Glossary of computer graphics

This is a glossary of terms relating tocomputer graphics.

For more general computer hardware terms, seeglossary of computer hardware terms.

0–9

2D convolution

Operation that applies linear filtering to image with a given two-dimensional kernel, able to achieve e.g. edge detection, blurring, etc.

2D image

2D texture map

Atexture mapwithtwo dimensions,typically indexed byuv coordinates.

2D vector

Atwo-dimensionalvector,a commondata typeinrasterizationalgorithms,2D computer graphics,graphical user interfacelibraries.

2.5D

Also pseudo 3D. Rendering whose result looks 3D while actually not being 3D or having great limitations, e.g. in camera degrees of freedom.

3D graphics pipeline

Agraphics pipelinetaking3D modelsand producing a 2Dbitmap imageresult.

3D paint tool

A3D graphics applicationfordigital paintingof multipletexture mapimage channels directly onto a rotated3D model,such aszbrushormudbox,also sometimes able to modify vertex attributes.

3D scene

A collection of3D modelsandlightsourcesin world space, into which a camera may be placed, describing a scene for3D rendering.

3D unit vector

Aunit vectorin3D space.

4D vector

A commondatatypein graphics code, holdinghomogeneous coordinatesorRGBAdata, or simply a3D vectorwith unused W to benefit from alignment, naturally handled by machines with 4-elementSIMDregisters.

4×4 matrix

Amatrixcommonly used as atransformationofhomogeneous coordinatesin3D graphics pipelines.

7e3 format

A packed pixel format supported by somegraphics processing units(GPUs) where a single32-bit wordencodes three 10-bitfloating pointcolor channels, each with seven bits ofmantissaand three bits ofexponent.

A

AABB

Axis aligned bounding box(sometimes called "axis oriented" ), abounding boxstored in world coordinates; one of the simplestbounding volumes.

Additive blending

Acompositing operationwhere$dst=dst+src,$without the use of analpha channel,used for various effects. Also known aslinear dodgein some applications.

Affine texture mapping

Linear interpolation of texture coordinates in screen space without taking perspective into account, causing texture distortion.

Aliasing

Unwanted effect arising when sampling high-frequency signals, in computer graphics appearing e.g. when downscaling images. Antialiasing methods can prevent it.

Alpha channel

An additional image channel (e.g. extending an RGB image) or standalone channel controllingalpha blending.

Ambient lighting

An approximation to the light entering a region from a wide range of directions, used to avoid needing an exact solution to therendering equation.

Ambient occlusion(AO)

Effect approximating, in an inexpensive way, one aspect ofglobal illuminationby taking into account how much ambient light is blocked by nearby geometry, adding visual clues about the shape.

Analytic model

Amathematical modelfor a phenomenon to besimulated,e.g. some approximation tosurface shading.Contrasts withEmpirical modelsbased purely on recorded data.

Anisotropic filtering

Advanced texture filtering improving onMipmapping,preventing aliasing while reducing blur in textured polygons at oblique angles to the camera.

Anti-aliasing

Methods for filtering and sampling to avoidvisual artefactsassociated with the uniformpixelgrid in3D rendering.

Array texture

A form oftexture mapcontaining anarrayof 2D texture slices selectable by a 3rd 'W'texture coordinate;used to reduce state changes in3D rendering.

Augmented reality

Computer-rendered content inserted into the user's view of the real world.

AZDO

Approaching zero driver overhead, a set of techniques aimed at reducing theCPUoverhead in preparing and submitting rendering commands in theOpenGLpipeline. A compromise between the traditional GL API and other high-performance low-level rendering APIs.

B

Back-face culling

Culling (discarding) of polygons that are facing backwards from the camera.

Baking

Performing an expensive calculation offline, and caching the results in aTexture mapor Vertex attributes. Typically used for generatinglightmaps,normal maps,or lowlevel of detailmodels.

Barycentric coordinates

Three-element coordinates of a point inside a triangle.

Beam tracing

Modification ofray tracingwhich instead of lines uses pyramid-shaped beams to address some of the shortcomings of traditional ray tracing, such as aliasing.

Bicubic interpolation

Extension ofcubic interpolationto 2D, commonly used when scaling textures.

