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MLGL: A Spatial Data Model for Mobile Geoinformatics and Cartography

The paper presents an innovative spatial data model approach named MLGL (Mapsheet-Layer-Grid-Level) to Mobile Geoinformatics and Cartography (MGC) for field land survey. First, the characteristics of MGC environment are analyzed. Then, one county's spatial data of land use is broken into several town map sheets according as the administrative boundaries. Each map sheet contains multi controllable attribute layers. For the purpose of reducing the data in viewable area, the layers are sliced into uniform grids and only one cell is specified to display each time. The R tree index and Grid index are established for each feature in one map sheet. Moreover, features generalization algorithm based on BLG (Binary Linear Generalization) tree is developed for implementing the Level of Detail (LOD) strategy in the viewable grid. In the research, Filter-Refinement query strategy is ubiquitously utilized in the map operations. Finally, a Mobile Spatial Index Library (MSIL) is deployed for integrating the MLGL model and providing the interfaces of index operation and database access. A land survey mobile application based on the MLGL model applied in 12 provinces proves the feasibility in practice.