Procedural Hair Card Generation Workflow
Modelling Hair Cards is one of the most tedious task in character creation. And as a tech artist I came up with this non destructive wrokflow to quickly create hair cards based on Xgen Groom in Maya, Hair Card Generate node in Houdini. And using this technique we can quckly create a bunch of Hair cards instead of Hand Placing them one by one. The texture for the hair cards has been created in Fiber Shop.
Starting with XGen. Create groom for the character you want. (For this demonstration just a normal combed version of hair. )
Select Convert to Interactive Groom.
Select Interactive Groom.
Export as Geometry Cache . This will save the groom as an alembic File on your disk.
Open Houdini and import the hair Alembic.
Set the rotation to y -90
Convert the alembic to NURBS curve Using the convert Node.
Use guide skin attribute lookup to convert NURBS to guides
Now hookup the guides from the guide Skin Attribute lookup to "Haircard Generate Node" and attach the skin node from the imported model
Mess Around The Parameters to your liking. for the shape of the hair cards
In the tab next to geometry in the same node you can chose to generate UVs for the cards. You can choose fixed scale or single tile
For this demonstration we are using Fixed scale so we can have stacked UVs for the cards. Join the UV unitize node to stack up all the UV islands
Once happy you can export the the mesh to any destination you like using ROP node.
Using the UV transform node we can easily modify the size of islands.
Back in maya import the mesh and apply material to it. And there we have it.