from the bottom surface that has
been extended slightly at each end.
2
Select the salad fork and start CageEdit.
3
Select the red curve as the Control object.
4
Edit the shape of the fork by point editing the Control object.
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Exercise 31—Using other deformation tools
To stretch an object
The Stretch command allows you to scale a selected area of an object in one direction.
1
Open the model StretchWrench.3dm.
2
Select the wrench.
3
Start the Stretch command (Transform menu: Stretch).
4
For the Start and End of axis, snap to the two locked points.
5
For the Point to stretch to, pull the
cursor to one side or another to
stretch or compress the wrench.
The section of the wrench that falls
between the points that set the
stretch axis is the part that is
deformed. The object outside of this
initial axis is moved, but not
deformed. The shape of working
parts of the wrench at either end are
not affected, but the overall object
is made longer or shorter.
To place a small detail on an object
Here the goal is to place the small detail that is off to the side of the cup onto the cup handle. The detail is easy
enough to build in a flat, orthographic orientation but would be quite tedious to build accurately in place on a
curved surface.
The OrientOnSrf command can place an object on an arbitrarily curved and oriented surface with good control
over the placement and can optionally also deform the object to match the curvature of the target surface.
1
Open the model OrientOnSrf_detail.3dm.
2
Start OrientOnSrf, and select the detail object.
3
For the Base point, snap to the point marked 1.
This will be the point that is placed on the target surface.
4
For the Reference point, snap to the point marked 2.
This point and the line between it and the base point will be used to set
scaling and orientation on the target surface. The current CPlane Z
direction will be mapped to the target surface normal.
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DEFORMATION TOOLS
The Surface to orient on is the handle surface of the cup.
In the dialog, make sure Rigid is not checked.
This will allow the object to deform against the target surface.
Set Scale and Rotation to Prompt so that you can set these
interactively as needed.
Rotation defaults to setting the line between the base and reference
points set above to the U direction of the target surface.
Click OK.
6
For the Point on surface to orient to, snap to the point on the handle
marked 3.
Notice that in the preview the location corresponding to the base point is
what tracks on the target surface.
With the command-line Copy=Yes option, you can place the object
without disturbing the flat original and you can place multiple copies.
Set Copy=Yes.
There are other command-line options for Flip, in case the object maps
to the wrong side of the surface, and IgnoreTrims. If IgnoreTrims is
set to Yes, the object can be placed anywhere on the underlying surface
of a trimmed face, otherwise location is restricted to the trimmed face.
7
Click to set the location point.
Since Scale was set to Prompt, you can drag interactively to scale the
object or you can type in a scale factor at the command-line. In this
case, a Scale factor of .7 works well.
8
You can rotate the object on its base point. Holding Ortho can lock the
angle to match the construction plane, or you can type in an angle at the
command-line. In this case, the Rotation angle is zero.
After setting the angle, the object is mapped to the target surface.
9
At this stage, you can continue to add details to the handle or press Enter
to end the command.
To deform an object in a spiral
In this example, we will deform the spokes of a wheel to give them a twisted look with the Maelstrom command.
1
Open the model Maelstrom.3dm.
2
Select the spokes of the wheel and start the
Maelstrom command (Deformation Tools toolbar).
3
In the Front viewport, set the Center of
Maelstrom at 0.
4
For the Radius, snap to the point on the locked
circle near the center of the wheel (1).
5
For the Second radius snap to the point to the
right of the wheel on the arc (2).
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DEFORMATION TOOLS
For the Coil angle, drag the cursor around the
circle about 15 degrees to deform the spokes into a
soft spiral shape.
To deform an object by flowing it along a curve
In this example, we will flow an object along a curve while recording history. This will allow us to do a secondary
deformation of the original object and see the update on the flowed piece.
1
Open the model Flow & Twist.3dm.
2
On the Status bar, turn Record History on.
3
Right-click the Record History pane, and select the Update Children
checkbox.
4
Select the polysurface and start the Flow command (Transform menu:
Flow Along Curve).
5
Set Copy=Yes, Rigid=No, Local=No, and Stretch=Yes.
6
For the Base curve select the straight line (through the center of the
polysurface).
7
For the Target curve, select the circle.
A copy of the polysurface flows around the circle.
8
Select the original polysurface, and
start the Twist command (Transform
menu: Twist).
