A raytraced scene consisting of a red sphere and a black torus, above a white plane. The thick red sphere has inner and outer radii in the ratio 5:7, and has refractive index 1.2. Caustics can be seen, as photon mapping was used in rendering. This took 16 hours to render at 5000x3750 on an Intel Pentium 1.8GHz machine with 1GB RAM.
Prateek Karandikar
CC BY-SA 4.0
Own work, created with POVRay