Errors in Per-Pixel Depth Correction

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This topic contains 8 replies, has 4 voices, and was last updated by  eclipsegeo 2 months, 3 weeks ago.

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  • #102977

    Dan Tamas
    Participant

    Hi everyone,

    I have some issues with the per pixel depth correction.
    When I try to use Calibrate Depth Lens tool the error says:
    “Could not calculate depth correction coefficients due to exception Attempt to solve linear system with rank-deficient matrix.”
    If I insist a bit more, it writes the following in the terminal:
    “Writing depth correction file /usr/local/etc/Vrui-4.2/Kinect-3.2/DepthCorrection-A70776X06644234A.dat”
    and gives the following error:
    Could not calculate depth correction coefficients due to exception IO::StandardFile: Unable to open file/usr/local/etc/Vrui-4.2/Kinect-3.2/DepthCorrection-A70776X06644234A.dat for writing due to error 13 (Permission denied)

    Does anyone know how to solve the issue? I really need the correction as I am using the software to export DEM’s for analogue modeling experiments.

    Thanks,
    Dan

    #103079

    Oliver Kreylos
    Moderator

    While capturing depth images, make sure that you have at least two different images covering each pixel (as the per-pixel equations are linear regressions).

    The error you’re seeing is a side effect of installing the Kinect package in a system directory. Use sudo ./bin/RawKinectViewer ... to run the application under an administrator account to get around it.

    #115710

    eclipsegeo
    Participant

    Could you elaborate more on “at least two different images covering each pixel”. You don’t mean the use of the checkerboard for the later steps? I’ve recently come across the rank deficient matrix error while trying to do my own intrinsic calibration.

    #115711

    Oliver Kreylos
    Moderator

    There are two separate calibration steps: per-pixel depth correction and full intrinsic calibration (which uses semi-transparent checkerboards).

    I advise against doing the second step. It’s not particularly useful for the AR Sandbox.

    The first step can be a big help in getting good feature alignment in the sandbox, as it takes out a non-linear distortion component. It’s described in the Kinect package’s README file and pretty straightforward. You have to point your Kinect at a flat surface, like a wall, from a few different distances and take a picture each time.

    #115721

    eclipsegeo
    Participant

    Thanks for the clarification. I’ve been following the readme for the per-pixel depth correction and again running into the error “Could not calculate depth correction… rank-deficient matrix.” I’ve saved multiple tie points but to no success; About many tie points would be suitable?

    #115723

    Oliver Kreylos
    Moderator

    Which version of the Kinect camera are you using?

    #115725

    eclipsegeo
    Participant

    Kinect 360, model 1414

    #115726

    rrbexams
    Participant

    Same issue I have been facing with 1473. That Permission Denied problem is killing me.

    #115742

    eclipsegeo
    Participant

    For anyone else running into the same problem, I solved my problem the other day but I can’t pinpoint the changing factor. More broadly it could have been the number of saved tie points. I followed the instructions in the ReadMe as follows but saved double the amount of tie points each time it tells you to save one. The second change was saving more tie points when you could see half of the two colours in depth (and again, saving two tie points at the same view). That seemed to fix the rank deficient matrix problem; you’ll get feedback in your command prompt mentioning that it wrote depth correction to a file.

    Afterwards, faced the permission denied error, which was easily solved by adding sudo in your command prompt as Oliver mentioned above.

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