Research On 3D Modeling And Visualization Of Coal Mine In The Network Environment

With the development of 3D and networking on GIS (Geographic Information Systems), the research of web3D GIS has become one of the focus issues in the fields of GIS. Through radar, remote sensing, drilling and mine survey, various mining geoscience information can be obtained; by applying GIS technology, the 3D mine spatial geography model can be established; the 3D geological body and mine shaft engineering can be reproduced by using visualization technology in manner of images. All of those have significant meaning in researching and analyzing the inherent law of geological problems, and improving the safety level and the scientific management level. The 3D simulation modeling method and simulation system of the coalmine gas explosion accident based on dynamics characteristics can reproduce the occurrence and progression of the accident, reinforce the perceptual knowledge and provide technical support for safety education and personnel training.In this paper, taking the underground tunnel as the object, aiming at the main problems of the 3D model of tunnels in the coal mine, considering the functional requirements of coalmine 3D GIS, the data model, modeling method of coalmine underground tunnel and the model's spatial analysis application have been studied. The main contents are as follows:(1)The key technology of 3D modeling on tunnel is described. According to the geometric space features of the different coalmine underground tunnel, (the technical route of taking the Spatial Point-Line-Surface as the basic element and taking the tunnel centerline as the basic frame of 3D modeling on tunnels is determined.) And the 3D Coordinate calculation method of feature points of straight tunnel and curved tunnel is given. In order to realize the smoothness of the graphic figure of tunnel model, two algorithms are presented: the algorithm of arc interpolation is used to smooth the constant-width tunnel, and an algorithm of Bezier Curve Interpolation is used to smooth the tunnel of unequal width.(2)The data structure of"node-arc"is established to reflect the 3D network spatial characteristic of the tunnels system ,and it is also the judgment basis to realize the transfixion of the cross network. The modeling methods for independent tunnels and cross tunnels are presented, and the transfixion of the roof,bottom surface and side in the tunnel is realized by using an algorithm for set intersection, union of graphic. Finally, the topological relation of the 3D tunnel itself and the relation between the tunnel and geological body are presented. These relations lay a good foundation for the application of 3D model and the analysis on space.(3)For visualization, based on the theory of graphics space interchange, the project researched the pipe and line rendering-based organizing mechanism of the data stream, 3D interactive pickup technique and Alpha color mixed transparent visualizing techniques. Rendering velocity was improved by using the index buffer to deal with the geologic tunnel data and by adopting geologic close block elimination key algorithm. Finally, the paper provided an algorithm that the pick up operation could be completed through the interaction between a point-free radial and the center of a triangular facet.(4) For Web3D information release, the project researched the realization of local 3D engine technique based on the server 3D engine technique and client plug-in Applet. By study on the space data structure in Java3D graphics system, we designed the Web 3D geologic tunnel Servlet engine, realized the generation and off-screen rendering of 3D graphic in the scene and the interaction between the server and client. Using the function of Java in data sequencing, the server could provide 3D graphic data and data communication for the client. The project gave the solution for the multi-client parallel management based on the Session mechanism, realized Web frame of the client using WT-ExtAPI, and ultimately presented an interactive Applet program for the client.(5) The project designed the system structures and functional module compartmentalization of C/S and B/S. The project also completed the application study of 3D integrated model presented for the geologic tunnel, realized the modeling of the integrated model, visualization of the interaction, cutting and the optimization of the route for succor.