Texture Baking - Blender Master Class: A Hands-on Guide to Modeling, Sculpting, Materials, and Rendering - page 146

To make sure that the ambient occlusion
map came out okay, turn on Textured Solid in the
Display panel of the Properties region in the 3D
Viewport. This displays the texture assigned to the
mesh on the model, allowing you to see the effect
of the ambient occlusion map. When you're happy
with the bake, save it as a .tga image. (You don't need
to use a high-bit-depth format this time, as the ambi-
ent occlusion map will work fine with 8-bit color.)
There may be one or two artifacts, but you can paint
these out later in GIMP once you begin texturing.

Baking Textures for the Spider Bot
For the Spider Bot project, I didn't need to bake
displacement or normal maps; the point of retopol-
ogy in this case was to eliminate the roughness from
the sculpts and end up with the smooth forms the
retopologized model now has. The model would still
benefit from an ambient occlusion map, though,
which will be useful during the texturing process.
To save time when painting colors for the textures,
it will also help to assign some basic materials with
different colors to the parts of the model and then
bake these colors into an image to serve as a guide
when painting textures.

Figure 10-9: Ambient occlusion settings for
baking ambient occlusion maps.

Baking Maps for Multiple Objects
In Chapter 8, I packed the UV coordinates for most
of the Spider Bot model onto a single UV grid so
that I'd require fewer texture images later on. Next
I needed to bake the maps for all of the objects
together. To do this, first make sure they all have
the same image assigned to their UV coordinates.
If so, you could simply select all of the objects for
the Spider Bot that share the same UV coordinates
and click Bake to bake all of the selected objects
at once.
But what if you want to be selective about which
parts of the model are visible when baking different
objects? Or if you wish to be able to correct parts
without rebaking the entire model? By default,
Blender will clear the texture every time you click
Bake, preventing you from baking multiple times
with different objects selected. To prevent this, turn
off the Clear setting in the Bake panel, and Blender
will replace only the parts of the image assigned
to the selected objects. This will allow you to bake
objects one at a time, in groups, or all at once, add-
ing to the texture map as we go along.

Figure 10-10: The baked ambient occlusion map. This contains
some artifacts from baking that we'll remove later by hand.