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FAQ

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Why are there black shadows in the depth image?

Shadow explanation diagram

Can optical polarization (or other tricks) be used to combine two Kinect sensors viewing the same scene from different angles?

Unfortunately, polarization is not generally preserved when reflecting off an object. Special surfaces can be used that preserve polarization, but the concept of tagging each Kinect's IR field by polarizing the light does not appear to be feasible. Initial tests using two simultaneous Kinect sensors suggest that they may not severely interfere with one another.

What is the frame size/bitrate of the rgb/depth stream etc.?

  • There are 242 packets for one frame for the depth camera (including 0x71 and 0x75 packets). All packets are 1760 bytes except 0x75 packet - 1144 bytes. Minus headers it gives 422400 bytes of data * 30 frames per second = 12672000 bytes/sec
  • There are 162 packets for one frame for the color camera (including 0x81 and 0x85 packets). All packets are 1920 bytes except 0x85 packet - 24 bytes. Minus header it gives 307200 bytes of data * 30 frames per second = 9216000 bytes/sec
  • The depth camera returns values with 11-bits of precision
  • The frame output of the RGB camera is a 640x480 Bayer pattern

See the Protocol Documentation and other documents of the Knowledge base.

I'm trying to troubleshoot a stability or performance issue, do you have any advice?

Depending on the platform and hardware, many factors may come into play. But in general, one should look into these:

  • is libfreenect properly compiled and installed from the latest source
  • usb bandwidth issues: are there too many devices sharing the usb port, has the Kinect been tried on a different port, is it connected directly or through a usb hub? Is there data loss on the usb cable? Is the full usb 2.0 bandwidth enabled on the computer? On a laptop one might add an external usb mouse to the setup to see if that changes anything
  • graphics card issues: some graphics card's driver may exhibit a particular behavior; trying a different one may help

Tip: in glview.c or other straight c project file, try freenect_set_log_level(f_ctx, FREENECT_LOG_SPEW); (as opposed to FREENECT_LOG_DEBUG) to enable a more verbose output for debugging purposes.