Can anyone tell me what’s going on here...? When I render this scene with GI turned on, depending on the position of the daylight system and the “average GI photons per light” setting, the renders are sometimes (but not always) coming out with values in the blue channel up to around 10000000, while red and green are in the range 0 to 1 as expected. If I decrease the number of photos (from 100000 per light to, say, 10000 per light) or change the time of day, it’ll render perfectly.

Scene details as follows:

3ds Max 2010 64-bit with latest patch running on Windows XP
mental ray
GI: on; default settings apart from:
- max sampling radius: 2.0m
- merge nearby photons: 0.2m
- optimize for final gather: on
- average GI photons per light: 100000
FG: on; “low” preset
Scene includes:
- 7 xref scenes (1 nested, 1 disabled)
- ~800000 polygons total plus some mr proxy objects
- daylight system - mr sun and mr sky
- 3 mr sky portal lights
- several photometric lights

I’ve attached a “wrong” render, plus a screen grab of the final gather stage, as well as a correct render.

Any ideas what’s going wrong?

OK, seems it’s not going to let me attach the images…

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In the Render Dialog, go to the Processing tab and make sure none of the Diagnostics are enabled.

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

Is it the Lighting Analysis thing?  Check the Effects tab under Environment and Effects.  Or maybe its the Psuedo Color blah blah blah under the Exposure Control.

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

I have seen this a number of times when bringing older files forward into newer versions of 3DS Max and Design.

I ended up having to go through every single material in the scene and convert them to new materials and it made the problem go away, it was incredibly frustrating, as I could never figure out why it was happening, but that did fix the problem.

Do you have a combination of legacy standard materials and new A&D and ProMaterials in the scene?

Jeff

http://www.wiley.com/WileyCDA/WileyTitle/productCd-047088262X.html

Hi, indeed your problem is odd… Try using a pure white material in MR override mat to figure it out where the problem lies: materials or illumination.

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