9
Twist the original polysurface 360
degrees, using the straight line as the
twist axis.
The polysurface created with the
Flow command and History updates
to match the twisted polysurface.
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14 Blocks
There are two main advantages to using blocks in Rhino:
• Identical objects can be edited or replaced at the same time.
• Since many identical objects refer to one definition, files with many repeated objects can be smaller,
sometimes much smaller, than files where each of those is its own independently defined object.
In Rhino, a block appears as a collection of objects. These can be simple 2-D or complex 3-D objects. A block can
be composed of lines, polylines, freeform curves, surfaces, polysurfaces, solids, dimensions, text, and even other
blocks. When a block contains other blocks, these are said to be nested. The level of nesting that may be used is
not limited.
Instances and definitions
Each block has a single definition. The definition is the set of objects that comprise the block. This definition is
hidden from the user. Its purpose is to provide the definition for the instances of the block that appear in the
model. There can be any number of instances of a block, but only one definition. Thus, when the user modifies a
block definition, all of the instances of that block will reflect the changes.
Defining blocks
Blocks can be defined using the Block command. This adds a new block definition and leaves one instance of the
block in place.
Block instances can be added by copying existing instances, or by using the Insert command. Insert allows you
to choose from a list of existing block definitions, or to browse to an external file.
Note: There may be block definitions in a file for which no instances appear. Deleting an instance does nothing
to the definition.
Insertion points
Each block has an insertion point. This is a base location for the block as a whole and is in fact the point used
when a block instance is added using the Insert command.
Embedded and linked blocks
When the definition of a block is saved in the Rhino file, the block is said to be embedded. If the block definition
exists as a separate file, the block is linked. In the latter case, saved changes to the external file are what govern
the appearance of the block instances in all of the files into which it is inserted.
Layers and blocks
Layers can be confusing when using blocks. It is important to keep in mind that any instance of a block will exist
on some layer just like any Rhino object. Typically, this is the layer that is current when the instance is inserted,
but the instance layer can be changed, just like any other type of object. However, each object in the block
definition also exists on some layer, independent of the block instance as a whole. For example, two instances of
the same block can be on different layers, but the objects comprising the block definition will be on the same
layers in each instance.
Turning on or off a layer containing an instance will show or hide the entire instance. Turning on or off layers of
the objects contained in a block will show or hide that part in every instance of the block, regardless of what layer
the instance is on.
Linked blocks' layers (reference layers) can be shown in the layer panel as normal layers, or displayed as special
reference layers.
Here are some rules that are good to keep in mind when using blocks:
• The layer that is current when the block instance is inserted is called the reference layer. The inserted
instance resides on this layer.
• The visibility of the entire block is controlled with the block reference layer.
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• If you turn the block reference layer off, the entire block will not be visible, regards less of the layers to which
the geometry is assigned.
• Objects in the block that have properties assigned by parent; will have a unique behavior when grouped
together in a block.
• Object properties of display color, plot color, and plot width can be assigned by parent.
• Objects assigned by parent and grouped into a block have a chameleon-like property. They change to display
the color and the plot weight of the block’s reference layer.
• This powerful feature allows a block to look different, without creating a separate block.
• The layer that is current when the block is made does not have any bearing on the block definition itself. The
layers of the objects in the block definition, and the layer that is current when an instance is inserted are
important in how the block instances behave with respect to visibility.
Editing blocks
Block definitions are most easily edited using the BlockEdit command, or by double-clicking on a block instance.
If the block is a linked block, editing will open the linked file in a new instance of Rhino and the current Rhino will
be suspended until that second Rhino is closed.
Exercise 32—Block basics
To make a block
1
Start a new model.
2
Draw a box and a sphere somewhere
near the origin.
3
Select the two objects
4
Use the Block command (Edit
menu: Blocks > Create Block
Definition) to make a block.
5
For the Block Base Point, snap to a
corner of the box.
The point you select will become the insertion point for the block.
6
In the Block Definition Properties dialog Name field, type Test 1, press OK.
7
Use the Insert command (File menu: Insert) to insert the new block.
8
In the dropdown list at the top of the Insert dialog, select Test 1.
Make sure to insert as Block Instance and not as a Group or
Individual Objects. Accept the defaults for Scale and Rotation.
9
Place the block in the Rhino scene.
