How do you compose HAIR?

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  08 August 2012
How do you compose HAIR?

So I am working on my composition and I decided to render my hair in Maya's shave and a haircut plug-in.
As you know rendering via this plug-in is extremely expensive and takes hours even if you set your setting to very low values. Moreover, you shouldn't render hair with more than 3-4 lights because they got very bright very fast.
The question is... how should I render hair to be able to compose to my scene? Here is a little thing I made:



The first image is white surface shader + white background (because I dont want to see back of the hair, it would be a complete mess).

Help pls :<
 
  08 August 2012
it seems more like a shading/rendering problem you have instead of a comp problem.

why do you use a white shader and not black? this would at least give no white fringe in the semitransperant areas
depending on which program you use for compositing i would be more or less easy to remove the white fringe

on the other side: isnt there something like a holdout/matte shader in maya?
 
  08 August 2012
Looks like a premultiplication issue to me.

Have you tried rendering with an unpremultiplied/straight alpha?
 
  08 August 2012
Hair have tip fading set, so they are going to move towards transparency as they grow (and inherit bg colour). The problem is setting an alpha so there is no head mesh visible, just plain hairs without back part of them. And shave and a haircut raises some problems when rendering alphas.. is unpremultiplied alpha the same as 1bit alpha?
 
  08 August 2012
I don't have any experience with the plugin you are using.
But you should have an option in your render settings to exclude the head from the alpha channel.
1bit alpha is NOT what you want, since it only gives you two values (0 = black = fully transparent, 1 = white = fully opaque) and no grey values (semitransparent).
 
  08 August 2012
Yes I know that... what I dont know is how to stop BG colour from affecting my hair. I want them semitransparent and but clean. And this alpha exclude thing.. never heard of that. How do you do this with Maya Fur?
 
  08 August 2012
I would just apply a black surface shader to the character. Go to the surface shader attributes and change the Out Matte Opacity to black. Then do a render and it should just be the hair by itself with a white alpha, while the mesh of the character will be blocking out the hidden areas of the hair.
 
  01 January 2013
thanks mick, was looking for the same thing. surface with matte fixed it.


btw your portfolio link is kinda funny to me as a german... the word "wix" either means spunk or hte imperative "masturbate!"

anyway
 
  01 January 2013
where do you have wix there?
 
  01 January 2013
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