Lightscape User Guide

Lighting analysis provides valuable design information if you use real-world lighting and materials in your scene. Use lighting analysis to evaluate the photometric performance of your scene.

Summary

In this chapter, you learn about:

•

Displaying light distribution

• Analyzing lighting statistics

•

Controlling analysis grids

• Using workplanes.

Displaying Light Distribution

Pseudo-coloring techniques are used to illustrate the distribution of light directly onto the surfaces of a 3D scene. You modify how this information appears using the Display panel of the Lighting Analysis dialog.

About Lighting Analysis

After you run the radiosity process, use lighting analysis to visualize the distribution of light over the surfaces of your model. You can query either luminance or illuminance and visualize the distribution of these quantities for any surface.

You view the distribution of light using pseudocoloring techniques or by superimposing a grid of illumination values over a selected surface.

Model after radiosity processing and ray tracing

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12 Lighting Analysis

Pseudo-Color Visualization

You use a pseudo-color representation to visualize the luminance or illuminance of your model.

Top: Pseudo-color display of luminance values using a Linear scale

Bottom: Pseudo-color display of luminance values using a Logarithmic scale

Lighting Quantities

Use the Quantity list to select an energy visualization quantity.

Select: To:

Luminance Visualize the distribution of light reflected off of the surfaces.

Illuminance Visualize the distribution of light incident on the surfaces.

Display Modes

Use the Display list to enable energy visualization modes.

Select:

Normal

Color

Gray Scale

To:

Turn off pseudo-color (or grayscale) visualization.

Display the lighting distribution using colors ranging from blue to green, yellow, and red. Low values are closer to blue and high values are closer to red.

Display the lighting distribution using gray levels from black to white. The higher the value of the target quantity, the brighter the color displayed.

Scale Options

Use the Scale list to select options related to visualization graphing scale.

Select: To:

Linear Map the target quantity to display colors using a linear scale. This is the default setting.

Logarithmic Map the target quantity to display colors using a logarithmic scale.

This is useful when the illumination of the surfaces of interest is low compared to the maximum illumination in the scene.

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Lightscape

Displaying Light Distribution

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Cutoff Values

Use the cutoff values to set graphing thresholds. Use the following thresholds to bracket a region of interest for bringing out more differentiation in a surface.

Use: To:

Minimum Set the threshold to a value below which the system maps values of the target quantity to the left-most display color or grayscale level of the color chart.

By default, Minimum is 0.

Maximum Set the threshold to a value above which the system maps values of the target quantity to the right-most display color or grayscale level of the color chart.

By default, Maximum is the maximum value of the target quantity in the current radiosity solution.

To set illuminance or luminance values:

1.

Choose Light | Analysis.

The Lighting Analysis dialog appears.

Note: When most values are contained in a small subset of the target quantity range, the display shows most of the environment in a single color.

Use minimum and maximum thresholds to narrow the region of interest and show more differentiation.

6.

Click Apply.

The model is displayed in pseudo-color. In this mode, you can adjust the view or zoom to check lighting values in different areas of your scene. You can also print pseudo-color displays with their accompanying scale.

7.

If necessary, adjust the range of light energy values by entering minimum and maximum range values in the appropriate boxes. This adjusts the amount of lighting differentiation. For instance, there are probably very bright areas in your scene near the lights that are skewing the range of displayed lighting values. Try clamping off some of these higher light energy values.

To turn off pseudo-color display:

1.

Choose Light | Analysis.

The Lighting Analysis dialog appears.

2.

Click the Display tab.

3.

From the Display list, select Normal.

2.

Click the Display tab.

3.

From the Quantity list, select Luminance or Illuminance.

4.

5.

From the Display list, select Color or Grayscale.

From the Scale list, select Linear or Logarithmic.

4.

Click Apply.

Pseudo-color is turned off.

Note: You can also disable pseudo-color display by clicking Cancel in the Lighting Analysis dialog.

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