Can someone explain differences between following kinds of ray tracing:
- backward RT
- forward RT
- recursive RT
I'm wondering which one is the best for which situation. I'm intrested in the adventages and disatventages of this, not definitions.
Forwards RT (light ray tracing) traces the light from the source to the eye. This kind of RT is quite hard (in terms of computation time) to solve, because you don't know in which direction a photon has to leave the source in order to hit the eye. However, this is necessary if you want to calculate advanced phenomena like caustics.
Backward RT does this in the opposite direction. It traces the ray backwards, from the eye through the projection plane into the scene. This allows a straight-forward implementation, but not all effects can be simulated.
Path tracing and bidirectional path tracing as a variation that tries to combine the advantages of both approaches (performance and variety of effects).
Recursive RT is an addition to backward RT in that you create secondary rays once you hit an object. This is necessary to simulate reflection and refraction.