[Radiance-general] Strange halo artifact in rendering

[Kai Babetzki]

Hi Mark,

I tried to run your example but I failed. Some files seem to be missing. 
What about increasing the roughness of your black frame?

Best Kai




	Freundliche Grüße
	Kai Babetzki
	Dipl.-Phys. Kai Babetzki
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-----Ursprüngliche Nachricht-----
Von: Mark Stock [mailto:mstock at umich.edu] 
Gesendet: Freitag, 15. März 2013 05:56
An: radiance-general at radiance-online.org
Betreff: [Radiance-general] Strange halo artifact in rendering

Folks,

I am stumped. There is a halo around a black box on a grey background in a rendering, and I can't figure out how to get rid of it (because I can't imagine that it's real).

I am preparing renderings for an art submission, and I am simulating a little model mountain inside a small flat black frame on a light grey wall, in a room with an array of ceiling lights and one spot. Here is what happens (rpict and mountain-removed rvu):

http://markjstock.org/transfer/whyTheHaloMaster.png
http://markjstock.org/transfer/whyTheHalo.png

The black material is plastic with 0.0 specularity.
The halo is independent of the ambient parameters.
The halo is independent of -lw refinement.
The halo is still there if the black box touches the wall or is offset a little.
The halo doesn't go away when I render at high resolution.

Can anyone tell me what is going on here? Unzip and run "make" on:
http://markjstock.org/transfer/whatGives.zip

Mark

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