NodeODM parameters/ workflow options for reducing point cloud noise

I need some tips on how to get a less noisy point cloud. I think I am getting way too many points that are just noise. I would like to try and reduce them, while at the same time holding actual data.

Some specific questions:

  1. Which ODM parameters deal directly with the data/noise ratio in a point cloud?
  2. Does image pre-processing make a difference? My current workflow involves running the photos through Lightroom in order to fix some exif issues with the DJI cameras. Does anyone have any experience with the effects of sharpening and contrast?
  3. How important is lens calibration? I have been using “auto” in the ODM settings. Can I improve the noise by calibrating the lens? How can I tell whether my workflow is calibrating the lens?
  4. What about creating a corrected rectilinear lens profile, the likes of which is used in other photography fields? Would this kind of correction yield better results or is it redundant with ODM camera correction methods?
  5. I am shooting with a 110degree lens (Laowa 7.5 mm, Zenmuse X5 camera) does a wide angle lens make calibration more important?

Thanks

Not knowing much about what you are seeing specifically, the first thing I would try is using --camera-lens set to fisheye first. 110 degrees is pretty wide, and auto might not be adjusting correctly.

Auto is likely to work better in the near future for wide lenses, see Yann’s ne here:

See if that helps, we and we tweak from there.

Here’s what I’m seeing

Screen Shot 2020-05-04 at 9.24.59 PM

It just appears to me that the point cloud density is too high, so I’d like to delineate and cull the worst, and keep the best.

The Lawoa 7.5mm is a rectilinear lens, not a fisheye. It does have a small amount of barrel distortion, which I could fix but I would need to create a profile for it, as I cannot seem to find one for it online. This would entail a bit of work so I would first like to know if it would help. so…

Does it help to have photos that are near-perfect in terms of distortion?

For what it’s worth, I had about 93% overlap with these images at about 200’ altitude.

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Is there any research aimed at determining how lens angle of view and corresponding flight height (cm/pixel remaining equal) plays into flight efficiency and accuracy?