Graphics Programs Reference
In-Depth Information
4.
Scale down the plane until it is the same size
you want the faces to be in your final retopolo-
gized mesh. Next, grab and place the plane over
a region of your mesh where you wish to start
retopologizing.
5.
Adjust the positions of the existing vertices.
Then, select one edge of the face and start
extruding out to create new faces, following
the contours of the mesh.
6.
Whenever you extrude a new face or grab an
existing one, it will be projected onto the sur-
face of any other mesh on screen (though other
objects you selected before you entered Edit
mode will be ignored).
Using the method described above, in a short
time you should be able to cover the surface of even
a complex mesh with the exact topology you want,
creating a new mesh with the same shape as your
original.
Figure 7-1: Quick retopology with the Shrinkwrap modifier.
First, create a simple mesh around your high-poly original.
Next, add a Shrinkwrap modifier to project the new mesh
onto the original. Here, an arm is retopologized just by extrud-
ing a circle along its length, roughly scaling and rotating it
into place, and then adding Subsurf and Shrinkwrap modifiers
to fit the new mesh to the sculpt.
Alternative Methods for Retopology
There are other useful ways to retopologize quickly
that are worth discussing. The first is to use the
Shrinkwrap modifier to project simple topol-
ogy over the surface of a mesh. With this method,
you first model a basic cage around the outside
of your original model (as shown in Figure 7-1),
extruding areas to create the topology you want.
The cage needs to match the original shape only
roughly because the next step is to add a Subsurf
(or Multires) modifier and a Shrinkwrap modifier
to the mesh, setting your original model as the tar-
get for the Shrinkwrap modifier. The Shrinkwrap
modifier then automatically conforms the new
mesh to the surface of the old one.
Shrinkwrap has a few methods for doing this,
and it's best to experiment to see what works best
for your model. I've generally found the most useful
methods to be the Nearest Surface Point and Project
modes. Note that there are some extra options for
Project mode and that you'll need to turn on both
Negative and Positive in the direction checkboxes
in order for your mesh to project in both directions
to conform to the target (unless the surface of the
new mesh is always above or below the surface of the
target).
This method of retopologizing works well when
you want to quickly retopologize a sculpt that needs
a better base mesh—for example, if you started a
head or even a whole body from a cube and then
wanted a base mesh with topology that does a better
job of supporting the basic forms.
The Shrinkwrap method is also useful for com-
bining models composed of multiple pieces into a
single mesh. For example, to create a one-piece ver-
sion of the Mayan glyphs discussed in Chapter 6, you
could project a simple grid mesh onto the glyphs, as
shown in Figure 7-2. Notice that I've repeated the
Shrinkwrap and Subsurf modifiers to capture all the
details. This repeating of modifiers is a useful trick,
especially when you are projecting onto a mesh with
a lot of sharp corners or deep creases and folds,
because the first shrinkwrap will miss details that
aren't visible when looking straight at the surface
of the target mesh. The resulting mesh can then be
easily sculpted or unwrapped and textured without
having to work with multiple part meshes.
Another method for retopology uses Blender's
Bsurfaces add-on, which has some neat tools for
retopology that allow you to draw lines with the
grease pencil and have them automatically con-
verted to a mesh, as shown in Figure 7-3.
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