Choosing a camera for ANY-maze

Choosing a camera for ANY-maze
Choosing
a camera
for ANY-maze
ANY-maze
www.anymaze.com
Choosing a camera for ANY-maze
1
2
3
4
5
Introduction .......................................................................................................................................... 4
1.1
USB webcams ................................................................................................................................ 4
1.2
Industrial USB cameras ................................................................................................................. 4
1.3
Analogue cameras ......................................................................................................................... 5
1.4
Using multiple cameras................................................................................................................. 5
USB cameras ......................................................................................................................................... 6
2.1
Introduction .................................................................................................................................. 6
2.2
Webcams - recommended specifications ..................................................................................... 6
2.3
Industrial cameras - recommended specifications ....................................................................... 6
2.4
Extending a USB cable................................................................................................................... 7
2.5
Mounting a USB camera ............................................................................................................... 8
Analogue cameras and digitisers .......................................................................................................... 9
3.1
Introduction .................................................................................................................................. 9
3.2
Choosing an analogue camera ...................................................................................................... 9
3.3
Choosing a lens ........................................................................................................................... 10
3.4
Choosing a digitiser ..................................................................................................................... 11
3.5
Video cables, connectors and camera mounts ........................................................................... 12
Connecting multiple cameras ............................................................................................................. 13
4.1
Introduction ................................................................................................................................ 13
4.2
Connecting multiple USB cameras .............................................................................................. 13
4.3
Connecting multiple analogue cameras...................................................................................... 15
4.4
Connecting a mix of USB and analogue cameras ........................................................................ 15
Lens calculations ................................................................................................................................. 17
5.1
Introduction ................................................................................................................................ 17
5.2
Lens angles .................................................................................................................................. 17
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5.3
Calculating the required horizontal lens angle ........................................................................... 17
5.4
Vari-focal lenses .......................................................................................................................... 19
Working in low light or darkness ........................................................................................................ 20
6.1
Introduction ................................................................................................................................ 20
6.2
Tracking in low light .................................................................................................................... 20
6.3
Tracking in darkness.................................................................................................................... 20
Installing and configuring cameras & digitisers .................................................................................. 22
7.1
Introduction ................................................................................................................................ 22
7.2
Installing USB cameras ................................................................................................................ 22
7.3
Installing and configuring an RTV-24 digitiser ............................................................................ 22
7.4
Testing your equipment with ANY-maze .................................................................................... 23
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1
Introduction
ANY-maze supports a range of different camera types, but some of these are now considered to be legacy
devices and if you're planning to buy a new camera then you'll essentially be choosing between:
 A USB webcam
 An industrial USB camera
 An analogue camera
1.1
USB webcams
USB webcams are inexpensive and provide good quality images in most conditions. They do, however,
have a couple of drawbacks. They have fixed lenses (you can't change the lens) which usually have a lens
angle of around 40°; this might be a problem if you have a large piece of apparatus, as the only way to
get the apparatus into the camera's field of view will be to move it further away. Also, they usually have
quite short captive cables, which means you can't unplug the provided cable and plug in a longer one.
That said, you can purchase extension cables.
Key points:
 Low cost - typically around $50
 Can't change the lens
 Short, captive cable (but can be extended by 4.8m)
 Good for use in normal lighting conditions
 Some cameras are infrared sensitive and can be used with infrared lights to track in the dark
 Recommended for apparatus which is not very large and which is not used in low light, for
example Plusmaze, Y-maze, open-field, etc.
1.2
Industrial USB cameras
Generally speaking, industrial USB cameras are the best choice for ANY-maze. They provide good quality
images in most lighting conditions, have interchangeable lenses and are always infrared sensitive, which
means you can use them to track in darkness using infrared lights. They don't have captive cables,
although their cable length is still limited to maximum USB cable length of 15 feet (4.8m), although this
can be extended by an additional 15 feet using a USB active extension cable.
Key points:
 Extremely flexible
 Interchangeable lens
 Maximum 4.8m cable (can be extended by an additional 4.8m)
 Good for use in all lighting conditions (except very low light)
 Infrared sensitive - can be used with infrared lights to track in the dark
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 Recommended for all apparatus
 Cost around $350 with a lens
1.3
Analogue cameras
Analogue cameras are designed for security applications and generally work very well in even extremely
low light. They also have interchangeable lenses and an essentially unlimited cable length. However, to
connect them to a PC requires a digitiser card which fits in a PCIe slot, something only found on desktop
computers. They also need to be connected to power, whereas USB cameras are powered by the USB
cable.