Bilinear interpolation

Linear interpolationextended to 2D, commonly used when scaling textures.

Binding

Selecting a resource (texture, buffer, etc.) to be referenced by future commands.

Billboard

A textured rectangle that keeps itself oriented towards the camera, typically used e.g. for vegetation or particle effects.

Binary space partitioning(BSP)

A data structure that can be used to accelerate visibility determination, used e.g. inDoom engine.

Bit depth

The number ofbits per pixel,sample, ortexelin abitmap image(holding one or mode image channels, typical values being 4, 8, 16, 24, 32)

Bitmap

Image stored by pixels.

Bit plane

A format forbitmap imagesstoring1 bit per pixelin a contiguous2D array;Several suchparallel arrayscombine to produce the a higherbit depthimage. Opposite of packed pixel format.

Blend operation

A render state controllingalpha blending,describing a formula for combining source and destinationpixels.

Bone

Coordinate systems used to control surface deformation (via Weight maps) duringSkeletal animation.Typically stored in ahierarchy,controlled bykeyframes,and other proceduralconstraints.

Bounding box

One of the simplest type ofbounding volume,consisting ofaxis alignedorobject alignedextents.

Bounding volume

A mathematically simple volume, such as a sphere or a box, containing 3D objects, used to simplify and accelerate spatial tests (e.g. for visibility or collisions).

BRDF

Bidirectional reflectance distribution functions(BRDFs),empirical modelsdefining 4D functions forsurface shadingindexed by a view vector and light vector relative to a surface.

Bump mapping

Technique similar to normal mapping that instead of normal maps uses so called bump maps (height maps).

BVH

Bounding volume hierarchyis a tree structure on a set of geometric objects.

C

Camera

Avirtual camerafrom whichrenderingis performed, also sometimes referred to as 'eye'.

Camera space

A space with thecameraat theorigin,aligned with the viewer's direction, after the application of theworld transformationand view transformation.

Cel shading

Cartoon-like shading effect.

Clipping

Limiting specific operations to a specific region, usually the view frustum.

Clipping plane

Aplaneused tocliprendering primitivesin agraphics pipeline.These may define theView frustumor be used for other effects.

Clip space

Coordinate space in which clipping is performed.

Clip window

A rectangular region in screen space, used duringclipping.A clip window may be used to enclose a region around aportalinportal rendering.

CLUT

A table of RGB color values to be indexed by a lowerbit depthimage (typically 4-8bits), a form ofvector quantisation.

Color bleeding

Unwanted effect in texture mapping. A color from a border of unmapped region of the texture may appear (bleed) in the mapped result due to interpolation.

Color channels

The set ofchannelsin abitmap imagerepresenting the visible color components, i.e. distinct from the alpha channel or other information.

Color resolution

Command buffer

A region ofmemoryholding a set of instructions for agraphics processing unitfor rendering a scene or portion of a scene. These may be generated manually inbare metalprogramming, or managed by low levelrendering APIs,or handled internally byhigh level rendering APIs.

Command list

A group of rendering commands ready for submission to agraphics processing unit,see also Command buffer.

Compute API

AnAPIfor efficiently processing large amounts of data.

Compute shader

Acompute kernelmanaged by a rendering API, with easy access to rendering resources.

Cone tracing

Modification ofray tracingwhich instead of lines uses cones as rays in order to achieve e.g.antialiasingor soft shadows.

Connectivity information

Indices defining [rendering primitive]s betweenvertices,possibly held in index buffers. describes geometry as agraphorhypergraph.

CSG

Constructive solid geometry,a method for generating complexsolid modelsfromboolean operationscombining simpler modelling primitives.

Cube mapping

A form of environment reflection mapping in which the environment is captured on a surface of a cube (cube map).

Culling

Before rendering begins, culling removes objects that don't significantly contribute to the rendered result (e.g. being obscured or outside camera view).

D

Decal

A "sticker" picture applied onto a surface (e.g. a crack on the wall).

Detail texture

Texture mapsrepeated at high frequency combined with amain textureon a surface to prevent a blurred appearance close to the camera.

Deferred shading

A technique by which computation of shading is deferred to later stage by rendering in two passes, potentially increasing performance by not discarding expensively shaded pixels. The first pass only captures surface parameters (such as depth, normals and material parameters), the second one performs the actual shading and computes the final colors.

