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View Full Version : Hair&fur and mental ray render questions.


MrSoda
04-21-2010, 01:04 PM
hi everyone,
i have some trouble with 3ds max hair and fur, i used mental ray and hair&fur as mrprim, photometric light but render very very slow when use ray traced shadow and shadow not really good, i searching and found this tip: http://mentalraytips.blogspot.com/search?q=hair , hair render look good but very bad shadow, increase resolution of shadow map but still very bad shadow.
I try some test with scanline render and look so cool and very fast render.
So my question is can anyone give me a solution how can render hair in mental ray with good shadow and nice detail like scanline :) .
Hope ur good guys can help me, thanks so much and sorry for my english. :D

jeb
04-21-2010, 01:28 PM
Mrprim is slow if you use the voxel default of 12, lower it to 1 and try again. i render lots of hair that way. i dont really see any differend with voxels at 12 or 1 other than long time renders.

also having lots of maps in the hair modifier to control density, color, and such make the translation time really long. so try using the least amount of maps to optimize render times.

oh and also be careful with tip fade and hair passes.

tip fade uses transparency to make the tip less visible, its cool but be aware that Mray has to calculate all those transparencies.

also hair passes make your hair geometry count multiplicate. each pass is a clone of each hair and then blended with transparency, so you basically are making double amount of hairs than your actual hair count and adding more transparency to calculate.

when you remove those long rendering options hair tends to be jaggy but thats because of antialias, you would have to use more antialias samples. i try to get around it by adding as much tip thickness as i can and still looks good. btw mental ray doesnt like tip thicknes =0.

hope it helps

MrSoda
04-21-2010, 05:02 PM
Hi Jeb,
Thanks so much :) , do you have much experienced with hair shadow? ray traced shadow take very long time to render :(

jeb
04-21-2010, 09:50 PM
Since i started using mental Ray back in version 8 I think I stopped using shadow maps. Indeed raytrace shadows take longer sometimes but they give the best results for me and I don't worry about flickering shadows or memory problems.

What many people recomend when rendering hair shadow are 2 things. Either activate the rasterizer in mental Ray rendering options and use shadow maps. You can activate deepshadow maps as In Maya to get better definition. But in max is called trasparent shadows(weird huh) .it's a checkbox In the light settings. You can search better Info about it In master zap's forum ( mentalraytips)

the other shadow option it to use puppet's Shaders_P pack. I really recomend you take a look at them if you haven't already. It has a great variety of shaders for many purposes. Just as a hint : you ca. Render ambient Oclussion with transparencies with the megatk shader for example.

It has a couple of shaders for hair too. HairTK and another for hair shadows. Haven't tried hair shadows much since I mostly just use Ray traced ones but the hairTK shader is awesome to give more hair looks than the default hair material In the modifier.

Anyway when using the rasterizer I think it's batter to just composite the hair because using the rasterizer for the whole image just kills the quality for me.

But tell me how slow are your renders can you post maybe a scene with something similar to what you want to render and maybe we can benchmark it. Something like a hairy teapot could do.

MrSoda
04-22-2010, 05:06 AM
U're awesome man :D , now i can speed up render than many times, muhhair is great plugin, i will continue with my character and can i ask u again if i have some questions?
Thank again, regards.

jeb
04-22-2010, 06:37 AM
NO prob man. i struggled a lot with hair too some time ago thats how i figured out all that stuff. even watchin all the tutorials i could find and the master clases from autodesk i couldnt get it to work. but after rendering millions of test changing every setting i got renderable and good results.

havent used muhair shader.. for what ive read its just like P_hairtk. or is it better in some way.. can you post some example?

MrSoda
04-22-2010, 07:34 PM
oh, sorry jeb, i'm in the vacations now and don't have my PC, i will post smthing when i back to work! :)

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