Key points:
 Extremely flexible
 Interchangeable lens
 Unlimited cable length
 Good for use in all lighting conditions, including very low light
 Infrared sensitive - can be used with infrared lights to track in the dark
 Recommended for all apparatus
 Require a digitiser card (which can only be fitted to a desktop computer)
 Cost around $250 with a lens, plus $200 for the digitiser (although the digitiser can connect
to 4 cameras)
1.4
Using multiple cameras
If you want to track in multiple apparatus simultaneously then you may need multiple cameras (remember
you can place multiple apparatus under a single camera, if they'll all fit). The issues relating to connecting
multiple cameras to a PC are discussed fully in the Connecting multiple cameras topic, but the key points
are:
 Connecting up to 3 USB cameras to a notebook is straightforward
 Connecting up to 6 USB cameras to a notebook can usually be achieved but depends on the
computer
 Connecting up to 15 USB cameras to a desktop is achievable, although usually it's cheaper
and simpler to use analogue cameras
 A single digitisers can be connected to up to 4 analogue cameras. It's usually possible to
install up to 4 digitisers in a desktop computer, for a total of 16 cameras.
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2 USB cameras
2.1
Introduction
USB cameras are usually the best choice for ANY-maze. USB webcams are inexpensive and work well in
many situations, while Industrial USB cameras are flexible and work very well in almost all apparatus. That
said, there are still some circumstances where analogue cameras can provide better performance and/or a
cheaper option - for more details about the pros and cons of the different camera types refer to Choosing
a camera.
 Webcams - recommended specifications
 Industrial cameras - recommended specifications
 Extending a USB cable
 Mounting a USB camera
2.2
Webcams - recommended specifications
Most modern USB web-cams are suitable for use with ANY-maze although we'd advise against very cheap
devices as these can provide poor quality images. We recommend devices from manufacturers such as
Microsoft and Logitech.
The only significant choice you'll need to make when selecting a webcam is the resolution. Although it
might seem that higher resolution will be better, this isn't usually the case as high resolution images just
require more processing without adding much additional information (from a tracking point of view). That
said, if you only plan to use a single camera then (unless you have an old computer) any resolution should
be fine, but if you want to connect multiple cameras, using devices with lower resolutions would be better.
2.3
Industrial cameras - recommended specifications
We recommend the industrial USB cameras from The Imaging Source, specifically their USB 2.0
Monochrome Industrial Cameras. That said, devices from other manufactures should work fine, as long as
they are provided with a DirectShow driver (most will be).
A few points to note:
 There is no benefit in using a colour camera with ANY-maze as it only processes and
displays black and white images.
 As is the case for USB webcams, choosing a high resolution Industrial camera is usually not
beneficial and, if you plan to connect multiple cameras, can actually be detrimental. A
resolution of 640x480 is usually perfectly adequate.
 Industrial cameras are available with two types of image sensor, CMOS and CCD. Both are
good and it make no difference in ANY-maze which you use. These sensors also come in
different sizes, typically 1/4 inch, 1/3 inch and 1/2 inch. Large sizes are more expensive, but
1/4 and 1/3 inch sensors are perfectly adequate for ANY-maze.
 The latest USB version is 3.0 and USB 3.0 cameras are now (in 2016) becoming available.
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There are no significant benefits to using USB 3.0 cameras with ANY-maze and, as these
devices are usually significantly more expensive than USB 2.0 cameras, we don't recommend
them, although they should work fine.
Choosing a lens
Industrial cameras are not supplied with a lens, so you will need to purchase one separately. Choosing a
lens is relatively simple once you've calculated the minimum lens angle you need - see Lens calculations.
However, you still need to consider the following points:
 Make sure you buy a lens that matches the sensor size of your camera. As mentioned above
cameras are available with different sized sensors and you must use a lens which matches
the camera's sensor size.
 Make sure you buy a lens that's compatible with your camera's lens mount, either C or CS.
Some cameras can accept either type of lens but some will only work with one or the other.
 Some lenses have fixed irises, some have manual irises and some have automatic irises.
Most industrial cameras do not support automatic irises so, you should use avoid this type
of lens. We recommend a manual iris lens.
