Lecture
Computer graphics is a branch of computer science concerned with creating images using computers. Today, computer graphics is a key technology in digital photography, film, video games, mobile phone and computer displays, and many specialized applications. A large amount of specialized hardware and software has been developed, with the displays of most devices being driven by computer graphics hardware. It is a broad and recently developed field of computer science. The term 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, referred to as computer-generated imagery (CGI).
Some topics in computer graphics include user interface design, sprite graphics, rendering, ray tracing, geometry processing, computer animation, vector graphics, 3D modeling, shaders, GPU design, implicit surface visualization, image processing, computational photography, scientific visualization, computational geometry, and computer vision, among others. The overall methodology depends heavily on the underlying sciences of geometry, optics, physics, and perception.
Computer graphics is responsible for displaying artwork and images in a way that is efficient and meaningful for the consumer. It is also used for processing image data acquired from the physical world, such as photo and video content. The development of computer graphics has had a significant impact on many types of media and has revolutionized animation, film, advertising, video games, and graphic design in general.
The term computer graphics has been used broadly to describe «almost everything on computers that is not text or sound». Typically, the term computer graphics refers to several different things:
Today, computer graphics is widespread. Such images can be found on television, in newspapers, in weather reports, and during various medical studies and surgical procedures. A well-constructed graphic can present complex statistics in a form that is easier to understand and interpret. In the media, «such graphics are used to illustrate articles, reports, theses» and other presentational material.
A great many tools have been developed for data visualization. Computer imagery can be divided into several different types: two-dimensional (2D), three-dimensional (3D), and animated graphics. As technology has advanced, three-dimensional computer graphics have become more common, but two-dimensional computer graphics are still widely used. Computer graphics emerged as a subfield of computer science studying methods for digitally synthesizing and manipulating visual content. Over the last decade, other specialized areas have developed, such as information visualization and scientific visualization, more focused on «visualizing three-dimensional» phenomena (architectural, meteorological, medical, biological, and so on), where the emphasis is on the realistic rendering of volumes, surfaces, light sources, etc., possibly with a dynamic (temporal) component".
The forerunners of modern computer graphics were advances in electrical engineering, electronics, and television that took place in the first half of the twentieth century. Screens have been able to display art since the Lumière brothers used mattes to create special effects for the earliest films, dating back to 1895, but such displays were limited and non-interactive. The first cathode ray tube, the Braun tube, was invented in 1897 - it, in turn, enabled the oscilloscope and the military control panel, more direct predecessors of the field, since they provided the first two-dimensional electronic displays that responded to program or user input. Nevertheless, computer graphics remained a relatively unknown discipline until the 1950s and the post-World War II period - during which the discipline arose from a combination of pure university and laboratory scientific research and the more advanced computers and further development by the U.S. military of technologies such as radar, advanced aviation, and rocketry developed during the war. Processing the enormous amount of information produced by such projects required new kinds of displays, which led to the development of computer graphics as a discipline.
The SAGE sector control room.
Early projects such as Whirlwind and SAGE introduced the CRT as a viable display and interaction interface and introduced the light pen as an input device. Douglas T. Ross of the Whirlwind SAGE system conducted a personal experiment in which a small program he had written captured the motion of his finger and displayed its vector (his traced-out name) on the display. One of the first interactive video games with recognizable interactive graphics - Tennis for Two - was created for an oscilloscope by William Higinbotham to entertain visitors in 1958 at Brookhaven National Laboratory and simulated a tennis match. In 1959, Douglas T. Ross again broke new ground while working at MIT on converting mathematical statements into computer three-dimensional vectors for machine tools, taking the opportunity to create an image of a Disney cartoon character in the display area.
Electronics pioneer Hewlett-Packard became a public company in 1957, ten years after its founding, and established strong ties with Stanford University through its founders, who were its graduates. This marked the beginning of a decades-long transformation of the southern San Francisco Bay Area into a leading center of computer technology, now known as Silicon Valley. The field of computer graphics developed alongside the emergence of computer graphics hardware.
Further advances in computing led to greater progress in interactive computer graphics. In 1959, the TX-2 computer was developed at MIT's Lincoln Laboratory. The TX-2 integrated a number of new human-machine interfaces. A light pen could be used to draw sketches on the computer using Ivan Sutherland's revolutionary Sketchpad software. Using the light pen, Sketchpad allowed the user to draw simple shapes on the computer screen, save them, and even recall them later. The light pen itself had a small photocell at its tip. This cell emitted an electronic pulse whenever it was placed in front of the computer screen and the screen's electron gun fired directly at it. By simply synchronizing the electronic pulse with the current location of the electron gun, it was easy to determine exactly where the pen was on the screen at any given moment. Once this was determined, the computer could draw a cursor at that location. Sutherland seemed to have found the ideal solution to many of the graphics problems he had encountered. Even today, many standards of computer graphics interfaces originated with this early Sketchpad program. One example of this is drawing constraints. For instance, if someone wants to draw a square, they don't need to worry about drawing four lines perfectly to form the edges of the box. One can simply indicate that they want to draw a box, and then specify the location and size of the box. The program will create a perfect box, of the correct dimensions and in the right place. Another example is that Sutherland's software modeled objects, rather than simply images of objects. In other words, with a model of a car, one could change the size of the tires without affecting the rest of the car. It could stretch the body of the car without deforming the tires.
