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Author Topic: How to remove the "snow" at the edges of the point cloud  (Read 1625 times)

rowild

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How to remove the "snow" at the edges of the point cloud
« on: December 21, 2023, 02:42:13 AM »
Hi!

I am rather new to Photogrammetry and to Metashape, which I use int he standard edition's trial version at the moment. I am particularly fascinated by the point cloud results Metashape generated and use them purely as "art".

I would like to get a little better and am currently struggeling with the problem of removing white noise at the edges of many of my point clouds. As the attached image shows, the trees in the point cloud seem to have snow on them – but there hasn't been any snow at the time of shooting those images. I assume it is an "artifact" from the bright background?

I've read that I can use the point cloud's filter option with values from 0 to 3. But those remove some green from the ground first, before any white is touched.

Is there another way to handle this "phenomenon"?

Thank you!

Alexey Pasumansky

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Re: How to remove the "snow" at the edges of the point cloud
« Reply #1 on: December 21, 2023, 04:34:13 PM »
Hello rowild,

Apart from the confidence filtering (that you can use with factor 1 and 2, for example), you can try to use selection by color option or even try to build the mesh from the depth maps, skipping the point cloud generation stage.

As for the confidence filtering back again, note that after points with the desired confidence value are selected, you can de-select part of it in the Model view by holding SHIFT key and using the the left mouse button to de-select the points from the existing selection.
Best regards,
Alexey Pasumansky,
Agisoft LLC

rowild

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Re: How to remove the "snow" at the edges of the point cloud
« Reply #2 on: December 21, 2023, 08:09:32 PM »
Thank you very much! That worked quite fine! Specifically the deselection feature (using SHIFT + mouse) was new to me. :-)

(Currently I am only interested in the point clouds, which I like very much from an estetically, and not the meshes. I hope that's all right.)

JMR

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Re: How to remove the "snow" at the edges of the point cloud
« Reply #3 on: December 21, 2023, 10:09:23 PM »

(Currently I am only interested in the point clouds, which I like very much from an estetically, and not the meshes. I hope that's all right.)
Hello rowild:
I just wanted to add that sometimes building a mesh and then sampling a dense cloud on the mesh leads to a much cleaner and pleasant dense cloud and it does not necessarily add processing time.
Workglow: align - build mesh from depth maps - build point cloud from mesh
Moreover, you gain the ability to choose the dense cloud density to your taste.

Regards
José Martínez
Geobit & Accupixel CTO


rowild

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Re: How to remove the "snow" at the edges of the point cloud
« Reply #4 on: December 21, 2023, 10:10:24 PM »
Oh! I didn't know that! Thank you for pointing that out! I will try that immediately!