Water with Character(s): Fluid Simulation with Articulated Bodies

We present an algorithm for creating realistic animations of characters that are interacting with fluids. Our approach combines dynamic simulation with data-driven (motion capture) and related kinematic motions to produce realistic animation in a fluid. The interaction of the articulated body with fluids is done by (a) incorporating joint constraints with rigid animation, and by (b) extending the Rigid Fluid method, which allows simulation of rigid bodies in a fluid, to deal with articulated chains. We introduce a constraintbased solver for coupling motion trajectories of articulated structures with fluid simulation. This solver takes as input the current state of the simulation and calculates the exact angular and linear accelerations of the connected bodies to incorporate motion trajectories into the simulation. These accelerations are used to estimate the forces and torques that are applied at each joint. These forces are used to conform the motion trajectories of the articulation data with the simulation of the fluid. We demonstrate results for animations such as swimming in water. The ability to have articulated bodies interact with fluids also allows us to generate simulations of simple water creatures that are driven by simple controllers.