Computer Graphics

Summary

Computer graphics involves the creation, display, and storage of images on a computer with the use of specialized software. Computer graphics fills an essential role in many everyday applications. Three-dimensional (3-D) animation has revolutionized video games and resulted in box-office hits in theaters. Virtual images of people's bodies and tissues are used in medicine for teaching, surgery simulations, and diagnoses. Educators and scientists are able to develop 3-D models that illustrate principles in a more comprehensible manner than a two-dimensional (2-D) image can. Through the use of such imagery, architects and engineers can prepare virtual buildings and models to test options prior to construction. Businesses use computer graphics to prepare charts and graphs for better comprehension during presentations.

Definition and Basic Principles

The field of computer graphics uses computers to create digital images or to modify and use images obtained from the real world. The images are created from internal models by means of computer programs. Two types of graphics data can be stored in a computer. Vector graphics are based on mathematical formulas that generate geometric images by joining straight lines. Raster graphics are based on a grid of dots known as pixels, or picture elements. Computer graphics can be expressed as 2-D, 3-D, or animated images.

The graphic data must be processed to render the image and display it on a computer movie screen. The work of computer graphics programmers has been facilitated by the development of application programming interfaces (APIs), notably the Open Graphics Library (OpenGL). OpenGL provides a set of standard operations to render images across a wide variety of platforms (operating systems). The graphics processing unit (GPU) found in a video card facilitates the presentation of the image.

There are subtle differences between the responsibilities of the computer graphics specialist and graphic or Web designers. Computer graphics specialists develop programs to display visual images or models, while designers are creative artists who use programs to communicate a specific message effectively. The end products of graphic designers are seen in various print media, while Web designers produce digital media.

Background and History

The beginning of computer graphics has been largely attributed to Ivan Sutherland, who developed a computer drawing program in 1961 for his dissertation work at the Massachusetts Institute of Technology. This program, Sketchpad, was a seminal event in the area of human-computer interaction, as it was one of the first to use graphical user interfaces (GUIs). Sutherland used a light pen containing a photoelectric cell that interacted with elements on the monitor. His method was based on vector graphics. Sketchpad provided vastly greater possibilities for the designer or engineer over previous methods based on pen and paper.

Other researchers further developed vector graphics capabilities. Raster-based graphics using pixels was later developed and is the primary technology being used. The mouse was invented and proved more convenient than a light pen for selecting icons and other elements on a computer screen. By the early 1980s, IBM's personal computer (PC) and Apple's Macintosh were marketed using operating systems that incorporated GUIs and input devices that included the mouse as well as the standard keyboard.

Major corporations developed an early interest in computer graphics. Engineers at Bell Telephone Laboratories, Lawrence Berkeley National Laboratory, and Boeing developed films to illustrate satellite orbits, aircraft vibrations, and other physics principles. Flight simulators were developed by Evans & Sutherland and General Electric.

The invention of video graphics cards in the late 1980s, followed by continual improvements, gave rise to advances in animation. Video games and full-length animated motion pictures have become large components of popular culture.

How It Works

Types of Images. Vector graphics uses mathematical formulas to generate lines or paths that are connected at points called vertices to form geometric shapes (usually triangles). These shapes are joined in a meshwork on the surfaces of figures. Surfaces on one plane are two-dimensional, while connecting vertices in three dimensions will produce 3-D images. Two-dimensional images are more useful for applications such as advertising, technical drawing, and cartography. Raster images, on the other hand, develop images based on pixels, or picture elements. Pixels can be thought of as tiny dots or cells that contain minute portions of the image and together compose the image on the computer screen. The bits of information that the pixels are able to process determine the resolution or sharpness of the image. Raster images are much more commonly used in computer graphics and are essential for 3-D and animation work.

Graphics Pipeline. The process of creating an image from data is known as the graphics pipeline. The pipeline consists of three main stagesmodeling, rendering, and display.

Modeling begins with a specification of the objects, or components of a scene, in terms of shape, size, color, texture, and other parameters. These objects then undergo a transformation involving their correct placement in a scene.

