Geometry pipelines
Encyclopedia
Geometric manipulation of modeling primitives, such as that performed by a geometry pipeline, is the first stage in computer graphics
systems which perform image generation based on geometric models. While Geometry Pipelines were originally implemented in software, they have become highly amenable to hardware implementation, particularly since the advent of very-large-scale integration
(VLSI) in the early 1980s. A device called the Geometry Engine developed by Jim Clark
and Marc Hannah at Stanford University
in about 1981 was the watershed for what has since become an increasingly commoditized function in contemporary image-synthetic raster display systems.
Geometric transformations are applied to the vertices of polygon
s, or other geometric objects used as modelling primitive
s, as part of the first stage in a classical geometry-based graphic image rendering pipeline. Geometric computations may also be applied to transform polygon or patch
surface normal
s, and then to perform the lighting
and shading
computations used in their subsequent rendering.
Picture System, but perhaps received broader recognition when later applied in the broad range of graphics systems products introduced by Silicon Graphics
(SGI). Initially the SGI geometry hardware performed simple model space to screen space viewing transformations with all the lighting and shading handled by a separate hardware implementation stage, but in later, much higher performance applications such as the RealityEngine
, they began to be applied to perform part of the rendering support as well.
More recently, perhaps dating from the late 1990s, the hardware support required to perform the manipulation and rendering of quite complex scenes has become accessible to the consumer market.
Companies such as NVIDIA
and ATI
(now a part of AMD) are two current leading representatives of hardware vendors in this space. The GeForce
line of graphics cards from NVIDIA were the first to implement hardware geometry processing in the consumer PC market, while earlier graphics accelerators by 3Dfx
and others had to rely on the CPU to perform geometry processing.
This subject matter is part of the technical foundation for modern computer graphics, and is a comprehensive topic taught at both the undergraduate and graduate levels as part of a computer science
education.
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....
systems which perform image generation based on geometric models. While Geometry Pipelines were originally implemented in software, they have become highly amenable to hardware implementation, particularly since the advent of very-large-scale integration
Very-large-scale integration
Very-large-scale integration is the process of creating integrated circuits by combining thousands of transistors into a single chip. VLSI began in the 1970s when complex semiconductor and communication technologies were being developed. The microprocessor is a VLSI device.The first semiconductor...
(VLSI) in the early 1980s. A device called the Geometry Engine developed by Jim Clark
James H. Clark
James H. Clark is an American entrepreneur and computer scientist. He founded several notable Silicon Valley technology companies, including Silicon Graphics, Inc., Netscape Communications Corporation, myCFO and Healtheon...
and Marc Hannah at Stanford University
Stanford University
The Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San...
in about 1981 was the watershed for what has since become an increasingly commoditized function in contemporary image-synthetic raster display systems.
Geometric transformations are applied to the vertices of polygon
Polygon
In geometry a polygon is a flat shape consisting of straight lines that are joined to form a closed chain orcircuit.A polygon is traditionally a plane figure that is bounded by a closed path, composed of a finite sequence of straight line segments...
s, or other geometric objects used as modelling primitive
Geometric primitive
The term geometric primitive in computer graphics and CAD systems is used in various senses, with the common meaning of the simplest geometric objects that the system can handle . Sometimes the subroutines that draw the corresponding objects are called "geometric primitives" as well...
s, as part of the first stage in a classical geometry-based graphic image rendering pipeline. Geometric computations may also be applied to transform polygon or patch
Patch
-Computing:* Patch , fix for a software program* Patch , UNIX utility* Patch, a 3-D Bézier curve used in computer graphics, or a primitive in some 3-D software packages* Patch Media, website for local news and events-Electronics:...
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...
s, and then to perform the lighting
Lighting
Lighting or illumination is the deliberate application of light to achieve some practical or aesthetic effect. Lighting includes the use of both artificial light sources such as lamps and light fixtures, as well as natural illumination by capturing daylight...
and shading
Shading
Shading refers to depicting depth perception in 3D models or illustrations by varying levels of darkness.-Drawing:Shading is a process used in drawing for depicting levels of darkness on paper by applying media more densely or with a darker shade for darker areas, and less densely or with a lighter...
computations used in their subsequent rendering.
History
Hardware implementations of the geometry pipeline were introduced in the early Evans & SutherlandEvans & Sutherland
Evans & Sutherland is a computer firm involved in the computer graphics field. Their products are used primarily by the military and large industrial firms for training and simulation, and in digital projection environments like planetariums.-History:...
Picture System, but perhaps received broader recognition when later applied in the broad range of graphics systems products introduced by Silicon Graphics
Silicon Graphics
Silicon Graphics, Inc. was a manufacturer of high-performance computing solutions, including computer hardware and software, founded in 1981 by Jim Clark...
(SGI). Initially the SGI geometry hardware performed simple model space to screen space viewing transformations with all the lighting and shading handled by a separate hardware implementation stage, but in later, much higher performance applications such as the RealityEngine
RealityEngine
RealityEngine refers to a 3D graphics hardware architecture and a family of graphics systems that implemented the aforementioned hardware architecture that was developed and manufactured by Silicon Graphics during the early to mid 1990s...
, they began to be applied to perform part of the rendering support as well.
More recently, perhaps dating from the late 1990s, the hardware support required to perform the manipulation and rendering of quite complex scenes has become accessible to the consumer market.
Companies such as NVIDIA
NVIDIA
Nvidia is an American global technology company based in Santa Clara, California. Nvidia is best known for its graphics processors . Nvidia and chief rival AMD Graphics Techonologies have dominated the high performance GPU market, pushing other manufacturers to smaller, niche roles...
and ATI
Ati
As a word, Ati may refer to:* Ati, a town in Chad* Ati, a Negrito ethnic group in the Philippines* Ati-Atihan Festival, an annual celebration held in the Philippines* Ati, a queen of the fabled Land of Punt in Africa...
(now a part of AMD) are two current leading representatives of hardware vendors in this space. The GeForce
GeForce
GeForce is a brand of graphics processing units designed by Nvidia. , there have been eleven iterations of the design. The first GeForce products were discrete GPUs designed for use on add-on graphics boards, intended for the high-margin PC gaming market...
line of graphics cards from NVIDIA were the first to implement hardware geometry processing in the consumer PC market, while earlier graphics accelerators by 3Dfx
3dfx
3dfx Interactive was a company that specialized in the manufacturing of 3D graphics processing units and, later, graphics cards. It was a pioneer in the field for several years in the late 1990s until 2000 when it underwent one of the most high-profile demises in the history of the PC industry...
and others had to rely on the CPU to perform geometry processing.
This subject matter is part of the technical foundation for modern computer graphics, and is a comprehensive topic taught at both the undergraduate and graduate levels as part of a computer science
Computer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...
education.