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166 Chapter 17: Rendering
viewports, they must line up with each other
exactly. There are no special requirements
for the mapping coordinates of the high-res
objects.
•
UV M atch—When chosen, normals are obtained
by matching the target object’s local UV
coordinates to those of the source. The objects’
UV coordinates (page 3–1028) need to be
perfectly alig ned. If you look at the objects
usingtheUnwrapUVWmodifier’sEdit UVWs
dialog (page 1–888), the low-res and high-res
objects must be lined up with each other
exactly. The high-res object needs to have
mapping coordinates on the same map channel
you are using for the low-res object.
Typically, the high-res object will have an
Unwrap UVW modifier assigne d to it, but this
is not required.
With this option, the high-res object does not
needtobeinthesamephysicallocationasthe
low-res object.
Tip: You can reset the cage (on the Cage rollout
(page 1–773)), because UV Match do es not use
it.
Use Cage—When on, bases projection on the
Projection modifier’s cage sub-object. When off,
uses an offset instead. Default=on.
Offset—Enabled only when Use Cage is turned
off. Offset is the distance above the surface of the
source object from which normals are projected.
Default=10.0 units.
Resolve Hit group
Thetworadiobuttonsareforscenesthathave
semitransparent objects, in which c ase more than
onehitcanbefoundforeachray.Theremaining
controls in this group are additional projection
controls.
•
Clo ses t—If there are multiple hits, use the
closest object.
•
Furt hest—(The default.) If there are multiple
hits, use the farthest object.
Hit Only Matching Materia l ID—When on,
projection is only between material IDs that
match. Turningthisoptiononenablesasingle
map to contain normal bump projections from
different high-res source geometry. De fault=off.
Include Work ing Model—When on, bakes from
thesourceobjectifnotargetobjectcanbefound.
Default=off.
Turning on Include Working Model can be a
quick fix when a lot of the projected rays miss the
target object (the Ray Miss Color will be apparent
in the rendered normals m ap). However, if the
low-res object occludes the high-res object, then
IncludeWorkingModelwillnothavethedesired
effect, and the nor mal map will not show high-res
detailsthatyouwantitto.Inthiscase,adjustthe
Projection modifier’s cage.
This toggle is also useful w hen the high-res
geometry is discontinuous (for example, a lattice
or an arr ay of c ylinders).
Ray miss check—When on, bakes missed rays as
well as rays that hit into the rendered texture, using
the Ray Miss Color. Default=on
•
Ray miss color—This color is baked into the
texturewhenprojectionfailstohitthetarget
geometry. Click the color swatch to display
a Color Selector (page 1–161) and change the
color used for missed rays. Default=red.
Normal Map Space group
There are four methods for projecting the normals:
•
World—Projec t using world coordinates. This
is useful mainly for objects that don’t move
or deform; otherwise, a moving object with