3D computer graphics

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3D computer graphics, sometimes called CGI, 3D-CGI or three-dimensional computer graphics are graphics that use a three-dimensional representation of geometric data (often Cartesian) that is stored in the computer for the purposes of performing calculations and rendering digital images, usually 2D images but sometimes 3D images. The resulting images may be stored for viewing later (possibly as an animation) or displayed in real time.

Contents

3D computer graphics, contrary to what the name suggests, are most often displayed on two-dimensional displays. Unlike 3D film and similar techniques, the result is two-dimensional, without visual depth. More often, 3D graphics are being displayed on 3D displays, like in virtual reality systems.

3D graphics stand in contrast to 2D computer graphics which typically use completely different methods and formats for creation and rendering.

3D computer graphics rely on many of the same algorithms as 2D computer vector graphics in the wire-frame model and 2D computer raster graphics in the final rendered display. In computer graphics software, 2D applications may use 3D techniques to achieve effects such as lighting, and similarly, 3D may use some 2D rendering techniques.

The objects in 3D computer graphics are often referred to as 3D models. Unlike the rendered image, a model's data is contained within a graphical data file. A 3D model is a mathematical representation of any three-dimensional object; a model is not technically a graphic until it is displayed. A model can be displayed visually as a two-dimensional image through a process called 3D rendering, or it can be used in non-graphical computer simulations and calculations. With 3D printing, models are rendered into an actual 3D physical representation of themselves, with some limitations as to how accurately the physical model can match the virtual model. [1]

History

William Fetter was credited with coining the term computer graphics in 1961 [2] [3] to describe his work at Boeing. One of the first displays of computer animation was Futureworld (1976), which included an animation of a human face and a hand that had originally appeared in the 1971 experimental short A Computer Animated Hand , created by University of Utah students Edwin Catmull and Fred Parke. [4]

3D computer graphics software began appearing for home computers in the late 1970s. The earliest known example is 3D Art Graphics , a set of 3D computer graphics effects, written by Kazumasa Mitazawa and released in June 1978 for the Apple II. [5] [6]

Overview

3D computer graphics production workflow falls into three basic phases:

  1. 3D modeling – the process of forming a computer model of an object's shape
  2. Layout and CGI animation – the placement and movement of objects (models, lights etc.) within a scene
  3. 3D rendering – the computer calculations that, based on light placement, surface types, and other qualities, generate (rasterize the scene into) an image

Modeling

The model describes the process of forming the shape of an object. The two most common sources of 3D models are those that an artist or engineer originates on the computer with some kind of 3D modeling tool, and models scanned into a computer from real-world objects (Polygonal Modeling, Patch Modeling and NURBS Modeling are some popular tools used in 3d modeling). Models can also be produced procedurally or via physical simulation. Basically, a 3D model is formed from points called vertices that define the shape and form polygons. A polygon is an area formed from at least three vertices (a triangle). A polygon of n points is an n-gon. [7] The overall integrity of the model and its suitability to use in animation depend on the structure of the polygons.

Layout and animation

Before rendering into an image, objects must be laid out in a scene. This defines spatial relationships between objects, including location and size. Animation refers to the temporal description of an object (i.e., how it moves and deforms over time. Popular methods include keyframing, inverse kinematics, and motion capture). These techniques are often used in combination. As with animation, physical simulation also specifies motion.

Materials and textures

Materials and textures are properties that the render engine uses to render the model. One can give the model materials to tell the render engine how to treat light when it hits the surface. Textures are used to give the material color using a color or albedo map, or give the surface features using a bump map or normal map. It can be also used to deform the model itself using a displacement map.

Rendering

Rendering converts a model into an image either by simulating light transport to get photo-realistic images, or by applying an art style as in non-photorealistic rendering. The two basic operations in realistic rendering are transport (how much light gets from one place to another) and scattering (how surfaces interact with light). This step is usually performed using 3D computer graphics software or a 3D graphics API. Altering the scene into a suitable form for rendering also involves 3D projection, which displays a three-dimensional image in two dimensions. Although 3D modeling and CAD software may perform 3D rendering as well (e.g., Autodesk 3ds Max or Blender), exclusive 3D rendering software also exists (e.g., OTOY's Octane Rendering Engine, Maxon's Redshift)

Software

3D computer graphics software produces computer-generated imagery (CGI) through 3D modeling and 3D rendering or produces 3D models for analytic, scientific and industrial purposes.

