Add nearest point to voxel centroid/center as reduction option for PointCloud::VoxelDownSample

[nvandamme]

Checklist

• I have searched for similar issues.
• For Python issues, I have tested with the latest development wheel.
• I have checked the release documentation and the latest documentation (for main branch).

Proposed new feature or change

Hi,

We're using extensively Voxel downsampling with nearest point to the voxel centroid and/or center, like exposed by PDAL:

• https://pdal.io/en/2.6.0/stages/filters.voxelcentroidnearestneighbor.html
• https://pdal.io/en/2.6.0/stages/filters.voxelcenternearestneighbor.html

This way remaining points are original points from the source and we can use this method as a non-deforming spatial subsampling (only the nearest point of the voxel center/centroid within the voxel radius is retained)

CloudCompare is also exposing this method as "Spatial subsampling".

• https://www.cloudcompare.org/doc/wiki/index.php?title=Edit%5CSubsample

References

https://github.com/PDAL/PDAL/blob/master/filters/VoxelCentroidNearestNeighborFilter.cpp
https://github.com/PDAL/PDAL/blob/master/filters/VoxelCenterNearestNeighborFilter.cpp
https://github.com/CloudCompare/CCCoreLib/blob/master/src/CloudSamplingTools.cpp#L241

Additional information

No response