Spacewar! running on the Computer History Museum's PDP-1
The phrase «computer graphics» itself was coined in 1960 by William Fetter, a graphic designer at Boeing. This well-known quote, cited in many secondary sources, is supplemented by the following sentence:
Fetter said that the terms were actually given to him by Verne Hudson of Boeing's Wichita Division.
In 1961, another MIT student, Steve Russell, created another landmark title in the history of video games - Spacewar!. Written for the DEC PDP-1, Spacewar! was an instant success, and copies began reaching other PDP-1 owners, and eventually DEC obtained a copy. DEC engineers used it as a diagnostic program on every new PDP-1 before it was shipped. Salesmen caught on quickly enough and, when installing new machines, would run the «world's first video game» for their new customers. (Higinbotham's Tennis for Two beat Spacewar by nearly three years, but it was almost unknown outside of research or academic circles.)
Around the same time (1961-1962) at Cambridge University, Elizabeth Waldram wrote code to display radio-astronomy maps on a cathode ray tube.
E.E. Zajac, a scientist at Bell Telephone Laboratories (BTL), created a film in 1963 titled «Simulation of a Two-Gyro Attitude Control System». In this computer-generated film, Zajac showed how the orientation of a satellite could be altered as it orbits the Earth. He created the animation on an IBM 7090 mainframe. Also at BTL, Ken Knowlton, Frank Sinden, Ruth A. Weiss, and Michael Noll began working in the field of computer graphics. Sinden created a film titled «Force, Mass and Motion,» illustrating Newton's laws of motion in action. Around the same time, other scientists were creating computer graphics to illustrate their research. At the Lawrence Radiation Laboratory, Nelson Max created the films «Flow of a Viscous Fluid» and «Propagation of Shock Waves in a Solid Form». The Boeing Aircraft Company created the film «Vibration of an Aircraft».
Also sometime in the early 1960s, automobiles gave computer graphics a boost thanks to the early work of Pierre Bézier at Renault, who used the curves of Paul de Casteljau - now called Bézier curves, after Bézier's work in this area - to develop three-dimensional modeling techniques for Renault car bodies. These curves would form the basis for much work on curve modeling in the field, since curves - unlike polygons - are mathematically complex objects to draw and model well.
Pong arcade version
Large corporations soon became interested in computer graphics. TRW, Lockheed-Georgia, General Electric, and Sperry Rand were among the many companies that began working with computer graphics by the mid-1960s. IBM quickly responded to this interest by releasing the IBM 2250 graphics terminal, the first commercially available graphics computer. Ralph Baer, a senior engineer at Sanders Associates, came up with a home video game in 1966 that was later licensed to Magnavox and named the Odyssey. Although very simplified and requiring fairly inexpensive electronic components, it allowed the player to move points of light around the screen. It was the first consumer product for computer graphics. David C. Evans was technical director of the Bendix Corporation's computer division from 1953 to 1962, after which he spent the following five years as a visiting professor at Berkeley. There he continued to take an interest in computers and how they interact with people. In 1966, the University of Utah hired Evans to build a computer science program, and computer graphics quickly became his primary interest. This new department would become the world's leading computer graphics research center through the 1970s.
Also in 1966, Ivan Sutherland continued to innovate at MIT when he invented the first computer-controlled head-mounted display (HMD). It displayed two separate wireframe images, one for each eye. This allowed the viewer to see a computer-generated scene in stereoscopic 3D. The heavy equipment required to support the display and tracker was nicknamed the Sword of Damocles, due to the potential danger if it fell on the wearer. After earning his doctorate from MIT, Sutherland became director of information processing at ARPA (the Advanced Research Projects Agency), and later became a professor at Harvard. In 1967, Sutherland was hired by Evans to participate in the computer science program at the University of Utah - a development that would turn the department into one of the most important graphics research centers for nearly a decade afterward, ultimately producing some of the most important pioneers in the field. There, Sutherland refined his headset; twenty years later, NASA would rediscover his methods in its virtual reality research. In Utah, Sutherland and Evans were much in demand as consultants for major companies, but they were frustrated by the lack of graphics hardware available at the time, so they began formulating a plan to start their own company.
In 1968, Dave Evans and Ivan Sutherland founded the first computer graphics hardware company, Evans & Sutherland. Although Sutherland had originally wanted the company to be based in Cambridge, Massachusetts, Salt Lake City was chosen instead because of its proximity to the research group of University of Utah professors.
Also in 1968, Arthur Appel described the first ray-casting algorithm, the first of a class of rendering algorithms based on ray tracing, which have since become fundamental to achieving photorealism in graphics by simulating the paths that rays of light travel from a light source to surfaces in a scene and into the camera.
In 1969, ACM initiated the Special Interest Group on Graphics (SIGGRAPH), which organizes conferences, graphics standards, and publications in the field of computer graphics. By 1973, the first annual SIGGRAPH conference had been held, which became one of the organization's main activities. SIGGRAPH grew in size and importance as the field of computer graphics expanded over time.
An important technological advance that made practical computer graphics technology possible was the emergence of metal-oxide-semiconductor (MOS) large-scale integration (LSI) technology in the early 1970s. MOS LSI technology made large computing capabilities possible in small MOS integrated circuit chips, which led to the development of the Tektronix 4010 computer graphics terminal in 1972, as well as the microprocessor in 1971. [13] The MOS memory chip - in particular the dynamic random-access memory (DRAM) chip introduced in 1970 - was also able to hold a kilobit of data on a single high-density memory chip, which made it possible to hold an entire standard-definition (SD) raster graphics image in a digital frame buffer, which was used by Xerox PARC to develop SuperPaint, the first video-compatible raster computer graphics system, in 1972.
