Trouble capturing small elements in scene

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    Steff

    first.. a much larger base with some news paper.. much bigger targets too..

    and at least 10 rows.. but maybe less images per row.

     

     

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    Alexander Shenkin

    Thanks for your thoughts, Steff.  The cameras align with no problem - so the base and the targets aren't issues (I process the images with aruco to generate GCPs prior to alignment).

    What is your rationale behind increasing the number of "rows", and how do you think that will address the issue of capturing smaller elements in the scene?

     

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    Steff

    well most branches are vertical..

    increasing the number of rows will help, it will give RC a more uniform cam positions to work with..

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    Alexander Shenkin

    Thanks Steff.  I see what you're saying (though not sure why the relative orientation of object vs rotational axes should matter), and I agree that spreading the photos across more rows might be desirable, but I think that developing some sort of theory about why the smaller features aren't being captured would be important for moving forward first...  any thoughts?

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    Steff

    well because these branches are like long wires, so more rows will help.. adding a different POV for each row..
    the space between the cameras on a given row is very small. But the space between 2 cameras, each from a different row is very large..

    so more uniform in this case is really going to play an important role in terms of precision.

    just to make sure... use high quality in reconstruction

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    Steff

    you will also get a more precise alignment to start with
    (with adding more rows)

    hope that helps/

     

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    tingelbobber

    i could also be that your branches are moving while capturing, so when you are turning the table, the branches will wiggle a bit i think. If the object moves only a bit you will see it in the result. also check how many pixels in this section are visible from camera.

    Great setup, minimal but efficient.

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    stevenramsey123

    Half the number of images in each row and double the number of rows.

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    Alexander Shenkin

    Thanks all.  @Oliver, good thinking about the branch wiggle.  I tried to arrange the setup such that there was no wiggle, and had even first planned to have the rotation stop and branch settle before each pic, but the acceleration was making things worse, and the constant speed seemed to keep things very stable.  Still, it's possible my eye wasn't picking up the movement.

    Regarding feature size, the section that I've highlighted as having gaps is about 5 pixels wide when furthest from the camera, and about 8-9 pixels wide when closest.  The image below is from its closest point.  Also of note is that it's not very sharp (how can you be when you're only 9 pixels wide).  I took these photos with f/16, as I wanted to keep the closest branches in focus, and hence wanted to keep DOF as wide as possible.

    I suspect that it's the resolution (i.e. 8 pixels wide) that is giving me trouble.  But I'm not really sure.  If there is really something about pixel widths, I've wondered about artificially increasing the resolution in photoshop (bicubic resampling or whatever).

    I've also included another example of a probelmatic area.  To my eye, the image should be enough for RC to grab onto and make some 3D points.  However, it doesn't.  Maybe this will give more clues about what's going on, and how to remedy it.  Thanks again.

    allie

     

    another problematic area:

     

     

    Closeup of the vertical branch section that RC doesn't register:

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