Реферат
на тему:
Computer graphics
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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
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
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
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