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302 Posts in 83 Topics by 32 members

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Forums » PicoScan UserGroup » Calibration

Moderators: Frank

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Author Topic: Calibration 4540 Views
  • Jaco Moolman
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    Community Member
    42 posts

    Calibration Link to this post

    12 January 2011 at 6:02am

    Hi there.

    Just some questions about better calibration. I think I might be doing something wrong.

    According to me the images looks pretty good, but pico does not think so. The projector is green @ about 66, but the camera is red at between 0 and 4, but from what I can see pico should be able to see the middle spot fine. Am I missing something? When you click on the captured image, it should show the points it recognized, but it does not get even one?

    I sometime get both green, but the little preview window is then almost completely red, which then should not get any calibration data.

    Attached Files
  • Christopher
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    Forum Moderator
    58 posts

    Re: Calibration Link to this post

    13 January 2011 at 2:20am

    Hi Jaco,

    Try reducing the exposure of the image, either by reducing the aperture, increasing the shutter or decreasing the ISO of the canon camera. Keep an eye on the Live View window at the bottom right, if you see lots of red in the image you're over exposed and if you see lots of blue you're under exposed. You're looking for a happy medium, possibly touching on the slightly over rather than under exposed.

    Let us know if this helps.

    Chris

  • Jaco Moolman
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    Community Member
    42 posts

    Re: Calibration Link to this post

    13 January 2011 at 6:07am

    Hi there.

    Thanks for the info. I will play again with the exposure setting, but I still can not understand why the pico can not see the markers on the images I attached. It looks pretty clear and sharp to me.

  • hal
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    Community Member
    38 posts

    Re: Calibration Link to this post

    13 January 2011 at 9:57pm

    Hi Jaco,

    have you correctly set the number of camera squares to 21x15, right? Sometimes happe to me that camera can't see its squares. I simply change the "chessboard color" and do a calibration, just after I came back to the right chessboard color and all works correctly. However, strange problem...

    Other hints about calibration: I've seen that if I calibrate a lot of chessboard's positions/camera+projector orientations, the RMS error is bigger, because the light conditions and the geometric infos chenge drastically. But the final scan result is correct and no deformated. If I keep low the calibration number of steps (only 4 or 6 chessboard positions) and if the differences between any chessobord orientations are very small, the RMS error is small, but the final mesh will be distorted.
    Just my 2c... ;-)

    Regards,
    Mattia

  • Jaco Moolman
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    Community Member
    42 posts

    Re: Calibration Link to this post

    14 January 2011 at 8:35am

    You know, now that you mention it.. I think I might not have set the board to green on red.. The app crashed the first time and I did not set it when I did the calibration the second time. I think this is what the problem it.. I will try again and report back. Thanks for the feedback.

  • Jaco Moolman
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    Community Member
    42 posts

    Re: Calibration Link to this post

    14 January 2011 at 9:28am

    You know, now that you mention it.. I think I might not have set the board to green on red.. The app crashed the first time and I did not set it when I did the calibration the second time. I think this is what the problem it.. I will try again and report back. Thanks for the feedback.

  • Nishad Karim
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    Community Member
    4 posts

    Re: Calibration Link to this post

    21 February 2011 at 9:54am

    Hello,

    I too have a query on calibrating my newly aquired PicoScan. Using a dark box, I've been able to successfully calibrate the scanner and produce decent 3d images. But, each time I switch off the scanner and load it up again, I find that the calibration settings have altered significantly even though the environmental conditions have remained the same. I need my work to be reproducible, hence having the same/similar settings is important. Can someone help in diagnosing the problem and finding a solution?

    Thanks,

    Nishad

  • Frank
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    Forum Moderator
    60 posts

    Re: Calibration Link to this post

    22 February 2011 at 10:55am

    Hi Nishad,

    You should be able to use the scanner over and over again without the need to recalibrate so long as the relationship between the camera and project with regards to position, zoom and focus doesn't change.

    When you say 'the calibration settings have changed', could you explain what you mean exactly? Could you also tell me how you are going about reusing the calibration as there are a couple of ways. Aslo be very careful when you turn off the project, as the button on the side can be a little stiff and by using it without care you may break the original calibration.

    Thanks Frank.

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