Efficient physically-based simulation of non-linear media

Modelling and simulating natural phenomena are two of the hardest tasks in virtual reality environments, owed to the complexity of the calculations involved. This fact becomes even more important for phenomena that are caused by the varying index of refraction in a medium (like mirages or the distortion caused by fire). Although there are some works on this topic, they sacrifice physical accuracy for efficiency, using heuristic methods that might achieve interactive rates in the best cases but do no consider physical simulation. Non-linear media (with non-homogeneous index of refraction) are costly to simulate precisely.This paper presents several techniques for simulate the effect of non-linear media on light rays, simulating natural phenomena in a more reasonable time than previous works without losing physical correctness. This can be ensured by following the ray equation for numerically calculating the path of light. The presented optimization techniques are based on this resolution method. Flight or driving simulators, as well as other virtual reality environments, could greatly benefit from this work.