Introducing Maya® 2008

Ways to Make NURBS

You can create a NURBS surface in several ways. The easiest way is to create a NURBS

primitive. You can sculpt the primitive surface by moving its CVs, but you can also cut it

apart to create different surface swatches or patches to use as needed, which you will see in

both the Red Rocket model as well as a Steam Pump model for the locomotive later in this

chapter. A primitive need not retain its original shape and frequently can be shaped to fit

the artist’s needs. Using the surfacing tools available under the Surfaces menu set, you can

detach, cut, and attach pieces into and out of a primitive to get the exact shapes you need.

You can also make surfaces in several ways without using a primitive. All these meth-

ods involve first creating or using existing NURBS curves (or curves on another surface)

to define a part or parts of the surface and then using one of the methods described in the

following sections to create the surfaces.

The Lofting Method

The most common surfacing method is lofting, which takes at least two curves and creates

a surface span between each selected curve, in the order in which they are selected.

Figure 5.1 shows the result of lofting two curves together.

Figure 5.1

A simple loft created

between two curves

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To create a loft, follow these steps:

1. Switch to the Surfaces menu set (press F4).

2. Draw the two curves.

3. Select the curves in the order in which you want the surface generated.

4. Choose Surfaces

➔

Loft or click the Loft icon in the Surfaces shelf ( ).

When you define more curves for the loft, Maya can create more complex shapes. The

more CVs for each curve, the more isoparms you have and the more detail in the surface.

Figure 5.2 shows how four curves can be lofted together to form a more complex surface.

Indeed, you can use almost any number of curves for a lofted surface.

Lofting works best when curves are drawn as cross-sectional slices of the object to be

modeled. Lofting is used to make a variety of surfaces, which may be as simple as tabletops

or as complex as human faces.

Figure 5.2

A loft created with

four curves that are

selected in order

from left to right

Revolved Surface

A revolved surface requires only one

curve that is turned about a point in

space to create a surface, like a wood-

worker shaping a table leg on a lathe.

First you draw a profile curve to create

a profile of the desired object, and then

you revolve this curve (anywhere from

0 degrees to 360 degrees) around a sin-

gle point in the scene to create the sur-

face. The profile will revolve around

the object’s pivot point, which is typi-

cally placed at the origin but can be

moved (as seen in the Solar System

exercise in Chapter 3, “Your First

Maya Animation”), and sweeps a new

surface along its way. Figure 5.3 shows

the profile curve for a wine glass.

The curve is then revolved around

the Y-axis a full 360 degrees to create the wine glass. Figure 5.4 is the complete revolved

surface with the profile revolved around the Y-axis.

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To create a revolved surface, draw and select your profile curve, then choose Surfaces

➔

Revolve.

A revolved surface is useful for creating objects such as bottles, furniture legs, and base-

ball bats—anything that is symmetrical about an axis.

Extruded Surface

An extruded surface uses two curves—a profile curve and a path curve. The profile curve is

drawn to create the profile shape of the desired surface. It is then swept from one end of the

path curve to its other end, creating spans of a surface along its travel. The higher the CV

count on each curve, the more detail the surface will have. An extruded surface can also

take the profile curve and simply stretch it to a specified distance straight along one direc-

tion or axis, doing away with the profile curve. Figure 5.5 shows the profile and path curves,

and Figure 5.6 shows the resulting surface once the profile is extruded along the path.

Figure 5.4

The revolved surface

Figure 5.3

A profile curve is drawn in the

outline of a wine glass in the

Y-axis.

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Figure 5.6

Once extruded, the

surface becomes a

bent I-beam.

Figure 5.5

The profile curve is

drawn in the shape

of an I, and the path

curve comes up and

bends toward the

camera.

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