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電腦生成圖像 (Computer-generated imagery，CGI)，簡稱電腦成像，又稱為電腦繪圖 (Computer Graphics，CG)，是指使用電腦產生的影像，更精確的如應用在影片中的3D特效，還有在電視節目、廣告及印刷媒體中也很常見。在電腦遊戲中常使用的即時運算圖形都屬於CGI的範圍（很少簡稱 CGI），也有些是用來做過場或是介紹用頁面，有時這被稱為 Full Motion Video, FMV（全動態視頻）。
Computer Graphics (什麼是電腦繪圖)
Computer graphics are graphics created using computers and, more generally, the representation
and manipulation of image data by a computer with help from specialized software and hardware. The development of computer graphics has made computers easier to interact with, and better for understanding and interpreting many types of data. Developments in computer graphics have had a profound impact on many types of media and have revolutionized animation, movies and the video game industry.
The term computer graphics has been used in a broad sense to describe "almost everything on computers that is not text or sound". Typically, the term computer graphics refers to several different things:
● the representation and manipulation of image data by a computer
● the various technologies used to create and manipulate images
● the sub-field of computer science which studies methods for digitally synthesizing and manipulating visual content
Computer graphics is widespread today. Computer imagery is found on television, in newspapers, for example in weather reports, or for example in all kinds of medical investigation and surgical procedures. A well-constructed graph can present complex statistics in a form that is easier to understand and interpret. In the media "such graphs are used to illustrate papers, reports, thesis", and other presentation material.
Many powerful tools have been developed to visualize data. Computer generated imagery can be categorized into several different types: 2D, 3D, and animated graphics. As technology has improved, 3D computer graphics have become more common, but 2D computer graphics are still widely used. Computer graphics has
emerged as a sub-field of computer science which studies methods for digitally synthesizing and manipulating visual content. Over the past decade, other specialized fields have been developed like information
visualization, and scientific visualization more concerned with "the visualization of three dimensional phenomena (architectural, meteorological, medical, biological, etc.), where the emphasis is on realistic renderings of volumes, surfaces, illumination sources, and so forth, perhaps with a dynamic (time) component
Computer Graphics Lighting (電腦繪圖光線)
Computer graphics lighting refers to the simulation of light in computer graphics. This simulation can either be extremely accurate, as is the case in an application like Radiance which attempts to track the energy
flow of light interacting with materials using radiosity computational techniques. Alternatively, the simulation can simply be inspired by light physics, as is the case with non-photorealistic rendering. In both cases, a shading model is used to describe how surfaces respond to light. Between these two extremes, there are many different rendering approaches which can be employed to achieve almost any desired visual result.
Computer graphics lighting can also refer to the job of lighting in computer animation. A computer graphics lighter will employ many of the same methods a live-action lighting designer or gaffer might employ. However, the computer graphics lighter will work within a computer graphics application.
Animation is the rapid display of a sequence of images to create an illusion of movement. The most common method of presenting animation is as a motion picture or video program, although there are other methods. This type of presentation is usually accomplished with a camera and a projector or a computer viewing screen which can rapidly cycle through images in a sequence. Animation can be made with either hand rendered art, computer generated imagery, or three-dimensional objects, e.g. puppets or clay figures, or a combination of techniques. The position of each object in any particular image relates to the position of that object in the previous and following images so that the objects each appear to fluidly move independently of one another. The viewing device displays these images in rapid succession, usually 24, 25 or 30 frames per second.
Computer Animation (電腦動畫)
Computer animation encompasses a variety of techniques, the unifying factor being that the animation is created digitally on a computer. This animation takes less time than previous traditional animation.
2D animation figures are created and/or edited on the computer using 2D bitmap graphics or created and edited using 2D vector graphics. This includes automated computerized versions of traditional animation techniques such as of, interpolated morphing, onion skinning and interpolated rotoscoping.
2D animation has many applications, including analog computer animation, Flash animation and PowerPoint animation. Cinemagraphs are still photographs in the form of an animated GIF file of which part is animated.
3D animation is digitally modeled and manipulated by an animator. The animator starts by creating an external 3d mesh to manipulate, a mesh is a geometric configuration that gives the visual appearance of form to an 3D object or 3D environment the mesh may have a lot of vertices which are to geometric
points which make up the mesh, it is given an internal digital skeletal structure called an armature that can be used to control the mesh with weights. This process is called rigging and can be programmed with movement with keyframes.
Other techniques can be applied, such as mathematical functions (ex. gravity, particle simulations), simulated fur or hair, effects such as fire and water simulations. These techniques fall under the category of 3D dynamics.