VRPhysicsEnvironment - A Framework For Collision Detection and Physical Modelling in a Virtual Environment

Abstract

Physical modelling in Virtual Reality is a new and expanding field. Most such applications are either graphically rich but present little usability and have poor object interactions or are physically correct but have little visual appeal. We design a framework, VRPhysicsEnvironment, that is at once graphically rich, has a wealth of object interactions and physical correctness. In order to achieve this framework, we identify three major components to such a project: collision detection, collision handling and a hierarchy of virtual objects. After presenting the current research that exists on these topics, we go on to show how we use a current algorithm to implement fast collision detection using oriented bounding boxes. We enclose each object inside a box of arbitrary orientation. By searching for planes which separate these boxes (or lack of these planes) we can determine quickly when two boxes collide, and hence the objects that these boxes enclose. To add an object to the environment, we must also add an interaction function for this object and every other existing object. Realising that this makes extending the environment slow and arduous, we create a generalised collision handling function that is independent of the object type hence adding objects no longer requires the addition of these object interaction functions. The generalised collision handling function handles all collisions as changes in velocity and force of the two objects involved. By exchanging momentum and force to one another, it is possible to model collisions accurately. We create an application that allows users to place objects in their initial states and then run and watch the simulation in real time. However, the user has no control over any of the objects during the simulation for this purpose we create a second application virtual table tennis. We add two user controlled objects to the environment a table tennis bat and a hand. After documenting the algorithms and implementations we use, we highlight some of the major problems inherent in the system, such as difficulty in modelling continuous events in discrete time intervals and the impact this has on the system. We also show areas in which the system can be improved and extended upon in future work.

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Technical Reports

[1] Colin Dembovsky. Vrphysicsenvironment - a framework for collision detection and physical modelling in a virtual environment. Technical Report Honours Project Report, Virtual Reality Special Interest Group, Computer Science Department, Rhodes University, Grahamstown, South Africa, November 1999. [DOC] [HTML] [PDF] [BibTeX]

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