The Research And Implementation Of Key Technology In Urban Pipe-Network Three-Dimension Visualization System

With the society development, urban pipe-network has become an important infrastructure for modern life and manufacture. So there is a great variety of pipe and the structure has becoming more complex. In our country, some of the urban management departments have realized the importance of pipe-network system and developed corresponding system. However, most of these systems were using two-dimension (2D) display form for pipe-network observation and management which can not show the depth information. Therefore, three-dimension (3D) pipe-network visualization system is needed to satisfy the user's requirement of visual and quick display. This paper focuses on the research and implementation of some key technologies in urban pipe-network visualization system, mainly containing object picking, spatial analysis and 3D walkthrough.Object picking is the basis of 3D interaction, which is also the basis of 3D object manipulation. Based on the mechanism of object picking in virtual world and Java3D modeling technology, a method was proposed. With this method, not only the 3D pipe could be picked, but also the attributes of the pipe can be acquired.Spatial analysis which is one of the key functions of GIS can give the visual decision supporting for users. Based on the characters of pipe-network, pipe-node adjacency list was used to build the topology of urban pipe-network, and then 3D spatial measurement and safe distance analysis function were implemented.Pipe-network walkthrough can give users better immersion, but modeling hard and memory deficiency are big problems. In order to resolve these problems, we have done researches on virtual world management, buffer strategy and sense scheduling. Cell-portal was used for the pipe and area division; dynamic cross list was used for cell object management. According to visual urgency degree, layered buffer mechanism based on database data and modeling data was set. Cell based scheduling method was used for pipe-network walkthrough, which belongs to large-scale virtual sense of real-time scheduling.Finally, we used Java technology for object picking, spatial analysis and 3D walkthrough related modules implementation. And these modules are also parts of urban pipe-network 3D visualization system. The system can give a vividly and quickly 3D visualization for users, and it is a good proof for the research values.