Deformation lattice

A means of controllingfree-form deformationvia a regular3D gridofcontrol pointsmoved to arbitrary positions, with polynomial interpolation of the space between them.

Degenerate triangles

Zero area triangle primitives placed in atriangle stripbetween actual primitives, to allow many parts of atriangle meshto be rendered in a single drawcall. These are rejected by the triangle setup unit.

Delaunay triangulation

A method for generating an efficient triangulating between a set ofverticesin aplane.

Depth buffer

Abitmap imageholding depth values (either aZ bufferor aW buffer), used forvisible surface determination,duringrasterizationof 3D scenes

Depth map

Abitmap imageortexture mapholding depth values. Similar to aheight mapordisplacement map,but usually associated with a projection.

Depth value

A value in adepth maprepresenting a distance perpendicular to the space of an image.

Diffuse lighting

In shading, a diffuse component of light is the light reflected from the surface uniformly into all directions. This component depends on the surface normal and direction to the light source but not on the viewer's position.

Direct3D

Microsoft Windows3D API, with similar architecture toOpenGL.

Displacement mapping

a method for adding detail to surfaces bysubdivisionand displacement of the resultingverticesfrom aheight map.

Distributed ray tracing

Modification ofray tracingthat casts multiple rays through each pixel in order to model soft phenomena such as soft shadows, depth of field etc.

Double buffering

Using a dedicated buffer for rendering and copying the result to the screen buffer when finished. This prevents stutter on the screen and the user seeing rendering in progress.

Drawcall

A single rendering command submitted to a rendering API, referring to a single set of render states.

E

Edge vector

Avectorbetween 2 positionverticesin apolygonorpolygon mesh,along anedge.

Environment mapping

Also reflection mapping, a technique of approximating reflections of environment on complex surfaces of 3D models in real time. A complete 360 degree view of environment needs to be prerendered and stored in a texture using a specific mapping (e.g.cube mapping,sphere mappingetc.)

Extents

The minimum and maximum values of an object orprimitivealong acoordinate axisor set of axes.

F

Fixed-function pipeline

A hardwarerendering pipelinewithoutshaders,composed entirely offixed-function units.A limited number of functions may be controlled by render states.

Fixed-function unit

A piece of hardware in agraphics processing unitimplementing a specific function (such as triangle setup or texture sampling), without programmable control byshaders.

Flat shading

Shading that assigns a uniform color to each face of a 3D model, giving it a "sharp-edge" look.

Forward rendering

A term for traditional3D rendering pipelineswhich sortlightsourcesapplicable to3D modelsin world space prior torasterization.Contrasts withDeferred shading.

Forward-plus rendering

An extension of forward rendering usingcompute shadersto placelightsourcesinto screen space tiles, to accelerate the use of manylightsources,bypassing some of the disadvantages ofdeferred shading.

Fractal

A complex, self-similar shape described by a simple equation. Fractals can be used e.g. in procedural terrain generation.

Fragment (pixel) shader

Shader processing individual pixels or fragments (values that may potentially become pixels).

Frustum culling

A stage in arendering pipeline,filtering out3D modelswhosebounding volumesfail an intersection test with theview frustum,allowing trivial rejection.

Fresnel

According toFresnel equations,surfaces show more specular reflections when viewed at near-grazing incidence. This effect is often simulated in computer graphics.

FXAA

An approximateantialiasingmethod performed in apost-processingstep which smooths the image in screen space, guided byedge detection(contrasting with the usualsupersamplingapproaches that require larger frame-buffers).

G

Geometry

Typically used to refer tovertex& rendering primitiveconnectivity information(distinct frommaterialsandtextures).

Geometry shader

In APIs such asOpenGLandDirect3D,geometry shader is an optional stage able to process 3D model geometry in more advanced ways than a vertex or tessellation shaders (e.g. turn primitives into other primitives).

G-buffer

A screen space representation of geometry andmaterialinformation, generated by an intermediate rendering pass indeferred shadingrendering pipelines.

Global illumination

Computing the global interactions of light within the scene, e.g. reflections of light from one object to another, by which realism is added.

