Working on refraction: This is the first attempt which just scattered the ray randomly when leaving the object (image uses 500 samples);
Ok this is as far as I got by the deadline… which is kind of a sad state of affairs. When leaving the object I am doing the same refraction equation again with no randomness involved but unfortunately it still looks very wrong (50 samples):
I will render a higher sample picture over night:
This is a render with 500 samples/pixel where instead of using the artificial material that absorbs purely based on the cosine term, it is a lambertian with r=0.8 . It is slightly darker, which is to be expected.
Putting another sphere into the scene revealed that sometimes the reflections were wrong because a negative cos was calculated. The issue was that the change of basis was done incorrectly for transforming the samples. Now it looks sane:
But you can still see a strange highlight at the top of the bottom sphere. My reflectance just based on the cos term, using a real material property, like stainless steel, results in a normal looking bottom sphere (1000 samples):
