Path tracing accumulation artifacts

[MohamedSakr]

a good RNG is C++ 11 mersenne twister , check https://github.com/SmallVCM/SmallVCM/bl ... rc/rng.hxx

[ingenious]

This looks like a color quantization artifact which becomes noticeable as your image converges and the random noise disappears. You could try writing the image to some floating-point high dynamic range image format (like EXR or HDR) and play with the gamma and exposure a bit to see if the artifacts really come from the renderer or from the conversion of the pixel values to 8-bit color.

[citadel]

This is possibly caused by self-intersection. Solution is to offset ray origins by a small amount along the surface normal.

[Brigadir]

Ingenious, you are right, thanks a lot!
It was quantization error. I have implemented a trivial random and then floyd dithering and it solved the problem a bit. However, a perfect solution requires more efforts. Probably it is needed to port a OpenImageIO library.