Location: The Render Manager > Renderer > Diagnostics
or
The Render Manager > Globals > mental ray > Diagnostics
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, the BSP tree, photon irradiance and density, final gathering, and object sizes and distances.
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Some diagnostic modes can be run simultaneously. In these cases, the second diagnostic mode that you activate produces a diagnostic rendering of the first diagnostic rendering. Unless this is what you want, make sure that only one diagnostic mode at a time is active. |
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.
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The sampling diagnostic mode is not appropriate for use with the rasterizer. This tool is designed to visualize adaptive sampling patterns and the rasterizer uses a fixed sampling pattern. |
The View BSP Tree diagnostics replace the rendered image with a color representation of BSP tree depth or leaf size, depending on which is selected.
Depth/size values are represented by a color scale where values of 0 are rendered black. As values increase, the scale moves through blue, green, yellow, and red. Areas where the maximum depth/size (specified on the Optimization tab) was reached are rendered white.
When the BSP depth and size are properly set, the depth diagnostic usually produces a fairly colorful rendering because highly detailed areas are subdivided more often, bringing the depth value closer to the specified maximum. The leaf size rendering, on the other hand, is usually fairly evenly colored since a properly balance BSP tree has about the same number of triangles in each leaf.
As a general rule, you should look for areas where the maximum depth/size was reached, and increase the depth/size value to compensate. For more information about the BSP tree, see BSP Raytracing Acceleration.
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For the BSP tree diagnostics to work, raytracing must be activated. It’s also a good idea to turn off scanline rendering so that only raytracing is computed. |
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.
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