Facial Expressions & RiggingTurning in ProjectsMatrix ComputationsVector Dot VectorVector Dot MatrixMatrix Dot MatrixHomogeneous VectorsSlide 8Homogeneous MatricesPosition Vector Dot MatrixSlide 11Slide 12Slide 13InversionDirection Vector Dot MatrixMatrix Dot Matrix (4x4)IdentityHuman Facial ExpressionsFacial FeaturesFacial Muscles‘Universal’ Expression GroupsFACSSlide 23Emotional AxesWrinklesFacial Expression ReadingFacial ModelingSlide 28Traditional ModelingPhotograph & DigitizeSculpt & DigitizeLaser ScanComputer VisionFacial Expression TechniquesSlide 35Texture Based MethodsBone Based MethodsShape Interpolation MethodsPose Space DeformationArtificial Muscle MethodsArtificial MusclesAnatomical MethodsSlide 43Shape InterpolationSlide 45Interpolation TargetsShape Interpolation AlgorithmPosition InterpolationNormal InterpolationShape Interpolation and SkinningMorph Target DOFsTarget StorageSlide 53Slide 54Morph::Update()Colors and Other PropertiesSlide 57RiggingSlide 59Slide 60Rigging and AnimationDOF TypesGrouping DOFsSlide 64DOF ExpressionsRig MappingsPush vs. PullPushing DOF Values*Rig MappingMinimalist RiggingFull Body MorphingSmooth Skin AlgorithmFacial Expressions & RiggingCSE169: Computer AnimationInstructor: Steve RotenbergUCSD, Winter 2004Turning in Projects‘turnin’ toolhttp://acs.ucsd.edu/info/turnin.phpMatrix ComputationsVector Dot Vector  zzyyxxzyxzyxbabababbbaaababaVector Dot Matrix zzzyzxzyzyyyxyxzxyxxxzyxcvbvavvcvbvavvcvbvavvvvvMvvvzyxzyxzyxcccbbbaaaMcbavzyxvvv Matrix Dot MatrixNML 333231232221131211333231232221131211333231232221131211nnnnnnnnnmmmmmmmmmlllllllll32132212121112nmnmnml NccNbbNaaMLMLMLHomogeneous VectorsTechnically, homogeneous vectors are 4D vectors that get projected into the 3D w=1 space wzwywxwzyxvvvvvvvvvvHomogeneous VectorsVectors representing a position in 3D space can just be written as:Vectors representing direction are written:The only time the w coordinate will be something other than 0 or 1 is in the projection phase of rendering, which is not our problem 1zyxvvv 0zyxvvvHomogeneous MatricesA homogeneous (4x4) matrix is written:The only time the right hand column will not be (0,0,0,1) is during view projection1000zyxzyxzyxzyxdddcccbbbaaaMPosition Vector Dot Matrix 11wzzzzyzxzyyzyyyxyxxzxyxxxzyxvdcvbvavvdcvbvavvdcvbvavvvvvMvvvdcbav zyxvvv1000zyxzyxzyxzyxdddcccbbbaaaMPosition Vector Dot Matrixdcbav zyxvvvv=(.5, .5,0,1)xyLocal Space(0,0,0)Position Vector Dot Matrixdcbav zyxvvvv=(.5, .5,0,1)xyLocal Space(0,0,0)xyWorld Space(0,0,0)abdMatrix MPosition Vector Dot Matrixdcbav zyxvvvv=(.5, .5,0,1)xyLocal Space(0,0,0)xyWorld Space(0,0,0)abdv’InversionIf M transforms v into world space, then M-1 transforms v’ back into local spaceIMMMvvMvv11Direction Vector Dot Matrix 00wzzzyzxzyzyyyxyxzxyxxxzyxvcvbvavvcvbvavvcvbvavvvvvMvvvcbavzyxvvv 1000zyxzyxzyxzyxdddcccbbbaaaMMatrix Dot Matrix (4x4)1000zyxzyxzyxzyxdddcccbbbaaaMNMM The row vectors of M’ are the row vectors of M transformed by matrix NNotice that a, b, and c transform as direction vectors and d transforms as a positionIdentityTake one more look at the identity matrixIt’s a axis lines up with x, b lines up with y, and c lines up with zPosition d is at the originTherefore, it represents a transformation with no rotation or translation1000010000100001IHuman Facial ExpressionsFacial FeaturesKey Facial FeaturesDeformable SkinHairEyesArticulated Jaw (teeth…)TongueInside of mouthEach of these may require a different technical strategyFacial Muscles‘Universal’ Expression GroupsSadnessAngerHappinessFearDisgustSurpriseFACSFacial Action Coding System (Ekman)Describes a set of ‘Action Units’ (AUs) that correspond to basic actions (some map to individual muscles, but other involve multiple muscles, or even joint motion)Examples:1. Inner Brow Raiser (Frontalis, Pars Medialis)2. Outer Brow Raiser (Frontalis, Pars Lateralis)14. Dimpler (Buccinator)17. Chin Raiser (Mentalis)19. Tongue Out20. Lip Stretcher (Risoris)29. Jaw Thrust30. Jaw Sideways31. Jaw ClencherFACSExpressions are built from basic action unitsHappiness:1. Inner Brow Raiser (Frontalis, Pars Medialis)6. Cheek Raiser (Orbicularis Oculi, Pars Orbitalis)12. Lip Corner Puller (Zygomatic Major)14. Dimpler (Buccinator)Emotional AxesEmotional states can loosely be graphed on a 2-axis systemX=Happy/SadY=Excited/RelaxesWrinklesWrinkles are important visual indicators of facial expressions, and have often been overlooked in computer animationFacial Expression ReadingBooks“Computer Facial Animation” (Parke, Waters)“The Artist’s Complete Guide to Facial Expression” (Faigin)“The Expression of Emotions in Man and Animals” (Darwin)Papers“A Survey of Facial Modeling and Animation Techniques” (Noh)Facial ModelingFacial ModelingPreparing the facial geometry and all the necessary expressions can be a lot of workThere are several categories of facial modeling techniquesTraditional modeling (in an interactive 3D modeler)Photograph & digitize (in 2D with a mouse)Sculpt & digitize (with a 3D digitizer)Scanning (laser)Vision (2D image or video)Traditional ModelingPhotograph & DigitizeSculpt & DigitizeLaser ScanComputer VisionFacial Expression TechniquesFacial Expression TechniquesTexture swapping/blendingBones (joints & smooth skin)Shape interpolation (morphing)Artificial muscles (FFDs…)Anatomical simulationTexture Based MethodsA very low quality approach to doing facial expressions is simply to swap or blend between various texture maps on the faceObviously, this is pretty cheezy and doesn’t really model actual skin