Grainy Shadows Using Final Gather?

[Anonymous]

Does anyone know why i'm getting grainy shadows?
I've got image based lighting set on texture to full white.
Final gather at 1024 accuracy.
And an area light set to ray traced shadows at the max settings for rays and ray depth.

[Anonymous]

if u want sharp shadow then
1:check the shadow rays option keep it low
another thing is check
2:check light radius.keep low

[halfstone]

the problem is likely your area light - but I'd suggest turning off final gather for your tests. Does the problem persist without fg? What kind of area light are you using? Your best bet is to create a spotlight and check the "area light" box in the mental ray settings - this will reveal sampling settings. The default U V sampling for a Mental Ray area light are 8 and 8 - this will give you grainy shadows. You should increase that to 16, then 32, then 64, etc. until you see the result you like.

The physical size of the area light object (scale) will affect the quality of your shadows also - it should be as small as you can get away with.

Point lights with MR area lights will give you better overall lighting, but on first look they're not possible. You have to create a spotlight, check the "area light" box in mental ray, adjust your sampling settings, then go back and switch the light-type to "point". Ignore the error message you get. To further adjust the settings, you have to convert BACK to a spotlight, adjust the settings, then re-convert to point.

Maya area lights are not so great in mental ray.

Area lights in general are expensive to render,and you're not getting the result they are intended for - which is soft, attenuated shadows with "light-wrap". In the scene you show - I'm not sure you really need this effect. Have you tried a spotlight with soft raytraced shadows?

[Anonymous]

wow that really helped me to understand the light types in maya, i'm a relative beginner so i can use all the insight that i can get! thanks! and i'll try out a spotlight too.

[Anonymous]

Alright! thanks for the help guys, i followed the spotlight suggestion and got a much better result this time.

[rdavis]

Outstanding advice. As a self-taught Maya user, I have never understood the different lights, but this explaination was easy to understand and very accurate to my situation as well. Thanks Much.

[halfstone]

This answer dates back to 2010; a lot has changed since then.  I've gotten very good results using physical area lights, which use a MILA light shader and a brute-force final gather.  You can size the area lights up pretty big - the larger the area the softer the shadows, in general.  The render settings in Maya can be broken down to optimize different aspects of the render - if your only problem is the shadows then you can leave the "Overall Quality" at 0.25 (which always seemed ridiculously low to me), but crank up the "Lighting Quality" and you'll focus all the quality settings to the shadows.  It's pretty efficient that way. 

I generally test the quality settings by doubling the numbers - 2, then 4, then 8 ... then once I get the quality I need I start backing the settings off to try to reduce render time without sacrificing too much quality. 

I suggest getting familiar with the MILA materials and the physical lights - mentalray is now optimized for this physical based setup. 

[Ambar_N]

would like to know more..