Modification of the stochastic ray tracing to reduce a noise on diffuse surfaces

Bidirectional Monte-Carlo methods of ray tracing allow you to effectively generate physically correct images of virtual scenes, reproducing a large number of optical effects. However, the resulting image contains noise inherent in stochastic algorithms. An original modification of the pixel brightness calculation process is proposed. It makes possible to significantly reduce noise on diffuse surfaces. The proposed method does not distort the texture and small-scale image details, because in fact the built-in tracing filtering applies not to the final image, but to effective illumination. The method works well for diffuse lighting but it is not beneficial for brightness created by direct or caustic lighting.