THE PROTOTYPE FOR Microsoft’s Kinect camera and microphone famously cost $30,000. At midnight Thursday morning, you’ll be able to buy it for $150 as an Xbox 360 peripheral.
Microsoft is projecting that it will sell 5 million units between now and Christmas. We’ll have more details and a review of the system soon, but for now it’s worth taking some time to think about how it all works.
Older software programs used differences in color and texture to distinguish objects from their backgrounds. PrimeSense, the company whose tech powers Kinect, and recent Microsoft acquisition Canesta use a different model. 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.
Using an infrared generator also partially solves the problem of ambient light. Since the sensor isn’t designed to register visible light, it doesn’t get quite as many false positives.
PrimeSense and Kinect go one step further and encode information in the near-IR light. As that information is returned, some of it is deformed — which in turn can help generate a finer image of those objects’ 3-D texture, not just their depth.