Just a guess based on doing a image diff (and without reading the rest of your question). The problem looks to me to be the refraction on the back side of the sphere. You might be:
- doing it backwards: e.g. reversing (or not reversing) the indexes of refraction.
- missing it entirely?
One way to check for this would be to look at the mount through a cube that is almost facing the camera. If the refraction is correct, the picture should be offset slightly but otherwise un-altered. If it's not right, then the picture will seem slightly tilted.
BCS
2010-08-23 04:18:22