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Flashcards

SIT354 Definitions

Dan All English 59 cards

Cards in this deck (59)

  1. 1Bump MappingBump mapping is a technique in computer graphics for simulating bumps and wrinkles on the surface of an object. This is achieved by perturbing the surface normals of the object and using the perturbed normal during lighting calculations.
  2. 2Bidirectional Reflectance Distribution FunctionsThe bidirectional reflectance distribution function (BRDF; ) is a function of four real variables that defines how light is reflected at an opaque surface. It is employed in the optics of real-world light, in computer graphics algorithms, and in computer vision algorithms.
  3. 3Alpha mappingAlpha mapping is a technique in 3D computer graphics involving the use of texture mapping to designate the amount of transparency/translucency of areas in a certain object.
  4. 4Shadow VolumesThe shadow volume technique creates sharp, per-pixel accurate shadows from point, spot, and directional lights.
  5. 5B-splineA B-spline, or basis spline, is a spline function that has minimal support with respect to a given degree, smoothness, and domain partition. Any spline function of given degree can be expressed as a linear combination of B-splines of that degree.
  6. 6Level of detailLevel of detail. ... In computer graphics, accounting for Level of detail involves decreasing the complexity of a 3D model representation as it moves away from the viewer or according to other metrics such as object importance, viewpoint-relative speed or position.
  7. 7Homogenous coordinatesHomogeneous coordinates are ubiquitous in computer graphics because they allow common vector operations such as translation, rotation, scaling and perspective projection to be represented as a matrix by which the vector is multiplied.
  8. 8Phong Specualr lightingIt describes the way a surface reflects light as a combination of the diffuse reflection of rough surfaces with the specular reflection of shiny surfaces.
  9. 9Stochastic PatternsMany “natural” patterns have a degree of irregularity or randomness. For shader writing we require a deterministic function. Most stochastic patterns used by shaders are based around the noise
    function.
  10. 10Enviromental Mappingenvironment mapping is an efficient image-based lighting technique for approximating the appearance of a reflective surface by means of a precomputed texture image. The texture is used to store the image of the distant environment surrounding the rendered object.
  11. 11Fourier TransformThe Fourier Transform takes a time-based pattern, measures every possible cycle, and returns the overall "cycle recipe" (the amplitude, offset, & rotation speed for every cycle that was found).
  12. 12Perspective Projectionthe perspective projection shows distant objects as smaller to provide additional realism.
  13. 13Normalized Device Coordinates (NDC)Normalized device coordinates (NDCs) make up a coordinate system that describes positions on a virtual plotting device. The lower left corner corresponds to (0,0), and the upper right corner corresponds to (1,1).
  14. 14Reflectivitythe property of reflecting light or radiation, especially reflectance as measured independently of the thickness of a material.
  15. 15Graphics PipelineIn computer graphics, a computer graphics pipeline, rendering pipeline or simply graphics pipeline, is a conceptual model that describes what steps a graphics system needs to perform to render a 3D scene to a 2D screen.
  16. 16Antialiasingantialiasing is a software technique for diminishing jaggies - stairstep-like lines that should be smooth. Jaggies occur because the output device, the monitor or printer, doesn't have a high enough resolution to represent a smooth line.
  17. 17Rasterization stageThe rasterization stage converts vector information (composed of shapes or primitives) into a raster image (composed of pixels) for the purpose of displaying real-time 3D graphics. While using a pixel shader is optional, the rasterizer stage always performs clipping
  18. 18Ray tracingIn computer graphics, ray tracing is a rendering technique for generating an image by tracing the path of light as pixels in an image plane and simulating the effects of its encounters with virtual objects.
  19. 19MipmappingMipmapping is used to remove the visual artifacts so that we get better quality picture and it is minification filter.
  20. 20Z-fightingZ-fighting, also called stitching, that occurs when two or more primitives have similar or identical values in the z-buffer. It is particularly prevalent with coplanar polygons, where two faces occupy essentially the same space, with neither in front.
  21. 21Perlin NoisePerlin noise is a procedural texture primitive, a type of gradient noise used to increase the appearance of realism in computer graphics, used to produce natural appearing textures on computer generated surfaces for motion picture visual effects.
  22. 22Painter's algorithmThe painter's algorithm, also known as a priority fill, is one of the simplest solutions to the visibility problem in 3D computer graphics. When projecting a 3D scene onto a 2D plane, it is necessary at some point to decide which polygons are visible, and which are hidden.
  23. 23Fractional Brownian motionIt basically consists of steps in a random direction and with a step-length that has some characteristic value. A key feature to fBm is that if you zoom in on any part of the function you will produce a similar random walk in the zoomed in part.
  24. 24Binary space partitioning (BSP)BSP is a method for recursively subdividing a space into convex sets by hyperplanes.
    BSP tree allows spatial information about the objects in a scene that is useful in rendering, such as their ordering from front-to-back with respect to a viewer at a given location, to be accessed rapidly.
  25. 25Procedural generationprocedural generation is a method of creating data algorithmically. In computer graphics, it is also called random generation and is commonly used to create textures and 3D models. it is used to automatically create large amounts of content in a game.
  26. 26Diffusing lightingDiffusing light means to soften it by reducing glare and harsh shadows. It can also be used to create a very soft, cinematic look. There are a number of ways to diffuse light.
