CSCE 641: Computer Graphics Lighting3D Rendering pipelineSlide 3OutlineLighting/IlluminationDirect and Indirect LightGlobal Illumination IISlide 8Slide 9Reflection ModelsSlide 11Slide 12Slide 13Types of Reflection FunctionsSlide 15Slide 16MaterialsIllumination ModelAmbient LightTotal IlluminationDiffuse LightSlide 22Slide 23Slide 24Slide 25Specular LightSlide 27Finding the Reflected VectorSlide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Multiple Light SourcesSlide 39Slide 40Other LightsAttenuationSlide 43Slide 44Spot LightsSlide 46Slide 47Slide 48Slide 49Implementation ConsiderationsSlide 51Opengl FunctionsNext Lecture1CSCE 641: Computer GraphicsLightingJinxiang ChaiScan conversion3D Rendering pipelineModeling transformationlightingViewing transformationProject transformationClippingImageTransform into 3D world systemIlluminate according to lighting and reflectanceTransform into 3D camera coordinate systemTransform into 2D camera systemClip primitives outside camera’s viewDraw pixels (includes texturing, hidden surface, etc.)Scan conversion3D Rendering pipelineModeling transformationlightingViewing transformationProject transformationClippingImageTransform into 3D world systemIlluminate according to lighting and reflectanceTransform into 3D camera coordinate systemTransform into 2D camera systemClip primitives outside camera’s viewDraw pixels (includes texturing, hidden surface, etc.)OutlineAmbient, diffuse and specular lightLight attenuation & spot lightsLighting/IlluminationColor is a function of how light reflects from surfaces to the eyeGlobal illumination accounts for light from all sources as it is transmitted throughout the environmentLocal illumination only accounts for light that directly hits a surface and is transmitted to the eyeDirect and Indirect LightGlobal Illumination IIGlobal Illumination IILighting/IlluminationColor is a function of how light reflects from surfaces to the eyeGlobal illumination accounts for light from all sources as it is transmitted throughout the environmentLocal illumination only accounts for light that directly hits a surface and is transmitted to the eyeReflection Models Definition: Reflection is the process by which light incident on a surface interacts with the surface such that it leaves on the incident side without change in frequency.Reflection Models Definition: Reflection is the process by which light incident on a surface interacts with the surface such that it leaves on the incident side without change in frequency.Reflection Models Definition: Reflection is the process by which light incident on a surface interacts with the surface such that it leaves on the incident side without change in frequency.Reflection Models Definition: Reflection is the process by which light incident on a surface interacts with the surface such that it leaves on the incident side without change in frequency.Types of Reflection FunctionsIdeal SpecularReflection LawMirrorTypes of Reflection FunctionsIdeal SpecularReflection LawMirrorIdeal DiffuseLambert’s LawMatteTypes of Reflection FunctionsIdeal SpecularReflection LawMirrorIdeal DiffuseLambert’s LawMatteSpecularGlossyDirectional diffuseMaterialsPlastic Metal MatteFrom Apodaca and Gritz, Advanced RenderManIllumination ModelAmbient LightUniform light caused by secondary reflectionsDiffuse LightLight scattered equally in all directionsSpecular LightHighlights on shiny surfacesAmbient Light A =intensity of ambient lightka=ambient reflection coefficientReally 3 equations! (Red, Green, Blue)Accounts for indirect illuminationDetermines color of shadowsAkIaTotal IlluminationAkIaDiffuse LightAssumes that light is reflected equally in all directionsHandles both local and infinite light sourcesInfinite distance: L doesn’t changeFinite distance: must calculate L for each point on surfaceLNSurfaceDiffuse Light C = intensity of point light sourcekd = diffuse reflection coefficient = angle between normal and direction to light)()cos( NLkCkCIddLNSurfaceNL)cos(Total IlluminationAkIaTotal Illumination)( NLCkAkIdaMaterialsPlastic Metal MatteFrom Apodaca and Gritz, Advanced RenderManSpecular LightPerfect, mirror-like reflection of light from surfaceForms highlights on shiny objects (metal, plastic)LNSurfaceRESpecular Light C = intensity of point light sourceks = specular reflection coefficient =angle between reflected vector (R) and eye (E)n =specular coefficientnsnsERkCkCI )()(cos LNSurfaceER)cos(REFinding the Reflected VectorLNSurfaceRFinding the Reflected VectorLNSurfaceR||LLFinding the Reflected VectorLNSurfaceR||LL)()cos(||NLNNL ||LLL Finding the Reflected VectorLNSurfaceR||LL LLR||Finding the Reflected VectorLNSurfaceR||LLLLLLR  ||||2Finding the Reflected VectorLNSurfaceR||LLLNNLR  )(2Total Illumination)( NLCkAkIdaTotal Illumination nsdaERkNLkCAkI )()( 5nTotal Illumination nsdaERkNLkCAkI )()( 50nTotal Illumination nsdaERkNLkCAkI )()( 500nMultiple Light SourcesOnly one ambient term no matter how many lightsLight is additive; add contribution of multiple lights (diffuse/specular components)Total Illumination nsdaERkNLkCAkI )()( Total Illumination inisidiaERkNLkCAkI )()(Other LightsAttenuation caused by fog, smokeSpot lightsAttenuationDecrease intensity with distance from lightd = distance to lightr = radius of attenuation for light)1,0max(),(rdrdatt )1,0max(),(22rdrdatt   2221,0max),(rdrdatt 22),(rderdattAttenuation iinisidiardattERkNLkCAkI ),()()(Attenuation iinisidiardattERkNLkCAkI ),()()(Spot LightsEliminate light contribution outside of a coneALSurfaceSpot LightsEliminate light contribution outside of a coneALSurface ALALALspotCoeff),cos(0),cos(Attenuation iinisidiaspotCoeffERkNLkCAkI )()(Spot Lights iinisidiaspotCoeffERkNLkCAkI )()(Spot Lights iinisidiaspotCoeffERkNLkCAkI