Character SkinningKinematic SkeletonsLinear Blend SkinningAssigning WeightsCharacter SkinningCOS 426Kinematic Skeletons• Hierarchy of transformations (“bones”) Changes to parent affectall descendent bones• So far: bones affect objects in sceneor parts of a mesh Equivalently, each point on a meshacted upon by one bone Leads to discontinuities whenparts of mesh animated• Extension: each point on a meshacted upon by more than one boneLinear Blend Skinning• Each vertex of skin potentially influenced by all bones Normalized weight vector w(v)gives influence of each bone transform When bones move, influenced vertices also move• Computing a transformation Tvfor a skinned vertex For each bone» Compute global bone transformation Tbfrom transformation hierarchy For each vertex» Take a linear combination of bone transforms»Apply transformation to vertex in original pose• Equivalently, transformed vertex position is weighted combination of positions transformed by bones∑∈=BbbvbvTwT)(( )∑∈=BbbvbdtransformevTwv)(Assigning Weights• Painted by hand•Automatic: function of relative distances tonearest bones• Smoothness of skinned surface depends on smoothness of
View Full Document
Unlocking...