This paper proposes the application of a variance reduction technique called weighted importance
sampling in shooting type global illumination algorithms. The sampling applied by shooting type
Monte-Carlo global illumination algorithms can mimic the power of the transfer, but not the BRDFs at the
visible target. Consequently, these algorithms are poor in rendering visible
specular surfaces. In order to eliminate these drawbacks, the BRDFs at the visible targets are
taken into account as an additional weighting of the sampling density.
After discussing the basic concepts we demonstrate the proposed idea with two
algorithms. The first one uses conventional rays, while the second one ray-bundles to transfer the
light in the scene.