Theatre Design & Technology - Fall 1990 - 43

Three-Dimensional Designing
MARK
s computer systems and threedimensional graphics softwate
become more and more sophisticated, a host of new techniques are made
available ro the thearrical designer. These
techniques can save the designer time
and efforr in the creation of extremely
versatile, useful models and professional
design presenrations. Along with this
greater sophistication, com purer modeling packages have become increasingly
complex, numerous and expensive.
Before investing time, money and
labor in expensive compurer 3-D graphics systems, it would help if the designer
undersrood various fearures of 3-D
applications. Software packages come on
the market and are updated with such
speed that a review of specific programs
would not be as useful as a general discussion of options available. The basic
principles discussed here apply ro all
computer systems. However, the
research for this arricle was done using
Apple Macinrosh computers and any
examples of software menrioned below
will reflect this.

REA

N E Y

of such programs is their high degree of
accuracy. Scenic models created in programs such as MacPerspective from B.
Knick Drafting can be constructed accurate ro 1" in scale and viewed in proper
perspective from any seat in the house.

ompu ers ecome more
sophisticated a host of new
techniques are made
available to the designer."

Figure 1. Three-dimensional computer
drawing created with Design Dimensions
software. Design by Michael Gold.

Constructing 3-D Obiects
Applications vary in their methods of
consrructing three-dimensional objects.
Some are more accurate, others offer
greater ease and speed of operation,
while others are necessary for the creation of complex shapes and special
effects. Many programs combine several
methods.
Coordinate input is the most basic
method of 3-D modeling. Lines are
drawn in three dimensions by using the
keyboard ro input X (width), Y (height)
and Z (depth) coordinates. This is the
most tedious method of 3-D creation.
For example, an arc is drawn by first
enrering coordinates ro define the arc's
plane, then the arc's cenrer must be
enrered followed by the arc's starring
point. Finally, an endpoinr or the number of degrees in the desired arc are
typed into the computer. The advantage

3-D Primitives are much easier and
faster ro use than single lines created
through coordinate input. Many programs give the user an on-screen palette
of simple geometric objects such as
cubes, cones, rods, spheres and pyramids. Applications withour uch palettes
are often accompanied by a disk library
of these simple shapes. After being
placed on the screen, primitives can be
easily resized, moved and combined ro
form more complex objects. For example, a thin block placed arop four long
thin rods forms a simple table. It is
importanr that programs using this
method have the ability to display
objects from a variety of angles so that
objects can be placed correcdy, relative
ro one another, in three dimensions.
Multiview Construction allows the
user ro view and edit shapes in several
drawing "windows" at the same time. A

common configuration is rop, side and
fronr view windows combined with an
isometric view that gives a rough
approximation of the 3-D object being
created. This method is parricularly useful for designers and draftsmen who rraditionally depict 3-D objects in three
view orrhographic projections. Most 3D applications offer multiple viewing
angles, and orthographic depictions,
however, many do not allow multiple
views on screen at the same time.
Extmding an object is one of the
most common construction techniques.
Extrusion means simply adding depth ro
a two-dimensional object. In some cases
depth is added in the Z direction by keyboard input, in others an object may be
stretched along the Z axis in a side or
rop view. By this method circles are
made inro cylinders and cubes are made
from squares. One extremely useful technique is ro make rough scenic models in
just minutes by extruding walls up from
a ground plan.
Revolving or ladling a shape works
just the way it sounds. A 2-D object is
revolved around a user-determined axis
that may be inside or outside the object.
Bettet programs allow the uset ro define
the amounr of rotation and the number
of facets on the rotated object. By using
these options, very complex objects can
be created. A circle can be revolved ro
form a sphere or a "doughnut" and an
"s" curve can make an eleganr vase.
SlIlface Sweeping is much like
revolving but can be much more sophisticated. Rather than juSt revolving a 2-D
shape around an axis, sweeping allows
the shape ro be revolved, resized, rotated
and translated as it is changed into a 3-D
object. Shapes such as bent cones,
twisted cubes or pyramids and snail
shells can all be constructed through surface sweeping.
Cross Sectioning is used in some
programs ro create complex irregular
objects that cannot be constructed from
regular
geometric
components.
Experimenration will yield an amazing

TD&T

1990 FALL

Table of Contents for the Digital Edition of Theatre Design & Technology - Fall 1990