Notice that the cursor follows the location that you set as the block base
point when the block was created. This is the insertion point.
10 Select the block instance and make one or two more copies of this
instance using the Copy command.
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To redefine a block
1
Double-click one of the block
instances.
This opens the Block Edit dialog,
returns the original geometry at
the block location, and turns all of
the other blocks to a dark shaded
color. The sphere and box now
select individually.
2
Use FilletEdge to fillet the edges of
the box, Move the sphere slightly,
and add a Circle.
3
Click OK on the Block Edit dialog.
Notice the other instances of the block placed and copied earlier are now
updated and look like the redefined block. Instead of a box and a
sphere, the blocks have a filleted box, a moved sphere, and a circle.
Exercise 33—Inserting files as blocks
The Insert command has options for insertion point, scale, and rotation. The block can be inserted as a block
instance, a group, or individual objects.
To insert a block
1
Open the Blocks-mm.3dm model.
2
Make the Fasteners layer current.
3
Use the Insert command (File menu: Insert) to insert the FILH-M6-1.0-25.3dm model.
4
In the Insert dialog, choose Insert as Block Instance, and click OK.
5
In the Insert File Options dialog, choose Embed and link, click OK.
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6
For the Insertion point, snap to the
center of one of the holes in the
cover.
7
Copy the cap screw around to all of
the other holes.
BLOCKS
To change the block
1
Start the Block Manager command (Edit menu: Blocks > Block Manager).
2
Select the block definition for the cap screw that you inserted.
3
Click the Properties button.
4
In the Block Definition Name box, type Fastener.
5
Under File name, choose Browse, select RH-M6-1.0-25.3dm, and click Open.
6
In the Block Definition Properties dialog, click OK.
7
In the Block Manager, click Update.
The cap screws change to the round head cap screws and the color
changes to match the layer color of the insertion layer.
Note: Even on a small file like this, the size difference can be significant. If
this file would have had the cap screws imported and then copied
around, it would be 35-40 percent larger than it is with block
instances. The use of blocks can help to reduce problems caused by
large file sizes.
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15 Troubleshooting
The troubleshooting tools are most often used for repairing files imported from other programs.
Some Rhino operations can make “bad objects” under certain circumstances. Bad objects may cause failure of
commands, shade and render badly, or export incorrectly.
It is good practice to use the Check (Analyze menu: Diagnostics > Check) or SelBadObjects (Analyze menu:
Diagnostics > Select Bad Objects) commands frequently during modeling. If errors can be caught right away the
objects can often be fixed more easily than if the bad part is used to make other objects.
If the goal is to create a rendering or a polygon mesh object, some errors can safely be ignored so long as they do
not get in the way of building the model itself in later stages.
For objects that must be exported as NURBS to other applications for further engineering or manufacturing, it is
best to eliminate as many errors as possible.
General strategy
The troubleshooting steps will be the same, whether or not the file was created in Rhino or another application.
Over time, you will discover patterns of problems and develop procedures to fix them.
Although the techniques used vary greatly depending on the individual file, we will focus on a general strategy for
repairing problem files
Start with a clean file
When possible, spending a little time in the originating application to export a “clean” file will save a great deal of
cleanup work later. Unfortunately, this is not always an option.
Guidelines for Repairing Files
1
Open the file.
2
Hide or delete extra data.
Use the SelDup command (Edit menu: Select Objects > Duplicate Objects) to find duplicate entities and
delete them or move them to a “duplicate” layer in case you need them later.
3
Hide curves and points.
Use the SelSrf command (Edit menu: Select Objects > Surfaces) to select all the surfaces or the SelPolysrf
command (Edit menu: Select Objects > Polysurfaces) to select all the polysurfaces, Invert (Edit menu:
Select Objects > Invert) the selection, and move the selected items to another layer and turn it off. This will
leave only surfaces or polysurfaces on the screen.
4
Check for bad surfaces.
The Check and SelBadObjects commands will determine if some of the surfaces in the model have
problems in their data structures. Move these surfaces to a “bad surfaces” layer for later clean up.
If the bad object is a polysurface, use the ExtractBadSrf command to extract the bad surfaces from the
original polysurface.
Then you can fix the bad surfaces and then use the Join command to reattach them to the good part of the
polysurface.
5
Shade the viewport and visually inspect the model.
