The current state of the methods for calculating global illumination in tasks of realistic computer graphics

Modern realistic computer graphics are based on light transport simulation. In this case, one of the main and difficult to calculate tasks is to calculate the global illumination, i.e. distribution of light in a virtual scene, taking into account multiple reflections and scattering of light and all kinds of its interaction with objects in the scene. Hundreds of publications and describing dozens of methods are devoted to this problem. In this state-of-the-art review, we would like not only to list and briefly describe these methods, but also to give some “map” of existing works, which will allow the reader to navigate, understand their advantages and disadvantages, and, thereby, choose a right method for themselves. Particular attention is paid to such characteristics of the methods as robustness and universality in relation to the used mathematical models, the transparency of the method verification, the possibility of efficient implementation on the GPU, as well as restrictions imposed on the scene or illumination phenomena. In contrast to the existing survey papers, not only the efficiency of the methods is analyzed, but also their limitations and the complexity of software implementation. In addition, we provide the results of our own numerical experiments with various methods that serve as illustrations for the conclusions.