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Mantra - Glitch / Flicker Error

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Hi!! :D

I'm a VFX student new to Houdini and i'm having some problems to render a "stone" shader because some of the stones in my displacement show some kind of glitch / flicker. I'm rendering in mantra in a 3-5 samples setup, I've tried to put normal node and it make the same error.

My shading setup for the displacement is "Zbrush displacement map + 2 stone textures with some fits + uv noise + uvxform, all of this connected to color mix that goes to displacement" my zbrush displacement is 8k resolution in tiff.




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displacement flicker may appear for many reasons. hard to tell without inspecting the scene. anyway if you're doing some displacement mixing on shader level, it is quite easy to get a displacement that is impossible to render artifact-free (polygons may cross each other, or may get extremely distorted, etc). one thing that might help thou is turning on "Render polygons as Mantra subdivision". you can find that on objects' Render parameters tab.

edit: after seeing the video it looks like it is just a problem of insufficient dicing. I suggest turning on "Render polygons as Mantra subdivision", adding "Re-dice displacements" object render parameter and you might also want to try "Uniform measuring" for Dicing on your Mantra node if you still see flickering (you might want to bump up Shading quality to values more than 1 with Uniform measure).

Edited by davpe
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4 hours ago, lukeiamyourfather said:

It might be the displacement bounds are not big enough so neighboring buckets end up missing geometry that should be displaced into them. It's hard to tell from the compressed movie though.

Thanks for the answer!! Is there a way to adjust the displacement bound or blur it??? 

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