Реферат

на тему:

Computer graphics

HYPERLINK

"http://upload.wikimedia.org/wikipedia/commons/5/5f/Utah_teapot_simple_2

.png"

Contents

Introduction

Overview

History

Subfields in computer graphics

Geometry

Animation

Rendering

Other subfields

Computer graphics is a sub-field of computer science which studies

methods for digitally synthesizing and manipulating visual content.

Although the term often refers to the study of three-dimensional

computer graphics, it also encompasses two-dimensional graphics and

image processing.

A modern render of the Utah teapot, an iconic model in 3D computer

graphics created by Martin Newell in 1975.

Overview

Computer graphics studies the manipulation of visual and geometric

information using computational techniques. It focuses on the

mathematical and computational foundations of image generation and

processing rather than purely aesthetic issues. Computer graphics is

often differentiated from the field of visualization, although the two

fields have many similarities.

Connected studies include:

Scientific visualization

Information visualization

Computer vision

Image processing

Computational Geometry

Computational Topology

Applied mathematics

Applications of computer graphics include:

Special effects

Visual effects

Video games

Digital art

History

One of the first displays of computer animation was Futureworld (1976),

which included an animation of a human face and hand — produced by Ed

Catmull and Fred Parke at the University of Utah.

There are several international conferences and journals where the most

significant results in computer graphics are published. Among them are

the SIGGRAPH and Eurographics conferences and the Association for

Computing Machinery (ACM) Transactions on Graphics journal. The joint

Eurographics and ACM SIGGRAPH symposium series features the major venues

for the more specialized sub-fields: Symposium on Geometry

Processing,Symposium on Rendering, and Symposium on Computer Animation.

As in the rest of computer science, conference publications in computer

graphics are generally more significant than journal publications (and

subsequently have lower acceptance rates)[1][2][3].[4]

Subfields in computer graphics

A broad classification of major subfields in computer graphics might be:

Geometry: studies ways to represent and process surfaces

Animation: studies with ways to represent and manipulate motion

Rendering: studies algorithms to reproduce light transport

Imaging: studies image acquisition or image editing

Geometry

Successive approximations of a surface computed using quadric error

metrics.

The subfield of geometry studies the representation of three-dimensional

objects in a discrete digital setting. Because the appearance of an

object depends largely on its exterior, boundary representations are

most commonly used. Two dimensional surfaces are a good representation

for most objects, though they may be non-manifold. Since surfaces are

rfaces are

not finite, discrete digital approximations are used. Polygonal meshes

(and to a lesser extent subdivision surfaces) are by far the most common

representation, although point-based representations have become more

popular recently (see for instance the Symposium on Point-Based

Graphics). These representations are Lagrangian, meaning the spatial

locations of the samples are independent. Recently, Eulerian surface

descriptions (i.e., where spatial samples are fixed) such as level sets

have been developed into a useful representation for deforming surfaces

which undergo many topological changes (with fluids being the most

notable example[5]).

Geometry Subfields

Implicit surface modeling - an older subfield which examines the use of

algebraic surfaces, constructive solid geometry, etc., for surface

representation.

Digital geometry processing - surface reconstruction, simplification,

fairing, mesh repair, parameterization, remeshing, mesh generation,

surface compression, and surface editing all fall under this

heading.[6][7][8]

Discrete differential geometry - a nascent field which defines geometric

quantities for the discrete surfaces used in computer graphics.[9]

Point-based graphics - a recent field which focuses on points as the

fundamental representation of surfaces.

Subdivision surfaces

Out-of-core mesh processing - another recent field which focuses on mesh

datasets that do not fit in main memory.

Animation

The subfield of animation studies descriptions for surfaces (and other

phenomena) that move or deform over time. Historically, most work in

this field has focused on parametric and data-driven models, but

recently physical simulation has become more popular as computers have

become more powerful computationally.

Subfields

Performance capture

Character animation

Physical simulation (e.g. cloth modeling, animation of fluid dynamics,

etc.)

Rendering

Indirect diffuse scattering simulated using path tracing and irradiance

caching.

Rendering generates images from a model. Rendering may simulate light

transport to create realistic images or it may create images that have a

particular artistic style in non-photorealistic rendering. The two basic

operations in realistic rendering are transport (how much light passes

from one place to another) and scattering (how surfaces interact with

light). See Rendering (computer graphics) for more information.

Transport

Transport describes how illumination in a scene gets from one place to

another. Visibility is a major component of light transport.

Scattering

Models of scattering and shading are used to describe the appearance of

a surface. In graphics these problems are often studied within the

context of rendering since they can substantially affect the design of

rendering algorithms. Shading can be broken down into two orthogonal

issues, which are often studied independently:

scattering - how light interacts with the surface at a given point

shading - how material properties vary across the surface

rial properties vary across the surface

The former problem refers to scattering, i.e., the relationship between

incoming and outgoing illumination at a given point. Descriptions of

scattering are usually given in terms of a bidirectional scattering

distribution function or BSDF. The latter issue addresses how different

types of scattering are distributed across the surface (i.e., which

scattering function applies where). Descriptions of this kind are

typically expressed with a program called a shader. (Note that there is

some confusion since the word "shader" is sometimes used for programs

that describe local geometric variation.)

Other subfields

physically-based rendering - concerned with generating images according

to the laws of geometric optics

real time rendering - focuses on rendering for interactive applications,

typically using specialized hardware like GPUs

non-photorealistic rendering

relighting - recent area concerned with quickly re-rendering scenes

PAGE

PAGE 7