Does it look like you expected it would? Are there obviously missing surfaces? Do surfaces extend beyond
where they should? The trimming curves needed to fix them may be on the “duplicate” layer.
6
Look at the Absolute tolerance setting in the Document Properties dialog on the Units page.
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Is it reasonable? Free-form surface modeling requires an intelligent compromise in modeling tolerance.
Surface edges are fitted to neighboring surface edges within the specified modeling tolerance. The tighter
the tolerance, the more complex these surfaces become and system performance suffers. There is no point
in fitting edges to a tight tolerance that is not supported by your down-stream manufacturing processes or
by the precision of the input data.
7
Join (Edit menu: Join) the surfaces.
When joining, edges are joined if they fit within the specified modeling tolerance. If they are outside the
tolerance, they are not joined. Joining does not alter the geometry. It only tags the edges as being close
enough to be treated as coincident, and then one edge is discarded.
Look at the results on the command-line. Did you get as many polysurfaces as you thought you would?
Sometimes there are double surfaces after importing an IGES file. Usually, one will be complete and the
second one will be missing interior trims. When the Join happens, you have no control over which of the two
surfaces it will select. If you suspect this has occurred, try joining two naked edges. If there is no nearby
naked edge where one should be, Undo the Join, and select for duplicate surfaces. Delete the less complete
surfaces and try the Join again.
8
Check for naked edges.
Naked edges are surface edges that are not joined to another surface. During the Join process, the two
edges were farther apart than the specified modeling tolerance. This may be from sloppy initial modeling, a
misleading tolerance setting in the imported IGES file, or duplicate surfaces. If there are too many naked
edges showing when you run the ShowEdges command (Analyze menu: Edge Tools > Show Edges),
consider undoing the Join and relaxing the absolute tolerance and try the Join again. It is likely that the
original modeling was done to a more relaxed tolerance and then exported to a tighter tolerance.
Note: You cannot improve the tolerance fitting between surfaces without substantial remodeling.
9
Join naked edges or remodel.
The joining of naked edges can be a mixed blessing. It is a tradeoff and may cause problems down-stream.
If your reason for joining the edges is for later import into a solid modeler as a solid, or a meshing operation
like making an STL file, using the JoinEdge command (Analyze menu: Edge Tools > Join 2 Naked Edges)
will not generally cause any problems. If you will be cutting sections and most other “curve harvesting”
operations, the sections will have gaps as they cross edges that were joined outside of tolerance. The gap to
be spanned is displayed prior to joining. If the gap is less than twice your tolerance setting, you can proceed
without worry. If the gap is too wide, consider editing or rebuilding the surfaces to reduce the gap. Join and
JoinEdge do not alter the surface geometry. They only tag edges as being coincident within the specified
tolerance.
10 Repair the bad surfaces.
It is best to repair one bad surface at a time, and Join them into the polysurface as you go. In order of least
destructive method to most radical, the problems that caused them to fail Check can be repaired by the
following:
•
•
•
•
Rebuild edges
Detach trim curves and re-trim
Rebuild surfaces (surfaces change shape)
Replace surfaces - harvest edges from surrounding surfaces, cut sections through bad surfaces and build
replacement surfaces from the collected curves.
11 Check for bad objects.
Sometimes joining surfaces that pass check can result in a polysurface that fails check. Generally, this is
caused by tiny segments in the edge or trimming curves that are shorter than the modeling tolerance.
Extract the adjoining surfaces, check them, use the MergeEdge command (Analyze menu: Edge Tools >
Merge Edge) to eliminate these tiny segments, and join them back in. You are finished when you have a
closed polysurface that passes Check and has no naked edges. As you are joining and fixing surfaces, it is
generally a good idea to run Check from time to time as you work.
12 Export.
Now that the model has been cleaned up and repaired, you can export it as IGES, Parasolid, or STEP for
import into your application.
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Exercise 34—Troubleshooting
To try these procedures
1
Open the model Check 01.3dm
This file has a bad object.
2
Find the bad object, fix it, retrim, and
rejoin the surfaces.
3
Open the file Check 02.igs.
This file has several problems. It is
representative of commonly found
problems with IGES files.
4
After repairing the bad object and
trimming it, look for other objects that
do not appear to be trimmed correctly.
