Problems with KinectViewer (calibration step 5)

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This topic contains 3 replies, has 2 voices, and was last updated by  Oliver Kreylos 4 years, 2 months ago.

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  • #100790

    Dennis
    Participant

    Hello,

    I’m trying to get through calibration step 5, but I cannot see any image that I can use as base for the measurement.

    RawKinectViewer shows both images (depth und real) correctly.

    Without step 5 I’m not able to calibrate the SARndbox (step 7), because I cannot get a “green object” for the calibration.

    Does anyone have a hint for this?

    Thanks in advance,
    Dennis

    #100793

    Oliver Kreylos
    Keymaster

    Most probably a scale issue. If you retrieved calibration data from your Kinect via “KinectUtil getCalib <index>”, you might receive distances in mm instead of cm.

    After starting KinectViewer, zoom out by rolling the mouse wheel up a few times. The 3D image should come into view shortly, and then start from there.

    #100796

    Dennis
    Participant

    Thank you, Oliver.

    I don’t have to do this zoom out, if I remove the IntrinsicParameters data file.

    But now I’m a bit confused, which way to use for the calibration: with or without the IntrinsicParameters data file?

    Some side effects: if I don’t have the IntrinsicParameters data file, the image on the KinectViewer tool ist extremely “blurry” and I don’t get a concrete image on the camera view, but the values of the measurements are round about the values you mentioned in your videos.
    On the other hand, if I use the InstrinsicParameters data file, the view of the KinectViewer tool is more clear, but the measurements values are round about ten times higher.

    So which way is the right/best way to get a correct calibration?

    Thanks for your help so far. You’re doing a great work here.

    Greetings
    Dennis

    #100798

    Oliver Kreylos
    Keymaster

    If you remove the intrinsic calibration file, the Kinect package will fall back to a built-in default calibration, which isn’t good, but gets the basics going. That built-in calibration file results in measurements in cm. The file you created by running KinectUtil getCalib results in measurements in mm, therefore all the measured numbers are 10 times larger. This was an oversight in the current Kinect package; I should have added code to make sure that calibration is always in the same units.

    The built-in default intrinsic calibration will be mostly OK for using the sandbox, because the projector calibration step will sort out most discrepancies. But the built-in calibration won’t properly align the depth and color cameras (the latter isn’t used for the sandbox), which is probably what you’re seeing in KinectViewer.

    For simplicity, go with the built-in default calibration right now, because otherwise you’d have to change a few numbers throughout other sandbox configuration files to account for the 10-times size difference.

    Once your sandbox works, you can go back and improve it by doing a full calibration including per-pixel depth correction.

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