making a cycles hair material

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making a cycles hair material

Postby jujube » Wed Dec 23, 2015 4:23 pm

Last time I tried to use particle hair on a human, it didn't quite work out to my satisfaction. It would look good far away/at low res, but in a high res render, it looked awful. At least with the default hair shader. So recently I decided to experiment with non-realistic hair shading.

transparent shader size 1 5000 hairs long hair.PNG

Here I tried using a transparent shader on hair growing out of a sphere. The particle settings were 5000 total hairs (particles x children) with root = 1 and tip = 0.5. (away from my regular computer, so it doesn't have the power to render smaller/more hairs)

90 percent transparent 10 percent emission.PNG

Here I used a mix shader with 90% transparent and 10% emission, both the same shade of red.

prettyful.PNG


stylized fairy hair.PNG

Then I went for a mix of hair and transparent, which then combines with an emission shader.

fairyhairbig.png

A larger render of the stylized hair node from the previous photo.

I can upload the blend file too if anyone wants to play with it.
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Re: making a cycles hair material

Postby joepal » Wed Dec 23, 2015 4:38 pm

Suggestion: use a colorramp with alpha, with particle info as input.

This way you can assign almost no transparency at root of strand, but full transparency at the tip. This makes the hair look more light and wispy.

Unfortunately I'm at my brother's for xmas so can't post a screenshot of the nodes. I hope the above is enough info to figure it out.
Joel Palmius (LinkedIn)
MakeHuman Infrastructure Manager
http://www.palmius.com/joel
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Re: making a cycles hair material

Postby loki1950 » Wed Dec 23, 2015 4:47 pm

The node set up that Thomas uses for Mhx2 particle hair is like that joel and gives good results adding a RBG control curve can be useful as well.

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Re: making a cycles hair material

Postby grinsegold » Mon Jan 04, 2016 1:09 pm

jujube wrote:Last time I tried to use particle hair on a human, it didn't quite work out to my satisfaction. It would look good far away/at low res, but in a high res render, it looked awful. At least with the default hair shader. So recently I decided to experiment with non-realistic hair shading.


First of all you have to have a decent scene lighting. If you have no directional light, you can't have highlights and shadows. I used an environment texture for my example, but to confuse you i made it invisible for the camera.
Bildschirmfoto-3.png

Second, you tried to ram a modern screw into the wall like a nail. That can't work. The Hair BSDF is no stand-alone default hair shader. You always want to combine the translucent aspect of hair with the glossiness. Here the most basic setup i can think of, using the Hair BSDF:
Bildschirmfoto-2.png

Every hair has a pigment called melanin. It has a reddish, brownish hue. Light hair has light values, for black hair the value of the color is nearly black. Use a hair info node and a color ramp to give the impression of hair that's getting more translucent at the tip. Also play with the shape-value in the Cycles render setting which you find where you set the thickness of root and tip. +1 gives very thin tips, while -1 is more like real hair with only the very tip to be pointy. The saturation of the reflection color usually is very low saturated, even for red hair.
Bildschirmfoto-4.png

As a rule of thumb you never want to give an object an emission that is no lamp.
Another crucial setting is the number of possible transmission bounces, especially for white hair. If you try to make white hair, and you only get grey, try to increase the transmission bounces.
Here a basic red hair:
Bildschirmfoto-5.png

Bildschirmfoto-6.png

aaand white hair:
Bildschirmfoto-7.png
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Re: making a cycles hair material

Postby jujube » Mon Jan 04, 2016 4:56 pm

Hmm, all very interesting, thanks for the advice/tutorial! I'll try it out.

(and the reason used the emission shader was not for the glow, but because that was the way to get the whole mesh to be one flat color. combined with the hair to reduce the appearance of the realism-killing stark shadows of the individual hairs that I tend to get sometimes even If I reduce the width of the strand all the way down. which, actually, I can still kind of see in your hairs. the effect where it looks like metal wires rather than soft natural hair. but maybe it's partly an issue of hair count?)
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Re: making a cycles hair material

Postby grinsegold » Mon Jan 04, 2016 10:26 pm

Absolutely. Increase the children and decrease the diameter of them. I have to admit that i was surprised to read that you are looking for flat hair color. You can get rid of a lot of definition by making the hair more transmittive.
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