The Utah teapot by Martin Newell, and its rendered stills, became a symbol of the development of CGI during the 1970s.
Subsequently, a number of breakthroughs in the field - especially important early breakthroughs in transforming graphics from utilitarian to realistic - took place at the University of Utah in the 1970s, which had hired Ivan Sutherland. He was paired with David C. Evans to teach an advanced computer graphics class that made major contributions to foundational research in the field and trained several students who would go on to found some of the industry's most important companies, namely Pixar, Silicon Graphics, and Adobe Systems. Tom Stockham headed the image processing group at UU, which worked closely with the computer graphics lab.
One of these students was Edwin Catmull. Catmull had just come from the Boeing company and was working toward a degree in physics. Having grown up on Disney, Catmull loved animation but quickly discovered he had no talent for drawing. Now Catmull (like many others) saw in computers a natural evolution of animation, and they wanted to be part of the revolution. The first computer animation Catmull ever saw was his own. He created an animation of a hand opening and closing. He was also a pioneer of texture mapping for painting textures onto three-dimensional models in 1974, now considered one of the fundamental techniques in three-dimensional modeling. One of his goals became creating a feature-length film using computer graphics - a goal he would achieve two decades later through his foundational role at Pixar. In the same class, Fred Parke created an animation of his wife's face. These two animations were included in the 1976 feature film «Futureworld».
Since the UU computer graphics lab attracted people from around the world, John Warnock was another of those pioneers; he later founded Adobe Systems and revolutionized the publishing world with his PostScript page description language, and Adobe would later go on to create the industry-standard photo-editing software Adobe Photoshop and the film industry's renowned special-effects program Adobe After Effects.
James Clark was there too; he later founded Silicon Graphics, a maker of advanced rendering systems that dominated the field of high-quality graphics until the early 1990s.
These pioneers made a major advance in computer 3D graphics at UU - the determination of hidden surfaces. To draw a representation of a three-dimensional object on the screen, the computer must determine which surfaces are «behind» the object from the observer's point of view, and therefore must be «hidden» when the computer creates (or renders) the image. The 3D Core Graphics System (or Core) was the first graphics standard to be developed. A group of 25 experts from the ACM Special Interest Group SIGGRAPH developed this «conceptual framework». The specifications were published in 1977 and became the basis for many future developments in the field.
Also in the 1970s, Henri Gouraud, Jim Blinn, and Bui Tuong Phong contributed to the foundations of shading in CGI through the development of Gouraud shading and the Blinn-Phong shading model, allowing graphics to move beyond a «flat» look and depict depth more accurately. Jim Blinn also introduced further innovations in 1978 by presenting bump mapping, a technique for simulating uneven surfaces and a forerunner of many of the more advanced mapping techniques used today.
The modern video game arcade, as known today, arose in the 1970s, when the first arcade games used real-time two-dimensional sprite graphics. Pong, in 1972, was one of the first computer arcade games to become a hit. In Speed Race of 1974, sprites moved along a vertically scrolling road. Gun Fight of 1975 depicted human-like characters, and «Space Invaders» of 1978 featured a large number of animated figures on screen; both used specialized barrel-shifter circuitry, made from discrete chips, to help the Intel 8080 microprocessor animate their frame-buffer graphics.
Donkey Kong was one of the video games that helped popularize computer graphics among mass audiences in the 1980s.
The 1980s saw the beginning of the modernization and commercialization of computer graphics. As home computers became widespread, a subject that had previously been of interest only to academics was adopted by a much larger audience, and the number of computer graphics developers grew significantly.
In the early 1980s, metal-oxide-semiconductor (MOS) very-large-scale integration (VLSI) technology led to the emergence of 16-bit central processing unit (CPU) microprocessors and the first graphics processing unit (GPU) chips, which started a revolution in computer graphics by providing high-resolution graphics for computer graphics terminals as well as personal computers (PCs). The NEC μPD7220 was the first GPU manufactured as a fully integrated MOS VLSI chip. It supported resolutions of up to 1024x1024, and laid the foundation for the burgeoning PC graphics market. It was used in a number of video cards and was licensed for clones such as the Intel 82720, the first of Intel's graphics processors. MOS memory also became cheaper in the early 1980s, which enabled the development of affordable frame buffer memory, particularly video RAM (VRAM), introduced by Texas Instruments (TI) in the mid-1980s. In 1984, Hitachi released the ARTC HD63484, the first complementary MOS (CMOS) GPU. It was capable of displaying high-resolution images in color mode and resolutions of up to 4K in monochrome mode, and by the late 1980s it was used in a number of video cards and terminals. [19] In 1986, TI introduced the TMS34010, the first fully programmable MOS graphics processor.
