The Application Of Bounding Volume Algorithm In Collision Detection Of Medical VR

With the development of the technology in virtual reality, people are more and more thinking of the problem of collision detection, because the real-time and exact collision detection is very important to improve reality and enhance immersion for virtual environment. Virtual surgery is an important application of virtual reality technology in medicine. It can offer a platform enabling the surgeons to practice on virtual patients, thus getting rid of financial and ethical problems brought by training on living animals or on cadavers. In virtual surgery, it requires both the abilities to interact in real-time with the virtual organs through a force-feedback device and to perform a real-time visualization of the deformations. But collision detection is the precondition of calculating the deformation of the tissue; and to receive the precision deformation of the organs depending on the collision detection result. So collision detection is quite important in medical VR.There are mainly two algorithms of collision detection using in virtual reality technology: space decomposition algorithm and hierarchical bounding volume algorithm. The aims of the two algorithms are to reduce the number of pairs of objects or primitives that need to be checked for contact. And then greatly enhance the efficiency of the collision detection. The hierarchical bounding volume algorithms are widely used, witch idea is to approximate the object with a simpler bounding volume that is a little bigger than the object. By building hierarchies on object, one can obtain increasingly more accurate approximations of the objects. So during traversing hierarchical bounding volume, it speeds up collision detection by getting rid of primitive pairs, which will not intersect clearly through rapid intersection test between bounding volumes and just deal with those whose bounding volume is intersected. There are several kinds of bounding volumes, some of which are only suitable for collision detection between rigid objects,and others are applied to conditions that including not only rigid objects but also soft ones.In this dissertation we mostly investigate the bounding volume algorithm in collision detection technology. We put forward a kind of hybrid algorithm梒ombining the hierarchical bounding volume method and the bounding volume coordinate chain method based on AABB bounding volume, which is one kind of the bounding volumes. This algorithm can improve the efficiency of collision detection, and it can be used in condition that including soft objects. At the same time, according to the characteristic of the virtual surgery, we propose to use the bounding volume coordinate chain method based on AABB in cutting process of soft tissue and organs in virtual surgery. And comparing to the hierarchical bounding volume method, we analysis the excellence of the algorithm. At last by a simulating demo we realize the collision detection between two rigid bodies.