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Found 2 results

  1. Pixel samples

    Can anyone shed some light on this... I was reading the help docs "Understanding Mantra rendering" when I noticed two apparently contradictory recommendations. Under Raytracing/PBR, Sample: "For surfaces with displacement and/or very high frequency textures, you might increase pixel samples up to a maximum of 9 × 9. For anything else, a good limit is 5 × 5." Then a little further down under PBR Shading "Because each sample only traces a few rays, different samples might compute completely different colors. For this reason, in PBR you will typically use 16×16, 32×32, or more samples per-pixel (pixel samples setting). Accumulating that many samples will average out the differences from sampling only a few rays." Am I missing something? Are these referring to the same 'pixel sample' settings? Thanks,
  2. Hi! I'm trying to speed up a fur rendering. For the most parts of the object 5x5 pixel samples will work fine, but at the edges of the object, where the fur becomes thinner, 9x9 samples are needed. My idea is to use an greyscale image as multiplier for the pixel sampling. The map could be created rendering ultra low res alpha channels - contract and smooth and invert the image, so that there is black where the inner object part is and grey to white where the outline or rim of the object is. Black = 5x5 samples - grey 6x6 - 8x8 samples - white 9x9 samples. That's the plan. I'm pretty new to houdini and do not know how to get values from an image nor if or how houdini can handle the grey values for every render tile due it needs to calculate the sum of digits for every tile to get only one value as sampling multiplier per tile. Even after googeling for hours i did not found an howto use image maps as values/multipliers. 5x5 samples ~6 minutes rendertime per frame 9x9 samples ~21 minutes rendertime per frame Thats why i would like to get this kinda adaptive sampling. Or is there another solution for my problem? Thanks.
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