If you load an old scene, double check the value of PixelVariance and adaptivemetric.To provide more flexibility during compositing, you can tell RenderMan to sample more in darker and lighter regions of an image so that you can change the exposure of the image without bringing more noise into the image. New controls for "exposure bracketing".0.015 is the default for the new variance metric For the old RenderMan contrast based metric, 0.005 was the default. The default value of the PixelVariance option is changing.Testing in a perceptual space has allowed us to remove darkfalloff as a parameter that controls the new RenderMan 23 adaptive sampling metrics (though it does remain for our compatibility metric, "contrast-v22").This will result in more even noise across areas in the image with varying exposure This improves reliability of the sampler and makes it behave closer to what the human eye sees. Pixel variance tests are done in a perceptual space.This means that you will need to put fewer renders back on the farm because they contain noisy regions ![]() The new approach will give more consistent levels of noise across an image (and across a variety of images) compared to previous versions of RenderMan. The new approach uses statistical variance to determine when to stop sampling the pixel. However, it had the disadvantage that it would sometimes do the wrong thing in areas of significant change on a surface. This had the advantage that it was more memory efficient. In the past, we used the notion of contrast changes in the pixel to determine when to stop sampling. The default approach has changed to how the adaptive sampler works.Important improvements to how RenderMan performs adaptive sampling have been made. When making rapid edits to heavy scenes and this setting is non-zero, the renderer will try to reduce tearing by updating the whole screen progressively with a dissolve-like effect using a new option we call "decidither" but is exposed as Interactive Refinement in bridge products where possible to allow updates to the technique without changing the artist workflow.Įnhanced adaptive sampling and a new default Quicker artist feedback via a new capability to control how the first iterations are updated to the screen. ![]()
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