Computer graphics terminals during this decade became increasingly intelligent, semi-autonomous, and standalone workstations. Graphics and application processing was increasingly shifted onto intelligent workstation systems, rather than continuing to rely on a central mainframe and minicomputers. Typical of the early transition to intelligent workstations with high-resolution computer graphics for the computer-aided design market were the Orca 1000, 2000, and 3000 workstations, developed by Orcatech of Ottawa, a subsidiary of Bell-Northern Research, and led by David Pearson, a workstation pioneer. The Orca 3000 was based on the 16-bit Motorola 68000 microprocessor and AMD bit-slice processors, with Unix as the operating system. It was aimed directly at the demanding side of the design sector. Artists and graphic designers began to view the personal computer, particularly the Commodore Amiga and the Macintosh, as a serious design tool capable of saving time and drawing more precisely than other methods. The Macintosh remains a very popular tool for computer graphics among graphic design studios and businesses. Modern computers of the 1980s often used a graphical user interface (GUI) to present data and information through symbols, icons, and images rather than text. Graphics is one of the five key elements of multimedia technology.
In the field of realistic rendering, Osaka University in Japan developed the LINKS-1 computer graphics system, a supercomputer that employed up to 257 Zilog Z8001 microprocessors, in 1982, with the goal of rendering realistic 3D computer graphics. According to the Information Processing Society of Japan: «The core of 3D image rendering is calculating the brightness of each pixel making up a rendered surface, from a given viewpoint, light source, and object position. The LINKS-1 system was developed to implement an image rendering methodology in which each pixel could be processed independently and in parallel using ray tracing. By developing a new software methodology specifically for high-speed image rendering, LINKS-1 was able to rapidly render highly realistic images. It was used to create the world's first 3D video of the entire sky in planetarium form, which was made entirely with computer graphics. The video was presented at the Fujitsu pavilion at the 1985 International Exposition in Tsukuba». [20] LINKS-1 was the most powerful computer in the world as of 1984. [21] Also in the field of realistic rendering, the general rendering equation was developed by David Immel and James Kajiya in 1986 - an important step toward achieving global illumination, necessary for photorealism in computer graphics.
The ongoing popularity of «Star Wars» and other science fiction franchises was significant for cinematic computer graphics at the time, as Lucasfilm and Industrial Light & Magic became recognized by many other studios as the leading studios for producing top-tier computer graphics for film. Important advances in chromatography («blue screen», etc.) were made for later films in the original trilogy. Two other videos also endured as historically significant: the iconic, almost entirely CGI music video by Dire Straits for their song "Money for Nothing" in 1985, which popularized CGI among music fans of the era, and a scene from Young Sherlock Holmes that same year featuring the first fully CGI character in a feature film (an animated stained-glass knight). In 1988, the first shaders - small programs designed specifically for shading as a distinct algorithm - were developed by Pixar, which had already split off from Industrial Light & Magic as a separate organization, though the public would not see the results of such technological progress until the following decade. In the late 1980s, Silicon Graphics (SGI) computers were used to create some of the first fully computer-generated short films at Pixar, and Silicon Graphics machines were considered the high-water mark in the field for a decade.
The 1980s are also referred to as the golden age of video games; systems that sold in the millions from Atari, Nintendo, and Sega, among other companies, introduced computer graphics to a new, young, and impressionable audience - as did MS-DOS-based personal computers, the Apple II, the Mac, and the Amiga, all of which also allowed users to program their own games if they were skilled enough. Advances in commercial real-time 3D graphics were made for arcade machines. In 1988, the first specialized boards for real-time 3D graphics were introduced for arcade machines, with the Namco System 21 and the Taito Air System. [23] On the professional side, Evans & Sutherland and SGI developed hardware for three-dimensional raster graphics that directly influenced the subsequent single-chip graphics processing unit (GPU), a technology in which a separate and very powerful chip is used in parallel with the CPU to optimize graphics processing.
During this decade, computer graphics were also applied in many additional professional markets, including local entertainment and education via E&S Digistar, vehicle design, vehicle simulation, and chemistry.
Quarxs, poster for the series, Maurice Benoît, François Schuiten, 1992
A striking event of the 1990s was the mass emergence of 3D modeling and the impressive rise in the overall quality of CGI. Home computers gained the ability to perform rendering tasks that had previously been limited to workstations costing thousands of dollars; as 3D modeling became accessible to home systems, the popularity of Silicon Graphics workstations declined, while the importance grew of powerful Microsoft Windows and Apple Macintosh computers running products such as Autodesk's 3D Studio or other home rendering software. By the end of the decade, the GPU would begin to rise to the prominence it enjoys today.
The field began to see the first rendered graphics that could truly appear photorealistic to the untrained eye (although they still could not fool a trained CGI artist), and 3D graphics became much more popular in games, multimedia, and animation. In the late 80s and early 90s, the first computer graphics series were created in France: La Vie des bêtes from the Mac Guff Ligne studio (1988), Les Fables Géométriques (1989–1991) from the Fantôme studio, and Quarxs, the first HDTV computer graphics series, by Maurice Benoît and François Schuiten (ZA production studio, 1990–1993).
In cinema, Pixar began its serious commercial rise in this era under Edwin Catmull, releasing its first major film in 1995 - «Toy Story» - a nine-figure critical and commercial success. The studio, which invented the programmable shader, would go on to have many animated hits, and its work on pre-rendered video animation is still considered an industry leader and a pioneer of research directions.
