ALTHOUGH THERE ARE NUMEROUS LIGHTING strategies within mental ray, it al l boi ls down to understanding two essential methods of global i l lumination; Photon Mapping and Final Gathering . Each can be used independently of the other, or they can be used together to give even more l ighting control . The key to using either of these methods is to understand the process. Once you understand what’s happening, you’l l understand what you can do to “tune out” the art i facts and “tune in” the solution. We’l l start with explaining photon mapping within mental ray.