Vincent Aalbertsberg

Hello everyone,

I noticed recently that the mtlx ambient occlusion node was no longer accessible in Houdini 21 (https://www.sidefx.com/docs/houdini/nodes/vop/mtlxambientocclusion.html). Is there any kind of replacement for it? Having pixel AO on the fly in materials is incredibly valuable to make quick improvements, are we just meant to either bake to attributes (which is limited by the geometry) or bake actual maps in cops (which is much longer, requires UV, has a limited resolution...)?

I use AO in materials so much in my day to day work, I'm a bit confused... Thanks !

brians
Try setting the KARMA_XPU_MAX_UNIFORM_VOLUME_SPANS envvar to a higher value. It defaults to 32, try 128 (or something)
Going too high will hurt performance, so be a little careful with it

Hello Brians,

That does fix it, thank you for the help! Do you have any pointers as to why this happens, so I can understand it better? Is it because of the very tangential viewpoint relative to the uniform volume edge? Is it linked to the refractive surface as well, or just the volume?

Anyway, I'm happy it's fixed, thanks again.

Hello,

In this animation where the camera goes through the ocean (using a houdini procedural ocean in karma XPU), there is a brief moment where a dark line is visible as the camera is going through the ocean... I join here a close up video of the artifact... I thought it would be fixed by adjusting sampling limits of either refraction or volumes, but even with those at a high value, nothing changes... Any clue what could cause this, and how I could fix it ?

Thank you !