CG Modeling 2: NURBS - An Introduction to Computer Graphics for Artists - page 270

14.5.1 Reference

As many professionals know, the quality of an artist's work is limited by the quality
of their reference. To practice your ability to acquire, create, and organize good
reference, get your own reference for this project. First pick a vehicle, and then get
the reference. For extra diffi culty, get reference for the undercarriage and interior
of the vehicle. Be aware that you will probably need to make some drawings to
clarify the reference you get.

14.5.2 Reference Curves

Build orthographic drawings of your vehicle in your CG application using curves.
To do this, you may trace imported images, but the tracing should be done with
curves so that you can snap to them. After you have orthographic views drawn as
curves, make new curves, using the existing ones as reference, that follow the
boundaries of surface features of your vehicle in 3D. This is called a tape model, as
if your curves are tape that has been placed onto the boundaries of a real car.
The original curve model and the tape model should be grouped separately and
then put on layers that can be turned on or off for the next step of the project. Check
the scale of the curve models to ensure they are the right dimensions.
Set the object's position so that the center of the front axle is located at the global
origin. This is an auto industry convention.

14.5.3 Build Curves

Build curves that surfaces can be built from to match the shapes in your two curve
models. Keep in mind that these curves have to result in four sided patches and that
they may need to be trimmed. Many shapes will only be possible by intersecting
patches to create new curves.
Begin with the wheels, rims, axles, and transmission. These parts are easier to
make than the body but will give you some practice with the tools before moving on
to more complicated shapes.

14.5.4 Patch Creation

Build patches from your curves. Set a goal for yourself that your patches will have
a clean isoparm layout. You may fi nd yourself rebuilding the object dozens of times
as you learn how to fi nd the right creation order and become capable of visualizing
the original surfaces from which trimmed surfaces are made.