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delavaca
09-06-2006, 06:56 AM
Hi everyone,

I´ve got an interior room and i´m using Mental Ray on 3DS Max 8 for render with GI & FG. The problem is that when i render the shadow appear very grainy, like noisy. I´ve got one MR Area Spot to simulate the sun, and 3 MR Area Omni in each window (there is 3 windows) for the general ilumination, and to make nice shadows in the objects inside the room.

The only way i found to solve it is to increase the sample value of the area lights to at least 13 in both U and V. The noise dissapear but the render time increase a lot.

Is there any other way to make clean area shadows? because with standard Max lights the shadows are too sharp.
Or does somebody know other way to iluminate interiors in MR? (with objects in the room)

Thanks in advance!!
Jelmer
09-08-2006, 08:52 PM
nope, that's the way to go about it, quality comes at a cost, in this case that is render time, but if you compare it with render systems like maxwell it's still pretty fast, and you only need the high quality for your final renders.
jeremybirn
09-08-2006, 11:26 PM
You certainly need some samples with a large area light. To get away with as few samples as possible, sometimes an area light can be scaled long in only one dimension, thin in another (like a flourescent tube), and you might only need more samples in U not as many in V. (10 x 2 samples takes less time than 10 x 10.)

Test your results with different anti-aliasing settings. Sometimes a different filter on your anti-aliasing smoothes out your shadows with slightly fewer samples needed.

If you render in separate passes, sometimes you can blur your shadow pass in the composite, and that lets you initially render the shadow pass with fewer samples but still get a smooth result.

FInally, make 100% sure you really need a large area light. In most cases, using ambient occlusion renders faster for very soft shading than a really big area light with lots of samples.

-jeremy
CaptainObvious
09-09-2006, 03:52 PM
If I were you, I'd try using only a luminous exterior or luminous geometry in the windows instead of area lights. You need higher FG settings, but it might still render faster without the area lights.
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