Research On Soft Tissue Modeling And Collision Detection Algorithm In Virtual Surgery

As an important application of Virtual Reality in Medicine,Virtual Surgery overcomes the limits of traditional surgery training mode.It is the result of combining Virtual Reality with Medicine,which includes computer graphics,human-computer interaction,artificial intelligence,etc.Soft tissue deformation simulation is the key technology of Virtual Surgery,which determines the success or failure of Virtual Surgery.In this paper,human soft tissue is studied and simulated.The geometry modeling,physical modeling,deformation modeling integration solving and Collision Detection are studied systematically based on the request of authenticity and real time of human soft tissue deformation simulation.Firstly,the geometric model of soft tissue is formed based on its geometric characteristic.The stomach and the liver is selected as the soft tissues,with whose medical image data and the 3D modeling tool the surface model of it are constructed.TetGen software is adopted to get the tetrahedron subdivision graph of the surface model of the liver because the liver is solid model.Finally,the surface model structure of stomach model and the volume model structure of liver model is obtained,which is the foundation of soft tissue deformation simulation.Secondly,The traditional Virtual Surgery system mostly model the subject entirely or select a solid region to get the physical model,which lead to insufficient of real time property and flexibility.The projection transformation technology of Computer graphics and local mass-spring modeling dynamically generated method are applied in this paper,which has preferable flexibility and is independent of the triangle index value and mesh topology of certain region,and that has enhanced the real time performance of deformation simulation by the premise of guaranteeing the authenticity and reliability of the simulation system.Thirdly,the method of numerical solver is applied to solve the dynamics model of the deformation in the process of soft tissue deformation.Mid-point method is selected by comparing the common algorithm like Euler method、Mid-point method、Runge-Kutta method.Lastly,Collision Detection of soft tissue plays an important role in Virtual Surgery,which influences the real time performance of the whole system.AABB hierarchical bounding is used to build the virtual surgical instrument tip and soft tissue considering the characteristic of them.The experimental results indicate that the soft tissue deformation simulation applying local mass-spring modeling dynamically generated method can obtain good deformation performance and satisfy real time performance.Further more,the Collision Detection algorithm employed in this paper can satisfy the demand of the soft tissue deformation simulation.