Voxel indices are not being computed correctly

[chambbj]

As reported on the mailing list:

The filter “voxelcenternearestneighbor” accepts a parameter “cell” which controls the voxel cell size. I cannot seem to get the software to accept a value lower than 1.0. ie. Any value lower than 1.0 outputs 1.0.

I verified this on my system. The cell parameter is being parsed correctly (values less than 1.0 are accepted), but because the division by the cell size occurs after the floor operation, we are losing the precision required to achieve a discretization of anything smaller than 1.0.

It impacts both filters.voxelcenternearestneighbor and filters.voxelcentroidnearestneighbor.