The Development And Application Of Three-dimensional Geography Information System (3D GIS) In The Field Of Forestry Resource Management

This article is the part of the Provincial key technologies R and D program of HeiLongjiang about the study on forestry resource survey and on management decision-making Geomatic technology (GC02B608) .Geography Information System (GIS) has been widely used in many fields related to geography and three-dimensional Geography Information System (3D GIS) is one of the GIS developmental tides. Many fields need GIS browse, display and analyze in the virtual three-dimensional spaces. Under this background, the article aims to study the application of 3D GIS in the field of forestry resource management and has explored a new kind of technological method.The research starts with building special data-base of 3D GIS and special analysis. It focuses on studying the technological method for constructing 3D special database with Imagis which make special analysis. At same time, this paper has studied the courses of Imagis further developmental. As well as the analytic function of 3D GIS has been system development with IDL.First, spacial database management system which applies on forestry resource management has been constructed by using Imagis. Spacial database has been also built through entitative unite and the joint between spacial database and enter attribute database has been completed. Based on Imagis visual GIS as plat, 3D spacial analysis primarily has been realized. These are the special analysis function related to forestry resource management. 3D flying browser has realized in 3DBrowser which is the model of Imagis extend try using DEM and RS data. We have explored further development interface of Imagis and attempted to make Imagis further development. The technology of further development will enable Imagis to make the construction of forestry resource management spacial database more flexible. The idea of further development has accomplished the conversion from enter ArcView data to DEM data of Imagis and solved the resource of basal data. Also compartment and DEM overlay by further development and the precision after overlay analysis is very high by batch booleam operation. This provides necessary ensurence for constructing 3D special database.Secondly, Analysis3D has been developed with IDL, and systematically realized parts of 3D GIS function. 3D GIS will further be closed to virtual reality. In the course of systematical realization, we successfully get outer data visualized by using the converting function of IDL coordinate system. Also the error that horizontal scale and vertical scale cannot be coherent has been canceled. 3D data can gain real-time through taking part the mouse event. And the factual problem that the edit and operation of 3D entities dimension has been solved. It is more random to investigate 3D landform and realize the observation of multi-visual-angles distinguishable ratio. According to corresponding arithmetic, special analysis and solid measure can be realized and every course has completed in 3D which make analytic resultmore visualize. At same time, the contour lines have been picked up in 3D and completed the function that the contour lines can be labeled automatically, which make the work improved efficiently and greatly. We have farther explored the application of IDL on RS digital image disposal and have realized color synthesis of RS digital image. The question of color composition in texture mapping also can be solved with IDL.Finally, the study has achieved interactive browser between 2D and 3D.This not only turns the information of contour lines which only professional can unscramble into 3D landform, but also enable the display of 2D and 3D mutual use to get excellent visual effect. What's more, dynamic show run time and texture mapping of RS image by color composition are provided with strongly impactive visual effect. This kind of real 3D browser and display lives up to what we see is what we want and it has become a bridge between 3D GIS and virtual reality.