In video games, in 1992, Virtua Racing, running on the Sega Model 1 arcade system board, laid the foundation for fully three-dimensional racing games and popularized real-time three-dimensional polygonal graphics among a broader audience in the video game industry. The Sega Model 2 in 1993 and the Sega Model 3 in 1996 subsequently pushed the boundaries of commercial real-time 3D graphics. Back on the PC, id Software released Wolfenstein 3D, Doom, and Quake, three of the first mass-popular three-dimensional first-person shooters, which received critical and public acclaim during this decade, using a rendering engine invented [uncertain] largely by John Carmack. The Sony PlayStation, Sega Saturn, and Nintendo 64, among other consoles, sold in the millions and popularized 3D graphics for home gaming. Some early-generation 3D games of the late 1990s helped popularize 3D graphics among console users, such as the platformers Super Mario 64 and The Legend of Zelda: Ocarina of Time, as well as early 3D fighting games such as Virtua Fighter, Battle Arena Toshinden, and Tekken.
Rendering technology and algorithms continued to improve significantly. In 1996, Krishnamurthy and Levoy invented normal mapping - an improvement over Jim Blinn's bump mapping. In 1999, Nvidia released the original GeForce 256, the first home video card marketed as a graphics processing unit or GPU, which, in its own words, contained «integrated transform, lighting, triangle setup/clipping, and rendering engines». By the end of the decade, computers had adopted common platforms for graphics processing, such as DirectX and OpenGL. Since then, computer graphics has only become more detailed and realistic thanks to more powerful graphics hardware and 3D modeling software. AMD also became a leading developer of graphics boards during this decade, creating a «duopoly» in this field that persists today.
Screenshot from the video game Killing Floor, built on Unreal Engine 2. Personal computers and console video games made a great graphical leap forward in the 2000s, gaining the ability to display in real time graphics that had previously only been possible pre-rendered and/or on business-grade hardware.
During this era, computer graphics became a ubiquitous phenomenon. Video games and CGI films spread computer graphics into the mainstream by the late 1990s and continued to do so at an accelerating pace in the 2000s. CGI was also adopted wholesale for television advertising widely in the late 1990s and 2000s, and thus became familiar to mass audiences.
The steady growth and increasing sophistication of graphics processors were crucial for this decade, and 3D rendering capability became a standard feature, as desktop computer manufacturers came to consider GPUs necessary for 3D graphics. Nvidia's GeForce line of video cards dominated the market in the early part of the decade, occasionally competing significantly with ATI. Throughout the decade, even inexpensive machines typically contained some form of 3D-capable GPU, as Nvidia and AMD introduced low-cost chipsets and continued to dominate the market. Shaders, which had been introduced in the 1980s to perform specialized processing on the GPU, would be supported on most consumer hardware by the end of the decade, significantly speeding up graphics and enabling substantial improvements in texture and shading in computer graphics through the widespread adoption of normal maps, bump mapping, and many other techniques for simulating large amounts of detail.
Computer graphics used in films and video games gradually became more realistic, up to the point of crossing into the uncanny valley. CGI films proliferated: traditional cartoons such as «Ice Age» and «Madagascar», as well as numerous Pixar offerings such as «Finding Nemo», dominated box offices in this space. Final Fantasy: The Spirits Within, released in 2001, was the first fully computer-generated feature film to use photorealistic CGI characters and be made entirely with motion capture. The film, however, was not a box-office success. Some commentators suggested this might be partly because the main computer-graphics characters had facial features that fell into the «uncanny valley». [note 1] Other animated films, such as «The Polar Express», also drew attention during this time. «Star Wars» also reappeared with its prequel trilogy, and its effects continued to set the bar for computer graphics in film.
In video games, the Sony PlayStation 2 and 3, the Microsoft Xbox line of consoles, and offerings from Nintendo such as the GameCube had many fans, as did Windows PCs. Striking CGI games such as Grand Theft Auto, Assassin's Creed, Final Fantasy, BioShock, Kingdom Hearts, Mirror's Edge, and dozens of others continued to approach photorealism, advancing the video game industry and making an impression, until this industry's revenues became comparable to those of film. Microsoft made a decision to simplify the delivery of DirectX to the world of independent developers through the XNA program, but this was not successful. However, DirectX itself remained commercially successful. OpenGL also continued to develop, and both it and DirectX improved significantly; the second-generation shader languages HLSL and GLSL became popular during this decade.
In scientific computing, GPGPU technology was invented for the bidirectional transfer of large volumes of data between the GPU and CPU, accelerating the analysis of many kinds of bioinformatics and molecular biology experiments. This technique was also used for bitcoin mining and found application in computer vision.
A close-up rendering of a diamond-plate texture using physically based rendering principles - an increasingly active area of research for computer graphics in the 2010s.
In the 2010s, CGI was nearly ubiquitous in video, pre-rendered graphics were nearly scientifically photorealistic, and real-time graphics on a suitably high-quality system could mimic photorealism to the untrained eye.
Texture mapping evolved into a multi-stage process with many layers; it became fairly common to implement texture mapping, bump or isosurface mapping, or normal mapping, lighting maps including specular highlights and reflection techniques, and shadow volumes all within a single rendering engine using shaders, which were developing significantly. Shaders are now almost essential for advanced work in the field, considerably complicating the manipulation of pixels, vertices, and textures on a per-element basis, with countless possible effects. Their shader languages, HLSL and GLSL, are active areas of research and development. Physically based rendering, or PBR, which implements many maps and performs advanced calculations to simulate real optical light flow, is also an active area of research, alongside advanced areas such as ambient occlusion, subsurface scattering, Rayleigh scattering, photon mapping, and many others. Experiments in the computational power needed to deliver real-time graphics at ultra-high-resolution modes, such as 4K Ultra HD, are beginning, though still out of reach for all but the highest-end hardware.
