The Render Manager > mental ray (Global Renderer)
The Render Manager > (expand a pass) > mental ray
Set a current pass and choose Render > Render > Renderer Options from the Render toolbar.
Options: View Photons, View Coordinate Grid, and mi Archives
Diagnostic rendering modes render altered representations of your scene, in which color coded statistical information is either added to the rendered image or replaces it entirely. Usually, this statistical information consists of dots, lines, bands of color, and so on, depending on the diagnostic mode that you select.
You can use diagnostic modes to get visual information about sampling, photon irradiance and density, final gathering, and object sizes and distances.
The View Sampling diagnostic replaces the image with a grayscale representation of sampling density, in the form of dots. The denser the cluster of dots, the more sampling is being performed. Pixels that have not been sampled are black, while pixels that have had the maximum amount of sampling, as defined on the Aliasing tab, are white. Red lines indicate the boundaries of the task. Samples that lie exactly on pixel boundaries belong to the lower and/or left pixel.
The View Photons diagnostics render color representations of either photon Irradiance or Density, depending on which you choose.
If you choose Density, you'll also need to set the Maximum value. This is the number of photons per unit of surface that you define as the maximum (100%). If you set this value to 0, an appropriate maximum is automatically sought.
In the diagnostic render, irradiance or density values are represented by a color scale where values of 0%, or thereabouts, are represented by blue. As values increase, the scale moves through cyan, green, yellow, and red which represents values of 100%. Higher values fade to white.
This diagnostic is useful for tuning the number of photons in a photon map and setting the various accuracy options, since the density (or irradiance) is estimated using those settings.
The View Coordinate Grid diagnostics overlay a grid of Object, World, or Camera space coordinates on the rendered image. The X, Y, and Z axes are represented by red, green, and blue lines respectively. The Size value determines the size of a single grid unit. These diagnostics can help you get a a good idea of object sizes, distances between objects, and so on.
The View Final Gather Points diagnostic overlays green, blue, and red final gathering points on the rendered image.
Green points are the initial final gathering points computed during preprocessing.
Blue points belong to objects that are using their own final gathering maps rather than the scene-wide final gathering map.
Red points are extra points that are computed at render time if the final gathering map needs additional information (extra samples) to complete the effect.
Generally speaking, your final gathering diagnostic renders should show mostly green/blue points and a small number of red points.
The rendering time per pixel can be shown in the render region or output to disk using the Pixel Time framebuffer. You can set the upper bound or whitepoint of the pixel time values with the Max Pixel Time (µS) setting.
When displayed in the region, the image is shown in false color to show trouble spots better. Blue pixels have low values, green pixels have medium values, and red pixels have high values.