Gouraud shading

Shading technique that computes values at triangle vertices and interpolates them across the surface. This is more realistic and computationally expensive than flat shading, and less than Phong shading.

Graphics processing unit

Hardwareused to accelerate graphical computations.

Graphical shader

Ashaderassociated with therendering pipeline;not acompute shader.

Grid cell index

Integercoordinatesin amultidimensional array.

H

HDR

High dynamic range imaging,animage formatusingfloating-pointvalues. Allows additional realism withpost processing.

Heightmap

A2D arrayortexture mapholding height values; typically used for defining landscapes, or fordisplacement mapping

Homogeneous coordinates

Coordinates of form(x,y,z,w)used during matrix transforms of vertices, allowing to perform non-linear transforms such as theperspective transform.

I

Image channel

A single component (referred to as achannel) of abitmap image;one of multiple components perpixel,e.g. forRGBorYUV color space,or additional channels foralpha blending

Image format

A specific way of representing abitmap imageinmemory,also refers toimage file formats.

Image generation

Synonymous withrendering;taking a 3D scene (or other form of encoded data) and producing abitmap imageresult.

Image generator

Ahardware acceleratorfor image generation, almost synonymous with agraphics processing unit,but historically used to refer to devices aimed atrealtime renderingforsimulation(e.g.Evans & SutherlandESIG line).

Image order rendering

Rendering methods that iterate over pixels of the screen in order to draw the image (e.g.raytracing).

Image plane

The plane in the world which is identified with the plane of the display monitor used to view the image that is being rendered.

Immediate mode rendering

The submission of rendering commands and rendering primitive data without the extensive use of managed resources; rendering primitive vertex attribute data may be embedded directly into a command list, rather than referencedindirectlyfrom resources.

Impostor

A dynamically renderedBillboardtexture mapused to stand in for geometry in the distance. A form oflevel of detailoptimization.

Incremental error algorithm

A set ofrasterization algorithmswhich use simpleinteger arithmeticto update anerror termthat determines if another quantity is incremented, avoiding the need for expensivedivisionormultiplicationoperations; e.g.bresenham's line algorithm,orrasterizingheightmaplandscapes.

Index buffer

A rendering resource used to define rendering primitive connectivity information betweenvertices.

Indirect illumination

Another term forglobal illumination.

Instancing

Rendering multiple objects (instances) using the same geometry data.

Intersection test

Determining if two pieces ofgeometryintersect,commonly required insimulation,rendering pipelines,and3D modellingapplications.

K

K-DOP

A type ofbounding volumeused for fast intersection tests; adiscrete oriented polytope (DOP).These generalisebounding boxeswithextentsadditional discreteplanes(e.g. diagonals formed by each pair of coordinate axes, etc.).

L

Level of detail(LOD)

If an object contributes less to the rendered result, e.g. by being far away from the camera, LOD chooses to use a simpler version of the object (e.g. with fewer polygons or textures).

Light probe

Object used to capture light parameters at a specific point in space in order to help compute scene lighting.

Low level rendering API

A library providing a minimalabstraction layerover agraphics processing unit's raw command lists, such asVulkan,LibGCM,orMetal (API).The user typically has more control over (and responsibility for)resourcemanagement,command buffers,synchronisation issues.

Lighting

Computations simulating the behavior of light.

Light vector

In shading calculations, a3d unit vectorrepresenting the direction ofincident lightonto a model's surface.

Light field

Adata structureapproximating the4D fluxoflight raysthrough a space (or in the general case, 5D); it may be captured using multiple cameras (e.g.light stage), or rendered from a3D modelbyray tracing.

Line primitive

A rendering primitive or modelling primitive representing aline segment,used forwireframes.

Lumels

A term fortexelsin thetexture maprepresenting alightmap.

M

Manhattan distance

Measure of distance between two points, different fromEuclidean distance,that sums the distances along principal axes.

Marching cubes

A method for triangulatingimplicit surfaces.

MegaTexturing

Texturing technique that works with extremely large textures which are not loaded into memory all at once, but rather streamed from thehard diskdepending on the camera view.

Microtexture

An alternative term sometimes used for Detail textures.

Mipmap

Method of preventingaliasingby storing differently scaled versions of the same image and using the correct one during rendering.

