Tiling of object-based geographic information system (GIS)

A method for displaying a topology having topological features on a display, the method comprising the steps of:

• dividing the topological region into tiles;
• layering tiles on different layers with a top layer having a single tile and lower layers of tiles have succeedingly greater numbers of tiles;
• accessing an object-based database comprising geometrical objects representing the topological features, each geometrical object associated with a particular tile, the geometrical objects being one of a polygon object, a polyline object and a point object representing the topological features, each of the geometrical objects including a geometry attribute defining the complete representation of a topological feature;
• selecting four tiles;
• fetching the geometrical objects associated with the four tiles;
• and
• drawing the fetched geometrical objects of one tile on the display.

A method of building an object-based database of a topology having topological features, the topological region being divided into tessellations on different layers, comprising the steps of:

• identifying the topological features as geometrical objects, the geometrical objects being one of a polygon object, a polyline object and a point object, the geometrical objects each having a feature identifier attribute and being associated with one or more tessellations on a layer, each of the geometrical objects including a geometry attribute defining the complete representation of a topological feature;
• storing the polygon objects in a polygon object database;
• storing the polyline objects in a polyline object database;
• and
• storing the point objects in a point object database.

An article, comprising:

• at least one sequence of machine executable instructions;
• a medium bearing the executable instructions in machine readable form,
• wherein execution of the instructions by one or more processors causes the one or more processors to:
• access an object-based database comprising geometrical objects representing topological features of a topological region, the topological region being divided into tessellations on different layers, the geometric features being associated with one or more tessellations on a layer, the geometrical objects being one of a polygon object, a polyline object and a point object, each of the geometrical objects including a geometry attribute defining the complete representation of a topological feature;
• fetch the geometrical objects associated with a plurality of tessellations one of which is to be displayed;
• draw the fetched geometrical objects associated with the one tessellation on a display.

A computer-readable medium having a data structure stored thereon for access by a GIS system, the GIS system displaying a topological region having topological features on a display, the topological region being divided into tessellations on different layers, the topological features being classified as geometrical objects having feature identifiers, the geometrical objects being one of a polygon object, a polyline object and a point object, the data structure comprising:

• a polygon object database having polygon objects each associated with a topological region, each polygon object having at least a feature identifier attribute and an ordered list of coordinates attribute and being associated with one or more tessellations on a layer;
• a polyline object database having polyline objects each associated with a topological region, each polyline object having at least a feature identifier attribute and an ordered list or coordinates attribute and being associated with one or more tessellations on a layer;
• and
• a point object database having point objects each associated with a topological region, each point object having at least a feature identifier attribute and an x-y coordinate attribute and being associated with one or more tessellations on a layer;
• wherein each of the geometrical objects include a geometry attribute defining the complete representation of a topological feature.