I/ITSEC : A Exposure setting of 40 will still allow the cameras to have good range while reducing unwanted light, especially in environments like trade shows
There is a basic description of the Exposure, Threshold and Illumination/Intensity in the Tracking Toolkits manual. I will expand on them a little more in this post.
http://www.naturalpoint.com/optitrack/s ... ml#h-4.2.2
- Threshold : This adjusts how bright a marker has to be before it will be identified by the cameras. Using a larger value such as "180" will help reduce the number of unwanted items in the scene.
Using too high of a value (over "230") can degrade the precision of the detected markers by reducing the number of pixels for the marker. This is because high values will only allow pixels at the brightest part of the marker (the center) to pass and will discard pixels at the edge which tend to be less bright. With V100 cameras it is ideal to leave the Threshold at around 150 and first use the Exposure to filter out unwanted light. - Exposure : This adjusts the camera's shutter timer which determines the amount of light a camera lets in during each frame. Using a smaller value such as "55" will help reduce the number of unwanted items detected in the scene. Short exposure durations also reduce the amount of smear caused by fast moving objects.
When the V100 is operating in strobe mode it sends out a burst of light which lasts for a brief period at the start of the frame, there is no need to expose for the rest of the frame since the camera's IR illumination is turned off after the strobe period. This allows the camera to get full IR illumination (markers remain bright and most of their pixels detected) in a scene while letting in very little of the ambient/background light.
Reducing the exposure below 55 reduces the strobe duration which in turn reduces the maximum range of the cameras. This can be useful if you are operating closer to the cameras and need them to emit less light to avoid blooming.
Please see this post for more information about how the strobe is linked to the exposure timing - Illumination/Intensity : This adjusts the brightness of the illumination provided by the OptiTrack camera's on board IR LEDs.
For best performance when using OptiTrack FLEX:V100 cameras, use the IR strobe mode. This mode is activated by setting the illumination value to "15". When strobe mode is active there is no benefit to using an exposure value larger than "70" since the LEDs cease to emit light after that time. To adjust the brightness of the LEDs in strobe mode, modify the exposure setting within the range of "1" through "70" (smaller values will result in less light).