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16 Polygon meshes
A mesh defines a shape using a set of point locations. A mesh knows the location of vertices, but does not know
about anything in between the vertices.
Although Rhino is a NURBS modeler, some tools are included to create and edit polygon mesh objects.
We will explore different methods for creating and editing meshes for different purposes. Downstream
requirements are the most important considerations when determining which technique to use for meshing. If the
mesh is going to be used for rendering, you will use different mesh settings than you would use for a mesh that
will be used for manufacturing (machining or prototyping).
Render meshes
When meshing for rendering, appearance and speed are the most important considerations. You should strive to
achieve a mesh with as few polygons as possible to get the look you require. The polygon count will affect
performance, but too few polygons might not give you the quality you are after in the final rendering. Generally, if
it looks good, then you have the right setting.
Meshes for manufacturing
Meshing for manufacturing is an entirely different situation. You should try to achieve the smallest deviation of the
mesh from the NURBS surface. The mesh approximates the NURBS surface and deviation from the NURBS surface
may be visible in the final manufactured part.
The original NURBS surface.
Meshing for manufacturing, if the
mesh is not accurate enough, you
will see visible polygon edges on
your final products.
Exercise 35—Meshing
1
Open the model Meshing.3dm.
2
Shade the Perspective viewport and inspect the curved edge between
the surfaces.
A series of angular gaps allows the background color to show.
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Using the same meshing setting, the
rendering system can hide polygon
edges and visually "smooth" the
mesh to show a smooth look.
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POLYGON MESHES
Get back to a wireframe view.
The edges appear to be exactly coincident. The gaps you saw in the
shaded view were due to the polygon mesh Rhino uses to create shaded
and rendered views. The polygons are so coarse at the edges that they
are clearly visible as individual facets.
4
In the Document Properties dialog, on the Mesh page, click Smooth &
slower.
5
Inspect the curved edge between the surfaces.
The overall rounded surface is smoother and cleaner looking but the
edges still have gaps.
Although it is possible to use the Custom settings to refine the shaded
mesh enough to eliminate the jagged edges, this will affect all render
meshes in the model. This will increase the amount of time necessary to
create meshes and may decrease the performance of shading and
rendering to unacceptable levels.
To eliminate the gaps without refining the mesh settings, join adjacent
surfaces to each other.
6
Join the three surfaces together.
The mesh is refined along each side of the joined edges so that they
match exactly across the edge. This eliminates the gaps visible earlier.
Rhino saves these polygon meshes with the file in order to reduce the
time needed to shade the model when it is reopened. These meshes can
be very large and can increase the file size considerably.
7
On the File menu, click Save Small.
This saves the file without the render meshes and the bitmap preview,
to conserve disk file space.
Note: The meshes created by render and shading modes on NURBS surfaces and polysurfaces are invisible in
wireframe display, not editable, and cannot be separated from the NURBS object. Render meshes are
managed for the current model in the Document Properties dialog, on the Mesh page. In addition, you
can change per object Render Mesh Settings on the Object Properties dialog.
Meshes from NURBS objects
The meshes created by the Mesh command are visible and editable, and separate from the NURBS objects from
which they were created.
Rhino has two methods for controlling mesh density: Simple Controls or Detailed Controls. With Simple
Controls, a slider is used to roughly control the density and number of mesh polygons. With Detailed Controls,
you can change any of seven settings and enable four check boxes to control the way the mesh is made.
The mesh is created in three steps based on the detailed criteria: initial quads, refinement, and adjustment for
trim boundaries. These steps are not shown to you; it is all automatic.
In the following exercise, we will discuss each of the seven detailed controls and illustrate their influence on the
model.
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Polygon Mesh Detailed Options
Density
Uses a formula to control how close the polygon edges are to the original surface. Values between 0 and 1.
Larger values result in a mesh with a higher polygon count.
Maximum angle
The maximum angle between adjacent faces in the mesh. Smaller values result in slower meshing, more
accurate meshes, and higher polygon count.
Maximum aspect ratio
The maximum ratio length to width of triangles in the initial grid quads.
Minimum edge length
Bigger values result in faster meshing, less accurate meshes and lower polygon count. Controls the minimum
length of the sides of quads and triangles of the mesh.
