Surfacing - Blender Foundations: The Essential Guide to Learning Blender 2.6 - page 202

Projection Painting
Now comes the brilliantly fun part. In the Object Data window,
LMB click the “final face unwrap” channel to make it active. A
quick check in the UV Editor should show the nicely unwrapped
face and the blank, black image.

Hit the T key to bring up the 3D view tool shelf. On the object
mode selector on the 3D view header, change from Object (or
Edit) mode into Texture Paint mode. Check your tool shelf to
make sure that it matches the settings in Figure 7.36 . Tool should
be set to Clone . Project Paint should be enabled, along with
Occlude , Cull , Normal , and Clone below it. Beside the Clone
checkbox you will see a little bit of text, which could possibly
be a portion of “final face unwrap.” The UI here isn't the hottest,
so you're going to have to be brave. In Figure 7.36 , it shows as
just the plain words “front face unwrap” with little other indica-
tion that it's a button or control. This text is actually a selector
that when LMB clicked shows all of the mesh's UV channels.
Choosing a channel here will use its unwrap and attached image
as a painting source.

Use this selector to choose the “front” UV channel you just
created. With your LMB, drag across the eye region of the black
head in the 3D view. You should be magically painting with the
front view texture image directly onto the model! You can't see
it at the moment, but you're actually cloning the image from the
source UV space into the final image in the nicely unwrapped UV
space. Depending on how well you got the front projection to
match the reference image, you should be able to just paint around
most of the head and get a decent result. Use the MMB in the 3D
view to rotate the head and make sure that you've not missed any
nooks and crannies with your brush. You might want to drop into
Local view with Numpad-\ to work with the head alone and
maximize the painting workspace with Shift-spacebar. Figure 7.37
shows the result of this first round of painting. Notice how faces
on the sides and top of the head have extremely stretched texturing.
This is because there isn't a lot of image data for these faces, which
appear very thin from the front projection.

Figure 7.36 The Brush and Project Paint
tool panels.

Now, switch your clone source to the side projection by LMB
clicking the Clone Source control on the tool shelf and choosing
the “side” UV channel. This time, don't paint the parts of the front of the face that look nice. Front