File formats

There are many varieties of files supporting 3D graphics, for example, Wavefront .obj files and .x DirectX files. Each file type generally tends to have its own unique data structure.

Each file format can be accessed through their respective applications, such as DirectX files, and Quake. Alternatively, files can be accessed through third-party standalone programs, or via manual decompilation.

Modeling

3D modeling software is a class of 3D computer graphics software used to produce 3D models. Individual programs of this class are called modeling applications or modelers.

3D modeling starts by describing 3 display models : Drawing Points, Drawing Lines and Drawing triangles and other Polygonal patches. [8]

3D modelers allow users to create and alter models via their 3D mesh. Users can add, subtract, stretch and otherwise change the mesh to their desire. Models can be viewed from a variety of angles, usually simultaneously. Models can be rotated and the view can be zoomed in and out.

3D modelers can export their models to files, which can then be imported into other applications as long as the metadata are compatible. Many modelers allow importers and exporters to be plugged-in, so they can read and write data in the native formats of other applications.

Most 3D modelers contain a number of related features, such as ray tracers and other rendering alternatives and texture mapping facilities. Some also contain features that support or allow animation of models. Some may be able to generate full-motion video of a series of rendered scenes (i.e. animation).

Computer-aided design (CAD)

Computer aided design software may employ the same fundamental 3D modeling techniques that 3D modeling software use but their goal differs. They are used in computer-aided engineering, computer-aided manufacturing, Finite element analysis, product lifecycle management, 3D printing and computer-aided architectural design.

Complementary tools

After producing video, studios then edit or composite the video using programs such as Adobe Premiere Pro or Final Cut Pro at the mid-level, or Autodesk Combustion, Digital Fusion, Shake at the high-end. Match moving software is commonly used to match live video with computer-generated video, keeping the two in sync as the camera moves.

Use of real-time computer graphics engines to create a cinematic production is called machinima. [9]

Differences with other types of computer graphics

Distinction from photorealistic 2D graphics

Not all computer graphics that appear 3D are based on a wireframe model. 2D computer graphics with 3D photorealistic effects are often achieved without wireframe modeling and are sometimes indistinguishable in the final form. Some graphic art software includes filters that can be applied to 2D vector graphics or 2D raster graphics on transparent layers. Visual artists may also copy or visualize 3D effects and manually render photorealistic effects without the use of filters.

Pseudo 3D and true 3D

Some video games use restricted projections of three-dimensional environments, such as isometric graphics or virtual cameras with fixed angles, either as a way to improve performance of the game engine or for stylistic and gameplay concerns. Such games are said to use pseudo 3D graphics. By contrast, games using 3D computer graphics without such restrictions are said to use true 3D.

See also

Graphics and software

Fields of use

Related Research Articles

<span class="mw-page-title-main">Rendering (computer graphics)</span> Process of generating an image from a model

Rendering or image synthesis is the process of generating a photorealistic or non-photorealistic image from a 2D or 3D model by means of a computer program. The resulting image is referred to as the render. Multiple models can be defined in a scene file containing objects in a strictly defined language or data structure. The scene file contains geometry, viewpoint, texture, lighting, and shading information describing the virtual scene. The data contained in the scene file is then passed to a rendering program to be processed and output to a digital image or raster graphics image file. The term "rendering" is analogous to the concept of an artist's impression of a scene. The term "rendering" is also used to describe the process of calculating effects in a video editing program to produce the final video output.

<span class="mw-page-title-main">Computer animation</span> Art of creating moving images using computers

Computer animation is the process used for digitally generating animations. The more general term computer-generated imagery (CGI) encompasses both static scenes and dynamic images, while computer animation only refers to moving images. Modern computer animation usually uses 3D computer graphics to generate a three-dimensional picture. The target of the animation is sometimes the computer itself, while other times it is film.