Rendering is the process of creating the actual image or animation from the scene. Rendering is analogous to a photograph or an artist's drawing of a scene. Aspects such as proper illumination and the visibility of objects are important at this stage.

The final image is displayed on a computer monitor with the use of advanced software, as well as computer hardware that includes the motherboard and graphics card. The designer must keep in mind that the image may appear differently on different computers or different printers.

OpenGL. OpenGL is an API that facilitates writing programs across a wide variety of computer languages and hardware and software platforms. OpenGL consists of graphics libraries that provide the programmer with a basic set of commands to render images. OpenGL is implemented through a rendering pipeline (graphics pipeline). Both vector and raster data are accepted for processing but follow different steps. At the rasterization stage, all data are converted to pixels. At the final step, the pixels are written into a 2-D grid known as a framebuffer. A framebuffer is the memory portion of the computer allocated to hold the graphics information for a single frame or picture.

Maya. Maya (trade name Autodesk Maya) is computer graphics software that has become the industry standard for generating 3-D models for game development and film. Maya is particularly effective in producing dazzling animation effects. Maya is imported into OpenGL or another API to display the models on the screen.

Video Games.Video game development takes a specialized direction. The term game engine was coined to refer to software used to create and render video games on a computer screen. Many features need to work together to create a successful game, including 2-D and 3-D graphics, a “physics engine” to prepare realistic collision effects, sound, animation, and many other functions. Because of the highly competitive nature of the video game industry, it is necessary to develop new games rapidly. This has led to reusing or adapting the same game engine to create new games. Some companies specialize in developing so-called middleware software suites that are conceived to contain basic elements that the game programmer can build to create the complete game.

Television. To create 3-D images for television, individual objects are created in individual layers in computer memory. This way, the individual objects can move independently without affecting the other objects. TV graphics are normally produced a screen at a time and can be layered with different images, text, backgrounds, and other elements to produce rich graphic images. Editing of digital graphics is much faster and efficient than the traditional method of cutting and pasting film strips.

Film. The film Avatar (2009) illustrated how far 3-D animation had been developed. The production used a technique called performance or motion tracking. Video cameras were attached to computers and focused on the faces of human actors as they performed their parts. In this manner, subtle facial expressions could be transferred to their animated avatars. Backgrounds, props, and associated scenery moved in relation to the actors.

Applications and Products

Game Development. Early video game technology used simple vector graphics, like Atari Inc.'s Pong, and many were text-based rather than graphical. In the late 1990s, full-motion video games were introduced using prerecorded animations and 2-D bitmap graphics based on parallel projection. Two-dimensional games using a top-down perspective were revolutionary in games like The Legend of Zelda and SimCity. The introduction of 3-D rendered graphics derived from triangle-based geometry allowed graphics to become more complex.

Modern game development is a major consumer industry. Graphics programmers, sometimes called rendering programmers, are typically experienced programmers skilled in math, rendering, and optimization. They are intricately involved in every aspect of game development, ensuring the final product is as visually appealing as possible. Without slowing down the game, graphics programmers work with artists and the programming team to meet design, artistic, and technical expectations.

Film. The influence of computer graphics in the film industry is largely related to animation. Animation predates computer graphics, but it is realism that gives animation its force. Entire films can be animated, or animation can play a supplemental role. Hollywood fantasies were previously based on constructing models and miniatures, but now computer-generated imagery can be integrated into live action.

Television. The conversion of the broadcast signal for television from analog to digital, and later to high definition, has made the role of the computer graphics designer even more important. It is common for many shows to have a computer graphics background instead of a natural background, such as when a weatherperson stands in front of a weather map. This development results in more economical productions since there are no labor costs involved in preparing sets or a need to store them.

Computer graphics were used in television advertising before film since they were more economical to produce. A combination of dazzling, animated graphics with a product or brand name can leave a lasting impression on the viewer.

