Hello, I have 3d models of grass from Megascans. I set-up materials using MaterialX. And when I rendering it on CPU, but rendering very-very-very slow (ETA for 720x960 50minutes), result is good but to get good quliaty I need to wait forever , so I decided switch to XPU, but for some reasons XPU looks like it has no shadows . SO this is the problem in some settings or current limitation of XPU, can it be somehow solved?
It seems to be the mipmapping on the opacity texture which is causing the issue. Because presumably, grass is very small geometry, meaning the UV-derivative code is calculating some pretty extreme values.
KarmaCPU and KarmaXPU calculate mipmapping slightly differently, which is why you're seeing a difference.
You could try disabling XPU mipmapping altogether? ie export KARMA_XPU_DISABLE_MIPMAPS=1
brians It seems to be the mipmapping on the opacity texture which is causing the issue. Because presumably, grass is very small geometry, meaning the UV-derivative code is calculating some pretty extreme values.
KarmaCPU and KarmaXPU calculate mipmapping slightly differently, which is why you're seeing a difference.
You could try disabling XPU mipmapping altogether? ie export KARMA_XPU_DISABLE_MIPMAPS=1
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Thanks. export KARMA_XPU_DISABLE_MIPMAPS=1 it can be done in wrangle in Solaris? and can be done only for specidic materials? or global for all scenes?
Hyperreal-Studios Thanks. export KARMA_XPU_DISABLE_MIPMAPS=1 it can be done in wrangle in Solaris? and can be done only for specidic materials? or global for all scenes?
you run it in the command line shell you use to launch Houdini. It's an environment variable and therefore global to the application.
brians It seems to be the mipmapping on the opacity texture which is causing the issue. Because presumably, grass is very small geometry, meaning the UV-derivative code is calculating some pretty extreme values.
KarmaCPU and KarmaXPU calculate mipmapping slightly differently, which is why you're seeing a difference.
You could try disabling XPU mipmapping altogether? ie export KARMA_XPU_DISABLE_MIPMAPS=1
Image Not Found
Would using an image format that doesn't already have mipmaps, e.g. png exr tif, as opposed to rat or exr with mipmaps, also effectively disable mipmapping since the mip levels don't exist? Does XPU automatically generate mipmaps for all images?
jsmack Would using an image format that doesn't already have mipmaps, e.g. png exr tif, as opposed to rat or exr with mipmaps, also effectively disable mipmapping since the mip levels don't exist? Does XPU automatically generate mipmaps for all images?
At the moment XPU does automatically generate mipmaps for all images (even if they don't exist in the file).
But that will probably change in the next version of Houdini (that area is being actively worked on). The goal is to have it behave more similarly to whatever KarmaCPU does.
