Research On Improved Boolean Operations And Its Application On Visual Arthroscopic Surgery System

Virtual Surgery is an important application of Virtual Reality in medicine, and its development has tremendous impact on modern surgery level. Recently years, as the development of endoscopic surgery, the research on endoscopic surgery system with both reality and force feedback has become the main orientation of Virtual Surgery. Arthroscopic surgery is a kind of endoscopic surgery, and its virtual system is a simulation of the arthroscopic operation process.Cutting operation is an important part of virtual surgery, and both its efficiency and reality must be ensured during the simulation. Cutting on organs and cutting on bones are the two kind of Cutting operations in virtual surgery. Our research is based on the cutting operation on bones which is expressed as a geometry mesh model.Since Boolean method has widely used in Computer Graphics, there are three kind of applications: constructive solid geometry models, texture synthesis, and operations on geometry mesh models. This thesis is mainly based on Computer Graphics. In the first part of thesis we discussed the essential theory of Boolean method, how it detects the intersected elements, and how it implements different operations on models. In this thesis we also discussed the normal Boolean method on geometry mesh models in 3D space. We present an improvement method according to several kinds of widely used Boolean operations, especially when the geometry mesh model is a kind of basic geometry element. We may use the geometry's variable function to accelerate the inside-outside test step.The mainly part of this thesis is that we present a fast improved Boolean method for cutting operation on geometry mesh models. This improved method is based on overleap the step of re-sequence for mesh models, which is time costing in normal methods. Our fast improved method is often used in the case when we need to cut a geometry mesh model use a curve or a polygon in straight direction. The mainly improvement of our method is that we overleap some time-costing step in Boolean operations and simplify 3D operation to 2D operation. We omit re-sequence operation of models, and the work of inside-outside test of 3D models is finished in 2D coordinate. We implement a smooth strategy after Boolean operation by keeping the vertices' vector, thus smooth operation is also time-saving compare to 3D smooth method.In the last part of this thesis, we further discussed how to simulate the drill operation and how to express the two tunnel meshes. For the trait of virtual endoscopic surgery, we made a further improvement to our method, such as eliminate T points in meshes, dynamic simulation of drill process, and so on.