Research And Implementation Of Regional Synthesis And Envelope Generation Algorithm Based On GIS Platform

In recent years, with the rapid development of GIS(geographic information system)theory and technology, the application of GIS have made great progress. In GIS-based applications, it often have some type of area need to be synthesized to generate a uniform area, and then to analysis and display the area. Due to the outside interference in the physical environment, such as terrain masking, electromagnetic interference, it will generate a lot of irregular regions.Nevertheless,the regional synthesis function in most existing GIS system can only deal with simple rules polygon envelope, so a lot of applications based on such platform just ignore the impact of the external environment. The result of envelope synthesis can only gain the graphics area in an ideal case,which cannot provide accurate data information for the system users. The calculation and display function of regional synthesis has an obvious defects in existing GIS platform, it is necessary to study the graphic envelope related algorithms, and applied the algorithms to the application system based on GIS platform.First, this paper introduces the research background and research contents,and describes an important application of the envelope generator and regional synthesis algorithm.Then, take an overview of the envelope generator and regional synthesis algorithms, and analysis the basic principles and processes of that algorithm. The research content includes envelope generator and regional synthesis algorithm’s execution process,algorithm composition and performance bottlenecks.And conduct a comparative analysis among common graphical description of the envelope method to select the suitable structure for the envelope algorithm.After that, two sub algorithm of the envelope generation is given.The first sub-algorithm is used to research topics free curve intersecting arcs and straight line segments closed curve intersection.Its main research work is as follows:Studied classic polygonal envelope intersection algorithm,and then bring out an improved Park curve intersection algorithm,which used curve monotonic method and combined with bounding box and sweep line.The algorithm reduces a large number of graphic intersection calculations, and its can be extended to using on the calculation of arc envelope intersection problem.The second sub-algorithm is subject to the two-dimensional graphics and computing algorithms.On the basis of getting the point of intersection between the two-dimensional free-form curves, research and analysis the envelope generate algorithm for producing new envelops.At the last part of the paper, a typical instance application of envelope generator and regional synthesis algorithm in the field of military simulation based on GIS is showed. Finally, summarizes the thesis work and analysis the research results, the existing problems and future work prospects.