Deformation And Cutting In Virtual Surgery System Of Soft Tissue

With the rapid development of computer technology in recent years,computer virtual reality technology has been widely used in various discipline,virtual reality technology plays a very important role especially within the medical profession.Virtual surgery system is a combination of virtual reality technology and medical products based on virtual reality technology.Virtual surgery system consists of geometric module,mechanical module,analysis module,deformation and visualization of cutting module.This thesis includes the following four aspects.The deforming of the object is due to an extel force,the first step of virtual surgery is collision detection,then getting access to external force information.The expressing of solid model is based on octree hierarchical sphere model in this essay.The information of tetrahedral is approximatively extracted by lexical analyzer principle.The principles and implementation steps based on octree collision detection is discussed in detail in this article.Deformation calculation principle of the mass spring element is discussed in detail.The thesis describes the dynamic calculations of the finite mass spring model,makes a special analysis of rapid deformation physical model methods based on midline support.Finally,through the three-dimensional surface mesh redraw,completing each step of rapid deformation combined with the rapid deformation physical model based on midline support and the finite mass spring element model.The thesis takes the cylinder model and major skeletal model of human hip joint as research examples.Simple cylinder deformation procedures and processes is givin in this dissertation,deformation results,the realization of skeletal geometry model and meshing,node import,grid redraw implementation process and deformation results are respectively given.Through the design of visual interface,we realize the calls for cylinder model and skeletal deformation model results.In the aspect of dynamic visualization of soft tissue deformation,this thesis analyzes the advantages and disadvantages of existing mainstream cut algorithm.The thesis take advantage of the improved algorithm for decomposing,namely a minimum unit subdivision algorithm.The model is divided into several tetrahedral units,fork points generated by detecting the cutting tool and the tetrahedral units between segments to determine the way tetrahedral units.In summary,based on the conventional finite mass spring element model,fast midline deformation modeling support structure combined with a surface mesh is、adopted to establish deformable model.The minimum unit subdividing is used to realize soft tissue cutting.This research approach is verified by instances of the deformation and cutting.