Depth Test
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Depth Test
A depth buffer, also known as a z-buffer, is a type of data buffer used in computer graphics to represent depth information of objects in 3D space from a particular perspective. Depth buffers are an aid to rendering a scene to ensure that the correct polygons properly occlude other polygons. Z-buffering was first described in 1974 by Wolfgang Straßer in his PhD thesis on fast algorithms for rendering occluded objects. A similar solution to determining overlapping polygons is the painter's algorithm, which is capable of handling non-opaque scene elements, though at the cost of efficiency and incorrect results. In a 3D-rendering pipeline, when an object is projected on the screen, the depth (z-value) of a generated fragment in the projected screen image is compared to the value already stored in the buffer (depth test), and replaces it if the new value is closer. It works in tandem with the rasterizer, which computes the colored values. The fragment output by the rasterizer is ...
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Z Buffer
A depth buffer, also known as a z-buffer, is a type of data buffer used in computer graphics to represent depth information of objects in 3D space from a particular perspective. Depth buffers are an aid to rendering a scene to ensure that the correct polygons properly occlude other polygons. Z-buffering was first described in 1974 by Wolfgang Straßer in his PhD thesis on fast algorithms for rendering occluded objects. A similar solution to determining overlapping polygons is the painter's algorithm, which is capable of handling non-opaque scene elements, though at the cost of efficiency and incorrect results. In a 3D-rendering pipeline, when an object is projected on the screen, the depth (z-value) of a generated fragment in the projected screen image is compared to the value already stored in the buffer (depth test), and replaces it if the new value is closer. It works in tandem with the rasterizer, which computes the colored values. The fragment output by the rasterizer i ...
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Z-fighting
Demonstration of z-fighting with multiple colors and textures over a grey background Z-fighting, also called stitching, or planefighting, is a phenomenon in 3D rendering that occurs when two or more primitives have very similar distances to the camera. This would cause them to have near-similar or identical values in the z-buffer, which keeps track of depth. This then means that when a specific pixel is being rendered, it is ambiguous which one of the two primitives are drawn in that pixel because the z-buffer cannot distinguish precisely which one is farther from the other. If one pixel was unambiguously closer, the less close one could be discarded. It is particularly prevalent with coplanar polygons, where two faces occupy essentially the same space, with neither in front. Affected pixels are rendered with fragments from one polygon or the other arbitrarily, in a manner determined by the precision of the z-buffer. It can also vary as the scene or camera is changed, causing ...
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Bandwidth (computing)
In computing, bandwidth is the maximum rate of data transfer across a given path. Bandwidth may be characterized as network bandwidth, data bandwidth, or digital bandwidth. This definition of ''bandwidth'' is in contrast to the field of signal processing, wireless communications, modem data transmission, digital communications, and electronics, in which ''bandwidth'' is used to refer to analog signal bandwidth measured in hertz, meaning the frequency range between lowest and highest attainable frequency while meeting a well-defined impairment level in signal power. The actual bit rate that can be achieved depends not only on the signal bandwidth but also on the noise on the channel. Network capacity The term ''bandwidth'' sometimes defines the net bit rate 'peak bit rate', 'information rate,' or physical layer 'useful bit rate', channel capacity, or the maximum throughput of a logical or physical communication path in a digital communication system. For example, bandwidth test ...
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Computer Storage
Computer data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers. The central processing unit (CPU) of a computer is what manipulates data by performing computations. In practice, almost all computers use a storage hierarchy, which puts fast but expensive and small storage options close to the CPU and slower but less expensive and larger options further away. Generally, the fast volatile technologies (which lose data when off power) are referred to as "memory", while slower persistent technologies are referred to as "storage". Even the first computer designs, Charles Babbage's Analytical Engine and Percy Ludgate's Analytical Machine, clearly distinguished between processing and memory (Babbage stored numbers as rotations of gears, while Ludgate stored numbers as displacements of rods in shuttles). This distinction was extended in the Von Neumann a ...
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Edwin Catmull
Edwin Earl "Ed" Catmull (born March 31, 1945) is an American computer scientist who is the co-founder of Pixar and was the President of Walt Disney Animation Studios. He has been honored for his contributions to 3D computer graphics (computer science), computer graphics, including the 2019 Turing Award, ACM Turing Award. Early life Edwin Catmull was born on March 31, 1945, in Parkersburg, West Virginia. His family later moved to Salt Lake City, Utah, where his father first served as principal of Granite High School (Utah), Granite High School and then of Taylorsville High School. Early in his life, Catmull found inspiration in Walt Disney Pictures, Disney movies, including ''Peter Pan (1953 film), Peter Pan'' and ''Pinocchio (1940 film), Pinocchio'', and wanted to be an animator; however, after finishing high school, he had no idea how to get there as there were no animation schools around that time. Because he also liked math and physics, he chose a scientific career instead. He ...
