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Help with hair shader

Posted: Wed Aug 21, 2013 2:36 am
by Rikk The Gaijin
I'm really struggling to find some good settings to render hair in a realistic way.
I want them to have all the physical properties real hair have, the shininess, the nice rim light they can pick up, and the scattering when are lit from the back.

The best I came up with is using the specular material, with 0.2/0.3 roughness, 0.1/0.2 scattering, some RGB value in the absorption, and playing around with scale and scatter direction, but they always look wrong, they kinda look like made of fiberglass or something...
Does anyone have any tip for realistic hair? I wish Octane had some dedicated hair shader, like Lagoa or Vray... :(

Here some example of what I'm trying to achieve:

Image

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Re: Help with hair shader

Posted: Wed Aug 21, 2013 7:06 pm
by xxdanbrowne
Are you using transmapped or high poly hair (like zbrush fibermesh)?

Re: Help with hair shader

Posted: Thu Aug 22, 2013 12:45 am
by Rikk The Gaijin
xxdanbrowne wrote:Are you using transmapped or high poly hair (like zbrush fibermesh)?
High-poly hair, it's impossible to get realism with flat planes.

Re: Help with hair shader

Posted: Thu Aug 22, 2013 4:48 am
by xxdanbrowne
Chopper and face_off were playing with fibermesh hair over in the poser section of this forum a few months ago. I don't know how far they got.

Re: Help with hair shader

Posted: Thu Aug 22, 2013 5:11 am
by face_off
High-poly hair, it's impossible to get realism with flat planes.
ZBrushcentral had some good shots from "The Last Of Us" which used planes and looked convincing. Not sure if it would be up to the standard you need though. I liked the polyhair approach because a) it could be animated, b) the falloff node could be used on it, and c) it is possible to get a lot of texturemap reuse on each of the planes. But no SSS might be a problem.

I spent some time exporting polyhair from ZB into Poser and rendering in Octane. The trick seemed to be to have many hair groups, so that you can use different Octane shaders on each (since there are no UV maps on ZB polyhair to use texturemaps). I got far enough into the process to know that it was a bigger undertaking than I had time for.

I'll be eagerly waiting to see what you come up with.

Paul

Re: Help with hair shader

Posted: Thu Aug 22, 2013 1:44 pm
by Rikk The Gaijin
face_off wrote:
High-poly hair, it's impossible to get realism with flat planes.
ZBrushcentral had some good shots from "The Last Of Us" which used planes and looked convincing. Not sure if it would be up to the standard you need though. I liked the polyhair approach because a) it could be animated, b) the falloff node could be used on it, and c) it is possible to get a lot of texturemap reuse on each of the planes. But no SSS might be a problem.

I spent some time exporting polyhair from ZB into Poser and rendering in Octane. The trick seemed to be to have many hair groups, so that you can use different Octane shaders on each (since there are no UV maps on ZB polyhair to use texturemaps). I got far enough into the process to know that it was a bigger undertaking than I had time for.

I'll be eagerly waiting to see what you come up with.

Paul
I would love to post my tests here, but I'm under a very strict NDA, so I can't... :(
Perhaps I can make one version just to be posted here, unrelated with my current task... :?
Also, I never used the falloff node, I need to search the forum how to use it (if anyone can link me some page I will appreciate it), I need to try it out.

Re: Help with hair shader

Posted: Thu Aug 22, 2013 2:54 pm
by xxdanbrowne
I still don't clearly understand how the falloff node works but Fooze talked me through how to use it to make a fabric shader in this thread:

http://render.otoy.com/forum/viewtopic.php?t=34069

Re: Help with hair shader

Posted: Fri Aug 23, 2013 12:16 am
by Rikk The Gaijin
Thank you, I'll try that out!

Re: Help with hair shader

Posted: Sat Aug 24, 2013 11:42 am
by Davve
maybe you can learn something from this

http://help.chaosgroup.com/vray/help/20 ... params.htm


I'm planning to do some hair shader tests in the near future, really curious what you come up with this far.

The most significant part of hair shading seems to be the dual specular component combined with proper transmission.

David

Re: Help with hair shader

Posted: Mon Aug 26, 2013 12:26 am
by Rikk The Gaijin
I tried VRay hair shaders, not only it's ridiculously slow to render, but it doesn't look very good in my opinion. I've found some interesting settings in Octane, but still far from being realistic. I can get one characteristic at the time, for example, I can get the nice back-scattering OR the specularity, but I can't get them both, or at least not the amount I want... :(