Detect overhang on a cliff into a pointcloud

[astephan]

Hi !

Is there a way to detect and isolate hangovers in a point cloud ?
It would be usefull to isolate them before running a rasterize process.
Thank you.

[daniel]

Sadly, apart from the Rasterize tool itself, I don't see any way to do that currently in CloudCompare... But maybe other users have some ideas?

[astephan]

Thank you Daniel,

And what about calculate normals and isolate the points with normals under 0° (horizon) ?

[DA523]

Check this attached simple example using normal filtering
I think it does not work if the cliff has multiple hangover layers ??
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Group5.zip

(1.84 MiB) Downloaded 533 times

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Group3.zip

(813.51 KiB) Downloaded 527 times

[daniel]

Another way is to use the 'Hidden Point Removal' plugin (look at the cloud from the side where you see the points you want to keep).

[astephan]

Thank you Daniel,

It works with a simple overhang and multiples too but with multiples, i have to isolate afterwards the 'second', 'third'... layers if i want to generate the contours. Not possible to just rasterise because of the overlays on the point cloud.

I will try to make the 2 operations : classify with normals <0 and use hidden point removal.

Thank you.

[Ana]

Hi everyone,

Stephan, could you find a way to detect multiple overhangs on a cliff at the end? I read you were planning to use normals<0 and Hidden point removal. Did it work? Could you share a descriptive workflow? (screenshots or a short video would be enormously appreciated)

Daniel, if you developed a procedure to calculate overhangs on vertical walls, it would be helpful if you let me know.

Thank you

Ana

[daniel]

I didn't develop any specific procedure. I was just thinking that the Rasterize tool, with its ability to extract the lowest or the highest points inside a raster cell, could maybe be used to detect the overhanging points. But it doesn't look very robust...