Research Of Topographic Map Batch Subdivision Method Based On FME

With the development of society,the science and technology of Surveying and mapping are also developing continuously.Different countries will establish different geodetic coordinate systems in different historical periods to meet the actual needs.In special geographic areas or engineering projects,the national unified coordinate system can not meet its actual requirements,so it is necessary to establish a small scale of independent coordinate system with local characteristics.However,these basic geographic information data are still stored in the format of CAD,which can not meet the needs of spatial data management and analysis,and need to be converted into a GIS database for management.Therefore,it is of great significance to analyze and study the coordinate transformation of topographic maps in order to comprehensively utilize the different formats of geographic information data in different coordinate systems and to achieve the sharing of data results.According to the complex subdivision topographic map coordinate system conversion,this paper firstly describes the coordinate transformation model.This paper introduces the basic theory of topographic map and coordinate system,and comprehensively analyses the data format of topographic map and the rules of division and numbering,the division of coordinate system in Geodesy and the commonly used measuring coordinate system.Then,the establishment of independent coordinate system is introduced in detail.Elevation domestication in projection deformation can be reduced by ellipsoid expanding,ellipsoid shift and ellipsoid distortion.Eight mathematical models are concluded and their accuracy and application scope are verified by examples.In view of the excessive zoning in the East-West direction,the mathematical model of ellipsoid rotation and the calculation of its parameters are also established.Data experiments are carried out to analyze the feasibility and accuracy of the model in terms of coordinate accuracy and deformation error.Based on ellipsoid rotation theory model and FME platform,a series of oblique coordinate transformation processing templates for topographic maps are established in this paper.Starting from the pretreatment,this paper generates the connection chart reflecting the relationship between the old and new outlines,and uses it to import the data step by step,to connect the geometry and attributes of the elements to form the whole map in a small range.According to project requirements,Python code of oblique axis conversion is compiled and self-defined projection coordinate system is created,coordinate transformation of the map is carried out,and the map is cut with the new outline,and legends are added to form a new complete topographic map.After completing all the data conversion,the GIS database is established and the quality of the new map is checked to obtain high quality data results.Considering the special problems such as multi-to-one edge matching,block element processing,note-texting conversion and clipping,this paper puts forward reasonable solutions,and evaluates the accuracy of data results in all aspects to meet the requirements of specifications and promote the sharing and development of basic geographic information data.