Maximum edge length
Smaller values result in slower meshing and higher polygon count with more equally sized polygons. When
Refine mesh is selected, polygons are refined until all polygon edges are shorter than this value. This is also
approximately the maximum edge length of the quads in the initial mesh grid.
Maximum distance, edge to surface
Smaller values result in slower meshing, more accurate meshes, and higher polygon count. When Refine is
selected, polygons are refined until the distance from a polygon edge midpoint to the NURBS surface is smaller
than this value. This is also approximately the maximum distance from polygon edge midpoints to the NURBS
surface in the initial mesh grid.
Minimum initial grid quads
Bigger values result in slower meshing, more accurate meshes, and higher polygon count with more evenly
distributed polygons. This is the minimum number of quads in the mesh before any of the other refinements
are applied. If you set a number for this and set all other values to 0, this will be the mesh returned.
To create a mesh using detailed controls
1
Select the object.
2
Start the Mesh command (Mesh menu: From NURBS
Object).
The Polygon Mesh Options dialog appears.
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In the Polygon Mesh Options dialog, click Detailed Controls.
The Polygon Mesh Detailed Options dialog appears. These settings are saved to the Windows Registry
when you exit Rhino.
4
In the Polygon Mesh Detailed Options dialog, set the
following, if they are not already set:
Density=0.5
Maximum angle=0.0
Maximum aspect ratio=0.0
Minimum edge length=0.0001
Maximum edge length=0.0
Maximum distance, edge to surface=0.0
Minimum initial grid quads=0
Check Refine mesh.
Uncheck Jagged seams.
Uncheck Simple planes.
Check Pack Textures.
Click OK.
A mesh is created using the default settings.
5
Hide the original polysurface, change
the viewport display mode to
Rendered, and use the Flat Shade
display mode to view the output.
The Flat Shade display mode shows
what the model would look like if it
were output for prototyping or
machining at this mesh density.
6
Undo the previous operation, repeat
the Mesh command, and then make
the following changes in the Polygon
Mesh Detailed Options dialog:
Maximum angle=0.0
Maximum aspect ratio=2.0
Click OK.
Note the changes in polygon count,
the shape of the mesh, and the
quality of the flat-shaded mesh.
7
Undo the previous operation, repeat
the Mesh command, and then make
the following changes in the Polygon
Mesh Detailed Options dialog:
Minimum initial grid quads=16
Note the changes in polygon count,
the shape of the mesh, and the
quality of the flat-shaded mesh.
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POLYGON MESHES
Undo the previous operation, repeat
the Mesh command, and then make
the following changes in the Polygon
Mesh Detailed Options dialog:
Minimum initial grid quads=500
Note the changes in polygon count,
the shape of the mesh, and the
quality of the flat-shaded mesh.
9
Undo the previous operation, repeat
the Mesh command, and then make
the following changes in the Polygon
Mesh Detailed Options dialog:
Maximum distance, edge to
surface=0.01
Minimum initial grid quads=0
Note the changes in polygon count,
the shape of the mesh, and the
quality of the flat-shaded object.
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PART IV:
Rendering
17 Rendering
With Rhino, creating design renderings of Rhino models is easy. Simply add materials, lights, and render.
There are several controls in the basic Rhino renderer that allows you to create some interesting special effects.
In the following exercise, we will render with and without isocurves, adjust colors, transparency, and ambient light
to create images with special effects.
Exercise 36—Rhino rendering
1
Open the model Finished Detergent Bottle.3dm.
2
On the Render menu, click Current Renderer, and then click Rhino
Render.
3
In the Document Properties dialog, on the Rhino Render page, scroll
down to the Miscellaneous section and check Use lights on layers that
are off.
4
Select the bottle and use the Properties command, on the Material page,
to assign it a Basic color of Light Gray. Set the Gloss Color to Light
Blue (R=163, G=163, B=194) and the Gloss Finish to 60. Name the
material Blue plastic.
5
Select the cap and use the Properties command, on the Material page, to
assign it a Basic color of Tan (R=222, G=172, B=112). Set the Gloss
Color to White and the Gloss Finish to 90. Name the material Tan
plastic.
6
Render the Perspective viewport.
To render with isocurves displayed
1
Start the DocumentProperties command.
2
In the Document Properties dialog, on the Rhino Render page, scroll down to
the Miscellaneous section and check Render surface edges and isocurves.
3
Render the Perspective viewport.
