Multiple kinects overlapping FOV, single computer

Question

We have an application where we are connecting four kinects with overlapping fields of view to a single PC. We would like to build a single point cloud from the four sources.

• Is using more than 2 kinects possible, does the driver support this?
• Does the driver support turning off the IR illumination, thus eliminating interference in the range data?
• What kind of frame rate can we expect? Can we throttle the driver somehow? Does the driver support polling?
• What other limitations are there?

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Originally posted by sedwards on ROS Answers with karma: 1601 on 2012-02-29

Post score: 5

Answer 1

1. I personally tried only 2 kinects on one pc, but the driver should support more. You should make sure though to use different usb-buses to not limit the data rate. (Not only different ports, but internally different buses)

2. No, you cant turn off the IR-Laser and still get range-data out of the kinect. The projected IR-pattern is like the right eye of the stereo system. So depth only works if each kinect projects its own pattern.

3. Depends. :) A very fast pc (>= quad 3ghz or something) may be able to support 2-4 kinects at full framerates, but you can reduce the resolution and/or framerates through the driver (dynamic reconfigure).

4. You should really try pointing more then one active kinect in the same direction/on the same object and see for yourself, how the results look like. It isnt neccessary to connect them all to the same pc, but all should have their IR turned on. I personally was surprised how well the two kinects performed, but you definitely see degradations in quality. And playing around with their relative alignment, to reduce the interference you already mentioned, might help.

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Edit: Ivan was faster. (And he is right too!) :) The amount of interference you might expect depends a lot on the angle of the kinects. And you should keep in mind, that the kinect does not support any kind of (hardware) synchronization. So the images you get from those might be slightly off in time. (but should be something < 100ms)

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Originally posted by Ben_S with karma: 2510 on 2012-02-29

This answer was ACCEPTED on the original site

Post score: 4

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Original comments

Comment by ahendrix on 2012-02-29:
As Ivan says, be careful about USB bandwidth. The Kinect uses most of the theoretical bandwidth of a USB 2.0 bus, so you can't put two on the same bus and get full frame rate out of both of them.

The Kinect generally doesn't work on a USB 3.0 bus.

Comment by ahendrix on 2012-02-29:
Also note that all of the current Intel chipsets only have two USB 2.0 busses. If you want more, you'll have to add USB cards.

Comment by Stephane.M on 2013-03-14:
Kinects works perfectly well on USB 3.0 since Ubuntu 12.04... :-)

Answer 2

Does the driver support turning off the IR illumination, thus eliminating interference in the range data?

I don't believe the driver supports that. You can manually occlude off the IR projector with a piece of tape, but I don't think you would want to do that. I don't think one Kinect will work with the IR pattern of a second Kinect. The interference might not be a big problem see this video for a working example

What kind of frame rate can we expect? Can we throttle the driver somehow? Does the driver support polling?

The driver supports throttling. Make sure to put the Kinects on different USB buses if possible. If you're having trouble with frame rate, turning the resolution down will probably help.

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Originally posted by Ivan Dryanovski with karma: 4954 on 2012-02-29

This answer was NOT ACCEPTED on the original site

Post score: 4