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| Dark patches in final gather in reflections
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I think I might have mentioned this before but not got an answer…
Can anyone tell me what’s causing the dark patches in the corners of the room reflected in these kitchen cupboards? They definitely only appear when I enable final gather and only in reflections - the rest of the scene is perfect. The attached image was done with the “medium” FG preset but the problem is much worse on “low” or “draft”.
Scene details:
Max 2010 64 bit
GI photons (1000000 or 2000000 per light) merge photons 0.1m; max sample radius 0.25m
FG, medium preset, filtering disabled
Lighting: mr sun and sky, mr sky portal & several photometric spot lights
Materials: all Arch & Design
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Hmm, no replies… is this a bug in mental ray?
I’ve tested it with a simple room with a mirror at the end, mr sun & sky, mr sky portal, GI & final gather and I’m defintely getting dark patches in the reflection (see attached image). Could someone else test this and confirm if it’s a bug?
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Yes I can reproduce the issue it is a FG one.
The only workaround seems to be the “Radius Interpolation Method”
(Instead of Num. FG Points)
See Attachments, both tests are FG only.
ivan
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Thanks Ivan. I’ll add this to the suspected bugs list.
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Here’s a thought… Final Gather is based on what the camera sees. If you have a mirror reflection, the objects/surfaces rendered in the reflection may not be included in the Final Gather calculations, giving you the black spots.
Try setting a camera at your mirror, and use it to calculate the FG map, saving the map. Then incrementally adding to that map, calculate from your final camera and see if that clears it up.
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
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I don’t want to contradict your suggestion Chris, but just for info; if the “Interpolation Over Num. FG Points” value is set to 0, there is no such issue.
The same is by using the “Radius Interpolation Method” as I already mentioned above.
Author: ivan iliev
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| Replied: 02 November 2009 06:56 AM
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Thanks for the suggestion Chris… Unfortunately someone beat you to it on the mental images forum (http://forum.mentalimages.com/showthread.php?t=5931). The FG map for the part of the room in the reflection turns out to be fine, although a bit short of FG points (if you run a diagnostic render with the FG points shown).
Bring on iray… FG will be a thing of the past in a few months, hopefully!
Author: Rich Wilson
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| Replied: 03 November 2009 06:00 AM
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Another weird thing - I can render the full view and see the dark areas, but then if I do a ‘render region’ around one of the dark areas, it looks normal.
3ds Max 2013, Maya 2013
Windows 7 Ultimate 64 Bit
Core i7, 12GB RAM
Nvidia Quadro FX 3700 (Driver 267.17)
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I’ve noticed that FG changes significantly when rendering a region. I might have to investigate this. How big was the area you were using - just large enough to enclose the dark patch?
Author: Rich Wilson
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| Replied: 03 November 2009 06:01 AM
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