 If you expect your target animals to be close to the lens (for example, if you'll be tracking
inside a place-preference box) then check that the lens will be able to focus at that distance.
 Generally speaking the best type of lens to buy is a vari-focal lens as these allow you to
zoom in and out so that your apparatus nicely fits the camera's field of view. This is
particularly beneficial if you want to work with different sized pieces of apparatus - a rat
plusmaze and a mouse Y-maze, for example.
2.4
Extending a USB cable
USB webcams are usually supplied with captive cables (you can't unplug the cable) of about 2 or 3 metres
length. As the camera has to be mounted over the apparatus and the computer will ideally be positioned
out of the animal's view, these short cables can be a problem.
Industrial USB cameras don't have a captive cable so you can purchase a long USB cable and use that, but
be careful - the USB specification mandates that cables are no longer than 15 feet (4.8m), some
manufacturers do make longer cables but these can be unreliable and we'd strongly advise against using
them.
If you need to extend a USB cable then you should use what's called an Active extension cable. These
include electronics which "repeats" the USB signal, thus allowing it to travel another 15 feet. Again, some
manufacturers exceed the distance specification, but you should avoid cables which are longer than 15
feet as they may prove to be unreliable. You should also avoid any extension cable which is not active,
unless the total length of all the cables from the camera to the computer will be no more than 15 feet.
We don't recommend connecting multiple extension cables together - so using a standard 15 foot cable
with a single 15 foot active extension, giving 30 foot (around 10m) in total, is the maximum distance you
can achieve.
We don't recommend a specific product, but a search of Google for "Active USB extension cable" will
usually turn up a wide range of options.
Finally, there are USB extension cables available which convert the USB signal to a network signal, which
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can then be transmitted through a long (50m or more) network cable, before being converted back to
USB again. In theory these should allow you to extend a USB cable well beyond the 10m limit, but we
have never tried them and so can't provide any sort of recommendation.
2.5
Mounting a USB camera
While it might seem an obvious thing to mention, don't forget that you'll have to mount your camera
above your apparatus. Industrial cameras come with a standard fitting in their base which allows them to
be screwed onto a camera mount, however USB web-cams don't include this feature.
As web-cams are usually very light the easiest way to mount them is simply to stick them to the ceiling
with duct tape - not too elegant but it works. Alternatively, if you have a suspended ceiling, cut a hole the
size of the lens in a ceiling panel and stick the lens through the hole - the panel will easily be strong
enough to support the camera's weight.
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3 Analogue cameras and digitisers
3.1
Introduction
ANY-maze will work with almost any analogue video camera you might encounter. There are a few
specialist cameras you can't use but any standard CCTV (closed circuit TV) camera, such as a security
camera will work fine (subject to the considerations described below).
Before going into the details, it's important that you understand that to use an analogue camera with
ANY-maze you'll need a digitiser (sometimes called a frame grabber or a capture card). These devices
convert the analogue video signal from the camera into digital data which ANY-maze can process. This, by
the way, is the key difference between analogue and USB cameras - USB cameras don't need a digitiser,
the video signal already being digital. For more details see Choosing a camera.
 Choosing an analogue camera
 Choosing a lens
 Choosing a digitiser
 Video cables, connectors and camera mounts
3.2
Choosing an analogue camera
As I already mentioned, ANY-maze will work with almost any analogue camera. However, if you plan to
work in low light you should pay particular attention to the camera's sensitivity. Here are the
recommended specifications.
Camera type
Use a black and white camera. ANY-maze will work with colour cameras but it doesn't
use the colour information so buying a colour camera is a waste of money. Indeed, even
if you use a colour camera the video pictures in ANY-maze will still be black and white.
CCD size
Modern analogue cameras use devices called CCDs to capture the video picture. These
come in various sizes but the most common are half inch and third inch. If you're going
to buy a camera for ANY-maze, buy one with a third inch CCD - they're cheaper and
perfectly good enough for ANY-maze. You may also encounter quarter inch CCDs they're not as good as third inch devices but should work OK.
Sensitivity
If you plan to work in low light conditions then make sure your camera has a sensitivity
of 0.1 lux or below. If low light work is not relevant then you don't need to concern
yourself about the camera's sensitivity. Note that colour cameras generally have a much
lower sensitivity than black and white cameras.
