Light simulation refers to the means of solving the global illumination problem governed by the rendering equation (or volumetric rendering equation when participating media are present). What is so special about this equation, is that its expansion results into an infinite series; practically, this means that we have to deal with very high dimensions. This can cause various numerical stability problems.
Dealing with the global illumination problem was traditionally being done with discretization methods, such as variants of finite elements. But these techniques are too coarse for the delicate needs of the human eye; even more, they are quite resource demanding. Stochastic methods on the other hand can lead to the actual solution, i.e. without inserting any bias. By applying progressively the stochastic methods, we can see the image refined over time.
In Thea Render we have developed a mathematical framework by selecting and improving the most robust numerical techniques. Even more, Thea Render can perform accurate volumetric light simulation, something that cannot be found in other highend commercial render solutions. Calculating in full visible spectral space, we made sure that there is no lighting detail you are going to miss.
