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  3. VOXL2 camera cal looks wierd

VOXL2 camera cal looks wierd

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  • ? Offline
    ? Offline
    A Former User
    wrote on last edited by
    #4

    That's to help you see what the checkerboard detector sees this "thresholding" takes the 0-255 image and setting each pixel to 1 or 0, making it significantly easier for the CV lib to find the checkerboard.

    The system has always done this, we just recently added it as default on the overlay because it makes it much easier to debug when you can see what the checkerboard detector is actually looking at. If it's having trouble finding the checkerboard, it's usually a lighting condition issue, make sure that your board is relatively matte (standard printer paper is usually pretty good), and you have it well lit but not directly reflecting the light at the camera as you'll run into issues where the center of the light completely washes out a section.

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    • Patrick HincheyP Offline
      Patrick HincheyP Offline
      Patrick Hinchey
      Contributor
      wrote on last edited by
      #5

      Oh I see. Ok it's on standard printer paper, I'll try to get some more diffuse lighting...

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      • ? Offline
        ? Offline
        A Former User
        wrote on last edited by
        #6

        For instance: the lighting conditions in our office are good and the thresholder ends up showing a very clear image of the checkerboard:
        Screenshot from 2023-01-25 10-00-44.png

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        • Patrick HincheyP Offline
          Patrick HincheyP Offline
          Patrick Hinchey
          Contributor
          wrote on last edited by Patrick Hinchey
          #7

          Yes my image is MUCH noisier than that even when it's not over/underexposed. Lighting is bright though...
          On another topic, should I be using --fisheye for the standard tracking cam?

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          • ? Offline
            ? Offline
            A Former User
            wrote on last edited by
            #8

            Yes! The standard tracking camera we ship is very fisheye, I'd be incredibly impressed if anyone was able to get a successful cal with the normal pinhole model.

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            • Patrick HincheyP Offline
              Patrick HincheyP Offline
              Patrick Hinchey
              Contributor
              wrote on last edited by
              #9

              Haha ok ^_^

              We moved out of the office to an overcast day outside. The image of the checkerboard looks good, how come it can't detect it?

              b19d8d35-c531-4048-8e0f-dbf3d4a52bf6-image.png

              b4333e43-345f-489f-bfa5-ef3104c8752b-image.png

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              • ? Offline
                ? Offline
                A Former User
                wrote on last edited by
                #10

                I'd recommend putting a strong white border around your checkerboard (at least half a square). If you look at mine we've just taped over the outer half of the outside squares with white tape, that also significantly helps the checkerboard detector when there's a well defined outer square.

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                • ? Offline
                  ? Offline
                  A Former User
                  wrote on last edited by
                  #11

                  Also it looks like you've specified a 6x8 board to the calibrator, but your board looks like it has 6x9 interior corners. This technically wouldn't matter too much since it'll find a valid 6x8 within that, but it'll run faster if it's not given 2 very similar solutions to have to choose between.

                  Patrick HincheyP 1 Reply Last reply
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                  • ? A Former User

                    Also it looks like you've specified a 6x8 board to the calibrator, but your board looks like it has 6x9 interior corners. This technically wouldn't matter too much since it'll find a valid 6x8 within that, but it'll run faster if it's not given 2 very similar solutions to have to choose between.

                    Patrick HincheyP Offline
                    Patrick HincheyP Offline
                    Patrick Hinchey
                    Contributor
                    wrote on last edited by
                    #12

                    @Alex-Gardner oops silly me!! The latency has been awful on this latest calibration, on the order of 2s, so that is probably a major contributor! Thanks I'll try with white tape an 6x9

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                    • Patrick HincheyP Offline
                      Patrick HincheyP Offline
                      Patrick Hinchey
                      Contributor
                      wrote on last edited by
                      #13

                      yessss 6x9 and a white background both improved detection rate, not just latency. Thanks for your help!

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