IR sensitivity
All black and white cameras are sensitive to infrared light, but some include an IR block
filter. Make sure you choose a camera without a filter as you'll then be able to use
infrared lights to track in darkness.
Resolution
Unless you plan to track very small targets (in relation to the apparatus size) then the
camera resolution is not likely to be important. If you do want to track small targets then
a horizontal resolution of 500 lines or greater is best.
Video output
1.0Vp-p 75ohms.
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As I said almost all cameras will meet this specification so, apart from sensitivity in low light, how do you
choose one? Well, there are some considerations.
 There are two common types of lens mount: C and CS. Some cameras use one type and
some use both. Be careful that your lens and your camera use the same type otherwise the
lens won't fit - in fact you can irreparably damage a camera by trying to attach the wrong
type of lens.
 Some lenses (see below) include an automatic irises so they can adjust to changing light
levels. This can be very useful if you plan to track in various lighting conditions - perhaps
with different apparatus. However, for auto irises to work the lens must connect to the
camera, so if you want to use an auto iris you need to make sure your camera will support
this feature - ask your supplier to confirm this.
 Different cameras use different power supplies. Some connect directly to the mains power
(120VAC or 240VAC), some connect to 24VAC power supplies and some to 12VDC supplies.
If you use a camera that uses 24VAC or 12VDC you will need to buy a separate power supply
too. For this reason we recommend you try to use a mains powered camera.
 If you plan to mount the camera inside a box (for example inside a light-dark box) or close
over an animal's home cage, then a board camera is probably the best solution. These are
very small cameras (typically 2-3 cm cubes) which usually use have a pre-installed (although
interchangeable) lens. They're cheap and their image quality is not fantastic, but if the target
animal is close to the camera they work well and take up almost no space.
 Although you might find some very cheap cameras on the market, the image quality is likely
to be poor. Although ANY-maze doesn't demand perfect quality, these cameras probably
won't be good enough. Expect to pay around $150 for a good camera.
3.3
Choosing a lens
Choosing a lens is relatively simple once you've calculated the minimum lens angle you need - see Lens
calculations. However, you still need to consider the following points:
 Make sure you buy a lens that matches the CCD size of your camera. As mentioned above
cameras are available with third inch and half inch CCDs (we recommend third inch), and
you must use a lens which matches the camera's CCD size.
 Make sure you buy a lens that's compatible with your camera's lens mount, either C or CS.
Some cameras can accept either type of lens but some will only work with one or the other.
 Some lenses have fixed irises, some have manual irises and some have automatic irises.
Using a fixed iris lens is not recommended with ANY-maze because you're likely to want to
track in various lighting conditions and a fixed iris will be restrictive. An auto iris is nice, but
costs more and must be supported by your camera - see above.
 If you expect your target animals to be close to the lens (for example, if you'll be tracking
inside a place-preference box) then check that the lens will be able to focus at that distance.
 Generally speaking the best type of lens to buy is a vari-focal lens as these allow you to
zoom in and out so that your apparatus nicely fits the camera's field of view. This is
particularly beneficial if you want to work with different sized pieces of apparatus - a rat
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plusmaze and a mouse Y-maze, for example.
3.4
Choosing a digitiser
A digitiser is a device which converts the video signal from an analogue video camera into digital data
which a computer can process. You may sometimes hear digitisers referred to as frame grabbers, capture
cards or video acquisition cards.
Unfortunately, there are no standards in the world of digitisers, with the result that each manufacturer has
its own proprietary system for capturing video images and making them available to application software
such as ANY-maze. This means that it's difficult for ANY-maze to support a broad spectrum of devices
because we need to develop specific software for each one.
That said, ANY-maze supports around 10 digitisers from various manufacturers, but today, all but one are
considered to be legacy devices. The one, non-legacy digitizer is the RTV-24 from Adlink Technology Inc.
This device is inexpensive, good quality and can connect to up to four cameras and capture images from
them all simultaneously - it is the digitiser we recommend if you plan to use analogue cameras.
Figure 1. The RTV-24 digitiser, which we recommend for use with ANY-maze.
The legacy devices, which will work with ANY-maze, but which we no longer recommend for new systems
are:
 The Picolo series of digitiser from Euresys s.a.
 The DT3120 and DT3153 from Data Translation Inc.
 The PCI1407, PCI1409, PCI1410 and PCI1411 from National Instruments Inc.
