Sun light cause reflection noise

[Micha_cg]

Hi,

old problem, posted here some months befor:

http://asgvis.com/index.php?option=c...90&topic=631.0

still no solution.

Today I setup a train interior with lighting per physical sky. The lighting looks very nice, but the reflections of the horrible bright sun cause bright noise at some places, so I can forget to use the physical sky and must look for an other solution.

It's a pity, that know problems are alive after months and I run in it again, - now during a big project.

Also the problem and a solution is well known from CG:

the sun reflections are a common problem in max as well. It has to do with the fact that the sun is very bright, so if the sun gets sampled, its weight in the sampling is so much that the pixel will be very bright. In max there is an option to switch of visibility, exactly to overcome this problem.

Interesting for me, if I set the sun intensity at 0.001 and the sky intensity at 1000, than I get a physical sky without sun light, but the bright reflections of the sun are still alive ...

[Micha_cg]

Re: Sun light cause reflection noise

Today I'm working on a water yacht scene. The sky is an important part of water scene, because it's very dominant. I need a clean sky and the physical sky could be a good, easy solution, but I must workaround the bright sun and can't use the Vray sky. That's frustrating, so much time is needed. If I would use the Vray sky, than interreflection between yacht and water would cause very long render times or noise ...

[Micha_cg]

Re: Sun light cause reflection noise

... here an example that show, that i'm not talking about a little problem only - the scene is perfect looking in a HDRI environment, but the sun/sky environment is a pain. I stopped the test, because the calculation was so slow.
I hope, the example show, how problematic the physical sky is and I can catch some interest. The problem is reported march 2007 first time.

[ALTO]

Re: Sun light cause reflection noise

Only one solution:
in Color Mapping check Sub-Pixel and Clamp Output

[Micha_cg]

Re: Sun light cause reflection noise

Thank you. Often I need the HDRI output and like my HDRI env renderings show me, this total bright sun isn't needed for a good looking image, so I'm not happy, that I should invest much time for sampling calculations. The "physical correct" Maxwell dosn't use a high sun intensity like this ... and it works.

[ALTO]

Re: Sun light cause reflection noise

Yes i know that...

try also with Area antialias filter, sometimes it helps without clamping the output

[Micha_cg]

Re: Sun light cause reflection noise

For now my goal is to avoid the sky allways. The risk, to render a new view, a detail of a scene, and the sun could cause a strong noice, is to high. Tight deadline dosn't allow an extra risks.