Path Raytracing

Global illumination effects can be rendered with path raytracing. On contrary to the distributed raytracing, for each ray hit, at most one ray is reflected or refracted when path raytracing is used. With sufficiently large trace depth limits, most of the indirect illumination effects are computed correctly. However, the results are very noisy and an extremely high number of samples is required for obtaining high quality images.

An implementation of the path raytracing is provided by the path_material shader which, for convenience, uses the same parameters as dgs_material.

Note that finalgather and globillum settings have no effect on the surfaces with path_material: the diffuse indirect illumination component is computed by reflecting at most one ray according to a Lambertian-distributed direction. There is no path_material_photon shader. For rendering speedup, finalgather and photon emission should be disabled. Comparing with the scenes using photon maps, the trace depth have to be increased.