[Numpy-discussion] spherical harmonic decomposition of 3dmodels

[Paul Rudin]

I'm trying to learn to use numpy/scipy, and at the moment I'm looking at
implementing a spherical harmonic shape descriptor for a 3d
model. Something along the lines described on page 8 of
<http://www.cs.princeton.edu/~funk/tog03.pdf>.

I've made code that does the voxelization bit from some geometry. That
is I've got something that calulates an NxNxN array with 1s at the
points near the meshes of the original model, and zeros elsewhere.

Using this grid I've got a function taking polar coordinates to 1 or 0,
but I've so far failed to use that function to make the 2D grid giving
the descriptor.

scipy.special.sph_harm gives me the spherical harmonic for a given
degree and coordinates, and my function can obviously be sampled at any
points, but putting them together so far eludes me. 

Any hints gratefully received...