The Research And Realization Of Virtual Environment Walkthrough And Interactive Technology Based On VRML

Since 1990s virtual reality technique has been one of the hot spots in IT field. It creates a living virtual environment by using communicate with it freely. Now VR is widely computer and allows the users used in the military, medicine, education, virtual travel, shopping, interactive entertainment etc.As a modeling language, VRML is regarded as the second generation of web language aiming at constructing interactive 3D multi-media on Internet. It can be used to describe attributes and behaviors of 3D objects, create virtual world, integrate texts, pictures, sounds, MPEG and so on. It can also be embedded with codes programmed by Java, JavaScript languages and makes the design of VR become more efficient.It is very popular to use VR in designing districts, city plans by virtual roaming technique. Roaming System is a virtual environment in specific ranges which includes vivid vision, hearing and feeling in one. Using some necessary equipments, users can walkthrough in this virtual world or observe virtual objects from any angle and they will feel themselves in the scene. They can also operate the objects inside virtual environment. Virtual walkthrough system is the integrated application of virtual reality skills, which has a promising future.The paper introduced Virtual Reality synoptically at first. It expatiated on the basic factors and characters of the VR system. It expounded the hardware and software realizations of VR also. The paper introduced synoptically the history of VRML, and its working theory and showed the expectation of VRML. The paper putted forward the background, significance and researchful contents of this task on the basic.In the aspect of research and realization of VR system, the methods are departed into several steps. At first, the prototype system should be in the progress of requirement analysis and function design. Then we combined VRML, and JavaScript to resolve this task. In the second steps we should analyze and compare these different modeling technologies and realize the building of 3d model. We should realize the conformity and function optimize of system model also. The emphasis of paper is to research and realize the alternation function of virtual campus system. It includes the realization of function such as cruise, controlling viewpoints, view in room, the alternation between 2d map and 3d model,collision, communications between JavaScript and scene etc. Chapter 1 brief introduction to the basic concept of virtual reality and characteristic of it. Then expatiate the background meaning, content and goal of our project.Chapters 2 introduce the principle and system architecture of VRML, especially focus on the important concepts such as node scene graph structure event system and extended mechanism.Chapter 3 describe a designing and implementation of virtual campus walkthrough system based on VRML, First of all introduce the concept of walkthrough system, then analyze and compare the two techniques of how to implement virtual walkthrough(geometry-based modeling and rendering一GBMR and image-based modeling and rendering一IBMR),at last probe into the techniques of 3D scene modeling and optimizing algorithm, preparing for the next chapter. in detail, especially focus on the scene modeling and some optimizing measures of how to improve scene rendering speed.Chapter 4 discussion hypothesized roams the interactive technology. Introduced roams the system concept, the realization method which the scene roams, the dissect viewpoint recording type roamed and has the realization method which the goal roams; Thoroughly analyzed A* to seek the road algorithm, roamed the system most short-path search for the next chapter tomake the theory preparation. Chapter 5 multi analysis A* algorithm realization thought and did the step, how and enhance the search speed to the different terrain G value consumption also to do the research, finally through compiled the JavaScript script procedure to realize roamed the most short-path search in the VRML hypothesized scene.On the end of paper it gives a conclusion and expectation and widens the ideas about VR system. The building of 3d alternation virtual campus system demonstrates the feasibility and practicability that we can build VR system through JavaScript and VRML.