Calibration Troubles

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    The last week I have been trying to calibrate our AR sandbox, and I am running across two errors that I believe may be related. I will describe them separately to clarify the problems.

    (1) In the projector calibration (Step 10 in the Complete Instructions topic), I keep getting an error where the circle target will not ‘turn green’ or sometimes will not show up at all when it is placed anywhere below the sand surface. I dig the hole, press the second button activating the capture background tool (screen turns red, then back to the crosshairs screen), but still the camera doesn’t seem to ‘see’ the target properly. The camera sees it just fine anywhere >2cm above the sand surface.

    (2) Also in the calibration step 10, I am having an issue with the crosshairs not appearing on the projected surface – they show up on the computer screen and I can see them in the program. This is only on the last set of crosshairs on each of the two lines, it happens on the bottom and the top rows on one side of the box only. They do not show up on the projected surface, it’s like it has a ‘blind spot’ on one side of the box. It looks like this: There appears to be only one white line running lengthwise down the sandbox, and it just ends instead of intersecting with another white line to form the crosshairs. It does this on both the bottom row calibration and on the top row calibration.

    Things I have tried:
    a) Adding -fpv to the projector calibration command in terminal. Result: Screen reduced to tiny field in bottom left corner of the box. Had to restart calibration program.

    b) Resetting the 3d coordinates captured in the Raw Kinect viewer. Result: Had no effect.

    c) Going through the entire program and just guessing where the crosshairs should be based on what I am seeing on the screen. The terminal window gives back an error saying that some of the points were negative values and calibration would have to be done again.

    Any ideas?


    ” I am having an issue with the crosshairs not appearing on the projected surface – they show up on the computer screen and I can see them in the program.”

    I think this is your problem. They should be one and the same, the Calibration screen needs to be projected onto the sandbox, in full screen mode.

    On my computer running Ubuntu with Nvidia display drivers this is handled by:

    – starting Calibration or SARndbox program
    – moving window so I can see the title bar [winkey/super-key + arrow]
    – grabbing window by the title bar and dragging it to one side until it pops over onto the projector display (seeing it on the sandbox)
    – pressing [F11] to go full screen
    – now do calibration routine


    • This reply was modified 5 years, 5 months ago by maphew.

    I have been working in full screen mode, however when I start the program it is obviously not in full screen mode and I have to change it. By that time it has already done it’s ‘capturing frames’ in the red screen thing. I’ve tried recapturing the background image before starting the calibration.

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