Procedural surface
Encyclopedia
In computer graphics
, a procedural surface is a representation of a surface as a mathematical implicit equation, rather than an explicit representation.
An explicit representation, for example, describes a line as the straight segment going through two given points. A procedural surface is one which is defined as a procedure.
For example, in CAD/Computer-aided manufacturing
milling
applications, an offset surface is a procedural representation because it is defined as the surface which is a fixed distance from another surface. Another well-known procedural edge on a 3D body is the silhouette edge
. This edge is defined as the collection of points on a surface whose outwards surface normal
is perpendicular to the view vector.
Another example of a procedural surface is a Blob
as illustrated in movies like The Abyss
in the scene where the creature made up of water reaches out and touches the character. The surface is defined as a surface which exists when two or more control points are oriented in such a way as to make the contribution potential exceed a certain threshold. Such procedural surfaces require far more processing to calculate, and for this reason are often used in pre-rendered rather than real-time applications.
This approach is commonly used by structural chemists and was defined by van der Waals
when defining a region of space where the electric charge equipotential surface
had a definite value.
Computer graphics
Computer graphics are graphics created using computers and, more generally, the representation and manipulation of image data by a computer with help from specialized software and hardware....
, a procedural surface is a representation of a surface as a mathematical implicit equation, rather than an explicit representation.
An explicit representation, for example, describes a line as the straight segment going through two given points. A procedural surface is one which is defined as a procedure.
For example, in CAD/Computer-aided manufacturing
Computer-aided manufacturing
Computer-aided manufacturing is the use of computer software to control machine tools and related machinery in the manufacturing of workpieces. This is not the only definition for CAM, but it is the most common; CAM may also refer to the use of a computer to assist in all operations of a...
milling
Milling machine
A milling machine is a machine tool used to machine solid materials. Milling machines are often classed in two basic forms, horizontal and vertical, which refers to the orientation of the main spindle. Both types range in size from small, bench-mounted devices to room-sized machines...
applications, an offset surface is a procedural representation because it is defined as the surface which is a fixed distance from another surface. Another well-known procedural edge on a 3D body is the silhouette edge
Silhouette edge
In computer graphics, a silhouette edge on a 3D body projected onto a 2D plane is the collection of points whose outwards surface normal is perpendicular to the view vector. Due to discontinuities in the surface normal, a silhouette edge is also an edge which separates a front facing face from a...
. This edge is defined as the collection of points on a surface whose outwards surface normal
Surface normal
A surface normal, or simply normal, to a flat surface is a vector that is perpendicular to that surface. A normal to a non-flat surface at a point P on the surface is a vector perpendicular to the tangent plane to that surface at P. The word "normal" is also used as an adjective: a line normal to a...
is perpendicular to the view vector.
Another example of a procedural surface is a Blob
Metaballs
Metaballs are, in computer graphics, organic-looking n-dimensional objects. The technique for rendering metaballs was invented by Jim Blinn in the early 1980s....
as illustrated in movies like The Abyss
The Abyss
The Abyss is a 1989 science fiction film written and directed by James Cameron. It stars Ed Harris, Mary Elizabeth Mastrantonio, and Michael Biehn. The original musical score was composed by Alan Silvestri...
in the scene where the creature made up of water reaches out and touches the character. The surface is defined as a surface which exists when two or more control points are oriented in such a way as to make the contribution potential exceed a certain threshold. Such procedural surfaces require far more processing to calculate, and for this reason are often used in pre-rendered rather than real-time applications.
This approach is commonly used by structural chemists and was defined by van der Waals
Johannes Diderik van der Waals
Johannes Diderik van der Waals was a Dutch theoretical physicist and thermodynamicist famous for his work on an equation of state for gases and liquids....
when defining a region of space where the electric charge equipotential surface
Equipotential surface
Equipotential surfaces are surfaces of constant scalar potential. They are used to visualize an -dimensional scalar potential function in dimensional space...
had a definite value.