  27. 27LightmapA lightmap is a data structure used in lightmapping, a form of surface caching in which the brightness of surfaces in a virtual scene is pre-calculated and stored in texture maps for later use.
  28. 28Ambient LightingAn ambient light source represents an omni-directional, fixed-intensity and fixed-color light source that affects all objects in the scene equally. Upon rendering, all objects in the scene are brightened with the specified intensity and color.
  29. 29Tessellationan arrangement of shapes closely fitted together, especially of polygons in a repeated pattern without gaps or overlapping.
  30. 30TransformsTranslation - Adding constant value to each pixel causes it to be displaced in the destination
    Scaling - Makes the image in the buffer larger or smaller
    Rotation - Rotating the image in the buffer on an axis
  31. 31Object Coordinate SystemCoordinates are specified in a manner convenicent to the object in isolation
  32. 32World Coordinate SystemObjects are transformed so that they all share some common coordinate system
  33. 33Eye/View/Camera Coordinate SystemThe world is transformed so that some privleged object (the camera) occupies a specific position
  34. 34Window Coordinate Systemto draw the image the vertex coordinates must be transformed in the coordinate system of the target image buffer
  35. 35Parallel ProjectionsDuring a projection, lines are projected through each point on the 3-dimensional object onto the display plane, to determine the corresponding point on the display plane, all of these projection lines are parallel to each other.
  36. 36Lambertian reflectionLambertian reflection is used as a model for diffuse reflection. This causes all closed polygons (such as a triangle within a 3D mesh) to reflect light equally in all directions when rendered. In effect, a point rotated around its normal vector will not change the way it reflects light.
  37. 37Specular reflectionsSpecular reflection is a type of surface reflectance often described as a mirror-like reflection of light from the surface. In specular reflection, the incident light is reflected into a single outgoing direction.
  38. 38Lighting Termsterms of models relating parameters of light, material and enviroment, approximations of reality
    Emissive, Ambient, Diffuse, Specular, Attenuation, Visibilty
  39. 39Directional LightingLight can be modelled as being very far away and no attenuation, referred to as parallel light, for example the sun light reaching the earth and intensity does not vary much
  40. 40AttenuationFalloff, distance the light can travel from its source, can be applied to any type of light
  41. 41Simple Harmonic PatternsRegular repeating patterns can be produced using periodic functions, such as sin and cos
    frequency number of times the pattern repeats
    amplitude change in intesity between diffrent patterns
  42. 42Interpolationinterpolation is a method of constructing new data points within the range of a discrete set of known data points.
    step - sharp jump from one value to another
    linear interpolation - lerp, mix
    smooth interpolation - no sudder change
  43. 43Texture ImagesProvide content not well suited to procedural generation, can be used for computationally expensive procedural operations converted into texture images
  44. 44Layering and compositingWrite layers of shader code using the divide-and-conqueror strategy to identify and describe each layer or compodent separately
  45. 45Types of ShadersVertex Shader
    Geometry Shader
    Pixel Shader
    Hull Shader
    Compute Shader
    Tessellation Shader
  46. 46Vertex Shaderare run for each vertex given to the graphics processor, purpose is to transform each vertex 3d position to 2d position on screen, can manipulate position, colour and texture coordinates
    per-vertex lighting, GPU animations, vertex displacement
  47. 47Geometry ShaderAdd or remove vertices from a mesh
    geometry tessellation, shadow volume extrusion, single pass render to cube map
    generate/add voluemtrix to expensive to run on CPU
  48. 48Pixel/Fragment Shadercalculates the colour of each pixel
    input comes from the rasteriser
    used for scene lighting, bump mapping and colour toning, output is a fragment colour
  49. 49Shader LanguageBased on C, Tends to support
    pre-processor directives, flow control, standard built-in functions, type qualifiers (in/out) various graphics applicable data types, matrix.
  50. 50Mapping TypesTexture mapping, Bump (normal) mapping, displacement mapping, enviorment (reflection) mapping, light mapping, parallax and relief mapping, alpha mapping, 3d texture mapping
  51. 51Texture Mappingimages containing colour values are mapped onto a surface
  52. 52Displacement MappingUsing an image that contain changes to the geometric position of points so that the surface points are physically displaced
  53. 533D Texture Mappingusing a 3d object to produce solid textures and other effects, can use nth dimentions
  54. 54Texture CoordinatesMapping between the texture coordinates from an image file buffer to the geometric coordinates on a primitive (triangle/polygon)
    the numbers typically fall between 0-1
  55. 55Sampling Spartial Domainmultiplcation with a spike field, we mesaure the image only where the spikes are (etc the center of the pixels)
  56. 56Sampling Frequency DomainConvolution with spike field, this layers multiple copies of the original signal one at each spike
  57. 57Stencil TestThe Stencil Test is a per-sample operation performed after the Fragment Shader. The fragment's stencil value is tested against the value in the current stencil buffer; if the test fails, the fragment is culled.
  58. 58TessellationTessellation is the Vertex Processing stage in the OpenGL rendering pipeline where patches of vertex data are subdivided into smaller Primitives. This process is governed by two shader stages and a fixed-function stage.
  59. 59Z-buffering/depth bufferingZ-buffering/depth buffering, is a technique in computer graphics programming that is used to determine whether an object (or part of an object) is visible in a scene. It can be implemented either in hardware or software, and is used to increase rendering efficiency.

Information

Description
A list of flash cards with a concept and definition of shader terms
Created by
Dan All · Jun 2018
Updated
Jun 7, 2018
Views
60
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