1.29 Diagnostic modes
mental ray supports a number of diagnostic modes that help visualizing and optimizing the rendering process. They modify the output image to include grid lines or dot patterns that indicate coordinate spaces or sampling or photon densities. These graphs allow simple detection of insufficient or excessive sampling densities, and help to tune parameters such as numbers of photons or sampling and contrast limits. Grid Mode This mode renders a grid on top of all objects in the scene, in object, camera, or world space. It?s useful to get an idea of the scene scale and to enable rough estimates of distances and areas.
Photon DensityModeThis mode replaces shows a false color rendering of photon density on all materials. This is useful when tuning the number of photons to trace in a scene, and to select the optimum accuracy settings for estimation of global illumination or caustics.
It also works well in combination with the Grid Mode described above. SamplesmodeThis mode shows how spatial supersampleswere placed in the rendered image, by producing a grayscale image signifying sample density. This is useful when tuning the level and the contrast threshold for spatial supersampling.
Diagnostic modes are enabled with the -diagnostic option on the command line, or the diagnostic statement in the options block in the scene description file.
