| Road engineering web three-dimensional (Web3D) visualization technology is an important substance of the realization of road engineering informatizatio, it can be run through the entire life cycle of design, construction and operation in the application of road works, therefore the study has important significance. In this paper, aiming to several key issues in the road engineering Web3D, such as road 3d modeling, network framework, massive 3d model data dispatch and rapid transmission, and integration with geographic information systems, the auther made an in-depth research by application of road route design, computer network technology, computer graphics and geographic information systems synthetically. The main research contents and achivements are as follows:(1) In the analysis and comparison of several commonly used computer network models and network architecture, three-tier B/S network architecture was designed based on the HTTP protocol that can fully meet the requests of reliability, scalability, flexibility of road works Web3D visulization.(2) Based on construction of geometric 3D model techniques , the rapid-establishment of elemental models that are composed of the whole road 3D scene was realized. The complex road 3D scene was divided into a number of elements of entities, and the 3D modeling method of those elements of entities was developed respectively. And then the entities were merged into a whole. The above process provided modeling foundation for the road engineering Web3D visualization.(3) Aiming at the contradiction between the rapid and real-time transmission of mass road 3D model data and current network bandwidth, a muti-resolution algorithm facing the transfer was proposed, which can separate the original 3D model into a most coarse model and a series of detail records in the server-side. And the above most coarse model has the ability to restore the original model automatically on the client-side. Therefore, the process of "while browsing, while downloading" for massive date downloading was achieved. Moreover, the technical combination of discrete processing, data caching and data compression has been used to further optimize the mass model data management and transmission.(4) The fast drawing method of client road 3D scene based on high-performance graphics was proposed, the integration of visual scope capture display list, VBO and other technologies was used to enhance the rendering effect of complex road 3D model on the remote client. And also the author discussed the practical vista of GPU programmable technology in road works Web3D visualization.(5) The technology of integration and interaction between Web3D and WebGIS was studied. Building a road engineering WebGIS platform based on MapXtreme, the author designed the client linkage mechanism and duplex communication mechanism of Web3D and WebGIS systems, and then the remote and rapid query of road design information and real-time construction information from interactive 3D scene and 2D electronic map on client was realized.(6) Under the instructor' s guidance and assistance of classmates, combining with some related subjects, applying the above mentioned methods and techniques and using J2EE, Jogl and other programming tools, the author developed a highway construction information remote visualization inquiry platform based on Web3D and WebGIS. And the above platform was applied to the construction management of Chang-Ji Highway and Guang-Ba Highway. The practice proved that the theories and methods of the road works Web3D visualization in this article are practical and correct. |
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