Modelling primitive

Basic elements from which3D modelsand 3D scenes are composed. Also known as aGeometric primitive.

Model space

Coordinate system in which a 3D model is created and stored.

Model transformation matrix

Atransformation matrixproducingworld coordinatesfrom a3D model'slocal coordinates.

Multiply blend

Ablending operationused forlightmaps,$dst=dst*src.$

N

Near clipping

The clipping of 3Drendering primitivesagainst the near clip plane. Necessary to correctly display rendering primitives that partially pass behind thecamera.

Nearest-neighbor interpolation

Simplest form of interpolation that for given position outputs the color of the nearest sample.

Noise

In real world data a noise is an unwanted distortion of the captured signal, e.g. in photography. In rendering, artificial noise, such aswhite noiseorPerlin noise,is often generated and added on purpose to add realism.

Normal mapping

Method of adding detail to the surface of 3D models, without increasing geometry complexity, by using a texture with precomputed normals that are used during shading.

O

OBJformat

A common 3D file format.

Object order rendering

Rendering methods that iterate over objects in the scene and draws then one by one (e.g.rasterization).

Occlusion culling

Culling (discarding) of objects before rendering that are completely obscured by other objects.

Occlusion query

A command passed to agraphics processing unitrequesting the testing ofbounding volumegeometry against thedepth bufferto determine if any contents in thepotentially visible set;used forhardware acceleratedocclusion culling.

Offline rendering

Non-real-time rendering.

OOBB

Anobject oriented bounding box(sometimes called object aligned); abounding boxstored in some object'slocal coordinate system

OpenGL

Commonly used 2D and 3D graphics renderingAPI.

Outcode

A smallintegerholding a bit for the result of every plane test (or clip window edge test) failed inclipping.Primitives may be trivially rejected if thebitwise ANDof all itsverticesoutcodes is non zero

P

Packed pixel format

Animage formatwhere theimage channelsare interleaved contiguously inmemory,possibly containing multiple channels within singlemachine words,equivalent to anarray of structuresfor bitmap data. Contrasts withplanar image formats.

Parallax mapping

Shader effect that adds detail with a sense of depth to a 3D surface, in a more realistic way than normal mapping.

Parameter gradient

Thederivativeof a vertex attribute with respect to screen spacecoordinatesduringrasterization,used forinterpolationacross a rendering primitive surface.

Particle effect

Effects consisting of a number of particles that behave by certain rules, typically used to simulate fire, smoke etc.

Path tracing

Photorealistic iterative rendering method based on tracing light paths.

Perspective correct texturing

Non-linear texture coordinate interpolation that takes into account perspective, eliminating distortion seen in affine texture mapping.

Phong lighting

A commonly used model of local illumination that computes the result as a sum of ambient, diffuse and specular elements of light.

Phong shading

Shading technique that uses interpolated normals.

Photogrammetry

Science and technology of making measurement from photographs, e.g. automatically creating 3D models of environment.

Photometry

Science of measuring light in terms of human perception.

Photon mapping

Photorealistic rendering algorithm based on tracing rays from the camera as well as light sources, able to simulate effects such ascaustics.

Physically based rendering(PBR)

Rendering algorithmsbased onphysics simulationoflight,includingconservation of energy,empirical modelsof surfaces.

Pixel

Smallest element of a raster image.

Planar image format

Animage formatwhere the image channels (or even bits) for a singlepixelis separated into severalparallel arrays,equivalent to astructure of arraysfor bitmap data.

Point cloud

A surface defined by a collection ofverticeswithoutconnectivity information.

Point sprite

A rendering primitive in3D graphics pipelines,allowing one vertex plus radius to define abillboard;corner vertices are automatically generated. Typically used forparticle systems

Polygon mesh

A3D modelconsisting ofverticesconnected bypolygon primitives.

Polygon primitive

A rendering or modelling primitive defining a flat surface connecting 3 or morevertices.

Portal

A means ofocclusion culling,defining a visible window between adjacentbounding volumes,used inportal rendering.

Post processing

Effects applied to abitmap imagein screen space after3D rendering pipeline,for exampletone mapping,some approximations tomotion blur,andblooms.

