Modeling relaxed hand shape for character animation

We present a technique for modeling the deformations that occur to hand pose under the influence of gravity when the hand is kept in a relaxed state. A dynamic model of the hand is built using Proportional-Derivative controllers as a first order approximation to muscles. A process for tuning the model to match the relaxed hand shape of subjects is discussed. Once the model is tuned, it can be used to sample the space of all possible arm orientations and samples of wrist and finger angles are taken. From these samples, a kinematic model of passive hand deformation is built. Either the tuned dynamic model or the kinematic model can be used to generate final animations. These techniques increase the realism of gesture animation, where the character often maintains a relaxed hand.