The Research Of Design And Application For Map Projection Library Of Seamless GIS

As long as the rapid development and widespread use of GIS, map have turned intomulti-media electronic map and network map from paper maps. At this time, if we use largescale map sheet as the unit in GIS study, the object is single sheet, the variety between bent planeis not so larger, deformation of projection and choice of projection have no big effects on GISanalysis and study, Because of the application requirements, people have to treat wider studyarea, plenty of point maps and vast quantities of geographical data. At its basis, it has beenrequired to process consecutive and seamless geographic information. So, seamless GIS is born.It can analyze geographical data more comprehensive with cooperation of different geographicalinformation management roofs. But in the study of seamless GIS, as the being of map sheet andMulti-spatial Data make the contradiction more complicated between bent plane, and thecontradiction will become more obvious with the enlarging of study area.So in spatial analysis and application, during choosing projection methods, single projectioncouldn’t solve the problem. We should establish perfect projection library and researchspecialized way of control and use in dynamic projection. The main finished studies as follows:1. Based on the analysis to the conception and theoretical frame of seamless GIS, we pointout the using problems in present map projection. Combining today’s situation of study at homeand abroad, we originally propose that we can use map projection library on the seamless GISsoftware platform which could reduce error spatial analysis and make the function more perfect.2. Studying the goals and significances of map projection library in seamless GIS. We alsostructure the important parameter and management method which needed in map projectionlibrary. And we analyze the functions of those parameters; expound the important projectioninformatin which are supported by projection library and explain it’s widely use. We design theparticular process which about enforcing specific projective function by using some parametersand functions in map projection library.3. This paper studies map projection library’s application system in map projection libraryespecially. We analyse the application structure of map projection library, then research the GISspatial data structure which is suitable for the map projection library, we also formulate anorganization and manage way by using work area, segment, attribute merge table and Projectionindex table’s spatial data. In this paper we list all kinds of factors in segment; data structures inattribute merge table and Projection index table. We set up the corresponding three-level indexcalling mechanism which aim at the index interview require of map data and projection type.4. Completing the design of the map projection library, we use actual points for the coordinate transformation, then compare the result with thecoretical value, so we can prove thefeasibility of map projection library. In the using of seamless GIS map projection library, aimedat the plenty sheet coexistence and different map projection types, we raise the way about usingcombined projection by give an example. And show some corresponding figures andmathematical formulas.5. We design and finish the functions of map projection library in seamless GIS by tests anddebugging the system, which using specific map data to fulfill. We explained various kinds ofmodules’ effects in system, realized the function about invoking and displaying relevant mapprojections. And on that basis, we conducted the applied experiments, which include length andacreage measure, and provide some pictures for example.