Graphics Reference
In-Depth Information
render time, because a two-sided polygon can be used in place of a larger poly-
set, required to defi ne the depth of an object correctly.
Up-axis
The axis that points in an upward direction. Also known as an
up- vector
.
Most CG applications use Y as the up-vector, some use Z.
U V
Designates two axis directions within geometric parameter space for NURBS
objects. An alternate name for a texture coordinate.
UV Layout
The pattern created by projected texture coordinates, whether or not
they have been edited.
UV Packing
A technique for compressing the amount of space required by texture
coordinates, to eliminate the largest amount of wasted pixels in a texture map.
UV Projection
The act of causing texture coordinates to come into being and be
attached to vertices.
Vanishing Point
The point at which all vectors converge. An element of linear
perspective .
Vector
A direction, as defi ned by the coordinates of a point and the world origin.
Vector Graphics
Images based on curves, as opposed to pixels.
Vertex
A coordinate in 3D space, used as a boundary for polygonal faces in quanti-
ties greater than two.
Weld
To fuse two or more geometry elements into one.
Wireframe
A method of displaying vertex and edge geometry on screen without
shading to describe faces.
World Origin
The coordinate 0, 0, 0.
World Space
The coordinate system used to contain all things in a CG environ-
ment, home to the world origin.
Wrong-way Normal
A polygonal face where the normal vector is pointing 180°
away from the front of the object
Zero edge-length Face
A face whose edges are each zero units in length.
Zoom
Moves the camera closer or farther away from an object, following a vector
perpendicular to the viewport.