<span class="mw-page-title-main">Vector graphics</span> Computer graphics images defined by points, lines and curves

Vector graphics is a form of computer graphics in which visual images are created directly from geometric shapes defined on a Cartesian plane, such as points, lines, curves and polygons. The associated mechanisms may include vector display and printing hardware, vector data models and file formats, as well as the software based on these data models. Vector graphics is an alternative to raster or bitmap graphics, with each having advantages and disadvantages in specific situations.

<span class="mw-page-title-main">Rasterisation</span> Conversion of a vector-graphics image to a raster image

In computer graphics, rasterisation or rasterization is the task of taking an image described in a vector graphics format (shapes) and converting it into a raster image. The rasterized image may then be displayed on a computer display, video display or printer, or stored in a bitmap file format. Rasterization may refer to the technique of drawing 3D models, or the conversion of 2D rendering primitives such as polygons, line segments into a rasterized format.

<span class="mw-page-title-main">Voxel</span> Element representing a value on a grid in three dimensional space

In 3D computer graphics, a voxel represents a value on a regular grid in three-dimensional space. As with pixels in a 2D bitmap, voxels themselves do not typically have their position explicitly encoded with their values. Instead, rendering systems infer the position of a voxel based upon its position relative to other voxels.

Autodesk 3ds Max, formerly 3D Studio and 3D Studio Max, is a professional 3D computer graphics program for making 3D animations, models, games and images. It is developed and produced by Autodesk Media and Entertainment. It has modeling capabilities and a flexible plugin architecture and must be used on the Microsoft Windows platform. It is frequently used by video game developers, many TV commercial studios, and architectural visualization studios. It is also used for movie effects and movie pre-visualization. 3ds Max features shaders, dynamic simulation, particle systems, radiosity, normal map creation and rendering, global illumination, a customizable user interface, and its own scripting language.

<span class="mw-page-title-main">Scientific visualization</span> Interdisciplinary branch of science concerned with presenting scientific data visually

Scientific visualization is an interdisciplinary branch of science concerned with the visualization of scientific phenomena. It is also considered a subset of computer graphics, a branch of computer science. The purpose of scientific visualization is to graphically illustrate scientific data to enable scientists to understand, illustrate, and glean insight from their data. Research into how people read and misread various types of visualizations is helping to determine what types and features of visualizations are most understandable and effective in conveying information.

2.5D perspective refers to gameplay or movement in a video game or virtual reality environment that is restricted to a two-dimensional (2D) plane with little to no access to a third dimension in a space that otherwise appears to be three-dimensional and is often simulated and rendered in a 3D digital environment.

<span class="mw-page-title-main">Non-photorealistic rendering</span> Style of rendering

Non-photorealistic rendering (NPR) is an area of computer graphics that focuses on enabling a wide variety of expressive styles for digital art, in contrast to traditional computer graphics, which focuses on photorealism. NPR is inspired by other artistic modes such as painting, drawing, technical illustration, and animated cartoons. NPR has appeared in movies and video games in the form of cel-shaded animation as well as in scientific visualization, architectural illustration and experimental animation.

<span class="mw-page-title-main">Real-time computer graphics</span> Sub-field of computer graphics

Real-time computer graphics or real-time rendering is the sub-field of computer graphics focused on producing and analyzing images in real time. The term can refer to anything from rendering an application's graphical user interface (GUI) to real-time image analysis, but is most often used in reference to interactive 3D computer graphics, typically using a graphics processing unit (GPU). One example of this concept is a video game that rapidly renders changing 3D environments to produce an illusion of motion.

<span class="mw-page-title-main">Software rendering</span>

Software rendering is the process of generating an image from a model by means of computer software. In the context of computer graphics rendering, software rendering refers to a rendering process that is not dependent upon graphics hardware ASICs, such as a graphics card. The rendering takes place entirely in the CPU. Rendering everything with the (general-purpose) CPU has the main advantage that it is not restricted to the (limited) capabilities of graphics hardware, but the disadvantage is that more semiconductors are needed to obtain the same speed.

