What is causing these White/Grey Artifacts (Mental Ray)

# 1 05-11-2012 , 07:55 PM

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What is causing these White/Grey Artifacts (Mental Ray)

I'm Building a scene in Maya 2011 that has a mirror in it that, obvioiusly, needs to reflect.
I've set up the settings of my Materials as I would normally for a reflective surface, but when I
render I get this problem with white/grey Arifacts in my Reflections.

This problem occurs with Reflections as well as Refractions and it also occurs in things like
Glass bottles and my windows etc.

I'm using Mental Ray Mia Material x passes (and I'm rendering with Mental Ray)
But also when I use a blinn for my "mirror"-material the problem still exists.

It has no problem reflecting or refracting Blinn materials, but to change all my materials to Blinn instead of Mia Materials is very undesireable.
I'm using standard Maya lights (spot, point, directional, etc.) and I'm not using mr. Physical Sky or any of the likes.
I'm pretty sure my Max Ray Depths etc. are sufficient, but please don't hesitate to comment any thoughts you might have, as I might have overlooked some tiny setting.

The First Attachment shows how it should be (I copied the scene, and mirrored it to the other side, then deleted the actual mirror.)
The Second Attachment shows the problem I get when turning on my mirror
Compare the two, then it will be obvious what my problem is

All help is appreciated ^^.

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# 2 05-11-2012 , 09:27 PM

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I see the textures disappeared. What file type are they? And what are the filter settings on the file node in Maya?

- Genny
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# 3 06-11-2012 , 07:24 AM

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Hi Raymon1989

Are you sure the mirror is a mirror? user added image

Look at the shadow of the mirror frame in the second image. The shadow should only be visible as a small V turned on its side right at the base of frame. The shadow right in the middle should not be there. This looks like a view of your "mirrored" scene thru a plane of glass.

Can you post a screen shot of the mirror material settings? (Diffuse, reflection, advanced reflection, refraction, advanced refraction and BRDF sections).

How did you construct the mirror? Is it a simple poly plane or did you go for a glass pane with a reflective back layer (Like a real mirror)?

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# 4 07-11-2012 , 06:35 AM

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You are right about the mirror in the screenshot not being an actual mirror, that has to do with the kind of project I'm working on. I have the exact same problem when the mirror IS reflective though, and these screenshots were showing the problem very clearly, so I didn't bother to make a new screenshot, my bad.

Here is a screenshot of the mirror actually reflecting, as you can see, the problem is there too. (It's a single plane for now though, I'd like to get my reflections working before doing any "fancy" effects with layers of glass over it etc.)

...and the Material Settings you asked for.

@GecT: All my Texture maps are PNG's, and the filter settings are 'quadratic' with most of them (some of them are set to 'off')

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# 5 07-11-2012 , 07:13 AM

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I think there was an issue with file texture filtering and reflections/refractions in version 2011. I remember disabling filtering and I also tried changing it to mipmap and killing the filter value(in the effects section) to get around it (my memory of it is a bit hazey to be honest). The bug was fixed in one of the hotfixes though.

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# 6 07-11-2012 , 09:15 AM

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You, just saved my life.

If I could I'd kiss you...although that'd probably get awkward.

Anyway, Thanks.

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# 7 07-11-2012 , 10:08 AM

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Out of curiosity. Which filter setting solved your problem?

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# 8 07-11-2012 , 12:37 PM

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Under the 'Effects' Tab, in your Texture-Nodes there's a 'Filter' slot, that is set default to 1.
What this 'Filter' does is it blurs any textures seen through a reflective or transparent object.

Setting it to 0 cancels this blurring effect and shows the reflection as it should.

Again, thanks GecT, This problem has been haunting my project for 8 weeks now, and with
the deadline drawing nearer I was about to panic.

Also a Big 'Thankyou' to the rest of you, I really appreciate you seriously looking into my problem.

Thanks,
Raymon1989

Last edited by Raymon1989; 07-11-2012 at 05:50 PM.

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