Canesta. I looked into their stuff before the Kinect came out. I am no expert in the field, but I thought their time-of-flight sensor is really clever. Basically, the speed of light is too fast to get an accurate ToF measurement within living-room distances using timers. So they use a technique where the intensity of the reflected IR is directly proportional to the ToF. Since you can measure intensity with much more accuracy and precision (and ease) than the time taken for light to travel a few meters, you get a pretty accurate 3D point cloud of the space being sensed. I can't find their white paper that explains this, but it's a good read.
That's interesting...was it an effect based on attenuation of the light? i.e. reflected photons from close objects will attenuate less than ones further away therefore intensity will be higher?
Something along those lines, but they also did something clever with the timing of emitting IR flashes and correlating the received number of photons with those flashes. I really wish I could recall more clearly, but I looked into it around 2007 - 2008. I tried finding the white paper, but all the links are dead :-( I might have a copy lying around, though... I'll try to dig that up.
Thanks for the link :) Do you happen to know how to download the pdf off scribd? It looks like you need to pay scribd to do it (or to read past the first few pages), which doesn't quite seem fair since I'm assuming they don't have a license to the content themselves, in which case it'd be someone else's copyrighted content they're profiting off...
Can't get it off scribd, but thanks to the magic of archive.org (seriously! amazing stuff), the entire pre-purchase canesta website is still up. Just look prior to mid 2010 or so. Here's the exact pdf in question:
Yeah, that was a pretty big turn-off. Scribd is already on my groan-when-I-go-there sites, but I'm pretty sure a service that lets me download a pdf is not something I'm interested in paying for since that was invented decades ago when it was called ftp.
Doesn't return the intensity of reflection depend on the color and surface finish of the target? i.e. a white sofa reflects more light than a black sofa?
