|
To start, you may want to load several image files of the front and
side of the head. An image of the top of the head is also useful but
not as important. You might also decide to use an existing model of
a head and then shape the curves around it. Some head templates and
models of heads can be found on the accompanying CD.
Beginning with
the first curve, start drawing it from the inside of the mouth, curve
it over the top lip, around the nose, forehead and skull and end at
the base of the neck (Figure 7-29).
Figure
7-29 The first curve defines the profile and middle of the head.
It starts on the inside of the mouth and ends at the base of the neck.
This curve is located
in the middle of the head and forms the outline of the head's profile.
The side view is used most often for this outline. Once you are finished
with this curve, you can either delete extra points or add some around
the mouth, nose and eye areas. In total, you should you should have
approximately twenty four to thirty points on the curve. Most of these
should be clustered around the lip, nose and mouth. Since you might
duplicate this curve to make all the rest, you do not want too many
points to push and pull around. On the other hand, it is best not to
have to worry about inserting points later on for extra detail. Most
modeling packages that implement lofting or skinning work best when
each curve has the same amount of points. This is also true when making
a spline cage. All the points on each of the splines will be manually
selected by you in the proper order and then connected as cross sectional
spans. Therefore, if any curves have more points than other ones, it
would be difficult to find a way to connect these extra points.
The total amount
of curves for one half of the face should not be greater than thirteen.
The face in Figure 7-30 uses eleven splines and twenty four points
on each spline. If you can manage to keep the points and curves to a
minimum, you will find it much easier to animate the face later on.
Surfaces also remain smoother when they have less points and curves.
Figure
7-30 The curves that define the facial features generally follow
the direction of the muscles.
If you plan to
use copies of the original curves, then the next step is to duplicate
the first. Rather than moving the entire curve away from the first,
it is better to select individual points. These should be moved parallel
to the first curve's points. Copy the second curve and move its points
to continue shaping the outline of the facial features and skull. If
your software has layers, then it might be easier to copy the first
curve, paste it into another layer, make the first layer visible underneath
it and then move the points on this second spline. Once the second curve
is completed, you can then paste it back into the first layer. You can
get an idea of how most of the curves and points will be placed by studying
Figure 7-30.
If you are using
a three dimensional head to model from, use the wire preview window
to move individual points according to the wireframe's surface. The
wire preview can be rotated until the selected point is visible against
the edge of the template's surface. This will let you see the relationship
of your points to curves on the mesh.
Duplicate and move
the new splines. Detailed areas such as those around the wings of the
nose and the nostril can saved for later. For now, just make the basic
outlines of each section. Later on, polygons can be subdivided and their
points moved for all the minute parts.
Check the flow
of the curves so that they flow evenly in both directions. The connecting
spans can be seen by temporarily selecting points in the right order
and making a connecting curve between the spline. Figure 7-31
illustrates how one can select points in order and then connect them.
Smooth out any severe angles.
Figure
7-31 The splines are joined by selecting the cross sectional points
in the right order and making them into a curve. The connecting spans
will create a spline cage.
After a while,
you should notice that the duplicated curves become shorter since they
no longer have to cover as great an area. Subsequently, the number of
points on these curves squeeze together into a tighter space. Points
that are closer together can make the surface bumpier. This type of
problem can occur around the cheeks, mouth, and the chin. Even though
correcting individual points can be tedious, in the long run it will
save you time.
Once you finish
making all the curves for half of the face, then connect each set of
points (Figure 7-31). Be sure to select each point in the right
order. Once they are selected, make a curve out of them. This spline
will connect the original curves. Continue selecting the cross sectional
points and making curves out of them. Once you are finished making all
the connecting splines, you should have a spline cage that looks somewhat
like Figure 7-32. At this point, it would be a good idea to tweak
the points on the cage to smooth out any bumps. Compare the spline cage
to your template(s) to see how the points match up.
Figure
7-32 The resulting spline cage. Notice how the cross sections follow
the contours of the facial muscles.
When you are satisfied
with all the curves and the placement of their points, then patch the
cage with a polygon mesh (Figure 7-33). .
Figure
7-33 Once the spline cage is patched, the
form becomes a solid polygon model.
This would make
a polygon mesh on top of the spline cage. Software like Lightwave 3DTM
uses an Auto Patcher plug-in. The subdivision level should be low so
that you can edit parts without worrying too much about detail. A subdivision
level of one will give you a basic form that can be edited. Higher subdivision
levels would make it too difficult to shape details since it would generate
many small polygons. One can always subdivide polys later on. It is
easier to do that than to go back to a simpler shape.
The polygon model
should now allow you to see a shaded preview. This should make it easier
to fix any trouble spots. At this point you are no longer working with
the spline cage, but rather directly with the polygon mesh. You can
begin to add points and split polys for details such as the nostrils,
lips, and so on. It would also be a good idea to save the spline cage
separately from the model. In the future, you can use it to create other
types of faces by changing its basic structure.
|
