So, putting realistic hair and fur on your characters is something I have been researching lately. For those of you who are looking for a solution to hair and fur, check out this link. You may find it useful:
http://polycount.com/discussion/183025/fibermesh-to-game-hair
One thing I don’t understand however, is how do hair cards actually render into hair? I understand how guide splines and curves work, but how does using cards in that work flow eventually render into hair?
They’re not actually using Fibermesh for the hair. The workflow goes that you use your 3D software to create several different swatches of hair, and you render that to a set of texture maps, at a basic level you would render a diffuse map for the color and then an alpha map. For some techniques you might render additional maps like one that fades from black to white along the hair so that you can control color along the length of the hair or rendering a depth map that can be used to give it more dimensions. But after that, you just have a texture map with a bunch of different swatches of hair rendered in it, you make some strips of polygons that you UV map to that texture map and then you place them by hand on the character.