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mhouse777 hobbyist avatar image
mhouse777 hobbyist asked ·

Hair card material question

Hello, does anyone have any information on where the depth and flow maps go in the standard surface material in Arnold ? That material has too many channels. Thanks

hair
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mhouse777 hobbyist avatar image
mhouse777 hobbyist answered ·

here's an image of my questionsnag-0088.jpg


snag-0088.jpg (141.8 KiB)
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mhouse777 hobbyist avatar image
mhouse777 hobbyist answered ·

Hi Ciro,

My apologies, Im talking about hair cards not procedural hair. Flow maps are for anisotropic highlights in the hair cards.thomas-pecht-thomas-pecht-2017-12-22-01.jpg

...this image is an example of hair cards,. the anisotropic highlights are from the flow maps. I think flow maps are vectors in tangent space and red and green denote the direction the vectors are pointing which influences the direction of the highlights.


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You need to move the flow map into -1 to 1 space, right now it sits in 0-1.

You do that by multiplying with 2 and subtract 1.
Then jack that up to the rotation of the anisotropics. And you would want to scale the range so it fits the 360 deg rotation as well if its drifting.

The depth can be used to weight transparency, or thin translucency ( tick think wall ) since its planes they have no depth and cannot be used with normal SSS.

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Mads Drøschler avatar image
Mads Drøschler answered ·

We don't know what the final result should look like.
Can you try show us something?

The flow map needs to be conformed into world space and added up with the regular UV and injected back in, in order to get negative flows.

I dont know what flow mapping does in hair, but I wrote a regular OSL flow map that both can accept the standalone flow map painter as well as scripted Vertex Brushing, or whatever really.

This is not a thing you plug in directly, you need to either code a shader or use some core nodes to obtain the correct result you need, and we cannot really say how that should be done before we know what kind of approach you use else where, obviously you are used to use flow map for hair, but we need to see some results or procedures in the application where you usually do this so we can write the Shader that does it by plug and play with OSL.

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mhouse777 hobbyist answered ·

Hello,

Here are the two maps. first is Flow *hair anistrophy . Depth map below.hair-tangent.pnghair-depth.png


hair-depth.png (407.5 KiB)
hair-tangent.png (389.3 KiB)
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There is a specific material for hair that you may find useful


https://docs.arnoldrenderer.com/display/A5AF3DSUG/Standard+Hair


I would start there and then see to what point you are going to need those maps.

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Ciro Cardoso avatar image
Ciro Cardoso answered ·

Do you have examples on how those maps look like?

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