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1022 Chapter 9: Sur face Modeling
Subdivision Displacement rollout
Specifies surface approximation settings for
subdividing the editable poly. These controls work
like the surface approximation settings for
NURBS
(page 1–1079)
surfaces. They are used when you
apply a
displacement map (page 2–1352) to the
editable poly.
Note: These settings differ from the Subdivision
Surface settings in that, while the latter are applied
at the same modifier-stack level as the mesh,
subdivision displacement is always applied at
the top of the st ack, when the mesh is used for
rendering. Thus, a Symmetry modifier applied to
an object using surface subdivision would affec t
thesubdividedmesh,butwouldnotaffectan
object that uses subdivision displacement only.
Subdivision Displacement—When on, polygons are
subdivided to accurately displace the poly object,
usingthemethodandsettingsyouspecifyinthe
Subdivision Presets and Subdivision Method
group boxes. When off, the poly is displaced by
moving existing vertices, the way the
Displace
modifier (p age 1–608)
does. Default=off.
Split Mesh—Affects the seams of displaced poly
objects; also affects texture mapping. When on,
the poly object is split into individual polygons
before it is displaced; this helps preserve texture
mapping. When off, the poly is not split and an
internal method is used to assign texture mapping.
Default=on.
Tip: This parameter is require d because of an
architectural limitation in the way displacement
mapping works. Turning Split Mesh on is usually
the better technique, but it can cause problems for
objects with clearly distinct faces, such as boxes,
or even spheres. A box’s sides might separate as
they displace outward, leaving gaps. And a sphere
might split along its longitudinal edge (found in
the rear for spheres created in the Top v iew) un less
you turn off Split Mesh. However, texture mapping
works unpredictably when Split Mesh is off, so
you might need to add a
Displace Mesh modifier
(page 1–499)
and make a snapshot (page 1–438)
of the poly. You would then apply a UVW Map
modifier (page 1–905)
and t hen reassign mapping
coordinates to the displaced snapshot poly.
Subdivision Presets group & Subdivision
Method group
The controls in these two group boxes specify
how the program applies the displacement map
when Subdivision Displacement is on. They are
identical to the
Surface Approximation controls
(page 1–1241)
used for NURBS surfaces.
Paint Deformation rollout
Paint Deformation lets you stroke elevated and
indented areas directly onto object surfaces. For
more information, see
Paint Deformation Rollout
(page 1–1065)
.