Research On Role-Based And Agent Oriented Collaborative Virtual Environment

The combination of Vritual Reality with network influences hugely humans to change their working and life styles. Moreover, the derivative system -collaborative virtual environment, which integrates VR, network, CSCW, multimedia and AI technologies, has become the next generation computing interface and has been applied on digital entertainment, real world simulation and abstract concept modeling.Giving emphasis on formal modling of collaborative virtual environment and controls on collaborative subjects and collaborative objects, this dissertation has detail research on the following topics involving role-based and agent oriented collaborative virtual environment, concurrency control for collaborative object and navigation control and area of interest management for collaborative subject. Based on some new notions and approaches introduced, this dissertation presents some new models and solutions for the topics mentioned above.On formal modeling for collaborative virtual environment, this thesis introduces role theory and agent technology. The concept role is applied to integrated avatar in CVE, agent in CVE and collaborative subject in CVE into one part, and bind privileges and duties with collaborative subject. Thus, this dissertation proposes a basic model for role-based and agent oriented collaborative virtual environment which includes an important concept - Intelligent Entity in Running State; furthermore, this thesis presents a role-based and agent oriented conceptual framework for collaborative subject in CVE. Considering the time factor as an important impact factor for the dynamic and real-time collaborative virtual environment, this thesis extends collaborative virtual environment from traditional 3D system to 4D systems that takes the time factor as the fourth dimension, and applies extended fuzzy-timing Petri Nets technology to formalize collaborative virtual environment with time factor integrated.On concurrency control of visual collaborative objects, this dissertation advances three principles which are cofilnct with each other at concurrent space: consistency, responsiveness and concurrency; and divides visual collaborative objects into two categories: concentrative and distributed. Under the considertation that the consistency is maintained and responsiveness and concurrency is optimized as much as possible, this thesis studies to seek an equilibrium point among thesethree criteria for both different visual collaborative objects. Hence, two independent concurrency control scheme is brought forward: role-based token speculation concurrency control sheme for concentrative visual collaborative objects and role-based distributed visual collaborative objects centric concurrency control scheme. Based on the basic policy of confliction avoidance, the former uses token scheme to guarantee consistency and introduces token speculation scheme to optimize system responsiveness and individual responsiveness through distribution of a token of a visual collaborative object before the user who actually attempts to perform a concurrent action on the visual collaborative object can be determined. Based on the basic policy of confliction elimination, the latter adopts relax WYSIWIS for consistency, and local manipulation for responsiveness and concurrency. The whole concurrency manipulation is divided into three steps: local manipulation improving responsiveness, server-side manipulation validation maximizing concurrency, and replica synchronization guaranteeing consistency.On navigation control of visual collaborative subjects, the research focuses on two aspects including global path planning and local collision detection. Considering particularity of optimizing criteria and semantics relativity for path planning, this dissertation presents applying semantics reach-ability to substitute geometry contiguity and revising the traditional A* algorithm to integrate several semantics relativity heuristic functions to achieve optimal path planning criteria. On the other hand, based on analysys of all possible...