Gdms Introduction

Gdms is the core library of OrbisGIS. It provides:

• Input/Ouput for several formats
• An abstraction layer above those sources
• A processing engine that supports Spatial SQL.

Short example

// the main entry point of Gdms
DataSourceFactory dsf = new DataSourceFactory();
// an existing data source in ShapeFile
dsf.getSourceManager().register("hello", new File("/tmp/myShapeFile.shp"));

// just going through the rows of a source
DataSource ds = dsf.getDataSource("hello");
ds.open();
for (int i = 0; i < ds.getRowCount(); i++) {
    System.out.println("Geometry as WKT: " + ds.getGeometry(i).toText());
}
ds.close();

// querying using SQL
DataSource ds = dsf.getDataSourceFromSQL("SELECT COUNT(*) FROM hello WHERE NOT ST_IsValid(the_geom);");
ds.open();
System.out.println(String.format("Found %d invalid geometries!", ds.getInt(0)));
ds.close();

Supported formats

• File formats
• TIF with TFW (.tif, .tiff, .tfw): TIFF image with ArcView world file
• AutoCAD DXF (.dxf): AutoCAD Drawing Exchange Format (input only)
• CSV (.csv): Character Separated Values format
• Esri ASCII Grid (.asc): Esri raster ASCII format
• Esri Shapefile (.shp, shx, .dbf): Esri geospatial vector format
• JPG with JGW (.jpg, .jgw): JPEG image with ArcView world file
• gdms (.gdms): Gdms native format
• MIF/MID (.mif, .mid): MapInfo Interchange Format (input only)
• PNG with PGW (.png, .pgw): PNG image with ArcView world file
• Solene (.cir, .val): Solene geometry & attributes format (output partially supported)
• VRML (.wrl): Virtual Reality Modeling Language (input only)
• DBF (.dbf): dBase format
• Databases
• H2: H2 Java Database Engine (and spatial extension h2spatial)
• HSQLDB: Hyper Structured Query Language Database Java Engine
• PostgreSQL: PostgreSQL Database Engine (and spatial extension PostGIS)

Spatial SQL Support

Documentation (still partial at this time) on the SQL capabilities of Gdms can be found here: Gdms SQL Language