Predicated rendering

A feature facilitatingocclusion cullingwithin agraphics pipeline,performed by a command list asynchronously form theCPU,where a group of rendering commands are flagged to be conditional on the result of an earlier occlusion query.

Premultiplied alpha

A variation of abitmap imageoralpha blendingcalculation in which the RGB color values are assumed to be already multiplied by an alpha channel, to reduce computations duringAlpha blending;uses theblend operation:dst *= (1 - alpha) + src;capable of mixingalpha blendingwithadditive blendingeffects

Primitive

A basic unit ofgeometryfor rendering or modelling.

Procedural generation

Generating data, such astextures,3D geometry or whole scenes by algorithms (as opposed to manually).

Procedural texture

A texture (very often a volume texture) generated procedurally by a mathematical function and with the use of noise functions.

Q

Quaternion

A means of representingrotationsin a 4D vector, useful forskeletal animation,with advantages forinterpolationcompared toeuler angles(i.e. not suffering fromgimbal lock).

R

Radiometry

Measurement of electromagnetic radiation such as light, defining measures such asfluxorradiance.

Raster graphics

Graphics represented as a rectangular grid of pixels.

Rasterisation

Converting vector graphics to raster graphics. This terms also denotes a common method of rendering 3D models in real time.

Ray casting

Rendering by casting non-recursive rays from the camera into the scene. 2D ray casting is a2.5Drendering method.

Ray marching

Sampling 3D space at multiple points along a ray, typically used when analytical methods cannot be used.

Ray tracing

Recursively tracing paths oflight raysthrough a 3D scene, may be used for3D rendering(more commonly for offline rendering), or other tests.

Recursive subdivision

The process ofsubdividingan object (either geometric object, or a data structure)recursivelyuntil some criterion is met.

Render mapping

Thebakingof a rendering of a3D modelsurface into atexture mapto capture surface properties. Also known as 'render surface map'.

Render pass

A stage in arendering pipelinegenerating some (possibly incomplete) representation of the scene.

Render states

Information controlling agraphics pipeline,composed of modes and parameters, including resource identifiers, andshaderbindings.

Render target

A graphics resource into whichrendering primitivesarerasterizedby agraphics pipeline.Render targets may beframe buffersortexture maps.

Render to texture

The process ofrasterizinginto atexture map(or texture buffer) for further use as a resource in subsequent render passes. Used forenvironment mapping,impostor rendering,shadow mappingandpost-processingfilters. Requires the ability to use atexture mapas arender target.

Rendering API

Asoftware libraryfor submitting rendering commands, and managing render states and rendering resources. Examples includeOpenGL,Vulkan,Direct3D,andMetal.Provides an abstraction layer for agraphics processing unit.

Rendering command

An instruction forrasterizinggeometry in a3D graphics pipeline,typically held in a command buffer, or submitted programmatically through arendering API.

Rendering equation

Mathematical equation used as a model of light behavior in photorealistic rendering.

Rendering primitive

Geometry that can be drawn by arasterizerorgraphics processing unit,connectingvertices,e.g. points,lines,triangles, quadrilaterals

Rendering resources

Data managed by a graphics API, typically held indevice memory,including vertex buffers, index buffers,texture mapsandframebuffers

Repeating texture

Atexture mapapplied with wrap-round UV coordinates extending between the 0-1 range (representing one unit of the image), exhibitingperiodicity.Contrasts with clamped, mirrored modes or unique mappings.

Resource

Data (often held in a buffer managed by a rendering API) read by agraphics pipeline,e.g.texture maps,vertex buffers,shaders,index buffers, or other pieces of3D modeldata.

RGB888

An RGB color value encoded as8 bitsperchannel.

RGBA

An RGB color value together with an alpha channel, typically held inbitmap imagesor intermediates inshading calculations.

RGBA888

an RGBA color value encoded as8 bitsperchannel

RGB color value

A3D vectordescribing a color using theRGB color model;may usefixed pointorfloating-pointrepresentations.

RGB image

Abitmap imageholding RGB color values in 3image channels

Rounding radius

A value used in smoothing the corners of ageometric figuresuch as a2D polygonor3D polygon mesh.

S

Scene graph

Data structurecommonly used to represent a 3D scene to be rendered as adirected acyclic graph.

