Microsoft Research has discovered that shaking Kinects, far from making them fall apart, makes them work together. See it in action in the video.
This is one of those ideas that once you have seen it you can't believe you didn't think of it first. The only barrier to thinking of it is that you might not be thinking big enough. If you find one Kinect with its depth camera sufficient, then you really won't be interested in this idea even though it is very clever. The idea of using more than on Kinect at a time extends what you can do by a lot and the idea isn't prohibitively expensive.
However there is a problem.
Multiple Kinects tend to interfere with one another. A Kinect measures the depth of a point by projecting a pattern of infrared dots into the scene and detecting how far they appear shifted due to parallax. This is great when there is only one Kinect but if you have more than one there is no way of separating out their dots. What this means is that one Kinect could project an infrared dot that another Kinect "sees" as its own and hence incorrectly estimates the distance.
The problem is that the Kinect light pattern isn't modulated in a way that lets one unit tell which dots belong to its projected pattern. Now the solution is obvious - modulate the patterns. This sounds difficult and probably involves changing the firmware - not according to Microsoft Research who say all you need to do is shake it.
The idea is simple - add a motor with an offset weight. Run the motor so that it shakes the Kinect and the result is an almost magical improvement in multisensor detection accuracy.
The reason it works is that the shaking moves the IR projector and the IR camera and so as far as the shaken Kinect is concerned there is no shaking of the projected dots. From the point of view of another Kinect however the dot pattern of the shaken projector moves around and interfere with its own pattern only for a small amount of time. The result is an instant improvement!
Watch the video if you don't believe me:
I'd say that a lot of Kinects will be wearing the sporty top-fitted motor complete with offset weight in the coming year. Microsoft Research call it Shake 'n' Sense and, had they held off until the beginning of next month it would have made a good April Fool - but it is real, it seems to work and it's a hack worthy of a prize.
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