Graphics Programs Reference
In-Depth Information
Figure 10-2: An ambient occlusion map, baked and applied to the mesh as a texture (the eyes here have been left black)
Of these, Tangent is probably the most
important; it lets you bake the normals of one
mesh to the surface of another by enabling the
Selected to Active setting, selecting your source
mesh (or meshes) and the target, and then
baking. This renders the normals of the source
mesh relative to the selected target mesh. This
map can then be used to distort the surface
normals of the mesh when it is rendered, giv-
ing the impression (when the map is applied as
part of the object's material) of having a lot of
detail in the surface when in fact the underlying
geometry can be much simpler. (See Figure 10-3
for an example of this effect.) Tangent space
normal maps are particularly useful because
the normals are recorded relative to the surface
of the mesh itself, so they work even when the
mesh is distorted from its original shape by
modifiers or further editing, so long as the UV
coordinates remain the same.
represents negative displacement, mid-gray rep-
resents zero displacement, and white represents
positive displacement. Use the Selected to Active
option to bake from a source mesh (or meshes)
to the active mesh.
The Displacement map is generally used as
an alternative to normal maps, and this map
can then be used as the input for the Displace
modifier or the Displace setting of a material
to deform a mesh into the shape of the source
mesh (see Figure 10-3). Alternatively, a baked
displacement map can be used as a bump map for
a material. (Bump maps work like normal maps,
giving the impression of surface detail by alter-
ing the shading of the surface, but they require
only black and white input.)
Normal maps are a very efficient way to
give the impression of detail, but they don't
affect the silhouette of the mesh or the cast-
ing of shadows because no real geometry is
displaced. Displacement mapping creates real
detail by deforming the mesh but requires
you to subdivide the mesh to provide suf-
ficient geometry to deform. In Figure 10-3,
a group of spheres has been baked to a
normal map (8 bit) and a displacement
map (32 bit). These maps have then been
Text u re s This bakes the diffuse color of any mate-
rials and colors applied to the mesh. This can be
useful for baking procedural colors and textures
into a UV map.
Displacement This converts the distance between
two meshes into a black-and-white image. Black
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