[CUDA] Normal estimation cuda duplicate of gpu module

[jmackay2]

GPU normal estimation is available in both the cuda and gpu modules. The cuda module version appears to be older and less maintained. Is there a benefit of keeping the cuda normal estimation around, or should it be deprecated in favor of just using the gpu module?

[mvieth]

Are you talking about the functions in https://github.com/PointCloudLibrary/pcl/blob/master/cuda/features/include/pcl/cuda/features/normal_3d.h ? I have not used them myself so far, but the comments do not make them seem very trustworthy ... Someone would have to take a detailed look at what they do exactly and how they compare to the normal estimation function(s) in the gpu module (e.g. also in terms of speed) before we can discuss deprecation