Glossary - An Introduction to Computer Graphics for Artists - page 302

Grid An arrangement of horizontal and vertical lines, spaced at equal intervals
from each other.
Grouping An operation that combines objects under a common node.
GUI Acronym for Graphical User Interface.
Hard Edge An edge that, at either end, has a minimum of two normals with differ-
ent values. Because the normals are different, any light calculation will result in
greater contrast along an edge defi ned in this way.
Helix A spiral.
Hierarchy A nested arrangement of subordinates and superiors.
Highlight The brightest portion of refl ected light on any given surface.
Hole A polygon with two or more complete borders, one inner and one outer, made
of adjacent edges that form two or more unbroken loops.
Homotopic Topologically identical.
Horizon Line An imaginary horizontal line located at the center of a lens that can
be used as an aid when drawing in perspective.
Hull An element of NURBS geometry that links control points with straight-line
segments.
I D Acronym for Industrial Design.
Illegal UV Space Any coordinates either smaller than zero or greater than one.
Inaccurate Not correct, not exact.
Incised Detail A polyset or surface with an internal boundary defi ned by edges or
curves, where all parts of the boundary are co-planar with their parent object.
Industrial Design A branch of design that specializes in the conceptualization of
objects intended for mass manufacture.
Instance A data node that represents another object, for rendering purposes. An
instance contains no geometry, but only translation information and the name of
the object represented.
Interactive The quality of responding nearly instantaneously to input.
Interface The method by which a computer user interacts with a computer program.
Intrinsic Color An object's absolute, unchanging color value, regardless of lighting
conditions.
Invoke To call up a command in a computer program, usually meant to cause the
command to be carried out.
Isolated Vertex

Any vertex that is connected to no more than two other vertices

by edges.
Isoparm An interior curve of a surface, as defi ned by identical positions on either
end of two non-adjacent surface borders.
Knot A component of a NURBS curve used to defi ne and regulate how a curve
fl ows through a given control point. The more knots are present, the sharper the
fl ow becomes.
Lamina Two or more faces that share all of their vertices.
Layer A method for treating objects differently within an interface, usually by
allowing items on different layers to be displayed differently, to more easily nav-
igate what would otherwise be an excessively complicated image.