 The DFG/1394-1 and the DFG/USB2PRO from The imaging source.
 Any other DirectShow compatible digitiser - that's a digitiser that is supplied with WDM
drivers for DirectShow.
How a digitiser connects to your computer
The RTV-24 is a PCIe expansion card which fit into a slot inside a desktop computer. This means that your
computer must have a free PCIe slot for the card, something which modern 'compact' desktops
sometimes lack.
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All the legacy digitisers also fit into PCIe (or in some cases older PCI) slots, except for the DFG/1394-1 and
DFG/USB2PRO which are FireWire and USB devices, respectively.
3.5
Video cables, connectors and camera mounts
Analogue cameras are rarely supplied with a video cable so you'll need to buy one. This isn't actually such
a bad thing as you can then buy a cable that's just the right length to reach from your camera to your
computer. However, be careful with connectors. There are two types of connectors in common use with
cameras, BNC and RCA. You need to check the type of connector on your camera and on the digitiser which is what the camera is going to connect to. You may well find that the camera has a BNC connector
and the digitiser has an RCA connector. Don't worry - the company that supplies the camera can probably
make a suitable length cable for you with the correct connectors on it. You can also buy adaptors to
convert from BNC to RCA or vice versa.
Don't forget you'll need a mount for your camera. Although these are simple to find you need to make
sure that you buy one which will allow the camera to be mounted pointing straight down when the
cable's attached - see figure 2.
Figure 2. Make sure your camera mount is big enough to allow the camera to point
straight down when the cable is connected.
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4 Connecting multiple cameras
4.1
Introduction
There are a number of situations when you may want to use more than one camera in ANY-maze:
1.
When you want to be able to be able to switch between different apparatus for different
experiments.
2.
When you want to track in more than one piece of apparatus at the same time.
3.
When you need more than one camera to see an entire piece of apparatus.
As ANY-maze can be used with USB or analogue cameras there are three possible situations to consider:
 Connecting multiple USB cameras
 Connecting multiple analogue cameras
 Connecting a mix of USB and analogue cameras
4.2
Connecting multiple USB cameras
There are three different scenarios to consider depending on what you're trying to achieve:
Scenario 1. Switching between different apparatus
In this scenario you don't intend to use more than one camera at the same time, rather you just want to
switch to different cameras depending on the apparatus you intend to use.
This is the simplest scenario and there are no special considerations. You can simply plug your cameras
into any available ports on your computer (or on a hub) and then switch between them from within ANYmaze. For example, you might install one camera over a plusmaze and another over a water-maze - you
could then simply select the appropriate camera depending on the experiment you wish to perform.
Scenario 2. Tracking in more than one piece of apparatus at the same time
This scenario is a little complicated because of issues with USB bandwidth. The USB bandwidth defines
how much data can be transferred across a USB connection in a set period of time. Suffice to say that as
you connect more cameras so the amount of data that need to be transferred increases and eventually
you'll reach the bandwidth limit. Now, you might be thinking that this shouldn't really be a problem if you
simply connect one camera to one USB port and another camera to another port and so on. However,
things aren't that simple because the bandwidth limitation doesn't apply to the USB port, it applies to the
USB controller, which is built into your computer. So, for example, you might have 3 USB ports on your
notebook but they may all connect to the same USB controller - this means they'll all have to share the
same USB bandwidth.
Trying to quantify the exact bandwidth limitation gets technical, but usually you can connect 3 USB
cameras to a single controller before you'll have any problems. So, if you want to connect, for example, 5
cameras, you'll need two USB controllers. Fortunately, most computers have multiple controllers in them
and you'll often find that the some of the computer's USB ports connect to one controller and some to
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another. So, in our example, you could connect 3 cameras to ports that connect to one controller (using a
USB hub, if necessary) and 2 cameras to ports that connect to the other controller.
Clearly this requires that you know the relationship between the USB ports and the USB controllers in your
computer and this is something that you can find out using the USB viewer built into ANY-maze.
Figure 3. The ANY-maze USB viewer shows the USB controllers in your computer and
the ports connected to each one.
As mentioned above, some computers have USB ports which connect to different USB controllers, but in
some machines all the ports connect to one controller and in any case it's unlikely that there'll be more
than two controllers with external ports. This raises the question, how do you connect more cameras if
you've exhausted all the ports/controllers that are available? There are a couple of things you can do:
 You can reduce the frame rate of the cameras, which means they'll send fewer images per
second which in turn means they'll use less bandwidth. Note that this doesn't always work,
because not all cameras can have their frame rate adjusted.
