How can I generate the id map of hair for photorealistic rendering?

windy_max

Hi everyone! I want to make a photorealistic hair of character in UE4, but now I have a problem. When I read the ue4 tutorial of photorealistic character, I found they use a Unique ID texture, and I also found the hair rendering of Uncharted 4 they also use id map for variable specular. I have no idea how to generate this id map. Cound you please tell me how to generate it easily?

The id map sample:
https://docs.unrealengine.com/latest/images/Resources/Showcases/PhotorealisticCharacter/ID.png

Koromo

I never used one of this but it seems a classic greyscale specular map blended with an anisotropic map also in grey.

EDIT: Ok the first result in google shows one person in ue4 forum explaining how he does the id maps:
https://forums.unrealengine.com/showthread.php?106055-Proper-Setup-For-the-New-Hair-Lighting-Model

So in summary the you make the id map with gradients via Photoshop as an example depending of the type of hair/strand density and it looks a LOT like the anisotropic workflow with colors.

windy_max

Thanks for replying. I will try to make the id map by your advice.

stororokw

The easiest way I can think of is using the global variable id to generate the unique id texture map.

windy_max

stororokw said:

The easiest way I can think of is using the global variable id to generate the unique id texture map.

Could you please tell me more detail about using global variable id to generate the id map? Any tutorials or wikis are great.Thanks you !

stororokw

https://knowledge.autodesk.com/support/maya/learn-explore/caas/CloudHelp/cloudhelp/2016/ENU/Maya/files/GUID-A502A05B-0AF2-4C66-8F64-0D5363BF0A38-htm.html

You can then assign a 0-1 value for each strand.

windy_max

stororokw said:

https://knowledge.autodesk.com/support/maya/learn-explore/caas/CloudHelp/cloudhelp/2016/ENU/Maya/files/GUID-A502A05B-0AF2-4C66-8F64-0D5363BF0A38-htm.html

You can then assign a 0-1 value for each strand.

Thanks for your reply. I read this doc and I found XGen is in Maya but I only have the 3ds max. Is there any similar modifier in 3ds max? XGen is still a good way for me maybe I can start to learn Maya if I can't find other solution. Thank you!

stororokw

Unfortunately not.
But, the method I use is to put the Value Variation to 100 and set the Mutant Color to white.

Or
You can use VRayHairInfoTex and use Random by Strand index as the output type.

windy_max

stororokw said:

Unfortunately not.
But, the method I use is to put the Value Variation to 100 and set the Mutant Color to white.

Or
You can use VRayHairInfoTex and use Random by Strand index as the output type.

Thank you! I will try this method.

Aneroit

What I did was just sending the high poly hair to zbrush, separating them, then sending them back to 3ds max, assigning different id to each object and viola! You can find scripts for 3ds max in google.
I think I used thees one:
http://www.scriptspot.com/3ds-max/scripts/elements-to-objects
http://www.scriptspot.com/3ds-max/scripts/auto-object-id

If you use first one, you don't have to use zbrush.

Have a good one!
PS. You have to make it grayscale in PS cause it will be colorful otherwise!