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Walk. Lite in Mobile GIS: A Schema to Extend and Symbolize Spatia. Lite Dr. X. Chen [email protected] com. cn Walkinfo Tech. Co. Ltd.
Background Walk. GIS • A GIS platform as of 1998 • Complying with OGC standards • Representing vector and raster geospatial data by Walk schema • Providing a C++-like script language for customization • A family of GIS products: Walk. Survey, Walk. IOffice, Walk. Floor, Walk. Check, Walk. FU, etc. • Originally designed for land survey in China, now widely used in land use investigation & planning, house property, transportation, population, etc.
Problems in 2013 • Traditional desktop-based system is somehow outdated • No application can be run on mobile devices • End users limited in specific areas • Difficulties encountered when translating various geospatial data
Walk. GIS Migration From Windows to Cross-Platform 1998 ~ 2013 ~ Platform Windows only Windows, Linux, Android Device Desktop, Mobile Base library Walk Library + GDAL/OGR Graphical UI GDI+, Skia Built-in data formats Walk MDB, SQL Server Spatial Walk SQLite (Walk. Lite), Walk MDB, etc. Vector data supported Shapefile, Auto. CAD dxf, Mapinfo Data formats supported by GDAL/OGR
Walk. Lite Walk schema applied in SQLite/Spatia. Lite: • Adapting OGR SQLite driver • Defining four meta-data tables: Walk. Layers, Symbol. Factory, Meta. Data, and Meta. Data. Def. • Each Walk. Lite layer corresponding to three tables: Ø Features Ø Symbols Ø Annotations (text annotations, raster and vector tiles)
Walk. Lite Layer Walk. Lite features: OGR SQLite layer containing • • • OGC SRS geometry OGC Feature ID and Walk Feature ID Createtime: Time of the feature creation Style ID: Symbol ID for feature style Feature attributes Spatia. Lite is used for spatial index
Walk. Lite: Annotations Walk. Lite annotations: OGR SQLite layer containing • OGC SRS geometry ü Points for the location of text annotations ü Polygons for the location of tiles • OGC Feature ID and Walk Annotation ID • Annotation: Text that stores the content of annotation or the file path of tile (Format supported by GDAL) • Style ID: Symbol ID for annotation style • Spatia. Lite is used for spatial index
Walk. Lite: Symbols Walk. Lite symbols: regular SQLite table • Styles ID referred by the features and annotations • Style: BLOB data serializing the symbol style • Style name and note
Advantages of Walk. Lite • Cross-platform: No data translation required between mobile application (data collection) and desktop application (data processing) • One schema for both vector and raster data, also map styling • Comparatively fast by using Spatia. Lite index
Walk. Lite Applications Walk. Lite-based mobile GIS App used in a number of Chinese provinces for: • • • Land investigation Land use Planning Cadastral inventory Real estate analysis …
Future Work? • Cross-platform SDK • Supporting i. OS • Walk. Lite driver in GDAL/OGR [ODBC-based Walk driver already in GDAL/OGR (version >=1. 10. 0)] • Further improving and optimizing the performance of Walk. Lite data
Questions? http: //www. walkinfo. com/en. html