A Hybrid Model Method for Accurate Surface Deformation and Incision Based on FEM and PBD

Shijie Tan,Jinjin Zheng,Hongjun Zhou,Tomàs Margalef

doi:10.1155/2021/8343312

Abstract

In some simulations like virtual surgery, an accurate surface deformation method is needed. Many deformation methods focus on the whole model swing and twist. Few methods focus on surface deformation. For the surface deformation method, two necessary characteristics are needed: the accuracy and real-time performance. Some traditional methods, such as position-based dynamics (PBD) and mass-spring method (MSM), focus more on the real-time performance. Others like the finite element method (FEM) focus more on the accuracy. To balance these two characteristics, we propose a hybrid mesh deformation method for accurate surface deformation based on FEM and PBD. Firstly, we construct a hybrid mesh, which is composed of a coarse volume mesh and a fine surface mesh. Secondly, we implement FEM on coarse volume mesh and PBD on fine surface mesh, and the deformation of fine surface mesh is constrained by the displacement of the coarse volume mesh. Thirdly, we introduced a small incision process for our proposed method. Finally, we implemented our method on a simple deformation simulation and a small incision simulation. The result shows an accurate surface deformation performance by implementing our method. The incision effect shows the compatibility of our proposed method. In conclusion, our proposed method acquires a better trade-off between accuracy and real-time performance.

Highlights

In some simulations like virtual surgery, an accurate surface deformation method is needed
We implemented our method on a simple deformation simulation and a small incision simulation. e result shows an accurate surface deformation performance by implementing our method. e incision effect shows the compatibility of our proposed method
E finite element method (FEM) is usually used for the numerical discrete model of constitutive equation in elastic mechanics [1]. e standard method is used to create physical elements according to each geometric element and to calculate the displacement of relevant element nodes according to the applied load [2]. e boundary conditions need to be well treated. e FEM can build different kinds of physical elements according to corresponding geometric units, such as triangle element in 2D and tetrahedral element in 3D [3]. e advantage of FEM is that it is close to the real world since it utilizes the actual physical parameters to get output with high accuracy of deformation

Summary

Introduction

In some simulations like virtual surgery, an accurate surface deformation method is needed. Others like the finite element method (FEM) focus more on the accuracy To balance these two characteristics, we propose a hybrid mesh deformation method for accurate surface deformation based on FEM and PBD. Kugelstadt et al proposed a fast co-rotated FEM using operator splitting for whole mesh model swinging and twisting [10] It acquires a good trade-off between accuracy and low time consumption but is not compatible with mesh dissection (model incision). Position-based dynamics (PBD) has been widely used in recent years Classical model methods such as FEM and MSM calculate the deformation according to Newton’s second law. Liu et al proposed a PBD method for tetrahedral element mesh model to simulate the deformation on soft tissue [16]

Results

Discussion

Conclusion