Raterize interpolate not filling holes

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bcarr
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Joined: Tue Oct 03, 2023 5:04 pm

Raterize interpolate not filling holes

Post by bcarr »

I have point clouds created using SfM photogrammetry and am using cloud compare to do M3C2 differencing with precision maps. I am then trying to rasterize the M3C2 result so I can calculate topographic volume changes. In rasterize, I have "fill with" set to interpolate, but the resulting grid still has empty cells in it (see attached screenshot).

My point clouds have varying point density and do have empty areas with no points due to these areas being poor locations for the SfM software (Agisoft Metashape) to find tie points. I was hoping the interpolate function would be able to fill these holes. From the CloudCompare user guide, I know the cells have to be within the "convex hull" of the cloud to be filled, but I think they are- the holes are located in the middle of the cloud on a pretty uniform slope and do not represent any kind of outlying protrusion or depression. Am I misunderstanding what "convex hull" means?

I have the step size set to 0.5 because this is the resolution of the DEM generated by Agisoft Metashpape for this data, so I know that the point density can support this grid size- at least by Metashape's algorithm.

Is there any way to change the settings such that interpolate can fill these holes?

Happy to provide more data or information if needed.
Attachments
Screenshot of rasterize for M3C2 result showing holes in middle of point cloud
Screenshot of rasterize for M3C2 result showing holes in middle of point cloud
Screenshot 2023-10-03 at 9.56.01 AM.png (321.44 KiB) Viewed 2667 times
daniel
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Re: Raterize interpolate not filling holes

Post by daniel »

How was this version of CloudCompare compiled? It seems that CGAL support is not enabled (we use CGAL to compute Delaunay triangulation so as to be able to use interpolation).

Anyway, you have another way to interpolate in the latest version: Kriging (it doesn't rely on CGAL, and it interpolates everywhere on the grid, not only inside the convex hull of the valid cells).
Daniel, CloudCompare admin
bcarr
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Joined: Tue Oct 03, 2023 5:04 pm

Re: Raterize interpolate not filling holes

Post by bcarr »

I don't know how to answer the question about compiling... I downloaded the .dmg file for my mac and then followed the installation instructions. I was using CloudCompare v2.12.3 installed and my Mac is running OS Ventura 13.5.2

Are there instructions somewhere for how to enable CGAL support? I couldn't find anything obvious with a quick google.

I just installed CloudCompare v2.13.alpha and "kriging" is not an option for me under "Fill with" for empty cells in the rasterize tool.

Can you provide any guidance? It seem like maybe the way in which I am installing CloudCompare is leaving out some features?
daniel
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Re: Raterize interpolate not filling holes

Post by daniel »

Ah, no, you answered: I believe CGAL and raster interpolation is not supported on this macOS version.

Maybe you'll have more chance by trying to download the version included in the CloudCompy package for macOS: https://www.simulation.openfields.fr/in ... d-binaries (it's currently the 4th package)

You can ignore the Conda/Python stuff, and run CloudCompare.app which is in the Cloudcompare folder of this package. At least one of the 2 interpolation options should work...
Daniel, CloudCompare admin
bcarr
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Joined: Tue Oct 03, 2023 5:04 pm

Re: Raterize interpolate not filling holes

Post by bcarr »

That worked! Thank you!
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