Using spatial continuity and discontinuity information to retrieve geographic entities

This paper presents three methods for representing spatial properties of geographic entity types in order to retrieve digital aerial photographs that contain these types. The three methods are semivariogram, edge tracing and an integration of the two methods. The first two methods are used to represent spatial continuity and spatial discontinuity information, respectively, associated with geographic entities, while the integrated method is used to represent both properties. The three methods are used to retrieve seven land cover types; factories, shopping centres, highways, forest, farmland, grasses and residential areas. Results show that between the two independent methods, the semivariogram method generally produces higher retrieval precision and more consistency across the seven types than the edge tracing method. The integrated method considerably outperforms the two independent methods.