CS 445 / 645 Introduction to Computer GraphicsReviewCombining EverythingThe Final Combined EquationWhat influences these terms?Direct illumination questionsDirect IlluminationSlide 8Slide 9OverviewGlobal IlluminationThe ‘Rendering Equation’Slide 13Slide 14Slide 15Slide 16Slide 17Approximating the Rendering EquationSlide 19Ray CastingSlide 21Slide 22Slide 23Slide 24Constructing Ray Through a PixelSlide 26Slide 27Ray-Scene IntersectionRay-Sphere IntersectionSlide 30Slide 31Slide 32Ray-Triangle IntersectionRay-Plane IntersectionRay-Triangle IntersectioOther Ray-Primitive IntersectionsRay Casting – direct illuminationShadowsRecursive Ray Tracing – second-order effectsMirror reflectionsTransparencySlide 42Refractive TransparencyRefractive TranparencySummaryCS 445 / 645Introduction to Computer GraphicsLecture 16Lecture 16LightingLightingLecture 16Lecture 16LightingLightingReviewWe have a model for determining the brightness We have a model for determining the brightness (radiance)(radiance) of a ray rooted at a point on a surface of a ray rooted at a point on a surface and oriented towards the cameraDirect and oriented towards the cameraDirect illumination onlyillumination only–Ambient termAmbient term–Diffuse termDiffuse term–Specular termSpecular termWe have a model for determining the brightness We have a model for determining the brightness (radiance)(radiance) of a ray rooted at a point on a surface of a ray rooted at a point on a surface and oriented towards the cameraDirect and oriented towards the cameraDirect illumination onlyillumination only–Ambient termAmbient term–Diffuse termDiffuse term–Specular termSpecular termCombining EverythingSimple analytic model: Simple analytic model: •diffuse reflection +diffuse reflection +•specular reflection +specular reflection +•emission +emission +•““ambient”ambient”Simple analytic model: Simple analytic model: •diffuse reflection +diffuse reflection +•specular reflection +specular reflection +•emission +emission +•““ambient”ambient”SurfaceThe Final Combined EquationSingle light source:Single light source:Single light source:Single light source:LnSLDALAEIRVKILNKIKII )()( --LnSLDALAEIRVKILNKIKII )()( --NLRVViewerWhat influences these terms?Influencing factorsInfluencing factors•Light positionLight position•Sample point positionSample point position•Camera positionCamera position•Surface angle with respect to light vectorSurface angle with respect to light vector•Surface angle with respect to camera vectorSurface angle with respect to camera vectorInfluencing factorsInfluencing factors•Light positionLight position•Sample point positionSample point position•Camera positionCamera position•Surface angle with respect to light vectorSurface angle with respect to light vector•Surface angle with respect to camera vectorSurface angle with respect to camera vectorDirect illumination questions•Camera moves from one position to anotherCamera moves from one position to another–Angle between light and surface unchangedAngle between light and surface unchanged–Angle between camera and surface changesAngle between camera and surface changes•A tracking camera follows object as it moves in sceneA tracking camera follows object as it moves in scene–Angle between light and surface changesAngle between light and surface changes–Angle between camera and surface unchangedAngle between camera and surface unchanged•An object moves from on position to anotherAn object moves from on position to another–Both angles have changedBoth angles have changed•Camera moves from one position to anotherCamera moves from one position to another–Angle between light and surface unchangedAngle between light and surface unchanged–Angle between camera and surface changesAngle between camera and surface changes•A tracking camera follows object as it moves in sceneA tracking camera follows object as it moves in scene–Angle between light and surface changesAngle between light and surface changes–Angle between camera and surface unchangedAngle between camera and surface unchanged•An object moves from on position to anotherAn object moves from on position to another–Both angles have changedBoth angles have changedProvides a way to measure radiance at a point in a Provides a way to measure radiance at a point in a specific directionspecific direction•What points?What points?–VerticesVerticesWhat do you do for points between vertices?What do you do for points between vertices?Provides a way to measure radiance at a point in a Provides a way to measure radiance at a point in a specific directionspecific direction•What points?What points?–VerticesVerticesWhat do you do for points between vertices?What do you do for points between vertices?Direct IlluminationThis becomes a problem of “shading”This becomes a problem of “shading”and we’ll discuss it laterand we’ll discuss it laterThis becomes a problem of “shading”This becomes a problem of “shading”and we’ll discuss it laterand we’ll discuss it laterProvides a way to measure radiance at a point in a Provides a way to measure radiance at a point in a specific directionspecific direction•What points?What points?–Other points to sample?Other points to sample?Provides a way to measure radiance at a point in a Provides a way to measure radiance at a point in a specific directionspecific direction•What points?What points?–Other points to sample?Other points to sample?Direct IlluminationThis is a form of ray casting.This is a form of ray casting.We’ll talk about it nextWe’ll talk about it nextThis is a form of ray casting.This is a form of ray casting.We’ll talk about it nextWe’ll talk about it nextDirect IlluminationProvides a way to measure radiance at a point in a Provides a way to measure radiance at a point in a specific directionspecific direction•What points?What points?•What directions?What directions?–Towards the cameraTowards the camera–No secondary effectsNo secondary effectsProvides a way to measure radiance at a point in a Provides a way to measure radiance at a point in a specific directionspecific direction•What points?What points?•What directions?What directions?–Towards the cameraTowards the camera–No secondary effectsNo secondary effectsOverviewDirect (Local) IlluminationDirect (Local) Illumination•Emission at light
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