In cinema, most animated films are now CGI; a great many CGI animated films are made each year, but few, if any, attempt photorealism due to ongoing concerns about the uncanny valley. Most of them are three-dimensional cartoons.
In video games, the Microsoft Xbox One, Sony PlayStation 4, and Nintendo Switch currently dominate the home space and are all capable of producing highly advanced three-dimensional graphics; Windows PCs remain one of the most active gaming platforms.
Raster graphics sprites (left) and masks (right)
2D computer graphics is the computer generation of digital images, mainly from models such as a digital image, and using techniques specific to them.
2D computer graphics is mainly used in applications that were originally developed based on traditional printing and drawing technologies, such as typography. In these applications, a two-dimensional image is not merely a representation of a real-world object, but an independent artifact with added semantic value; therefore, two-dimensional models are preferred because they provide more direct control over the image than three-dimensional computer graphics, whose approach is closer to photography than to typography.
Pixel Art
Pixel graphics is a major form of digital art, created using raster graphics software, where images are edited at the pixel level. The graphics in most older (or relatively limited) computer and video games, graphing calculators, and many mobile phone games are largely pixel graphics.
Sprite graphics
A sprite is a two-dimensional image or animation that is integrated into a larger scene. Originally including only graphical objects handled separately from the video display's bitmap memory, it now encompasses various methods of graphical overlay.
Originally, sprites were a method for integrating unrelated bitmaps so that they appeared to be part of the normal bitmap on the screen, for example, creating an animated character that could be moved around the screen without altering the data defining the entire screen. Such sprites can be created using electronic circuits or software. In circuit design, a hardware sprite is a hardware construct that uses configurable DMA channels to integrate visual elements with the main screen, as it overlays two separate video sources. Software can simulate this using special rendering techniques.
Vector graphics
An example showing the effect of vector graphics compared to raster (bitmap) graphics.
Vector graphics formats complement raster graphics. Raster graphics represent images as an array of pixels and are typically used to represent photographic images. Vector graphics involve encoding information about the shapes and colors that make up an image, which can provide greater flexibility in rendering. There are cases where it is best to work with vector tools and formats, and cases where raster tools and formats are best. There are cases where both formats are combined. Understanding the advantages and limitations of each technology, and the relationship between them, is likely to lead to effective and efficient use of the tools.
Three-dimensional graphics, compared to two-dimensional graphics, is graphics that uses a three-dimensional representation of geometric data. For performance purposes, it is stored on the computer. This includes images that may be intended for later display or for viewing in real time.
Despite these differences, three-dimensional computer graphics relies on the same algorithms as two-dimensional computer graphics do in the frame, and on raster graphics (as in 2D) in the final rendered display. In computer graphics software, the distinction between 2D and 3D is sometimes blurred; 2D applications may use 3D techniques to achieve effects such as lighting, and 3D primarily may use 2D rendering techniques.
3D computer graphics is the same as 3D models. The model is contained within a graphics data file, apart from the rendering. However, there are differences, which include that a 3D model is a representation of any 3D object. Until the model is displayed visually, it is not graphics. Thanks to printing, 3D models are not confined solely to virtual space. 3D rendering is a way of displaying the model. It can also be used in non-graphical computer modeling and calculations.
An example of computer animation created using motion capture
A fractal landscape, an example of computer graphics.
Computer animation is the art of creating moving images using computers. It is a subfield of computer graphics and animation. It is increasingly created using computer 3D graphics, although computer 2D graphics is still widely used for stylistic needs, low bandwidth, and faster real-time rendering. Sometimes the target of the animation is the computer itself, but sometimes the target is another medium, such as film. It is also called CGI (computer-generated imagery or computer graphics imagery), especially when used in films.
Virtual entities can contain and be controlled by various attributes, such as transformation values (position, orientation, and scale) stored in the object's transformation matrix. Animation is the change of an attribute over time. There are several animation methods; the elementary form is based on creating and editing keyframes, each of which stores a value at a given time for each attribute to be animated. 2D/3D graphics software will interpolate between each keyframe, creating an editable curve of the value displayed over time, resulting in animation. Other animation methods include procedural and expression-based techniques: the former groups related elements of animated objects into sets of attributes useful for creating particle effects and crowd simulation; the latter allows a computed result returned from a user-defined logical expression, combined with mathematics, to automate animation in a predictable way (useful for controlling bone behavior beyond what the hierarchy offers when setting up a skeletal system).
To create the illusion of motion, an image is displayed on the computer screen and then quickly replaced by a new image similar to the previous one but slightly shifted. This technique is identical to the illusion of motion in television and film.
Images are typically created by devices such as cameras, mirrors, lenses, telescopes, microscopes, etc.
Digital images include both vector images and raster images, but raster images are more commonly used.
In the enlarged portion of the image, individual pixels are displayed as squares and clearly visible.
In a digital image, a pixel (or picture element [29]) represents a single point in a raster image. Pixels are arranged on a regular two-dimensional grid and are often represented by dots or squares. Each pixel is a sample of the original image, with a greater number of samples generally providing a more accurate representation of the original. The intensity of each pixel is variable; in color systems, each pixel typically consists of three components, such as red, green, and blue.
