Wide stripes in pointcloud

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timmmerd
Posts: 1
Joined: Fri Dec 16, 2022 1:12 pm

Wide stripes in pointcloud

Post by timmmerd »

Hello everyone,

I am still new to the cloudcompare software as I'm trying to use it for a school project, but a issue has occurred
where there are wide stripes across the point clouds ( see attachments) when im using the software and when I'm exporting it.

When i open the exported .57 or LAZ file in Archicad/Vectorworks or photoshop the stripes are still occurring and I'm wondering how to get rid of them
in cloudcompare or what will prevent it from happening.

thanks in advance.
example stripes cloudcompare.jpg
example stripes cloudcompare.jpg (991.7 KiB) Viewed 1885 times
example stripes bug.jpg
example stripes bug.jpg (1.48 MiB) Viewed 1885 times
thanks in advance
daniel
Site Admin
Posts: 7707
Joined: Wed Oct 13, 2010 7:34 am
Location: Grenoble, France
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Re: Wide stripes in pointcloud

Post by daniel »

This looks like 'flight lines' overlap (the airborne lidar captures large sections at each pass of the plane, with a slight overlap with the previous pass so as to not miss some areas). This induces a local increase of the density.

To remove that effect, you can use the 'Subsample' tool to reduce the density so that it's the same everywhere. You can either do it by trial and error, or you can segment a (large) portion of the cloud without any overlap, and compute the local density (Tools > Other > Compute geometric feature). By analyzing the resulting scalar field (with 'Edit > Scalar fields > Show Histogram', or 'Edit > Scalar fields > Compute Stat Params') you could determine the right density value and be able to derive the right subsampling distance?
Daniel, CloudCompare admin
daniel
Site Admin
Posts: 7707
Joined: Wed Oct 13, 2010 7:34 am
Location: Grenoble, France
Contact:

Re: Wide stripes in pointcloud

Post by daniel »

And the top image is more concerning to me due to its very low sampling in some areas. Have you applied a Global Shift to avoid using large coordinates while the cloud is open in CC?
Daniel, CloudCompare admin
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