Terminology


Term Definition
Coordinate System It is the basis for defining and locating in space all objects in a computer graphics scene. It has an origin and some axes emanating from such origin. The axes are usually oriented at right angles to one another.
Cartesian Coordinate system A system where a point is located in space by a set of three coordinates representing the distance along three perpendicular axis labeled X, Y, Z.
World (Global) Coordinates The space in which objects are described
Local Coordinate System It is used to define the geometry of an object independent of the global system
View Coordinate system It locates objects in 3D space relative to the location of the observer
Normalized Device Coordinate (NDC) For the purpose of a standard approach to all graphics equipment, the notion of NDC has been invented, so graphics patterns can be discussed using a standard coordinate system (range from -1 to 1 or from 0 to 1) independent of any particular graphics device.
Homogeneous Coordinates The representation of n component vector by (n+1) component vector is called homogeneous coordinates (e.g. P(x,y)=P(x,y,1))

Terminology


Term Definition
Vector In computer graphics, a vector is just a fancy math term for a direction and a length. "Two miles east" is an example of a vector. A vector is also sometimes said to describe a displacement. A displacement is just a distance traveled in a particular direction.
Unit vector A vector of length, or magnitude, 1
Dot Product A mathematical operation of two vectors that produces a scalar
Point It is just a dot. In CG the smallest thing we can draw directly is a pixel. A point is often drawn as one pixel, but we might also use a small clump of pixels
Polygon Is a bunch of line segments connected end to end in a closed loop
2D Stands for two-dimensional. Two-dimensional objects are always flat because they have only two dimensions: width and height
3D Stands for three-dimensional. Three-dimensional objects exist in a volume and have dimensions of width, height, and depth. For example, a rectangle drawn on a piece of paper is 2D, whereas a cardboard box is 3D
X-Axis The horizontal axis which represents width.

Terminology


Term Definition
Y-Axis The vertical axis which represents height.
Z-Axis The axis which represents depth