Graphics is a visual representation on a surface, such as a computer screen. Examples include photographs, drawings, graphic images, maps, engineering drawings, or other images. Graphics often combine text and illustration. Graphic design may consist solely of the deliberate selection, creation, or arrangement of typography, as in a brochure, flyer, poster, website, or book, without any other elements. The goal may be clarity or effective communication, an association with other elements of culture may be evoked, or simply a distinctive style may be created.
Primitives are the basic units that a graphics system can combine to create more complex images or models. Examples include sprites and character maps in 2D video games, geometric primitives in CAD, or polygons or triangles in 3D rendering. Primitives may be supported by hardware for efficient rendering, or as building blocks provided by the graphics application.
Rendering is the creation of a 2D image from a 3D model using computer programs. A scene file contains objects in a strictly defined language or data structure; it will contain information about geometry, viewpoint, texture, lighting, and shading as a description of the virtual scene. The data contained in the scene file is then passed to a rendering program for processing and output to a digital image or raster image file. The rendering program is usually built into computer graphics software, though others are available as plugins or as entirely separate programs. The term «rendering» may be understood by analogy to an «artist's rendering» of a scene. Although the technical details of rendering methods vary, the general problems that must be overcome in creating a 2D image from a 3D representation stored in a scene file are designated as the graphics pipeline, along a rendering device such as a graphics processing unit. A graphics processing unit is a device that assists the processor in computations. If a scene is to appear relatively realistic and predictable under virtual lighting, the rendering software must solve the rendering equation. The rendering equation does not account for all lighting phenomena, but it represents a general lighting model for computer imagery. «Rendering» is also used to describe the process of calculating effects in a video editing file to produce the final video output.
3D projection
3D projection is a method of displaying three-dimensional points on a two-dimensional plane. Since most modern methods of displaying graphical data are based on flat two-dimensional media, this type of projection is widely used. This method is used in most real-time 3D applications and typically uses rasterization to produce the final image.
Ray tracing
Ray tracing is a technique from the family of image-order algorithms for generating an image by tracing the path of light through pixels in an image plane. This technique provides a high degree of photorealism; usually higher than that of conventional scanline rendering methods, but it requires much greater computational cost.
Shading
An example of hatching.
Shading refers to depicting depth in 3D models or illustrations through varying levels of darkness. It is a process used in drawing to depict levels of darkness on paper by applying denser material or a darker shade for darker areas and less dense or lighter shading for lighter areas. There are various shading methods, including cross-hatching, in which perpendicular lines of varying closeness are drawn in a grid to shade an area. The closer the lines are together, the darker the area appears. Similarly, the farther apart the lines are, the lighter the area will be. This term has recently been generalized to mean that shaders are applied.
Texture mapping
Texture mapping is a technique for adding detail, surface texture, or color to a computer graphic or 3D model. Its application to three-dimensional graphics was first proposed by Dr. Edwin Catmull in 1974. A texture map is applied (mapped) to the surface of a shape or polygon. This process is similar to applying patterned paper to a plain white box. Multitexturing is the simultaneous use of more than one texture on a polygon. [30] Procedural textures (created by adjusting the parameters of an underlying algorithm that produces the output texture) and bitmap textures (created in an image-editing application or imported from a digital camera) are, generally speaking, common methods for implementing texture definition on 3D models in computer graphics software, while the intended placement of textures onto a model's surface often requires a technique known as UV mapping (arbitrary, manual arrangement of texture coordinates) for polygonal surfaces, whereas non-uniform rational B-spline (NURBS) surfaces have their own intrinsic parameterization used as texture coordinates. Texture mapping as a discipline also includes techniques for creating normal maps and bump maps that correspond to the texture to simulate height and reflection maps, to help simulate gloss and light reflections, as well as environment mapping to simulate specular reflectivity, also known as shininess.
Anti-aliasing
Rendering resolution-independent objects (such as 3D models) for viewing on a raster (pixel-based) device, such as a liquid crystal display or a CRT television, inevitably causes aliasing artifacts, primarily along geometric edges and texture-detail boundaries; these artifacts are informally called «jaggies». Such problems are addressed using anti-aliasing techniques, which make images more pleasant for the viewer but may require certain computational costs. Various anti-aliasing algorithms (such as supersampling) can be used and then tuned for the most efficient rendering relative to the quality of the resulting images; a graphic artist must consider this trade-off if anti-aliasing techniques are to be used. A pre-anti-aliased raster texture, displayed on screen (or in a screen location) at a resolution different from that of the texture itself (for example, a textured model at a distance from the virtual camera) will exhibit aliasing artifacts, while any procedurally defined texture will always show aliasing artifacts, since they are resolution-independent; techniques such as MIP mapping and texture filtering help address texture aliasing problems.
A volume-rendered CT scan of a forearm with different color schemes for muscle, fat, bone, and blood.
Volume rendering is a technique used to display a two-dimensional projection of a discretely sampled three-dimensional data set. A typical 3D dataset is a group of 2D slice images acquired by a CT or MRI scanner.
These are usually acquired in a regular pattern (for example, one slice per millimeter) and usually have a regular number of image pixels in a regular pattern. This is an example of a regular volumetric grid, with each volume element, or voxel, represented by a single value obtained by sampling the immediate area surrounding the voxel.
