renderhaus

I have tried everything I know to elliminate these "noise" artifacts, but no dice. Here's my basic set-up.

Max 2008
Mental Ray
(2) Area Lights with Area shadows (sphere light-area shadows)
Photographic Exposure Control
Daylight System (originating from behind camera)
A&D (metal) materials

How can I get rid of these artifacts?

Thanks.

Attached Images

COMBO UNIT 02a.jpg (194.8 KB, 154 views)

mesht

i get a lot of those effects in my renders too, esp when using metals and matte plastic mat. i'm not sure what's the cause, could be due to the Fast Interpolation settings?

SandmanNinja

In my experiments, I've found that a high value (greater than 2.5) of Initial Final Gather Density will increase your detail while introducing noise (I think it's trying to increase the detail in the surface of the texture and gets carried away).
I usually use a value of 3.

Use a bit of Interpolation to reduce any noise (Interpolate Over Num Final Gather Points). Higher values of Interpolate Over Num Final Gather Points do not add a lot of overhead to your render times and it tends to smooth out noise. Downside: it removes local detail.
1=very blotchy; 30= pretty good; 200=Very Smooth

Hope this helps.
I usually use 30 for test renders and 100 for renders towards the end of the project.

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daveb867

maybe increasing the glossy samples of the a&d material that gives you the problem would eliminate it, although this will increase your render times.

also if you are using max 08/09 which i believe you are if you are using p/graphic exposure, replace your area lights with sky portals, assign a blackbody shader to each sky portal and then they become area lights with kelvin temperature controls. from my experience the sky portals are a lot less noisy than standard area lights.

hope some of this helps or maybe i have misunderstood

Justin Hunt

Could be a few things

1) low glossie samples on the metal
2) Low samples on the area lights
3) Low image sampling

For each ofthose increase the samples. Also play with the fast interpolate settings. try increasing the neighbouhoor samples. Higher numbers produce soft/blurrier results, too high can cause blockyness.

Agree with the use of portal lights instead of area light, as they give more realistic reflections. Although with higher shadow samples can cause slower renders. Worth it though

Nice models by the way

jhv

SandmanNinja

Dave - good tip about the blackbody shader. I'll have to play with that sometime.

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daveb867

sandman: the blackbody shader is really useful when you want to eliminate that blue tint your interiors are given from a daylight/sky portal combination

set the scene up the same as you would normally for an interior with daylight and portal, then assign the b.body shader to the portal and change the kelvin to the same value that you have set for your white balance in your exposure control and voila you have a white room rather than and blue tinted one, or just play with the kelvin temp to get different coloured tints, comes in very handy when customers don't like the 'real world' blue tint that you get as standard.

(thanks to jeff.p for letting me see the light with that one)

renderhaus

Thanks to everyone for the recommendations. I will try increasing area light and image samples first (tried increasing glossiness samples before, but did not eliminate all noise). I'm ust a bit hesitant to replace my area lights with sky portals, as the finished scene will be a brew/pub with exposed can lights doing 90% of the illumination.

Of course, if these other mods don't do the trick, I'll have to give it a try.

Thanks.

kbotnen

Can you post a wire? It might have something to do with to small faces? Not enough to sample from? Just something I vaguely remember from someone else.

-K-

cferman

Try turning off your physical sky and then matte the two images together. Having physical sky on in the environment usually always gives me spikes like that somewhere...