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rhythmone
08-24-2009, 07:43 PM
I have yet to venture into full lighting for hair and am hoping for some high level tips.
I have a character that has:
head hair via a lofted over curves setup
eye lashed via a regular hair setup
eye brows via a regular hair setup

I made the mistake of doing some lighting / shadow exploration when I was working on my eye lashes... but now with all the hair in the scene I am seeing that what I setup for the lashes is not appropriate for the head hair.

On top of all this I am assuming that scene lighting (and changes that will inevitably occur there) will further complicate things... so what I am wondering from some of you hair gurus out there:
Is it realistic to think that the scene lighting will be able to be used to light the hair, or do you basically find yourself creating lighting just for the hair?
What about shadow baking? since each system could be isolated and baked independently... would that be worth pursuing?
And what about passes? I am bummed that my version of maya will render a shadow pass for the geometry (face), but INCLUDES self cast shadows, so apparently I cannot isolate the shadows that come from the hair only?
Jbocko
08-25-2009, 01:05 PM
I usually use Shave for my hair but, the techniques I use for lightning should work for Maya hair. I setup my scene lighting first and get that to where I am 80% done (a few tweaks on shadows left and what not). Then I start working on the hair. I will usually create a two spotlight setup for the actual head hair and light link them to only affect the hair and not the geometry. Then I do a spotlight per eye for the eye brows and maybe a spotlight for beard hair if needed. The trick is to make sure the lights you set up for each section are only linked to the hair pieces you are working on and not other things in the scene. This might not be the best route to take but I usually get a nice result from it as I can make really fine tweaks to each section. After the hair is done I finish tweaking the scene lights and move on from there.

I have seen some projects that use the lighting for the entire scene on the hair as well, but it is normally hair or Shave that has been converted to geometry.

As for the shadow passes, I am fairly sure you can just turn off cast shadows for all the geometry and only leave cast shadows on for the hair. That should give you just a shadow pass for the hair. (I may be wrong)

I myself have never used the shadow baking for hair. I normally just paint a darker color map where the hair is and it does a good job (usually) of faking ambient shadows.

It would be interesting to see some other people's techniques for hair lighting on here, might be a good thread.
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