Whether you love or hate the User Interface that the Microsoft Kinect implements (some people just don’t like to wave their arms to change channels), the technology behind it is incredibly interesting. You get a sense of how interesting it is by watching this video, where a guy uses his night-vision goggles to see the infrared star map that the Kinect system uses to sense people in its field of view:

What the Kinect system is doing is shooting out beams of infrared light and measuring how long it takes them to reflect off of objects in the scene and return to an infrared camera. Light travels about a foot per nanosecond (a meter in 3 nanoseconds), so measuring the time for thousands of points in the scene creates an accurate depth map of your living room, and the people inside it. According to this article:

The camera transmits invisible near-infrared light and measures its “time of flight” after it reflects off the objects.

Time-of-flight works like sonar: If you know how long the light takes to return, you know how far away an object is. Cast a big field, with lots of pings going back and forth at the speed of light, and you can know how far away a lot of objects are.

Primesense created the technology, and according to Primesense the depth map is accurate to about 1 cm and is updated 60 times per second.

This video goes into some detail about what is happening with the infrared light source and the infrared camera, as well as the software that interprets the data:

The Kinect system is getting good reviews, like this one:

Microsoft Kinect for Xbox 360

It’s finally here. After three years of development, evolving from a rumor to a product that’s made headlines with high-profile appearances on Oprah, Ellen, and The Late Show with Jimmy Fallon, Kinect for Microsoft Xbox 360 (formerly Project Natal) is a reality. Microsoft has touted Kinect ($149.99 direct) as the next level of motion control, one that eschews physical, hands-on controllers by using the human body itself for input. It’s a lofty task to undertake, certainly one far riskier than what Sony has done with the PlayStation Move ($99.99, 4 stars), which uses Nintendo Wii-like remotes (albeit, ones that are far more accurate). Microsoft has succeeded in making its spin on motion gaming not only a reality, but an insanely fun Xbox add-on that uses Kinect’s depth-sensing camera and microphone in a revolutionary way that kills any accusations of it being a Wii-inspired gimmick.

For more info see:
- How Microsoft Kinect Works
- How Xbox 360 Works

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