Page 225 - Concise Encyclopedia of Robotics

OBJECT-ORIENTED GRAPHICS O
One method by which a robotic vision system can define things is called
object-oriented graphics, also known as vector graphics. This is a powerful
technique that uses analog representations, rather than digital ones, to
depict various shapes.
An example of an object-oriented graphic is a circle in the Cartesian
coordinate plane, defined according to its algebraic equation. Consider
2
2
the circle represented by the equation x + y = 1. This is called a unit circle
because it has a radius of one unit, as shown in Fig. 1. The equation is easy
for a computer to store in memory. Another, even simpler, rendition of
this circle is its equation in polar coordinates (Fig. 2). In this system the
unit circle is represented simply by r = 1. Both of these equations are math-
ematically exact representations of the circle, not digital approximations.
A digital, or bit-mapped, rendition of the unit circle requires approx-
imation.The precision depends on the image resolution. An object-oriented
representation is often more precise, and it avoids the problem of jaggies,
also known as aliasing, that is always an artifact of a bit-mapped image.
Compare BIT-MAPPED GRAPHICS.
See also COMPUTER MAP and VISION SYSTEM.

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