Black Splotches in FG


I’ve recently been getting these black artifacts appearing when i render this character.

Final Gather rays_500
min radius_.25
max radius_.5
secondary diffuse bounces checked

rendered in maya/mental ray
any ideas? thanks in advance



the black spots that are visible were common. Are you using maya 7.?

Wat you could do to remove those patches are. Have a better lighting system. Next try reducing the min radius and increase the max radius.

Also, try increasing the rays.

this should solve the problem.



I got those once when using muhHair shader in max2008.


thanks Shantanu for the advice, I’m using maya 8.0. I increased the rays to 700, and set the min radius to .045 and max radius to .055. These seem like such small numbers but anything else still results in splotches.

Also, do all the lights in the scene need to emit photons or just the key light? I have 5 altogether. Thanks again in advance.


HI, your model is too small. For rendering in mental ray try scaling your model bigger than your grid. They redo the max radius. keep the min as 0.1.

let the photons emit from the key light and also use decay rate for smoother light.


Looks like the classic NaN error mr causes sometimes, usually when using a combination of FG, some shaders, blurry reflections, HDRI in my experience (in XSI that is).

You can try figuring out what exactly causes it (switch shaders), or try an anti NaN lens shader like

EDIT: Is your model scaled down ? For some weird reason I get more chance at NaN pixels when my models aren’t 1,1,1 and freezing transformations sometimes helps.
Don’t ask me how and why tho. :slight_smile:


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