NURBS Lesson 1: Introduction|Create a NURBS curve using the control vertice

Polygon Lesson 1: Beyond the lesson

In this lesson you learned some basic techniques of polygonal modeling:

 You can create complex polygonal models with surprisingly few techniques.
 Starting from a primitive surface such as a cube, you extrude, split, scale, move, and rotate faces
of the primitive to create a rough likeness of the object.
 You then adjust vertices to tune the shape, and finally smooth the edges between faces where
desired.

Polygonal modelin
g has many timesaving features not covered in this lesson. For example, Boolean
operations (union, intersection, and so on) are a common way to create a new object from the

interaction of two existing objects.

If you're planning to use your polygonal surfaces where the poly count is constrained, such as with
computer games, Maya has a number of tools for minimizing the number of polygonal faces of an object
such as the Reduce Tool. Fewer faces means simpler geometry—This is critical when fewer polygons
means increased interactive performance.

Lesson 2: Sculpting a NURBS surface describes how to use the Sculpt Geometry Tool. With this tool, you
can drag your mouse to push, pull, and smooth a surface without first selecting vertices. Though the
lesson shows how to shape a NURBS surface, you can apply most of the same techniques when sculpting
polygonal surfaces. If you want to learn more about a particular tool or feature that has been presented
in this lesson, refer to the Maya Help.

NURBS Lessons: Introduction

NURBS (Non-Uniform Rational B-splines) use a method of mathematically describing curves and surfaces
that are well suited to 3D applications. NURBS are characterized by the smooth organic forms they
produce.

NURBS surfaces can be quickly modeled and edited using a variety of techniques. NURBS surfaces are
created using one or more NURBS curves that define the profile of the shape that you want for a surface,
and then using a specific construction method to create the finished surface.

NURBS curves and surfaces have many applications and are the preferred surface type for industrial and
automotive designers where smooth forms with minimal data are required to define a particular form.
NURBS curves are ideal for defining a smooth motion path for an animated object. With NURBS, a surface
can be modeled and then converted to a poly mesh.

In this chapter, you will learn some basic techniques for working with NURBS curves and surfaces in Maya. This chapter includes these lessons:

 Lesson 1: Revolving a curve to create a surface
 Lesson 2: Sculpting a NURBS surface
 Lesson 3: Lofting curves to create a surface

NURBS Lessons: Preparing for the lessons

To ensure the lessons work as described, do these steps before beginning:

1. Select File > New Scene to create a new scene before starting each lesson.
2. Make sure the Construction History icon (below the menu bar) is on:  . (If it is turned off, it
has a large X across it.)
3. Select the Modeling menu set. Unless otherwise noted, the directions in this chapter for making
menu selections assume you've already selected the Modeling menu set.

NURBS Lesson 1: Introduction



and then create a surface using one of the various NURBS surfacing tools available in Maya. In this
lesson, you create an egg holder using NURBS curves and the Revolve Tool.

In this lesson you learn how to:
 Create a NURBS curve using the control vertice (CV) creation technique.
 Use the grid for visual reference when modeling.
 Determine the start and end points for a NURBS curve and its direction.
 Create a revolved NURBS surface using the Revolve tool.
 Change the display shading smoothness for a NURBS surface.
 Edit a NURBS surface by editing its initial profile curve when it is linked to the surface by
construction history.

Creating a profile curve
Revolve is a common modeling technique similar to shaping a vase on a spinning potter's wheel. You must
first create a profile curve in an orthographic view and use the Revolve Tool to create a surface.

To create a profile curve
1. Make sure you've done the steps in NURBS Lessons: Preparing for the lessons.
2. Select Panels > Layouts > Four Panes so you can see multiple views of the scene.
3. Select Create > CV Curve Tool.
This is the most commonly used tool for drawing curves.



4. In the front view, click the numbered positions as shown in the figure. Make sure the first and last
positions are on the grid's Y-axis (the thickest vertical line of the front view's grid).
Also, click three times in the same spot for positions 9, 10, and 11. This is necessary to create a
sharp point or corner in the curve.
To change the position of the most recent point clicked, you can middle-mouse drag it.
5. (Windows and Linux) After you click position 13, press Enter to complete the curve's creation.
(Mac OS X) Press Return to complete the curve's creation.
The points you clicked in the scene view become the control vertices (CVs) of the completed
curve. CVs are points you manipulate to alter the shape of a curve (or surface). These points
often lie away from the curve.
It takes a little practice to be able to predict exactly where a curve will be positioned when you
click CV positions with the CV Curve Tool. Once you've learned the technique, you'll be able to
create and edit curves with graceful symmetry. By default, you must click at least four points to
create a curve with the CV Curve Tool.
For some advanced operations in Maya, you need to know the meaning of the start of a curve
and the curve direction. The start of a curve is the first CV you create when you draw the curve.
It is indicated by a small hollow box at the first CV, visible as you create the curve. Curve
direction is shown on the second CV after the start of the curve, indicated by a small u icon as
you create the curve.

Creating a revolve surface
With the Revolve surface tool, a curve is rotated about an axis to create a surface. The user can define
the axis of revolution.

To create a revolve surface
1. With the curve selected, select Surfaces > Revolve. This creates the egg holder surface from the
revolved profile curve. Examine the results in the perspective view.
Maya does not delete the profile curve. In a subsequent step, you'll edit the profile curve to alter
the shape of the surface.
2. Select the surface and rename it Eggholder in the Channel Box.
3. With the pointer in the perspective view, press 5 (for Shading > Smooth Shade All). This displays
the egg holder as a shaded surface rather than a wireframe in the perspective view.
4. Press 1, 2, and 3 to switch between the different degrees of display smoothness. (These hotkeys
correspond to the menu items under Display > NURBS Smoothness.)
The finer the smoothness, the greater the impact is on interactive performance when you work
with complex models.
The smoothness display only affects the scene view. Rendered images display with high quality
smoothness regardless of this setting.