Glossary - An Introduction to Computer Graphics for Artists - page 301

False Gap When a polygon has a reversed normal and appears to be missing, but
is not.
Flag A geometry element with an attached variable that is recognized by a render
or game engine, but is invisible in a fi nished rendering .
Flicker When the renderer is forced to decide which of two coincident faces is in
front of the other. Because they are coincident , it cannot determine that either is
truly in front of the other. The renderer will then either try to draw both at the same
time or it will switch from one to the other and back again. Either way, because the
renderer alternates between two or more faces in the same space, the change from
one polygon to the next will be noticeable as an alternating pattern..

Floating Face One or more faces that belong to a polyset but are not physically
connected to the main body of the polyset.
Focal Length The distance between lenses in a camera. The greater the distance,
the larger the lens elements and housing become and the less distorted any image
passing through the lens will be. A long focal length lens is called a Zoom lens ,
and a short focal length is called a fi sh-eye lens.
Fold Axis An axis around which a face or group of faces is rotated.
Four-sidedness A CG object that has four sides, or, an object that is broken into
pieces, each of which has four-sides. The ability to see how a real world object
may be broken down into four-sided CG objects without destroying its likeness.
Fractal A complex geometric pattern that repeats its larger details in successively
smaller forms into infi nity.
Fractal Complexity A quality of certain fragmented physical structures that,
because they endlessly repeat at smaller scales, can be described as having
dimensions that exceed their normal spatial dimensions.
Frame rate The number of frames rendered in a real-time renderer per-second. A
common frame rate is 30 frames per second.
Game engine Software designed to perform all functions necessary to allow a
game to be interactively played.
Gap A condition where a polyset is missing one or more faces.
Geodesic Sphere A sphere built entirely of equally spaced vertices, connected as
triangles. Spheres of this type can only have a certain number of triangles or they
will not be complete.
Geometric Subdivision A method of measurement that relies on successive divi-
sion of geometric primitives, like circles, squares, and triangles to derive mea-
surements and position information.
Geometry An object defi ned by rules of mathematics that defi ne the properties of
points, lines, faces, surfaces, solids, and angles.
Global Axes The three major axes, X, Y, and Z, which intersect at global coordi-
nate 0, 0, 0.
Global Coordinates A coordinate based on the location of 0, 0, 0.
Global Operation An operation that affects all things in a scene equally.
Global Origin The coordinate 0, 0, 0.
Graphic Communication The act or the product of communication with images.