Skeleton Animation Skinning Based On Position- Based Dynamics

Skeletal animation technology is widely used in games,animations and movies.The rise of skeletal skinning technology has provided great convenience for animators.At the same time,it improves the efficiency of animation production.Therefore,the requirements for simulation quality and speed of animation are correspondingly higher.The main method of skeleton animation is linear blend skinning approach and the dual quaternion skinning approach.However,the deformation resulting from the classical technology suffers from some undesirable effects.The linear blend skinning approach usually leads to artefacts like volume loss and candy-wrapper effect.The dual quaternion skinning method suffers from an undesirable joint-bulging at the joints.Both of the two methods require manual improvement.It is time-consuming and need great effort.It is hard to achieve satisfactory results,especially in real time applications.Therefore,how to build an efficient skinning system is a problem that needs to be solved in skeletal animation.This article focuses on the skeletal animation skinning method based on position-based dynamics after comparing several commonly used skeletal animation skinning methods.This method is easy to implement and fast to compute.It is controllable and stable as well.This paper combines the position-based dynamics with energy constraint to improve the linear blending skinning method to achieve better skinning effect.This paper mainly includes the following work.(1)Since the linear blending skinning could lead to volume loss of the model,we generate a tetrahedral mesh of the input skin mesh using a Delaunay tetrahedral method.This step divides the model into smaller units and add volume information to the model,which is the basic of later volume preservation.(2)The skin is first deformed with a classic linear blend skinning approach,which usually lead to artifacts like the candy-wrapper effect or volume loss.Then we enforce the geometric constraints which displace the positions of the vertices to mimic the behavior of the skin and achieve effects like volume preservation.The proposed method presents a better visual effect compares with purely linear blending skinning.(3)We adopt the method of energy constraint to handle large deformed elements which could accelerate the system's convergence rate.The experimental results show that our method can effectively improve the skinning effect of the linear blending skinning algorithm.This method solved the volume loss problem.At the same time,the implementation of the energy constraint speeds up the convergence of the system,therefore this method has a high skinning speed.