Metropolis light transport
Metropolis light transport (MLT) is a global illumination application of a Monte Carlo method called the Metropolis–Hastings algorithm to the rendering equation for generating images from detailed physical descriptions of three-dimensional scenes. The procedure constructs paths from the eye to a light source using bidirectional path tracing, then constructs slight modifications to the path.
Source: Wikipedia — Metropolis light transport (CC BY-SA 4.0)