 You can add another USB controller to your computer. USB controllers can be purchased on
expansion cards which plug into a PCIe slot in your computer. Each card usually has a single
USB controller, so this means you can connect up to 3 more cameras to each card. Only
desktop computers have PCIe slots (and even then you should check, because so-called
compact desktops sometimes exclude them). This means you can't add more controllers to a
notebook PC.
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Scenario 3. You need more than one camera to see the entire apparatus
This scenario is very similar to the previous one, in that you will need to connect more than one camera
and capture images from all of them and the considerations are identical.
4.3
Connecting multiple analogue cameras
As you would expect, if you want to connect more than one analogue camera to your computer then each
one will need to connect to a digitiser. As for USB cameras, the exact requirements will depend on what
you're trying to do.
Scenario 1. Switching between different apparatus
The simplest solution in this case is to just use a single digitiser and physically plug in the correct camera
for your experiment. However some digitisers, including the recommended RTV-24 device, have
connections for more than one camera, allowing you to connect multiple cameras and simply switch
between them from within ANY-maze.
Scenario 2. Tracking in more than one piece of apparatus at the same time
In this scenario you will obviously need to have multiple cameras connected to your computer at the
same time. In this using the recommended RTV-24 digitiser is the best solution as it includes four camera
inputs all of which can capture images simultaneously. (Some other digitisers include multiple connections
which can only capture an image from one camera at a time - with 4 cameras connected this will typically
reduce frame rates to around 6 frames per second.)
Of course, there's nothing to stop you using more than one digitiser so, for example, by using 4 RTV-24s
you could capture on 16 inputs simultaneously, although this would require that you are using a desktop
computer with 4 available PCIe slots.
Scenario 3. You need more than one camera to see the entire apparatus
This scenario is very similar to the previous one, in that you will need to connect more than one camera
and capture images from all of them.
4.4
Connecting a mix of USB and analogue cameras
There's no reason why you shouldn't use a mixture of USB and analogue cameras with ANY-maze indeed if you want to automate a range of apparatus this may offer the best solution.
For example let's imagine we want to automate the following equipment:
 A plusmaze
 Two place preference boxes
 A water-maze in which you want to track in low light
A good solution might be:
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 A USB webcam, to automate the plusmaze.
 Four industrial USB cameras (one on either side of each box) to automate the place
preference boxes.
 A good quality analogue camera (which will be very sensitive in low light) connected to an
RTV-24 digitiser to automate the water-maze.
With this set up you'd be able to choose whether to perform an experiment in the plusmazes, in the two
place-preference boxes simultaneously or in the water-maze, without having to move or reconnect any
cameras.
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5 Lens calculations
5.1
Introduction
To ensure that your apparatus will fit in your camera's field of view you need to perform a simple
calculation. This will tell you the minimum lens angle that you need.
5.2
Lens angles
Any lens has a value called its lens angle (sometime also called its angular field of view) which essentially
tells you how wide the camera's view is - see figure 4.
Figure 4. The lens angle alpha determines how wide the camera's field of view is.
As you may realise, a lens might have a different lens angle in the horizontal and vertical planes and, in
fact, there are three lens angles you might encounter - horizontal, vertical and diagonal, but the horizontal
angle is the most commonly quoted. What's more if you know one you can make an approximate
calculation of the others:
Horizontal = Vertical / 0.75
Horizontal = Diagonal x 0.80
These won't give exact answers but should be close enough for our purposes. Nevertheless, if at all
possible, I'd suggest you try to find out the horizontal angle of any lens you want to use.
5.3
Calculating the required horizontal lens angle
Generally speaking you'll be constrained to a minimum lens angle by the size of your apparatus and the
height of the ceiling in the room you want to use. As you'd expect the bigger your apparatus is, the
further away from it the camera will have to be in order to see it all. However if the camera reaches the
ceiling and still can't see all the apparatus then you'll need a wider angle lens - see figure 5.
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Figure 5. With this lens the camera can't see the entire open field. You'd need to
move the camera up (which is likely to be difficult) or use a lens with a wider angle.
