Creating Topo Geometry Objects

Currently, TopoGeometry objects can only be defined by specifying their component topology elements. We do support both basic TopoGeometry and hierarchical TopoGeometry. Basic TopoGeometry objects are those composed by base topolocal elements (faces, edges, nodes). Hierarchical TopoGeometry objects are composed by other TopoGeometry objects.

Each TopoGeometry object belongs to a specific Layer of a specific Topology. Before creating a TopoGeometry object you need to create its TopologyLayer. A Topology Layer is an association of a feature-table with the topology. It also contain type and hierarchy information. We create a layer using the AddTopoGeometryColumn() function:

                schema_name, table_name, column_name, feature_type,

The function will both add the requested column to the table and add a record to the topology.layer table with all the given info.

If you don't specify [child_layer] (or set it to NULL) this layer would contain Basic TopoGeometries (composed by primitive topology elements). Otherwise this layer will contain hierarchical TopoGeometries (composed by TopoGeometries from the child_layer).

Once the layer is created (it's id is returned by the AddTopoGeometryColumn function) you're ready to construct TopoGeometry objects in it:

                feature_type,   -- 1:(multi)point, 2:(multi)line,
                                -- 3:(multi)poly, 4:collection
                layer_id,       -- as returned by AddTopoGeometryColumn
Last modified 14 years ago Last modified on Mar 16, 2010, 5:43:22 AM
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