forums.naturalpoint.com

My Slim v100 is not picking up IR reflected off markers properly. I am using a track IR 3 for comparison. When I put a marker in front of the track IR it picks up the reflected IR (emitted from track IR's LEDs) brilliantly, and does not pick up IR reflected off other sources (eg my hand). However, when I use the track IR's LEDs to illuminated the marker while viewing with the v100, the v100 is not picking up any more IR off the marker than off my hand! And to actually pick up any IR on the v100 (when the IR filter is in place) the threshold must be set low and the exposure high such that ordinary light globes are also being picked up. Adjusting the direction the track IR's IR light relative to the position of the v100 does not improve the reflectance off the marker. I have tried this with and without the IR filter in place on the v100. I have tried this with both the 1.9mm and 2.6mm M12 lenses (which on my order receipt are listed as having no in-built IR bandpass filtering). Both the track IR and the v100 were tested with the same program I derived from the optitrack SDK.

Does the IR bandpass filter on the v100 have a directionality? i.e. do its properties change depending on the direction its facing?

I am baffled by this problem. If anyone can help me with this I would be very grateful.

The light source should emit from as close to the lens's line of sight as possible to get decent results with retroreflective markers. This is why our cameras have LEDs directly around the lenses. If you are unable to mount a light source on the board, try illuminating from behind and off to the side a little.

http://en.wikipedia.org/wiki/Retroreflector

Thanks for your reply. I will check out if this solves the problem. Its important for my application to have a large FOV - if I made a ring of emitters to go around the M12 1.9mm lens such that whole of its FOV was illuminated, could I get good tracking throughout the FOV with a retroreflective marker? Or is there other problems with a large FOV that makes illuminating retroreflective markers in the periphery a problem?

I set up an array closer to the lens and that fixed the illumination problem I originally described. Thanks for the good advice!