利用POM和DLG数据的矢量地理PDF地图快速制作

An Efficient Geospatial PDF Map Producing Method Using POM and DLG Data Aggregation

  • 摘要: 矢量地理PDF(portable document format)地图具有数据量小、通用性强等特点,是一种具备查询、量算等功能的新型电子地图,其应用需求和前景广阔。单纯利用数字线划图(digital line graphic,DLG)数据,通过符号化和制图编辑等处理制作矢量地理PDF地图的过程持续时间长,工作量大。充分利用已有的地图制图成果来快速制作矢量地理PDF地图,避免影响已有的制图生产工序流程,对提高矢量地理PDF地图生产效率具有重要意义。提出了一种矢量地理PDF地图制作的方法,利用出版原图(publication originals of map,POM)与DLG数据,通过数据预处理、地图坐标系统构建、数据聚合处理与压缩流程,快速生成矢量地理PDF地图。该方法省略了符号化和制图编辑处理流程,经试验验证,制作矢量地理PDF地图的效率高,成果数据量较POM和DLG数据总量显著压缩,适用于DLG和POM数据源条件具备的矢量地理PDF地图大规模快速生产。

     

    Abstract:
      Objectives  Vector geospatial PDF (portable document format) map is a new type of electronic map, which has the characteristics of small data size, strong generality, etc., and has the function of geospatial query and calculation. Its applying needs and prospects are broad. As the method by using digital line graphic (DLG) data only, to make vector geospatial PDF map through symbolization and cartographic editing has a long process and heavy workload, it is of great significance to make full use of the existing map data to quickly produce vector geospatial PDF map. As result, it avoid affecting the existing map production process, and improve the vector geospatial PDF map making more efficient.
      Methods  This paper presents a quick method of making vector geospatial PDF map, which uses publication origins of map (POM) and DLG data by data preprocessing, map coordinate system construction, data aggregation and compression. (1) Data preprocessing. Based on multi-source spatial data engine, POM and DLG data sources are loaded, integrated and utilized. Through the process of feature layer extraction, entity type extraction, coordinate extraction and attribute extraction, the useful and important objects in DLG are extracted. The POM data is processed by combining different color pages, replacing and overprinting layers, and setting the minimum page range. Select control points with known coordinates in POM page. We have completed the data preparation of vector geographic PDF map making. (2) Construction of map coordinate system. The map coordinate system model is designed and defined as a composite of six coordinate systems including DCS (data source coordinate system), GCS (geometric coordinate system), PCS (projection coordinate system), ECS (equal scale map coordinate system), FCS (file coordinate system) and OCS (output coordinate system). It also defined a series of mutual transformation parameters and functions. The coordinate system of the map is solved by knowing the coordinates of the control points and the rotation angle of the map. The coordinate registration of POM and DLG data is completed by using six coordinate system transformation parameters. (3) Data aggregation and compression. The POM with map graphical information and DLG with geographic information extracted are aggregated in the coordinate system after registration to generate a new PDF file. Using a variety of methods, the redundant data of PDF file is compressed without reducing the data accuracy. And a new vector geographic PDF map is generated.
      Results  This method omits the process of symbolization and cartographic editing. The experimental results show that the efficiency of making vector geospatial PDF map is high, and the map results data size is significantly compressed compared with the total amount of POM and DLG Data.
      Conclusions  It is suitable for large-scale rapid production of vector geospatial PDF map with DLG and POM data source conditions.

     

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