Hi all, still (as in “never-ending) learning mr. :)

I’m working on an interior scene using a skylight and an mr portal. It’s basically a perspective animation of a room without a ceiling using skylight. The mr portal is used to focus the light into the room. The mr portal dimension is equal to the room dimension.

This room contains a glassed in shower stall. I have used geometry which is a two sided box for the glass, and geometry which is a flat plane. Slightly different results with each, but one problem persists.

In the attached shot, you are seeing the flat plane geometry. it looks acceptable, but the reflection reveals the identical problem I had with the 2 sided box… notice the odd pattern showing up in the glass in the reflection.

When I used the 2 sided box geometry, this pattern was evident in the primary glass display (as opposed to the reflection).

When the camera is animated, this pattern is static, like a UVW map using the Screen mode.

I have turned on and off the FG, the GI, raised the sample amount for the shadows on the mr portal, changed IR and reflectivity amounts in the material… hell, even simply changed the angle of the camera-to-glass.... just trying to figure out where this pattern is coming from.

...I’m stumped! Has anyone got a suggestion?

Graham

Graham Calhoun
President
Forensic ProMedia

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What material are you using for your mirror? And what are the settings for this material?

Could it be a problem with your raytrace ray depth?  It looks like a problem with reflecting your refraction.

Can you zip and post the scene?  Feel free to remove anything not pertinent to testing this.

3DS Max Design 2011 64-bit - Advantage Pack
Dell Precision T5500, Dual Six Core Xeon X5650 @ 2.67GHz, nVidia Quadro 5000, 24 GB RAM, Win 7 Enterprise 64-bit
Minneapolis, MN, USA

Hey, thanks for checking this out for me. I’ve included a zip file for your perusal. After taking out a lot of stuff, the glass actually got worse, so it should be pretty evident.

Graham Calhoun
President
Forensic ProMedia

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17918_MFDExdVgzXm24m3Fuvam.zip

Very strange.  I think it’s a combination of several things, but I’ve found a solution for you.  I think.  Change your Standard materials to something mental ray likes.  I changed the material on the wall inside the shower to a Arch & Design material, and the speckliness went away.  Strangely, I added a sphere with no material in the shower and it also had the strange speckled look. 

Typically, when using mental ray it’s suggested to stick with the non-standard lights (Daylight, photometric).  And many others have experienced anomolies when mixing standard and PM lights (ie, Skylight and Skyportal).

3DS Max Design 2011 64-bit - Advantage Pack
Dell Precision T5500, Dual Six Core Xeon X5650 @ 2.67GHz, nVidia Quadro 5000, 24 GB RAM, Win 7 Enterprise 64-bit
Minneapolis, MN, USA

For interior renders I like to use a mix or Daylight and Photometric Light using regular skylight always give you that weird pattern on glass.

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17930_ag1v7WA9HqR5sd19YJRG.zip

I also have no explanation, but the issue is a kind of interaction with the Portal light and the glass materials. See attachment the second image is a simple daylight without portal light and there is no “pattern” at all.

ivan

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Thank you very much for the time spent on this, Jorge, Ivan and Chris. I really appreciate your help.

I’m slow in coming to realize that “standard” and “mr” aren’t the best of friends! Getting used to using Arch Design or Pro Materials is daunting, especially when you just want to throw something on there to see how it looks!

Chris, your solution was right on! Yes, as you observed, the sphere has that odd pattern on it in the reflection in the mirror, but… for now… my problem is solved.

Thanks again.

Graham Calhoun
President
Forensic ProMedia

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This may be a bit late but what’s the diffuse colour of your glass? Final gather seems to get confused if you have two surfaces close together with the diffuse colour of one (usually glass) set to pure black. Setting it to very dark grey instead seems to sort this out.