The wire color is the same as the layer color because the object's wire color is
set to By Layer.
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Use the Properties command, on the Object page, to change the Display
Color to black, and then Render the Perspective viewport.
The objects are rendered with black isocurves.
To render a transparent material with isocurves displayed
1
Use the Properties command, on the Material page, to change
Transparency to 70, and then Render the Perspective viewport.
The objects are rendered with black isocurves and the material is transparent.
2
Use the Properties command, on the Object page, to change the Display
color to white, and then Render the Perspective viewport.
The objects are rendered with white isocurves and the material is
transparent.
3
Experiment with these adjustments to get the desired effect.
4
Turn on the Lights layer and adjust the properties of the lights for more subtle
changes.
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Rendering properties
With Rhino’s Material Editor, you can assign any combination of color,
reflectivity, transparency, highlight, multiple bitmaps, and
environments.
In the following exercise, we will add environment settings, add
materials and lights, create custom materials, edit materials, add
decals to objects, and render a scene.
Exercise 37—Rendering a scene
To set up the rendering properties
The rendering properties include environment settings, render, and ambient light settings.
1
Open the model Mug.3dm.
2
From the Panels menu, click Environments and
Ground Plane to open the panels we will use to set a
background environment, and to add an infinite ground
plane to the scene.
This can also be accomplished by right-clicking on the
Properties panel tab.
3
In the Environments panel, set the background to
Environment and click [+] to add an environment.
4
In the Open dialog, double-click Environments, click
Rhino Interior.renv, and then click Open.
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In the Ground Plane panel, check On for Ground
plane options.
The ground plane will automatically be set for the
default material.
6
Render the Perspective viewport.
To assign materials to layers
1
In the Layers panel, select the Floss Blister layer, and click in its Material column.
2
From the Layer Material dialog, choose Thin Clear Plastic from the dropdown list, and click OK.
3
In the Layers panel, select the Floss Container and Toothpaste Tube layers, and click in the Material
column of one of them.
4
From the Layer Material dialog, choose White Shiny from the dropdown list, and click OK.
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Scene lighting
So far, we have used the default lighting in Rhino. This invisible light comes from over the viewer’s left shoulder.
It is enough to illuminate the model and to give you a starting point. The default light is on only if no other lights
are on in the scene and it cannot be modified. In order to control the lighting, we are going to add our own lights.
To add lights
1
From the Render menu, click
Create Spotlight.
2
Make a large spotlight that shines on
the scene from the front and slightly
above as shown on the right.
Use elevator mode, or turn on the
spotlight’s control points and drag
them to move the light into
position.
Spotlight, front view
Spotlight, right view
Spotlight, perspective view
3
Adjust the Properties of the light as shown:
Shadow intensity=40
Spotlight hardness=50
Light intensity=50
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RENDERING
Render the Perspective viewport.
This makes a nicer image, but two or three lights in a scene
improve the rendering. We are going to add another light to create
highlights on the mug.
To add a second light
1
Select the first light.
2
In the Top viewport, Mirror the light across the vertical axis.
3
Adjust the Properties of the light as shown:
Shadow intensity=60
Spotlight hardness=30
Light intensity=40
Spotlight, front view
4
Render the Perspective viewport.
To add a third light
1
From the Render menu, click Create Spotlight.
2
Make a large spotlight that shines on the scene from the below.
This light will be used to add a little light to the underside of the
toothpaste tube and the floss packet.
3
Adjust the Properties of the light as shown:
Shadow intensity=0
Spotlight hardness=25
Light intensity=20
Spotlight, front view
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Render the Perspective viewport.
It is important to turn the shadow intensity to 0 so that the light will
penetrate through the ground plane.
To make a material from scratch and assign it to a layer
1
Open the Layers dialog.
2
In the Layers dialog, select the Mug layer, and click in the Material
column.
3
In the Layer Material dialog, click More Types.
4
In the Types dialog, click on Basic Material and then click OK.
5
Name the material Green Ceramic.
Set the following:
Color to Green (R=21, G=210, B=180)
Gloss finish to 90
Gloss color to (R=198, G=247, B=255)
Reflectivity to 30
Reflectivity color to (R=21, G=225, B=180)
6
Render the Perspective
viewport.
