View Full Version : Noise in Refraction

07 July 2009, 02:19 AM

I am currently having a problem with my my glass material. Where there is refraction I am receiving a lot noise. I believe the problem is with the bump on the floors material. When turned off there's no noise in the refraction. I'm using a blinn for the floors material and a the mia_X for the glass. I experimented changing the bump files filter type and changed the blinn to a mental ray material and still I have noise. The change in noise I've seen was when i bumped up the antialiasing. Would anyone know a fix to this? Is high antialiasing the only fix. Any help would be greatly appreciated.


07 July 2009, 02:44 AM
Both the file node and bump node have filter sliders under the effects tab.

try playing with the filter slider in the bump node too

maybe turn off filtering on the file node, and just use the bump node filter. Or vice versa. Altho, only do that if its a still shot, otherwise the texture might flicker.

also could try elliptical filtering,topicNumber=d0e515341

if none of that works. Then I would just make the refraction ever so slightly blurry.

altho someone else might have a better idea. I have never noticed that problem myself, but I imagine its common to all of our mental rays.

Maybe stick that texture and that cup in a scene everyone can download and play with?

07 July 2009, 04:17 AM
The issue you are having has to do with the anti aliasing setting. In order to get rid of this type of artifact, you need to increase the min/max sample settings to at-least 0/2. You may need to go higher as well. You can make this adjustment on the object itself if you do not wish to super-sample the entire scene.

If the issue is only showing up in the refraction/reflection of the glass, then it has to do with the glass and not the boards. Having said that, it may be exacerbated by the relatively low settings you have in contrast threshold. If you are attempting a final render, I would lower that setting to at-least 0.025 or 0.01. If you where to lower this you would quite possibly still have the issues you are seeing in the glass reflection/refraction, so you need to lower both anti aliasing and the contrast threshold.

07 July 2009, 02:25 PM
I have the same problem, posted here:

I followed your recomendations, but notinhg seems to work.:sad:

When using super high sampling (3-5) and 0.01 contrast, it does get little better, but not good, and the render time... OMG. I'm completely stuck with this

Takiko: did you solve it somehow?

07 July 2009, 03:15 PM
Can you send me your scene and I'll take a look?


07 July 2009, 08:50 PM
...this isn't present in Maya materials, only with mia_x or mia_material?

This problem was NOT present in 2008, as I did a great deal of glass/caustic rendering with photographic texture nodes and never saw anything like this. Back then I only used mia_material, not mia_material_x.

So I think it's either a bug in mia_x or something in the GI/FG settings?

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07 July 2009, 08:50 PM
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