Three-dimensional modeling is the process of developing a mathematical wireframe representation of any three-dimensional object, called a «3D model», using specialized software. Models may be created automatically or manually; the manual process of preparing geometric data for 3D computer graphics is similar to plastic arts such as sculpture. 3D models can be created using several approaches: using NURBS to create precise and smooth surface sections, polygonal mesh modeling (manipulating faceted geometry), or subdividing a polygonal mesh (advanced tessellation of polygons resulting in smooth surfaces similar to NURBS models). A 3D model can be displayed as a two-dimensional image through a process called 3D rendering, used in computer simulations of physical phenomena, or animated directly for other purposes. The model can also be physically created using 3D printing devices.
Charles Csuri
Charles Csuri is a pioneer of computer animation and digital fine art and created the first computer art in 1964. The Smithsonian Institution recognized Csuri as the father of digital art and computer animation, as did the Museum of Modern Art (MoMA) and the Association for Computing Machinery - SIGGRAPH, which recognized him as a pioneer of computer animation.
Donald P. Greenberg
Donald P. Greenberg is a leading innovator in the field of computer graphics. Greenberg is the author of hundreds of papers and has been a teacher and mentor to many well-known graphic artists, animators, and researchers, such as Robert L. Cook, Marc Levoy, Brian A. Barsky, and Wayne Lytle. Many of his former students have received Academy Awards for Technical Achievement, and some have received the SIGGRAPH Achievement Award. Greenberg was the founding director of the NSF Center for Computer Graphics and Scientific Visualization.
A. Michael Noll
Noll was one of the first researchers to use a digital computer to create artistic patterns and to formalize the use of random processes in creating fine art. He began creating digital art in 1962, making him one of the first digital artists. In 1965, Noll, together with Frieder Nake and Georg Nees, was among the first to publicly exhibit computer art. During April 1965, Noll's computer works were exhibited at the Howard Wise Gallery alongside Bela Julesz's random-dot patterns.
A modern rendering of the Utah teapot, an iconic model in 3D computer graphics, created by Martin Newell, 1975.
A modern rendering of the Utah teapot, an iconic model in three-dimensional computer graphics, created by Martin Newell in 1975.
Computer graphics is a subfield of computer science studying methods for the digital synthesis and manipulation of visual content. Although the term often refers to the study of three-dimensional computer graphics, it also encompasses two-dimensional graphics and image processing.
Computer graphics studies the manipulation of visual and geometric information using computational methods. It focuses on the mathematical and computational foundations of image creation and processing, rather than on purely aesthetic questions. Computer graphics is often distinguished from the field of visualization, although the two fields have much in common.
Related fields of study include:
Applications of computer graphics include:
There are several international conferences and journals where the most significant results in the field of computer graphics are published. Among them are the SIGGRAPH and Eurographics conferences and the Association for Computing Machinery's (ACM) Transactions on Graphics journal. The joint series of Eurographics and ACM SIGGRAPH symposia includes major venues for more specialized subfields: the Symposium on Geometry Processing, the Symposium on Rendering, the Symposium on Computer Animation, and High Performance Graphics.
As in the rest of computer science, conference publications in computer graphics tend to be more significant than journal publications (and therefore have lower acceptance rates).
A broad classification of the main concepts of computer graphics might be as follows:
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 environment. Because an object's appearance largely depends on its exterior, boundary representations are most often used. Two-dimensional surfaces are a good representation for most objects, although 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 the most common representation, although point-based representations have become more popular recently (see, for example, the Symposium on Point-Based Graphics). These representations are Lagrangian, meaning that the spatial arrangement of the samples is not fixed. More recently, Eulerian descriptions of surfaces (i.e., with fixed spatial samples), such as level sets, have been developed into a useful representation for deforming surfaces that undergo many topological changes (the most notable example being fluids).
Subfields of geometry
The subfield of animation studies descriptions of surfaces (and other phenomena) that move or deform over time. Historically, much of the work in this field has focused on parametric and data-driven models, but more recently physical simulation has become more popular as computers have become more computationally powerful.
Subfields
Indirect diffuse scattering modeled using path tracing and irradiance caching.
Rendering generates images from a model. Rendering can simulate light transport to produce realistic images, or can produce images with a specific artistic style in non-photorealistic rendering. The two main operations in realistic rendering are transport (how much light passes from one place to another) and scattering (how surfaces interact with light). See the section «Rendering (computer graphics)» for more details.
Transport
Transport describes how lighting in a scene is transferred from one place to another. Visibility is an important 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 in the context of rendering, since they can substantially affect the design of rendering algorithms. Shading can be broken down into two orthogonal problems, which are often studied independently:
The first problem relates to scattering, i.e., the relationship between incoming and outgoing light at a given point. Descriptions of scattering are usually given in terms of a bidirectional scattering distribution function, or BSDF. The latter question concerns how different types of scattering are distributed across a surface (i.e., which scattering function applies, and where). Such descriptions are usually expressed through a program called a shader. (Note some confusion here, since the word «shader» is sometimes used for programs that describe local geometric variations.)
Other problems
The study of computer graphics is a subfield of computer science that studies methods for the digital synthesis and processing of visual content. Although the term often refers to three-dimensional computer graphics, it also encompasses two-dimensional graphics and image processing.
As an academic discipline, computer graphics studies the manipulation of visual and geometric information using computational methods. It focuses on the mathematical and computational foundations of image creation and processing, rather than on purely aesthetic questions. Computer graphics is often distinguished from the field of visualization, although the two fields have much in common.
Computer graphics can be used in the following fields:
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