Image and bump maps
Instead of simply using color for your material, you can use an image of a material. You can scan photographs
and real objects like wallpaper and carpet, create patterns in a paint program, or use images from libraries of
textures from other renderers, or other sources of bitmap images.
Image mapping uses bitmap images to add detail to the material. You can use images to alter many attributes of
the material’s surface including its color pattern and apparent three-dimensional surface quality (bump).
Procedural bumps add a random roughness or knurled quality to the surface.
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To create a new material from an existing material
1
In the Materials panel, right-click White shiny, and then
click, Duplicate.
2
Name the duplicated material Toothpaste Cap.
3
In the Textures section, under Color, click (empty –
click to assign).
4
In the Open dialog, double-click on Tube Bump.png.
5
In the Textures section, click on Tube Bump to see
additional settings.
6
In the Mapping section, set the U Repeat to 8.
7
Assign the new material to the Toothpaste Cap layer or
assign it to the object. Adjust the mapping as necessary.
8
Render the Perspective viewport.
The cap has a grooved appearance. The repeat number
determines how close together the grooves appear.
Decals
A decal is the method Rhino uses to apply an image bitmap to a specific area of an object.
The decal mapping type tells Rhino how to project the decal onto your object. The four mapping types, planar,
cylindrical, spherical, and UV, are described below.
Decal options
Planar
The planar mapping type is the most common mapping type. It is appropriate when mapping to flat or gently
curved objects.
Cylindrical
The cylindrical mapping type is useful for placing decals onto objects that curve in one direction, such as labels
on wine bottles.
The cylindrical projection maps the bitmap onto the mapping cylinder with the bitmap’s vertical axis along the
cylinder’s axis, and the horizontal axis around the cylinder, like a wine bottle label.
Spherical
The spherical mapping type is useful for placing images onto objects that curve in two directions. The spherical
projection maps the bitmap onto the mapping sphere with the bitmap’s vertical axis (height), curving from
pole to pole, and the horizontal axis curving around the equator.
Initially the mapping sphere’s equator is assumed to be parallel to the current construction plane, and the
sphere’s axis is parallel to the construction plane z-axis. Later you can modify its orientation.
UV
UV mapping stretches the image to fit the whole surface. The U- and V-directions of the surface determine
which direction the map is applied. There are no controls.
UV mapping works well for organic shapes, hair, skin, and plant structures.
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On trimmed surfaces and polysurfaces, only parts of the image may appear in the rendering. UV mapping
stretches the bitmap over the whole UV range of the surface. If some of that range has been trimmed away,
the corresponding parts of the bitmap will not be visible.
To map a decal with planar projection
1
Turn on the Decal reference planes
layer.
2
Select the toothpaste box.
3
In the Properties panel, on the
Decals page, click Add
4
Select the Minty Green-Box
Upper.jpg.
5
Click Open.
6
Click Planar and then OK.
7
Using object snaps, pick locations for the decal Location (1), the Width
(2), and Height (3) direction of the decal.
These three points define the decal plane’s location and extents. The
decal plane must lie on or behind the surface of the object. The decal
projects up from the decal plane. Portions of the surface that lie behind
the decal plane will not show the decal.
After the decal is placed, you can click the control points on the decal
control wireframe to move, rotate, or stretch the decal.
8
Press Enter or right-click to set the location.
Place more decals
1
Continue to place bitmaps on the sides, flaps, and ends of the box.
2
Use planar mapping to put the decals on the floss container and the
toothpaste tube.
The magenta rectangles were created to assist with placement of the
decals.
3
Render the Perspective viewport.
To map a decal with cylindrical projection
The circle of the mapping cylinder is initially parallel to the current construction plane, and the cylinder’s axis is
parallel to the construction plane z-axis.
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1
Select the mug.
2
Start the Properties command (Edit menu: Object Properties).
3
In the Properties panel, on the Decals page, click Add.
4
Select the Sailboat-002.tif.
5
In the Decal Mapping Style dialog, click Cylindrical.
6
Use the magenta circle for the Center of cylinder and a Radius
or Diameter for the decal.
RENDERING
The controls then let you click the control points on the decal
control wireframe to move, rotate, or stretch the decal cylinder.
7
Press Enter or right-click to set the location.
8
Render the Perspective viewport.
9
Turn on the toothbrush layers.
10 Adjust the materials settings and lighting as needed to get the
desired results.
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