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Proper Setup For the New Hair Lighting Model

So 4.11 is finally out and I’ve finally got around to try and convert my hair into a material using the new model. Unfortunately the results I get are lackluster at best. I literally just copy / pasted the material from the content examples and plugged in my textures.

The issue is, as far as I can tell that my characters have very long hair as opposed to the dummy in the example content. My hair is very grainy and at certain spots completely transparent although there’s a ludicrous amount of poly strips covering the head. Plus there are tons of DFAO artifacts (black splotches) and if I set the root color to anything close to red my screen starts flashing with a glaring green flash.

My guess is that my “unique value” and “root to tip” textures aren’t quite up to snuff and perhaps what I see as ludicrous isn’t enough polys for the hair to look proper… Also what is the backlut parameter? Doesn’t seem to do anything for me.

Could you perhaps go into a few more details on how e.g. Sparrows head is created along with those two value textures? Are the braids tubes or also poly stripes?

My scene only had a movable directional and a movable skylight in it.

In Content example project hair material seems to be bugged. Backlit parameter does nothing and it seems to use ridiculous high value for it by default. Hair just turn fully white when looking towards light source.

Indeed it seems bugged. Any clarification would be splendid.

Can you open the Character Render map?

CharRend.jpg

Yes. No Problems to open the Map.

84260d0c1c2a878a4037ab5bb0aad8d416db6268.jpeg

All well here too on that end. Original issue still stands though.

Do you have TemporalAA enabled? It’s been awhile since I watched it, so I don’t remember why, but they did say on the live stream that the hair shader requires TemporalAA.

I believe so. Gonna double check on Monday but unless it somehow defaulted to something different then I should have it on.

It’s not caused by temporalAA.

I am hoping now that the work week has started someone will have the time to look into this. I see a lot of great hair results but I cannot begin to even come close to those, I feel like I am missing something.

Hey, without seeing images of your hair it is going to be almost impossible for somebody from Epic to suggest anything.

There can be so many things wrong with hair. Most of the pitfalls are not specific to the hair shading model but rather your textures, mips and mesh setup. If your hair is almost see through I’d be curious to see your mips since mips can often get way too thin for thin texture detail. If that is the case you may have to either sharpen or boost the mips, or simply use math in the shader to increase the opacity mask brightness based on camera distance. The shading model part shouldn’t affect anything other than the lighting/specular, not the masking.

Hair_Shading_Bug.jpg

This is how content example hair looks. Backlit parameter simply seems to not work at all.

Hey @RyanB, I am out of the office and will provide images in the morning. Thank you!

Edit: Also, if possible I’d pay to hear how you guys generate the unique value and root-to-top gradient textures.

@RyanB - Here are the images together with the textures I use. The shader is pretty much identical to the example shader, with the slight change that, before I apply the PDO I pull the mesh toward the camera using WPO to avoid hair going into the head and creating bald spots.

And the textures.

Root To Tip:

Alpha:

Random Color Variation (Didn’t know how to create a unique-value texture):

Heightmap:

I think my issue is partially in the textures and partially the fact that the dithering setup used in the example shader works well for hair fins, where each ends in a hair tip. My hair however is long and covers the entirety of the head, which is why I asked how you guys created textures (and the model) for Sparrow’s hair.

Best regards,
Damir H.

I would also like to know more of how Epic created the textures for sparrow’s hair. Bump

I am starting to suspect that the textures might have been created with Houdini rather than Max / Maya. Could be wrong though.

well I would like to know what certain texture slots do in general for the hair shading model. I guess they do render it out in the 3d package of some sort?

They actually talked about what the textures do in their paragon live stream. Authoring them however is a completely different thing. Would still love some input on how Sparrow’s hair was made.

I’m having a lot (and I mean really a lot) of problems with this new shader.
I’ve tried to analyze every second of the livestream video about Paragon but it’s pointless: the example material seems to be a “dull” version of the very beautiful shader used in Paragon.
I’ve re-painted 3 times my textures (thicker hairs, thinner hairs, more contrastedm more or less depth,ecc) in order to have root-tip, depth and color ID maps, but I always end up with awful results.
In particular I have a very bad lighting, strange dark areas depending on tangents value and a very bad and huge dithering effect… way far from the subtle and almost unnoticeable one that we can see in the video.
I clearly understand that Epic wants to keep some tech results inside, but the example mat is not very beautiful to see ingame and the lack of any documentation doesn’t help.
My character has a bob haircut so I can’t have a lot of short strands… At the moment I still have better results with old materials… and I’m quite sad about that :slight_smile:

Hey berna,

Can you share how you create the ID maps etc.?

Best regards,
Damir H.