

Inside the Kinect: 4 mics, IR, color, B/W cameras - gvb
http://eetimes.com/electronics-news/4210649/Kinect-s-BOM-roughly--56--teardown-finds-

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joezydeco
_The system also detects motion by using one infrared camera—classified as
Class 1, which indicates that it's not LED-based— and two image sensors, the
firm said._

The infrared component is a bit more sophisticated than the article implies.
Check out this video:

<http://www.youtube.com/watch?v=r7nRKU0nFxA>

This looks like a LASER projecting a pattern through a hologram or some other
kind of interference pattern.

The videos of the open-source driver working don't show any of this stuff,
unless the Kinect unit already processes this and that's where the depth map
comes from.

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gvb
Excellent find!

I was really puzzled what a "Class 1 infrared camera" was, but it makes
perfect sense to have a Class 1 laser[1] with an infrared camera to pick up
the spots. This also makes a lot more sense for detecting distance via
triangulation: discrete spots are going to be _much_ easier to triangulate
than doing a two-camera vision system, e.g. detect unpredictable edges,
correlate the two cameras' edges, and determine distance.

The hologram projection concept makes a lot of sense. A full scanning laser
would be prohibitively expensive. A hologram projection would be robust and
cheap, but less accurate and require much more software processing.

[1] <http://en.wikipedia.org/wiki/Laser_safety#Class_1>

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gvb
On further thought, I over-thought that. Parallax calculations aren't
necessary. Since the points will be projected at an angle, the distance to the
object being painted ("spotted") is going to be directly proportional to the
distance between spots.

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joezydeco
Looking at the datasheet for the PrimeSense reference system that Microsoft
used, it does mention a "registration image" and a laser:

<http://www.primesense.com/?p=514>

