3D computer graphics
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3D computer graphicsworksgraphic art that were created withaiddigital computersspecialized 3D software. In general,term may also refer toprocesscreating such graphics, orfieldstudy3D computer graphic techniquesits related technology.
3D computer graphicsdistinct from 2D computer graphicsthatthree-dimensional virtual representationobjectsstored incomputer forpurposesperforming calculationsrendering images. In general,art3D graphicsakinsculpting or photography, whileart2D graphicsanalogouspainting. In computer graphics software, this distinctionoccasionally blurred; some 2D applications use 3D techniquesachieve certain effects such as lighting, while some primarily 3D applications make use2D visual techniques.
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2 Creation3D computer graphics 3 ReflectionShading Models 4 3D graphics APIs 5 3D graphics software 6 External links |
Technology
OpenGLDirect3Dtwo popular APIs forgeneration3D imagery onfly. Many modern graphics cards provide some degreehardware acceleration based on these APIs, frequently enablingdisplaycomplex 3D graphicsreal-time. However, it's not necessaryemploy any onetheseactually create 3D imagery.
Creation3D computer graphics
The processcreating 3D computer graphics can be sequentially divided into three basic phases:
- Modelling
- Scene layout setup
- Rendering
Modelling
The modelling stage could be described as shaping individual objects thatlater used inscene. There existnumbermodelling techniques; Constructive Solid Geometry, NURBS modellingpolygonal modellinggood examples. Modelling processes may also include editing object surface or material properties (e.g., color, luminosity, diffusespecular shading components—more commonly called roughnessshininess, reflection characteristics, transparency or opacity, or indexrefraction), adding textures, bump-mapsother features.
Modelling may also include various activities relatedpreparing3D modelanimation. Objects may be fitted withskeleton,central frameworkan object withcapabilityaffectingshape or movementsthat object. This aids inprocessanimation,thatmovement ofskeleton will automatically affectcorresponding portions ofmodel. See also Forward kinematic animationInverse kinematic animation.
Modelling can be performed by means ofdedicated program (e.g., Lightwave Modeler, Rhinoceros 3D, Moray), an application component (Shaper, Lofter3D Studio) or some scene description language (asPOV-Ray). In some cases, thereno strict distinction between these phases;such cases modellingjust part ofscene creation process (this iscase,example,Caligari trueSpace).
Scene layout setup
Scene setup involves arranging virtual objects, lights, camerasother entities onscene which will later be usedproducestill image or an animation. If usedanimation, this phase usually makes use oftechnique called "keyframing", which facilitates creationcomplicated movement inscene. Withaidkeyframing, insteadhavingfix an object's position, rotation, or scalingeach framean animation, one needs onlyset up some key frames between which statesevery frameinterpolated.
Lightingan important aspectscene setup. As iscasereal-world scene arrangement, lighting issignificant contributing factor toresulting aestheticvisual quality offinished work. As such,can bedifficult artmaster. Lighting effects can contribute greatly tomoodemotional response effected byscene,fact whichwell-knownphotographerstheatrical lighting technicians.
TesselationMeshes
The processtransforming representationsobjects, such asmiddle point coordinate ofsphere andpoint on it's circumference intopolygon representation ofsphere,called tesselation. This stepusedpolygon-based rendering, where objectsbroken down from abstract representations ("primitives") such as spheres, cones etc,so-calles meshes, whichnetsinteconnected triangles.
Meshestriangles (insteade.g. squares)popular ashave provenbe easyrender using scanline rendering.
Polygon representationsnot usedall rendering techniques,in these casestesselation stepnot included intransition from abstract representationrendered scene.
Rendering
Rendering isfinal processcreatingactual 2D image or animation fromprepared scene. This can be comparedtakingphoto or filmingscene aftersetupfinishedreal life. Photo-realistic image qualityoftendesired outcome, andthis end several different,often specialized, rendering methods have been developed. These range fromdistinctly non-realistic wireframe rendering through polygon-based rendering,more modern techniques such as: scanline rendering, raytracing or radiosity.
Rendering software may simulate such cinematographic effects as lens flares, depthfield or motion blur. These artifacts are,reality,by-product ofmechanical imperfectionsphysical photography, but ashuman eyeaccustomedtheir presence,simulationsuch artifacts can lend an elementrealism toscene. Techniques have been developed forpurposesimulating other naturally-occurring effects, such asinteractionlightatmosphere, smoke, or particulate matter. Examplessuch techniques include particle systems (which can simulate rain, smoke, or fire), volumetric sampling (to simulate fog, dustother spatial atmospheric effects),caustics (to simulate light focusing by uneven light-refracting surfaces, such aslight ripples seen onbottom ofswimming pool).
The rendering processknownbe computationally expensive, givencomplex varietyphysical processes being simulated. Computer processing power has increased rapidly overyears, allowing forprogressively higher degreerealistic rendering. Film studios that produce computer-generated animations typically make use ofrender farmgenerate images intimely manner.
Often renderersincluded3d software packages, but theresome rendering systems thatused as pluginspopular 3d applications. These rendering systems include Final-Render, Brazil r/s, V-RayPixar Renderman.
