I’ve managed to do reverse engineering of circuit boards using GIMP and rough alignment of layers using images like the one pictured. I want to use images to reverse engineer parts in CAD, but the minor lens distortion of a camera on a phone at ~20cm high on top of a stack of objects to keep it eyeballed flat is not enough. The result is off in multiple planes. There are minor errors in my curves in the transparent CAD part pictured, but the hole pattern is correct. The picture has been calibrated to 20mm against the ruler. Any suggestions on how to make this usable for replicating the ellipse that crosses the holes ±0.05mm?

  • ijon_the_human@lemmy.world
    51·
    6 days ago

    A scanner would be your best bet.

    But you could go wild and ditch the photo idea.

    The original piece was modeled in CAD. Simply follow the logical path for how it was originally done.

    Measure the outermost dimensions and draw a rectangle as construction geometry. Then play around drawing a couple of circles - chances are that the top and bottom curves are circles and are trimmed and joined with eachother with say blend curve to preserve tangency.

    Also measure the distance of the holes to the rest of the geometry. How far are they from the top and sides. You could measure their distance to eachother crosswise too to narrow down the measurement error.

    The geometry is built around simple measurements, if you can work out the sketch tools and constraints, you can probably match the original with high precision.

    • j4k3@lemmy.worldOP
      21·
      6 days ago

      That is what the purple overlay is already. However there are multiple ellipses that are not the same and very minor variation is important. The original part was likely made using surfacing workflow and not a parametric sketch type workflow. The error really needs to be ±0.05 or better, thus the reason it is worth chasing the picture based reverse engineering.

      • spicehoarder@lemm.eeEnglish
        1·
        6 days ago

        Are you sure the part is as complex as you say? It just looks like lense distortion to me. You can’t get an accurate copy from a simple photo. You need special equipment to capture the true proportions