Maya Hair and VRay Rendering ~ Help?

#1

Hello all!

I have a Maya Hair System being shaded with a VRayHairMtl Shader (I am rendering in VRay) This is my first time using the hair system in Maya, which is where my problem is.

Here are two test render frames showing the problem (blown up to 200%)
https://vimeo.com/93734205

The hair on certain parts of the head seems to disappear or shift around very quickly on a frame by frame basis.

Here are my current settings :
Adaptive DMC Sampling 1min / 35Max
Filter : Area / 1.0
Linear Workflow On
Brute Force \ Light Cache for GI
Brute Force : 20 Subdivisions \ 3 Depth
Light Cache : Default Values except retrace threshold is on

All lights are VRay Rect Lights (Area Lights) with samples at or above 64 (I keep cranking them up to be sure it’s not a shadow problem).

The hair itself :
I think maybe the only important values here would be the dynamic values, since it appears to be shifting. Dynamic values are all disabled and the hair system is parented to the head so it just moves along with it.

I do have overlaying clumps which are likely penetrating, with slight hair interpolation turned on.

Any ideas? I’ve been tweaking and re-rendering for days now. With how far I’ve cranked up all my settings it’s taking 3 hours to render the hair portion at 720HD. I am feeling more and more like it probably has less to do with quality and more to do with the hair setup, but I am new to both VRay and Maya Hair so would appreciate any wisdom from you more seasoned players.

Thanks!

#2

Ok I recreated my hair with half of the reference curves, half the number of hair per clump, and made sure my hair mode was set to ‘static’ and still have the same problem.

I was working on the assumption that maybe the hair was actually moving, passing through each other, and it still looks that way, but I don’t know what to do other than set it to static and turn off dynamics.

Ill keep playing.

#3

Perhaps try creating a cache for the hair, it may be having issues sampling for motion blur with a non cached dynamic.

#4

Thank you Kobes, I will give that a try!

I am starting to think has more to do with the hair system and less to do with the rendering setup … as I’ve pushed my settings to a 9hr render (256 samples on all my lights, crazy AA settings, etc etc) and still have the problem.

Ill update when I find the answer.

#5

Just wanted to update with an answer. The problem wasn’t with render or quality settings. It was with the maya hair system itself. Some follicles were popping around randomly, causing the problematic effect, even though all were set to static with collision and dynamics off.

The solution was to change all the follicles ‘Start Direction’ to ‘Surface Normal’

I don’t know if I set something up incorrectly to cause the problem, any insight?

#6

Just out of curiosity. How did you apply a vray shader to the hairsystem? I have an old mental ray scene which I am updating to vray right now, but I can´t get the hair to render. It just does not work.
Would be great if you could point this out.

Thanks in advance.

#7

blazelet: try to set static at the ‘Simulation Method’ as well.

Duke: in your ‘hairSystemShape’ go in attributes/VRay/Hair Shader, an ‘Extra VRay attributes’ slot will appears then u can connect a vray shader on it…

Hope i was helpful :slight_smile: