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Modeling Hair... one approach....
Step 42.
Take photos of your subject's head from several angles, side, top, front, back. Using a software package such as photoshop, create alpha channels to separate the hair from the skin.
Once these alpha channels are created you can create a Hair texture with an alpha channel similar to the one on the far right. Your images may look very different depending the hair your working with.
I create my alpha channels by copying a channel from the RGB channels. Which one I use depends on the contrast of the channel. I try to use the one that has the darkest background with the brightest area to mask.
For example Cooper's hair is blond so I used the green channel since it gave me nice light tones in the hair and a dark area outside the hair.
Once I have my channel I begin Dodging and burning the edges with the options set to Shadows and highlights respectively. This helps brighten the hair to a white and creates a black mask on every thing else.
My last step is to do a levels to make sure the blacks are black and the whites are white.
Save the final image as a Targa with an alpha channel.
Step 43.
In AM create a new rotoscope in the TOP view by right mouse clicking (cmnd click on the Mac) and selecting New/Rotoscope.Load your Hair Targa.
Make the Rotoscope uneditable by clicking on the hand next to its name in the project workspace.
Step 44.
Draw a spline in the top view with enough points to create a hair piece that's will mold around the skull well but won't be two cumbersome to edit.Begin extruding the spline to create a grid that covers your rotoscope. Only do half the hair.
Step 45.
Select the Corner points that don't cover hair and delete them. They aren't necessary if they don't have a texture.
Step 46.
Select the Grid and copy/flip/attach to create the hair grid.
Step 47.
Right mouse click (cmnd click on the Mac) and select new/decal/Fullhair.FullHair was the name of my Targa, you'll select your image.
The Decal will appear for positioning and will be larger than your rotoscope.
Step 47a.
Scale the decal down to match the size and shape of the rotoscope. Then right mouse click (cmnd click on the Mac) and select "Apply" from the pulldown.The far right image shows the shaded view of the hair on the grid. But there is a problem. The hair has now transparency do to the fact that it defaulted to a color map.
Step 47b.
In the project workspace open the images folder under the Decal you just created. Change the image type to "Cookie-Cut" in the Type pulldown.Viola, very flat transparent hair.
Step 48.
Now our old friend the Magnet tool.Here is where you need some patience and practice.
Set your magnet to roughly the size of the grid. Using the 2 key in birds eye view select the center point and pull it up. The 2 key constrains the movement on the y plane.
This will pull up a bump in the hair. Its already starting to look better.
Step 49.
You can also select multiple points and manipulate even faster. Keep doing this until you have a rough hair piece in the shape of a skull. It doesn't have to be perfect, we'll save those tweaks for when its positioned on the head.
Step 50.
Position the hair over the skull and continue to tweak. Lock the hair so you don't move points on the skull.Notice how some of the mesh "collides" Its OK because the hair doesn't appear on that part of the grid.
If you don't see this kind of collision with the detail turned up and no textures showing then you probably have the hair sitting to far off the head at the edges.
The idea is to have it "bubble up and out from the skull, but be snug at the edges to mimic the shape of real hair.
Step 51.
I created a displacement map from my texture using the high pass filter in photoshop. The idea here is to have the darkest part be just slightly darker than 50% gray. If its darker than that the hair will be displaced to far into the skull. Same with the light areas. There shouldn't be tom much contrast in the map.
Step 52.
In the project workspace right mouse click (cmnd click on the Mac) on your images folder under your hair decal. Select "Add Image/ Other" and load your displacement map.Change the image type to "Displacement"
Step 53.
Set the Displacement percentage to some small number like 2%. The amount will depend on the contrast in you map and its grayscale values.
Step 54.
This is the result. Its just a real-time render, but you can see it works pretty well.This definitely not the only way to do hair and probably not even the best way to do it. But it is fairly easy to do and the results are decent.
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