To calculate the lens angle, the first thing you need to do is to measure: the distance from the camera lens
to the surface of the apparatus, the width of the apparatus and the depth of the apparatus - we'll call
these measurements a, b and c respectively and they should be in centimetres - see figure 6.
Figure 6. The three dimensions you need to measure to calculate the required lens
angle for a piece of apparatus.
Next follow these steps:
1.
If c is greater than b then swap b and c
2.
If c ÷ 0.75 is greater than b then make b = c ÷ 0.75
3.
Multiply b by 1.1
4.
Divide b by 2
5.
Subtract the approximate height of the animal (when rearing) from a. For a rat a value of
15cm is OK.
6.
The required horizontal lens angle = arc tan (b ÷ a) x 2.
You can use the calculator that's part of Windows to calculate the arc tan. Open the calculator,
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which can usually be found on the Start menu under Programs - Accessories. Select the View
menu and if Scientific isn't selected then select it. Calculate b ÷ a. Next ensure that the Degrees
option is selected, then check the Inv box and finally click the tan button. Don't forget that the
final lens angle is this value multiplied by 2.
Here's a worked example for a typical plusmaze, where: a = 200 b = 110 c = 110
1. b and c are the same so nothing to do
2. c ÷ 0.75 = 147
147 is greater than 110
therefore b = 147
3. b = 147 x 1.1 = 162
4. b = 162 ÷ 2 = 81
5. a = 200 - 15 = 185
6. Lens angle = (arc tan (81 ÷ 185)) x 2 = arc tan(.438) x 2 = 23.5 x 2 = 47°
We need a lens with a horizontal lens angle of at least 47°. In fact, in the 3rd step we added 10% to the
value of b giving us a little leeway in the minimum acceptable value for the lens angle - for example, a 45°
lens would be fine.
Of course, if you're planning to use ANY-maze with different pieces of apparatus, a plus-maze and a Ymaze perhaps, then you should calculate the required lens angle for each of them and use a lens with at
least the largest angle reported, although in this situation you'd probably do better to use a vari-focal
lens.
5.4
Vari-focal lenses
If your budget will run to it then, without doubt, the best type of lens to use with ANY-maze is a vari-focal
lens. With these lenses you can alter the lens angle and thus zoom in and out so your apparatus nicely fits
the camera's field of view. This can be particularly important if you plan to use different apparatus,
especially if they're dramatically different sizes. For example, if you have a fixed angle lens suitable for a
rat water-maze then, if you put a mouse plus-maze under it, the apparatus will only fill a small part of the
picture and the mouse itself will be tiny. Of course, even a vari-focal lens only has a range of lens angles
(perhaps 35º-75º) so you should still check that your apparatus will fit it.
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6 Working in low light or darkness
6.1
Introduction
Many behavioural experiments are performed in either low light or complete darkness, but clearly you'll
still want to track your animals; this topic explains how you can do this.
6.2
Tracking in low light
Some black and white analogue cameras are extremely sensitive and can produce surprisingly clear
images even in very low light conditions. For example, cameras with sensitivity of 0.01 lux are not
uncommon (or very expensive) and these will work well in even extremely dim conditions. Note that
colour cameras don't share this high sensitivity.
Black and white industrial USB cameras are also quite sensitive, although not to the same extent as
analogue cameras. Nevertheless, they can often create usable images in low light. USB webcams, on the
other hand, are usually even less sensitive and while they may produce an image in low light, it will
typically be low contrast and quite noisy.
Having said all that, if you have high contrast between your animal and the background of the apparatus
(for example, a white rat on a black maze), ANY-maze will usually track satisfactorily even if the image
quality is quite poor. However, if you want to detect the full area of the animal, for example to determine
precisely when the animal enters a zone, or you want to detect freezing, then low-contrast, noisy images
will not suffice. In these cases you should use a very sensitive camera and/or use the techniques for
tracking in darkness - see the next section.
6.3
Tracking in darkness
Most of the cameras you can use with ANY-maze are infrared sensitive. This means you can illuminate
your apparatus with infrared light, which the animal won't be able to see, but which will allow the camera
to produce an image as if the apparatus were brightly lit.
