Spherical and Cylindrical coordinates Output Volume

[crisbour]

Configure output volumes to sample values in cylindrical or spherical coordinates as well, as this might be more useful for some scenarios:

• Spherical: for a point source, this can be quite an effective way to represent radiance out from a street light bulb, an LED in a scene or fluorescence from a tightly focused beam
• Cylindrical: Radiance inside a material from any axially symmetrical source

Having the volumes in this coordinates eases post-processing requirements to change from cartesian voxels. Changing from cartesian voxels to cylindrical/spherical is not trivial since measurements locus are in the center of the voxels, but desired system voxels will not overlap, so a complex 3D interpolation is necessary to map the values