Texture Baking - Blender Master Class: A Hands-on Guide to Modeling, Sculpting, Materials, and Rendering - page 144

this time because the silhouette of our character is
broadly fine and normal mapping doesn't require
extra geometry (it doesn't physically displace the
mesh). Next, from the Render tab of the Properties
editor, set the Bake mode to Normals and Normal
Space to Ta ngent , enable Selected to Active , and
click Bake (see Figure 10-7).
The resulting map will be a bluish texture, with
other colors denoting areas of the sculpt that face
in different directions relative to the normals of
the unsubdivided duplicate mesh. This texture may
later be applied as part of the object's material to
give the effect of mimicking the surface forms of
the sculpted mesh (see Figure 10-8). See “Adding
a Normal Map” on page 194 to learn how to apply
normal maps as part of a material.

Applying the Displacement Map
To make sure that the displacement map worked
correctly (and to apply it to our model for use in
our final renders), we can apply it to our duplicated
model using the Displacement modifier. Having
added a Subdivision Surface modifier to the dupli-
cated body object, we have the geometry we need,
so we can simply add a Displacement modifier to
the object as well.
To assign the displacement map, we use the
image we baked as input for a texture ; this texture
can then be assigned as the input for the displace-
ment modifier. (Here, I'm using the more rigorous
definitions that I discussed at the beginning of this
chapter.)
The easiest way to create and modify a tex-
ture block is to add a material to the model, if you
haven't already (we created a MatCap material in
Chapter 6 that we no longer require; we can either
use this or create a new one), and then add a new
texture to this material using the Textures tab of
the Properties editor by clicking the +New button
with an empty texture slot selected. Give the texture
a useful name like Body_Displacement , then set the
type of this texture to Image or Movie . In the Image
panel that appears, open your displacement map.
Now return to the Modifiers tab and, in the
Displacement modifier, use the texture drop-
down menu to select the texture you just created.
Leave Direction set to Normal and set Texture
Coordinates to UV . A strength of 1.0 should give
the correct amount of displacement. Adjusting the
View Subdivision Levels setting on the Subdivision
Surface modifier will let you see more or less of the
detail generated by the displacement map.

Baking Ambient Occlusion
In addition to the displacement map, we also want
to bake our ambient occlusion map from our high-
poly sculpt onto the final mesh. This process is sim-
pler than producing the displacement map:

1. Select the sculpt and then the final mesh. Set

the Bake mode to Ambient Occlusion .

2. Select Normalize to ensure that the ambient

occlusion map uses the whole range between
black and white to store the occlusion.

3. To get the best-quality ambient occlusion map,

adjust Blender's world lighting settings in the
World tab of the Properties editor, which con-
tains all the settings for ambient occlusion
and environment lighting (see Figure 10-9).
(See Chapter 13 for more on these settings.)
Enable Ambient Occlusion (set to Multiply )
from the Ambient Occlusion panel.

Baking Normal Maps
While we won't use one for our final renders, nor-
mal maps are a useful and quick-to-render alter-
native to displacement maps. They are frequently
used in game engines because they are fast enough
to use in real-time applications. They can also be
used with the Blender Internal renderer to give the
impression of extra detail without requiring such
dense geometr y.
The process of baking a normal map is very
similar to baking a displacement map. First, you
assign a new blank image to your duplicated mesh
(it doesn't need to be 32 bit). Then, select the sculpt
first and then the duplicate. We don't need to apply
a Subdivision Surface modifier to the duplicate

4. In the Gather panel, turn the Attenuation

Distance down to 0.2 and enable Falloff and
set it to 1.0 . This causes only close-together
geometry to cause shadowing and speeds up
rendering.

5. Set the samples to 24 to reduce the noise in the

results.

Having saved a displacement map externally,
you can simply bake over the displacement map
image, remembering to save it as something differ-
ent once the ambient occlusion map is baked. Click
Bake and let the ambient occlusion map render (see
Figure 10-10).