Screen space

Thecoordinate spaceof the resulting2d imageduring3D rendering.The result of3D projectionongeometryincamera space.

Screen space ambient occlusion(SSAO)

Technique of approximating ambient occlusion in screen space.

Screen space directional occlusion

An enhancement ofScreen space ambient occlusion(SSAO) taking direction into account to sample theambient light,to better approximateglobal illumination.

Shader

A subroutine written in ashading languagedescribing:vertex transformations,skinning, and possiblyvertex lighting(invertex shaders);shading calculations(inpixel shaders); control overtessellation(tessellation shaders); orgeneral purpose computation.

Shading calculation

Surface lightingandtexturing blendingoperations, e.g. includingspecularity,bump mappingetc.

Shadow buffer

A synonym for shadow map.

Shadow map

A texture buffer holding depth values rendered in a separate render pass from the perspective of alightsource,used inShadow mapping;it is typically rendered onto other geometry in the main rendering pass.

Shadow volume

One of the techniques of adding shadows to 3D scenes.

Signed triangle area

Found using half the Z component ofcross productof a pair of screen-space triangle edge vectors, useful forbackface cullingand computing parameter gradients intriangle rasterization.

Skybox

Method of creating background for a 3D scene by enclosing it in a textured cuboid (or another environment map).

Sliverous triangle

Sliver triangle

A triangle with one or two extremelyacute angles,hence a long/thin shape, which has undesirable properties during someinterpolationorrasterizationprocesses.

Software renderer

Rendering software that doesn't use specialized hardware (aGPU) for its computations, i.e. only usesCPUfor rendering.

Sparse texture

A texture that can partially reside in the video memory to reduce video memory usage and loading time.

Spatial hashing

A form ofhashingto acceleratespatial testinge.g. forAI,collision detection,typically using agrid cell indexas akey.

Specular exponent

Controls the glossiness in thePhong shadingmodel.

Specular highlights

In shading, specular highlight is a bright highlight caused by specularreflections,more prominent on metallic surfaces. These highlights depend on the viewer's position as well as the position of the light source and surface normal.

Spline

Acurvedefined bypolynomial interpolationthroughcontrol points.

Sprite

2D image moving on the screen, with potential partial transparency and/or animation.

State changes

The passing of changes in render states in agraphics pipeline,incurring a performance overhead. This overhead is typically minimised by scenesorting.

Stencil buffer

A buffer storing an integer value for each according screen pixel, used e.g. to mask out specific operations and achieve specific effects.

Stereo rendering

Rendering the view twice separately for each eye in order to presentdepth.

Surface normal vector

In shading calculations, thenormalto a3D modelsurface, typically compared with the light and view vectors to compute the resulting visible colour. Also used fordisplacement mapping.

Swizzled texture

Atexture mapstored out of the natural pixel order; seeSwizzling (computer graphics).For example, it may be stored inmorton order,giving improvedcache coherencyfor 2Dmemory access patterns.

T

Terrain rendering

Rendering oflandscapes,typically usingheightmapsorvoxels.

Tessellation

Converting a general 3D surface into polygonal representation, important because of HW being optimized for rendering polygons.

Texel

Texture element, a pixel of a texture.

Texture cache

A specialised read-onlycachein agraphics processing unitfor bufferingtexture mapreads, accelerating texture sampling operations.

Texture sampling

The process oftexture lookupwithtexture filtering.Performed by a texture sampling unit in agraphics processing unit

Texture sampling unit

Afixed-function unitperforming texture sampling; also known as atexture mapping unit.

Texture buffer

A region ofmemory(or resource) used as both a render target and atexture map.

Texture map

Abitmap image/rendering resource used intexture mapping,applied to3D modelsand indexed byUV mappingfor3D rendering.

Texture space

Thecoordinate spaceof atexture map,usually corresponding to UV coordinates in a3D model.Used for somerendering algorithmssuch astexture space diffusion

Transform feedback

A feature of arendering pipelinewhere transformed vertices may be written back to a buffer for later use (e.g. for re-use in additionalrender passesor subsequent rendering commands), e.g. caching the result ofskeletal animationfor use inshadow rendering.