<span class="mw-page-title-main">Virtual cinematography</span> CGI essentially

Virtual cinematography is the set of cinematographic techniques performed in a computer graphics environment. It includes a wide variety of subjects like photographing real objects, often with stereo or multi-camera setup, for the purpose of recreating them as three-dimensional objects and algorithms for the automated creation of real and simulated camera angles. Virtual cinematography can be used to shoot scenes from otherwise impossible camera angles, create the photography of animated films, and manipulate the appearance of computer-generated effects.Virtual cinematography is the set of cinematographic techniques performed in a computer graphics environment

<span class="mw-page-title-main">3D rendering</span> Process of converting 3D scenes into 2D images

3D rendering is the 3D computer graphics process of converting 3D models into 2D images on a computer. 3D renders may include photorealistic effects or non-photorealistic styles.

<span class="mw-page-title-main">Computer graphics (computer science)</span> Sub-field of computer science

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. The individuals who serve as professional designers for computers graphics are known as "Graphics Programmers", who often are computer programmers with skills in computer graphics design.

<span class="mw-page-title-main">Computer graphics</span> Graphics created using computers

Computer graphics deals with generating images with the aid of computers. Today, computer graphics is a core technology in digital photography, film, video games, cell phone and computer displays, and many specialized applications. A great deal of specialized hardware and software has been developed, with the displays of most devices being driven by computer graphics hardware. It is a vast and recently developed area of computer science. The phrase was coined in 1960 by computer graphics researchers Verne Hudson and William Fetter of Boeing. It is often abbreviated as CG, or typically in the context of film as computer generated imagery (CGI). The non-artistic aspects of computer graphics are the subject of computer science research.

The history of computer animation began as early as the 1940s and 1950s, when people began to experiment with computer graphics – most notably by John Whitney. It was only by the early 1960s when digital computers had become widely established, that new avenues for innovative computer graphics blossomed. Initially, uses were mainly for scientific, engineering and other research purposes, but artistic experimentation began to make its appearance by the mid-1960s – most notably by Dr Thomas Calvert. By the mid-1970s, many such efforts were beginning to enter into public media. Much computer graphics at this time involved 2-dimensional imagery, though increasingly as computer power improved, efforts to achieve 3-dimensional realism became the emphasis. By the late 1980s, photo-realistic 3D was beginning to appear in film movies, and by mid-1990s had developed to the point where 3D animation could be used for entire feature film production.

<span class="mw-page-title-main">3D modeling</span> Form of computer-aided engineering

In 3D computer graphics, 3D modeling is the process of developing a mathematical coordinate-based representation of any surface of an object in three dimensions via specialized software by manipulating edges, vertices, and polygons in a simulated 3D space.

<span class="mw-page-title-main">Computer-generated imagery</span> Application of computer graphics to create or contribute to images

Computer-generated imagery (CGI) is the use of computer graphics to create or contribute to images in art, printed media, video games, simulators, and visual effects in films, television programs, shorts, commercials, and videos. The images may be static or dynamic, in which case CGI is also called computer animation. CGI may be two-dimensional (2D), although the term "CGI" is most commonly used to refer to the 3-D computer graphics used for creating characters, scenes and special effects in films and television, which is described as "CGI animation".

This is a glossary of terms relating to computer graphics.

References

  1. ↑ "3D computer graphics". ScienceDaily. Retrieved 2019-01-19.
  2. ↑ "An Historical Timeline of Computer Graphics and Animation". Archived from the original on 2008-03-10. Retrieved 2009-07-22.
  3. ↑ "Computer Graphics".
  4. ↑ "Pixar founder's Utah-made Hand added to National Film Registry". The Salt Lake Tribune . December 28, 2011. Retrieved January 8, 2012.
  5. ↑ "Brutal Deluxe Software". www.brutaldeluxe.fr.
  6. ↑ "PROJECTS AND ARTICLES Retrieving Japanese Apple II programs". Archived from the original on 2016-10-05. Retrieved 2017-03-26.
  7. ↑ Simmons, Bruce. "n-gon". MathWords. Archived from the original on 2018-12-15. Retrieved 2018-11-30.
  8. ↑ Buss, Samuel R. (2003-05-19). 3D Computer Graphics: A Mathematical Introduction with OpenGL. Cambridge University Press. ISBN   978-1-139-44038-7.
  9. ↑ "Machinima". Internet Archive. Retrieved 2020-07-12.
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