May be we could rasterize current view, run segment anything on it, then project the colors into the cloud.
I know the color projecting may not be easy but has been a forever requested feature, so here another excuse to implement it :D
this is a segmentation from a screen capture of a point cloud
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to make it perfect, may be the ideal scenariow ould be to move camera over a path and every nth frames segment anything, this way if a point accumulates a class n number of times you would get a more robbust segmentation (I think).
Just an idea. Cheers.