Triangulation

The process of turning arbitrary geometric models intotriangle primitives,suitable foralgorithmsrequiringtriangle meshes

Triangle primitive

The most common rendering primitive definingtriangle meshes,rendered bygraphics processing units

Triangle setup

The process of ordering triangle primitive vertices, calculatingsigned triangle areaand parameter gradients between vertex attributes as a prerequisite forrasterization.

Triangle setup unit

Afixed-function unitin aGPUthat performs triangle setup (and may performbackface culling), prior to actualrasterization.

Trilinear filtering

Extension of bilinear filtering that additionally linearly interpolates between different Mipmap levels of the texture, eliminating sharp transitions.

Triple buffering

Improvement of double buffering for extra performance by adding another back buffer.

Tristrip

A common rendering primitive defining a sequence of adjacenttriangle primitives,where each triangle re-uses 2verticesfrom the previous one.

Trivial accept

The process of accepting an entirerendering primitive,3D model,orbounding volumecontents without further tests forclippingorocclusion culling.The opposite of trivial rejection.

Trivial rejection

Rejecting a rendering primitive or3D modelbased on a cheap calculation performed early in agraphics pipeline,(e.g. usingoutcodesinclipping). The opposite of trivial accept.

U

Unified memory

Amemory architecturewhere theCPUandGPUshare the sameaddress space,and often the samephysical memory.It is common in Inteland AMDprocessors with integrated graphics,SoCsandvideo game consoles.Supported on somediscrete GPUswith the use of anMMU.

UV coordinates

Coordinatesintexture space,assigned as vertex attributes and/or calculated invertex shaders,used fortexture lookup,defining the mapping from texture space to a3D modelsurface or any rendering primitive.

UV unwrapping

The process of flattening a3D model's surface into a flat2D planein a contiguous, spatially coherent manner fortexture mapping.

V

Vector graphics

Graphics represented as a set of geometrical primitives.

Vector maths library

A library defining mathematical operations onvector spacesused in3D graphics,concentrating on3Dand 4D vectors, and 4x4 matrices, often with optimisedSIMDimplementations.

Vertex buffer

A rendering resource managed by a rendering API holdingvertexdata. May be connected by primitive indices to assemble rendering primitives such astriangle strips.Also known as aVertex buffer objectinOpenGL.

Vertex cache

A specialised read-onlycachein agraphics processing unitfor buffering indexed vertex buffer reads.

Vertex shader

Shader processing vertices of a 3D model.

View transformation

Amatrixtransforming world space coordinates intocamera space.

View vector

In shading calculations, a 3D unit vector between thecameraand the point of interest on a surface.

View frustum

A truncated pyramid enclosing the subset of 3D space that projects onto a 'viewport' (a rectangular region in screen space, usually the entire screen).

Virtual reality

Computer-rendered content that (unlikeaugmented reality) completely replaces the user's view of the real world.

Volume texture

A type oftexture mapwith 3 dimensions.

Voxel

An extension ofpixelsinto 3 dimensions.

VSync

Vertical synchronization, synchronizes the rendering rate with the monitor refresh rate in order to prevent displaying only partially updated frame buffer, which is disturbing especially with horizontal camera movement.

Vulkan

High performance, low level graphics API byKhronos Group.

W

W buffering

Adepth bufferstoring inverse depth values, which has some advantages forinterpolationand precision scaling.

Weight map

A set of Vertex attributes controlling deformation of a3D modelduringskeletal animation.Per-vertexweightsare assigned to control the influence of multiple bones (achieved by interpolating the transformations from each).

Window

A rectangular region of a screen orbitmap image.

Wireframe

May refer toWireframe modelsorwireframe rendering.

Wireframe rendering

A rendering of a3D modeldisplaying onlyedgeconnectivity;used in3D modelling applicationsfor greater interactive speed, and clarity formesh editing.

World space

The globalcoordinate systemin a 3D scene, reached by applying amodel transformation matrixfrom the objects'local coordinates.

Z

Z buffer

A2D arrayholding depth values in screen space; a component of aframebuffer;used forhidden surface determination.

Z order

Amorton orderspace filling curve,useful for increasingcache coherencyof spatial traversals.

Z test culling

A form ofocclusion cullingby testingbounding volumesagainst aZ buffer;may be performed by agraphics processing unitusing occlusion queries.