ReflectionShading Models
Modern 3D computer graphics rely heavily onsimplified reflection model called Phong reflection model, which should not be confusedPhong shading whichan entirely different subject.
This reflection model andshading techniquesgives rise to, applypolygon-based rendering only. That is, raytracingradiosity does not use it.
In refractionlight, an important concept isrefractive index. In most 3D programming implementations,termthis value"indexrefraction," usually abbreviated "IOR."
Popular reflection rendering techniques3D computer graphics include:
- Flat shading: A technique that shades each polygonan object based onpolygon's "normal" andpositionintensity oflight source.
- Gouraud shading: Invented by H. Gouraud1971,fastresource-conscious vertex shading technique usedsimulate smoothly shaded surfaces.
- Texture mapping: A techniquesimulatinglarge amountsurface detail by mapping images (textures) onto polygons.
- Phong shading: Invented by Wu Tong Phong, usedsimulate specular highlightssmooth shaded surfaces.
- Bump mapping: Invented by Jim Blinn,normal-perturbation technique usedsimulate wrinkled surfaces.
3D graphics APIs
3D graphics have become so popular, particularycomputer games, that specialized APIs (Application Programmer Interfaces) have been createdeaseprocessesall stagescomputer graphics generation. These APIs have also proved vitalcomputer graphics hardware manufacturers, asprovidewayprogrammersaccesshardwarean abstract way, while still taking advantage ofspecial hardwarethis-or-that graphics card.
These APIs3D computer graphicsparticularly popular:
3D graphics software
While theremany 3D modellinganimation packages, The five that have gained most popularity are:
- Alias Wavefront's Maya - Perhapsmost popular 3D software inindustry as2003. Used by many ofleading visual effects studioscombinationPixar's Photorealistic Renderman. Well regarded due toflexible plugin APIMEL scripting interface. Version 5 assept 2003.
- discreet's 3D Studio Max - Originally written by Kinetix (a divisionAutodesk) assuccessor3D Studio. Kinetix was later mergedAutodesk's latest acquisition, Discreet Logic. Current version asOct 20036.0. Widely used ingames industryby home users.
- Newtek's Lightwave 3D - originally developedAmiga computersearly 1990s,later evolved into an advancedwidely used 3D graphicsanimation package, now availableWindows, Mac OSMac OS X. Current version7.5 (aslate 2003). It consiststwo components: ModelerLayout (scene editor). It isfavorite among hobbyists,is usedmany major visual effects facilities such as Digital Domain.
- Avid's Softimage XSI - Biggest contenderMaya's dominance.In 1987, Softimage Inc,Montreal-based company wrote Softimage|3D which quickly becamemost popular 3D programthat period. In 1994, Microsoft purchased Softimage Inc. They started rewriting SI|3DWindows NT. That effort was called Softimage|XSI. Microsoft sold SoftimageAvid1998. Till version 1.5, XSI was playing catchuptermsfeaturesits predecessor SI|3D. But since version 2.0, it'scomplete packageis likelywintop spot that its predecessor enjoyed. Current version aslate 20033.54.0 rumoredbe released soon.
- Curious Labs' Poser -lower-end packageassembling, rendering,animating 3D content supplied inAlias Wavefront OBJect file format, Poser also haslarge online community supporting its use inhobby market. While Poser does not provide forcreationoriginal mesh objects,does allow contentbe imported and, due'hackable' configuration files, has drawn one oflargest user-bases onmarket.
- Anim8or by Steve Glanville - A freeware package that can perform basic modelinganimation. It also has rudimentary rendering capability, but it's real strengthin developingusing bone structuresanimated figures.
- Blender - A free modellerrenderersuch features as supportscripting.
- Corel Bryce 5 - A 3D landscape generatingrendering application. Featuresgraphical user interface, basic boolean modeling, mesh model import capability,rudimentary animation capability. Although not as powerful as most ofother rendering programs,can still produce stunning resultscapable hands.
- Caligari trueSpace - An integrated 3D graphics applicationan intuitive interface. A distinctive featurethis applicationthat all phases3D graphics creationperformed withinsingle program. Not as advanced as leading packagesthis domain but provides such features as physical phenomena simulation (e.g., wind, gravity, body collisions) out-of-the-box.
- Cinema4d - Fast rendering engine, radiosity rendering.
- formZ - Offers topological manipulationgeometry.
- POV-Ray - Advanced, free raytracing software. Uses its own scene description languagefeatures like macros, loopsconditional statements. It's completely free albeit not released under GPL. Does not includebuilt-in modeller.
- Moray - A modellerPOV-Ray.
- RealSoft3D - LinuxWindows 3D modellerrenderer
- Rhinoceros 3D - A powerful NURBS modeller.
- Universe by Electric Image - ModelingAnimation suiteone offastest 3D renderers that exists.
- Wings 3D by Bjorn Gustavsson - Open source modeling program thatplatformOS independentruns underErlang operating environment. This programcapableexporting models invarietycommonly used formats.
See also: VRML
External links
