All images from Maya 2008 Character Modeling and Animation: Principles and Practices by Tereza Flaxman.

VFXWorld continues excerpting a new series from the Thomson Course Technology book Maya 2008 Character Modeling and Animation. VFXWorld readers will take on the challenge of animating realistic and compelling characters using the latest version of Maya, the powerful 3D graphics and modeling software. Excerpts will show beginning to intermediate animation students and enthusiasts how to create professional quality characters, explaining the full character animation process from pre-production to final full body and facial animation.

NURBS curves are commonly used in modeling organic shapes. They are very powerful and flexible, but also complex. This excerpt from Chapter 5 describes the types of curve creation tools available in Maya, and explains some of the relatively obscure terminology needed to understand NURBS modeling.

NURBS stands for non-uniform rational B spline. Fortunately, you don't need to understand the name to take advantage of this highly useful modeling method. NURBS modeling allows you to specify smooth curves using a small number of controls. These curves can be used to build up complex organic surfaces. NURBS is commonly used for modeling cars, animals, and human bodies. Because NURBS retains detail when scaled up, it is often used in motion picture production. In this chapter, you will use Maya's NURBS tools to model a fish. You will then learn two new animation techniques to animate the fish: path animation and dynamics. In path animation, you first draw a curve representing a desired movement over time and then attach an object or character to the path. The process works much like direct keyframing, except that all in-between positions are constrained to the path.

Dynamics is Maya's built-in module that simulates real-world physics. Dynamic simulations are very useful for secondary motion (motion that is a consequence of the direct intentional movements of a character). In this case, you will use dynamics to simulate the motion of the fish's fins and tail through the water. A second important use of dynamics is to connect a character to the surrounding environment. Here, you will use dynamics to simulate water movement, including the wake and splashing "caused" by the fish.

NURBS Curves
NURBS curves form the basis upon which NURBS surfaces are built.

NURBS Terminology
NURBS modeling introduces a number of technical terms that may not be familiar to you. Most of these elements have a distinct visual representation in Maya's interface. A single continuous NURBS curve is usually composed of multiple segments, known as spans.

NURBS curves contain two kinds of points: edit points and control vertices.

• Edit points (EPs). EPs are markers on the NURBS curve itself that indicate the extent of a span. In Maya, an edit point is represented by an x on the curve.

• Control vertices (CVs). CVs are points that control the position of the curve between the EPs. CVs are not necessarily on the curve itself.