Research On Realistic Hair Simulation Methods Based-on Mass-spring Model

Hair simulation is very popular in the simulation of the human body. Compared with other substance, hairs have very huge quantity and complicate movement patterns, which decide that it is very difficult to model and simulate. So, the dynamic simulation of hairs is an important research area in computer graphics. So this paper focused on the following areas aiming to seek for a tradeoff between the realistic effects and real time performance.Firstly, focusing on the real-time quality of the mass-spring system and the realistic performance of the physical model method, this paper propose a new hair strand model in view of the classic mass-sring model. To avoid the defect that the partical velocity and position were failed to renovate, this paper improve the traditional mass-spring model. To be specific, one altititude spring was added to the traditional model, took place of the angle spring, thus complicate computation was avoid and the distortion of bending and torsion were well simulated.Secondly, how the Lagrangian dynamic equation can be decoupled and efficiently solved was showed. The hair was discretized. The energies of per element were got by employing finite element methods. For simplicity, constant shape functions were used. These shape functions result in particularly simple expressions when integrated over the element length. In the system of resulting equations, the angular velocity together with the quaternions was brought to be the state variables. The resulting system of equations was decoupled. An efficient numerical solution of Lagrangian equation has been got. The requirement of fast simulation of hair was satisfied.Thirdly, In order to get more detail behaviors of hairs,we simulate each hair strand using mass-spring models as opposed to clumped modles.For sake of efficiency,we propose a method that combines Lagrangian thchniques and Eulerian techniques to handle self-collision of hairs.Our approach divided the hair space into many cells ,and the hair density and velocity of each cell are calculated in the center,then we applies Lagrangian techniques to every particles,thus,the velocity and position of each particle are updated within one time step.The experiments demonstrate that our method can simulate dynamic hairs efficiently.Finally, the system of hair simulation was implemented. The scheme based on the new mass-spring model system and the algrithms for body collision and self-collison were verified. Experiments indicate that the requirement of fast and realistic simulation of hair was satisfied. Results show that the tasks of this paper are useful in hair simulation.