Study On Acceleration Techniques Of Physically Based Computer Animation

Physically based computer animation is always a hot topic in computer graphics especially in the special effects industry for films and games. Only physics makes more realistic. However, the complexity of the physical computation often leads to serious performance degradation, so it is necessary to investigate on the acceleration techniques. This paper aims to solve the problem by seeking for a tradeoff between the realistic effects and real time performance, to meet the needs from various applications.This paper focuses on the study in three aspects, including physically based tree animation with new method to accelerate the calculation of tree's branch deformation; general purpose computation on GPU (Graphics Processing Unit) which takes advantages of the parallelism and the programmability of graphics hardware to accelerate the calculation; physically based fluid simulation by GPU to accelerate the computation of Navier-Stokes equations, and simulate the on-surface flow in real-time.The main contributions of this thesis are mainly in the following aspects:â–¡ First ever attempt on coupling the on-surface flow with water absorption which to control the rendering of wetting effects. And stains transportation, erosion and deposition are also incorporated into the on-surface flow.â–¡ Based on the Navier-Stokes equations, we use GPU as a co-processor with CPU to simulate the smoke flowing with complex obstacles in 2D and 3D domains. To make sure stability with large time-step, the semi-Lagrangian method is used to compute the advection term and the implicit iteration method is used to compute the pressure-Poisson equation and the diffusion term. To process the complex obstacles, we introduce the modification texture which is used to embody various boundary conditions and the offset texture which is used to indicate the right directions to the obstacles.â–¡ Accelerate the algebra operations with GPU. To utilize the full potential of GPU, we take advantages of the four channels and the whole pipelines to reduce the number of rendering pass.â–¡ Use FEM (Finite Element Method) to compute the deformation of tree in wind. To accelerate the simulation, this paper takes a hybrid FEM way to alleviate the computation burden with different strategies for different kinds of branches. For those non-end branches with small swing, static analysis is enough to get their deformation; while for those non-end branches, we use step-by-step Newmark integration to calculate their vibration. Furthermore, we use shadow mapping technique based on GPU to achieve a realistic appearance.