HdRestir 0.g — Direct-Light Integrators and MIS
Direct lighting can be sampled from the light or discovered by sampling the BSDF. Each strategy succeeds in different parts of the scene, but combining them correctly requires both paths to agree on probability measures and support.
This chapter separates the path and direct-light integrators, derives both branches of the MIS estimator, and traces light-selection probability, solid-angle PDFs, visibility, and spectral contribution through the code.
