Graphics Programs Reference
In-Depth Information
NURBS modeling is losing its popularity overall to newer and better polygonal modeling and
subdivision techniques. It is, however, an excellent way to create smooth surfaces and dif-
ficult organic shapes, even though the resulting geometry is frequently converted to poly-
gons for rigging, texturing, and rendering.
You'll get important hands-on practice with NURBS surface modeling with NURBS
patching in the next chapter.
Try This
Open a new scene (choose File
➔
New Scene). In the new scene, you'll create a
few curves on the ground plane grid in the Perspective (
persp
) panel. Maximize the per-
spective view by moving your cursor to it and pressing the spacebar. Choose Create
➔
CV
Curve Tool. Your cursor turns into a cross. Lay down a series of points to define a curved
line on the grid. Notice how the actual Bézier curve is created between the points (CVs)
as they're laid down.
Subdivision Surfaces
Subdivision surfaces
incorporate the best of polygons and NURBS modeling to give you
the ease of polygon creation plus the smoothness and organic forms of NURBS geometry.
Subdivision surfaces usually start as polygonal surfaces. You then use NURBS math
to smooth the rough polygon surfaces by subdividing them according to how the model
needs to look. For example, you can easily turn a poly cube into a sphere by using subdi-
visions to subdivide the faces into smaller and smaller faces that are rearranged to form
the sphere along smooth curves used to define this new surface.
With this technique, you can create simple poly models quickly and then overlay them
with levels of detail to define the new smooth surface. You can go back to the original
poly model at any time to make large-scale changes quickly and efficiently.
Furthermore, with subdivision surfaces, you have the added advantage that your sur-
face won't tend to crease or tear at the seams as NURBS models made of patches of sur-
faces are prone to do. This leads to better models with which to animate organics.
The disadvantage of subdivision surfaces is that they require even more computation
than NURBS, and keeping models in subdivisions will cost you a lot of memory. It's
almost always the best practice to convert subdivisions (SubDs) back to polygons. You'll
also get hands-on practice with subdivision surface modeling in the next chapter.
Choosing a Method
Maya provides highly effective tools for all three types of modeling, so you can make a
model with any technique in as much detail as necessary. The choice depends on how you
prefer to model.