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Viewing Frustum
In 3D computer graphics, the view frustum (also called viewing frustum) is the region of space in the modeled world that may appear on the screen; it is the field of view of a perspective virtual camera system. The view frustum is typically obtained by taking a frustum—that is a truncation with parallel planes—of the pyramid of vision, which is the adaptation of (idealized) cone of vision that a camera or eye would have to the rectangular viewports typically used in computer graphics. Some authors use ''pyramid of vision'' as a synonym for view frustum itself, i.e. consider it truncated. The exact shape of this region varies depending on what kind of camera lens is being simulated, but typically it is a frustum of a rectangular pyramid (hence the name). The planes that cut the frustum perpendicular to the viewing direction are called the ''near plane'' and the ''far plane''. Objects closer to the camera than the near plane or beyond the far plane are not drawn. Sometimes, ...
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W-buffer
A depth buffer, also known as a z-buffer, is a type of data buffer used in computer graphics to represent depth information of objects in Three-dimensional space, 3D space from a particular Perspective (graphical), perspective. Depth buffers are an aid to Rendering (computer graphics), rendering a scene to ensure that the correct Polygon (computer graphics), polygons properly occlude other polygons. Z-buffering was first described in 1974 by Wolfgang Straßer in his PhD thesis on fast algorithms for rendering occluded objects. A similar solution to determining overlapping polygons is the painter's algorithm, which is capable of handling non-opaque scene elements, though at the cost of efficiency and incorrect results. In a Graphics pipeline, 3D-rendering pipeline, when an object is projected on the screen, the depth (z-value) of a generated Fragment (computer graphics), fragment in the projected screen image is compared to the value already stored in the buffer (depth test), and ...
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Accuracy And Precision
Accuracy and precision are two measures of ''observational error''. ''Accuracy'' is how close a given set of measurements ( observations or readings) are to their ''true value'', while ''precision'' is how close the measurements are to each other. In other words, ''precision'' is a description of '' random errors'', a measure of statistical variability. ''Accuracy'' has two definitions: # More commonly, it is a description of only '' systematic errors'', a measure of statistical bias of a given measure of central tendency; low accuracy causes a difference between a result and a true value; ISO calls this ''trueness''. # Alternatively, ISO defines accuracy as describing a combination of both types of observational error (random and systematic), so high accuracy requires both high precision and high trueness. In the first, more common definition of "accuracy" above, the concept is independent of "precision", so a particular set of data can be said to be accurate, precise, both, ...
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Shadow Mapping
Shadow mapping or shadowing projection is a process by which shadows are added to 3D computer graphics. This concept was introduced by Lance Williams in 1978, in a paper entitled "Casting curved shadows on curved surfaces." Since then, it has been used both in pre-rendered and realtime scenes in many console and PC games. Shadows are created by testing whether a pixel is visible from the light source, by comparing the pixel to a z-buffer or ''depth'' image of the light source's view, stored in the form of a texture. Principle of a shadow and a shadow map If you looked out from a source of light, all of the objects you can see would appear in light. Anything behind those objects, however, would be in shadow. This is the basic principle used to create a shadow map. The light's view is rendered, storing the depth of every surface it sees (the shadow map). Next, the regular scene is rendered comparing the depth of every point drawn (as if it were being seen by the light, rather tha ...
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Graphics Cards
A graphics card (also called a video card, display card, graphics adapter, VGA card/VGA, video adapter, display adapter, or mistakenly GPU) is an expansion card which generates a feed of output images to a display device, such as a computer monitor. Graphics cards are sometimes called discrete or dedicated graphics cards to emphasize their distinction to Graphics processing unit#Integrated graphics, integrated graphics. A graphics processing unit that performs the necessary computations is the main component of a graphics card, but the acronym "GPU" is sometimes also used to refer to the graphics card as a whole. Most graphics cards are not limited to simple display output. The graphics processing unit can be used for additional processing, which reduces the load from the central processing unit. Additionally, computing platforms such as OpenCL and CUDA allow using graphics cards for General-purpose computing on graphics processing units, general-purpose computing. Applications o ...
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Video Game Graphics
A variety of computer graphic techniques have been used to display video game content throughout the history of video games. The predominance of individual techniques have evolved over time, primarily due to hardware advances and restrictions such as the processing power of central or graphics processing units. Text-based Some of the earliest video games were text games or text-based games that used text characters instead of bitmapped or vector graphics. Examples include MUDs (''multi-user dungeons''), where players could read or view depictions of rooms, objects, other players, and actions performed in the virtual world; and roguelikes, a subgenre of role-playing video games featuring many monsters, items, and environmental effects, as well as an emphasis on randomization, replayability and permanent death. Some of the earliest text games were developed for computer systems which had no video display at all. Text games are typically easier to write and require less proce ...
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3D Computer Graphics
3D computer graphics, or “3D 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. 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 gr ...
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