To use this technique you will need two things:
 An infrared sensitive camera. Almost all analogue and industrial USB cameras are infrared
sensitive and many USB webcams are too. Any easy way to check is to view an image from
the camera (for example, in the ANY-maze Video page), then point a television remote
control at the camera and press a button. If you see a bright spot appear at the end of the
remote control then the camera can see infrared. By the way, here we are talking about near
infrared, there are also thermal imaging cameras available which are sensitive to longwavelength infrared, but these are very expensive.
 infrared lights to illuminate the apparatus. Infrared lights are quite inexpensive and usually
take the form of a bank of infrared emitting LEDs - see figure 7. These can be found quite
easily by searching Google for "Infrared illuminator". One thing to be careful about is the
beam angle, if it is narrow then you'll be lighting the apparatus with something like a flashlight, which will tend to make the centre very bright and the edges dim. One way to address
this is to point the device upwards so the light reflects of the ceiling, which usually helps to
disperse it.
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Figure 7. Infrared illuminators are inexpensive and can be used "light" the apparatus
so ANY-maze can track in darkness.
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7
7.1
Installing and configuring cameras & digitisers
Introduction
All cameras and digitisers are provided with instructions so installing them is normally a fairly simple task.
However, after installation some devices still need to be configured to work with ANY-maze and, of
course, you will always want to test everything is working OK.
 Installing USB digital cameras
 Installing and configuring an RTV-24 digitiser
 Testing your equipment with ANY-maze
7.2
Installing USB cameras
Installing USB cameras is usually very simple and we recommend you follow the instructions supplied with
your device. However, we do have a few comments:
 Generally it's best to install the software which came with the camera before you plug the
camera in.
 If possible plug the camera into a USB port that connects to a USB controller that doesn't
have any other high bandwidth devices attached to it. This won't be an issue if you don't
have any other USB devices (or you just have a USB mouse), otherwise you might want to
read the Connecting multiple cameras topic which goes into this issue in more detail.
Once you've installed your camera you're ready to test it with ANY-maze.
7.3
Installing and configuring an RTV-24 digitiser
It's important, when installing an RTV-24 digitiser, that you install the driver software before physically
installing the digitiser in your computer - here are full instructions:
 First install the driver software that came with your device. The procedure is described in
section 3.2 of the RTV-24 manual and is quite straightforward. Note that you only need to
install the driver in order to use the digitiser with ANY-maze; you don't need to install the
software package.
 Next, you should physically install the digitiser card in your computer - details on how to do
this are in section 3.1 of the RTV-24 manual.
 When you restart your computer after installing the card you will probably see eight
messages from Windows about new hardware devices being found - this is normal, just ask
Windows to automatically install the hardware (although, if relevant, you can tell it to skip
checking on the Internet for a newer driver).
By default, ANY-maze will assume you'll be using the digitiser with an NTSC camera - this is the standard
in the US and many other countries outside Europe. If, however, you will be using the digitiser with a PAL
camera (the European standard) then you need to configure it before it will work correctly:
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1.
Start ANY-maze.
2.
Switch to the Video page
3.
Click the
4.
A window will open listing the video capture devices installed in your computer. This
should include four entries for your RTV-24 digitiser (because it contains four separate
capture ports). Click on any of the entries for the card you just installed.
5.
Now click the Configure button just below and to the right of the list.
6.
The RTV-24 digitiser configuration window will open. Here you can specify the default
camera type you will be using with the device and also specify any RTV-E4 video
extension cards you have installed.
7.
After selecting the camera type (and specifying any installed RTV-E4 cards), simply click
OK on all the open windows.
Setup video devices button in the ribbon bar.
You're now ready to test the device with ANY-maze.
7.4
Testing your equipment with ANY-maze
Once you've completed the installation of your camera or digitiser you should test it's working with ANYmaze.
1.
If it's not already installed, install ANY-maze.
2.
If you're using an analogue camera then connect it to your digitiser. Make sure the
camera is connected to the power and, if necessary, is switched on. If you're using a
digital camera then make sure it's connected to the computer.
3.
If your camera has a lens cap remove it!
4.
Run ANY-maze.
5.
Switch to the Video page.
6.
Your device should be listed on the left side of the page.
7.
Click on the item in the list. The image from the camera should appear in the main area of
the window.
If your device is not listed, or it is listed but you can't get your video picture to appear, don't panic - there
are a number of perfectly benign reasons why this might occur. Refer to the Problems with cameras topic
for further assistance.
And don't forget, if you get stuck we're here to help, just contact ANY-maze technical support
(techsuppport@anymaze.com).
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