Medicine. Computer graphics typically work in concert with other advanced medical imaging technologies, such as computed tomography, magnetic resonance, and positron emission tomography, to aid in diagnosis and treatment. The images obtained by these technologies are reconstructed by computer graphics techniques to form 3-D models, which can then be visualized. The development of virtual human bodies has proven invaluable in illustrating anatomical structures in healthy and diseased subjects. These virtual images have found application in surgery simulations and medical education and training. The use of patient-specific imaging data guides surgeons to conduct minimally invasive interventions that are less traumatic for the patient and lead to faster healing. Augmented reality provides a larger view of the surgical field and allows the surgeon to view structures that are below the observed surface.

Science. Computer graphics has proven valuable to illustrate scientific principles and concepts that are not easily visible in the natural environment. By viewing virtual 3-D models of molecular structures or viruses moving through tissues, a student or scientist who is a visual learner is better able to grasp these concepts.

Architecture and Engineering. Computer-aided design has greatly helped the fields of architecture and engineering. Computer graphics was initially used only as a replacement for drafting with pencil and paper. However, the profession has come to recognize its value in the early stages of a project to help designers check and reevaluate their proposed designs. Multimedia designs such as animations and panoramas are very useful in client presentations. The designs allow clients to walk through a building virtually and interactively look around interior spaces. Engineers can also test the effect of various inputs to a system, model, or circuit.

Business. Presentation of numeric data in graphs and charts is an important application of computer graphics in business. Market trends, production data, and other business information presented in graphic form are often more understandable to an audience or reader.

Education. Computer graphics has proven very useful in education because of the power of visualization in the learning process. There are many benefits to using computer graphics in educationstudents learn at their own pace at their own time, the instruction is interactive rather than passive, the student is engaged in the learning process, and textual and graphical objects can be shared among applications via tools such as cutting and pasting, clipboards, and scrapbooks.

Careers and Course Work

Computer graphics specialists must have a unique combination of artistic and computer skills. They must have good math, programming, and design skills, and be able to visualize 3-D objects. The specialist must be creative, detail-oriented, and able to work well individually and as part of a team.

Course offerings can vary considerably among universities, so the student must consider the specialties of the prospective schools in relation to the field in which he or she is most interested. For example, the student may want to focus more on software design than on graphics design. Essential courses can include advanced mathematics, programming, computer animation, geometric design and modeling, multimedia systems and applications, and software engineering.

Computer graphics can be applied to a vast number of fields, and its influence can only increase. In addition to animation in video games and film, computer graphics have proven valuable in architectural and engineering design, education, medicine, business, and cartography. Typical positions for a computer graphics specialist include 3-D animator or modeler, special effects designer, video game designer, and Web designer.

Computer graphics specialists can work in the public or private sector. They can also work independently. Although companies prefer to hire candidates with a bachelor's degree, many workers in the field have only an associate's degree or vocational certificate.

In the private sector, computer graphics specialists can be employed by architectural, construction, and engineering consulting firms, electronics and software manufacturing companies, and petrochemical, food processing, and energy industries. In the public sector, they can work at all levels of government and in hospitals and universities.

Social Context and Future Prospects

The demand for quality graphics grew across industries in the late twentieth and early twenty-first centuries. From cell phones to the medical field, using computer graphics became common, and demand for quality programmers increased. As technology evolved in the first twenty years of the twenty-first century, producing high-quality video games grew from a USD$4 million industry to a USD$200 million industry. Though the early market focused on juvenile males, modern video game developers create games for a wide audience of all genders and ages. Major producers include Sony Interactive Entertainment, Epic Games, Nintendo, Microsoft Gaming, and Tencent Interactive Entertainment. As virtual reality software emerged, graphics continued to evolve to create realistic experiences. Using modeling in biology, physics, and drug design improved education and research.

Computer graphics will continue to profoundly affect the visual arts, freeing the artist from the need to master technical skills to focus on creativity and imagination in their work. The artist can experiment with unlimited variations in structures and designs in a single work to see which produces the desired effect. Continuing advances in producing virtual images and 3-D animation will enhance understanding of scientific principles and processes in education, medicine, and science.

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