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Methods to automatically derive landforms have typically focused on pixel-based, bottom-up approaches and most commonly on the derivation of to pographic eminences. In this paper we describe an object-based, top-down algo rithm to identify valley floors. The algorithm is based on a region growing ap proach, seeded by thalwegs with pixels added to the region according to a threshold gradient value...
The discontinuities in boundaries and exteriors that regions with holes expose offer opportunities for inferences that are impossible for regions without holes. A systematic study of the binary relations between single-holed regions shows not only an increase in the number of feasible relations (from eight between two regions without holes to 152 for two single-holed regions), but also identifies...
Closed, watertight, 3D geometries are represented by polyhedra. Current data models define these polyhedra basically as a set of polygons, leaving the test on intersecting polygons or open gaps to external validation rules. If this testing is not performed well, or not at all, non-valid polyhedra could be stored in geo-databases. This paper proposes the utilization of the Constrained Delaunay Tetrahedralization...
Geospatial data sharing is an increasingly important subject as large amount of data is produced by a variety of sources, stored in incompatible formats, and accessible through different GIS applications. Past efforts to enable sharing have produced standardized data format such as GML and data access protocols such as Web Feature Service (WFS). While these standards help enabling client applications...
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