View Full Version : Grainy Light/Shadow in MRAY

02 February 2005, 12:04 AM
I have a directional light coming in through a window. I want it to have nice soft edges but with MR it comes out all grainy (see image). What can I do to fix this?


02 February 2005, 01:24 AM
Well first of all, a resolution of 6000 is huge!! You shouldn't generally go above 1024. I think you should turn the samples up from 6 to something like 32.

Also, spotlights work much better with shadow mapped shadows because the shadow map only needs to cover the spotlight cone area. A directional light means the shadow map has to cover the entire scene as viewed from that direction.

02 February 2005, 08:41 AM
Also note that due to mental rays insanely fast raytracing engine, shadow maps can actually be slower than ray traced shadows.

I'd use a raytraced area light for any truly "soft" looking light myself.


02 February 2005, 09:54 AM
Turn off "Cast Shadows" in the render options for the floor, that will eat up your shadow map resolution for no reason.

Ray traced shadows can also be slower than dmap shadows, just depends on the situation. Problem is most people don't know how to tune either one properly heh.

02 February 2005, 10:14 AM
raytraced shadows, thats the answer, now with Maya 6.5 you can "try" to use shadow maps with mentalray.

02 February 2005, 05:10 PM
Jozvex: Gracias Amigo, that definitely helped out a lot. I can't find much documentation on what these settings actually do so sometimes I end up tweaking the wrong thing.

MasterZap, Bill, Slipknot: I'll try playing around with raytraced shadows and area lights (and turning off cast shadows) and post my results today hopefully. Thanks!

On a side note, if anyone is still looking at this thread, what's the best way to make the fabric more fabric-y. Right now it's just a lambert with a color map. I tried a bump map, and it slowed down the render time big time and I just couldn't get a subtle enough effect. But I'm a noob so maybe I'm just not doing it well.


02 February 2005, 08:51 PM
hey bonedog, you might try adding some kind of a cloth like texture to the bumpmap channel of your material and then mess with the place2d texture node to get the right size for the repetition of the pattern. then just select the bump2d node and lower that bump value way down to something like 0.1 or below.
there is a cloth procedural texture in maya.

i might be completely wrong here though, as i dont really know what i'm doing either.
good luck man

02 February 2005, 09:24 PM
"raytraced shadows, thats the answer, now with Maya 6.5 you can "try" to use shadow maps with mentalray"

DMap shadows have always worked with mental ray and are a lot of the time better in general shadow situations than just turning on ray traced shadows. Of course with mental ray 3.3 you won't get any transparency, and I haven't tested it with 3.4 yet (still awaiting our cd's...).

02 February 2005, 12:00 PM
What really bugs in MR4Maya is that it's not possible yet to tweak the Shadow Bias even though you're using Maya 6.5 :( inspite that it was implemeted in mr 3.3 as someone said here in cgtalk.

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02 February 2006, 01:00 PM
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