Glossary - An Introduction to Computer Graphics for Artists - page 304

Möbius Strip A type of surface that, as a mathematical construct, has only one
side and cannot be fi lled with properly oriented triangles.
Naming To name a node .
N-gon A polygon with more than four sides.
Node A data fl ag that may contain information about any element or group of ele-
ments in a CG fi le. Used to store grouping, hierarchical, and connectivity data.
Non-manifold Geometry that may not be unfolded fl at without overlap.
Non-planar A condition where at least one point of a minimum of four points does
not lie within a plane as defi ned by any other three points.
Normal A perpendicular vector used to defi ne the orientation of a geometry
element.
Normal Map A texture map containing normal information from one object, as
projected onto another object's UV set. This type of map is used in some render-
ers to represent high-resolution 3D information on low-resolution models.
Null Node A node with no attached data.
NURBS Acronym for Non-Uniform Rational Bezier Splines .
Object The top node of a data entity.
Observation Skill The ability to see, understand, and communicate what one has seen.
Obtuse Angle An angle greater than 90°, but less than 180°.
Occlude To progressively block the passage of light.
Offset To translate from a specifi c point, group of points, or vectors.
One-sided An object that has been fl agged to the renderer as one which should be
rendered on one side only, usually the side that defi nes the positive direction of
its normals.
Opacity Map A texture that defi nes the degree of transparency of an object. These
are typically grayscale images, where each gradient value corresponds to a cer-
tain percentile of transparency. Also called transparency map.
Open A curve or surface whose endpoints, whether they meet or not, are not cur-
vature continuous and fused together.
Optimization The act of making a fi le more effi cient, usually by removal of
unneeded elements.
Orientation The constant outward direction of any given point, group of points, or
any other element.
Organic A natural object, grown, not made
Organization The orderly arrangement of data.
Orthographic Aligned at 90° to the picture plane.
Overlapping UVs UV coordinates that belong to faces that are covered, partially
or completely, by UV sets belonging to other faces.
Padded Numbers Numbers used as suffi xes at the end of an object name. The
padding consists of leading zeroes at the beginning of the number. These cause
the numbers to sort properly in a computer. Failing to do this will result in the
number “2” coming after the number “002” or “19”.
P a n Moves the camera within a camera plane as defi ned by the current viewport
Parallel Never convergent, always equidistant alignment of two or more linear
things, like edges or curves (whether straight or not).