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Articles 1 - 6 of 6
Full-Text Articles in Databases and Information Systems
Areas Of Same Cardinal Direction, Periyandy Thunendran
Areas Of Same Cardinal Direction, Periyandy Thunendran
Electronic Theses and Dissertations
Cardinal directions, such as North, East, South, and West, are the foundation for qualitative spatial reasoning, a common field of GIS, Artificial Intelligence, and cognitive science. Such cardinal directions capture the relative spatial direction relation between a reference object and a target object, therefore, they are important search criteria in spatial databases. The projection-based model for such direction relations has been well investigated for point-like objects, yielding a relation algebra with strong inference power. The Direction Relation Matrix defines the simple region-to-region direction relations by approximating the reference object to a minimum bounding rectangle. Models that capture the direction between …
Generating Linear Orders Of Events For Geospatial Domains, Suzannah Hall
Generating Linear Orders Of Events For Geospatial Domains, Suzannah Hall
Electronic Theses and Dissertations
Events in the world do not occur in neat chronological order, but may take place, for example, during or overlapping each other, or as simultaneous events. Efficient summaries of real-world events are important in many disciplines and require events to be modeled in a linear fashion. This thesis focuses on modeling events as intervals and using relations between the events to derive linear orders from more complex partially ordered sets. A method is developed for mapping Allen's thirteen temporal relations to only two relations, before and equals, which allow a linear ordering of all events present in the set. This …
Structuring A Wayfinder's Dynamic And Uncertain Environment, Michael D. Hendricks
Structuring A Wayfinder's Dynamic And Uncertain Environment, Michael D. Hendricks
Electronic Theses and Dissertations
Wayfinders typically travel in dynamic environments where barriers and requirements change over time. In many cases, uncertainty exists about the future state of this changing environment. Current geographic information systems lack tools to assist wayfinders in understanding the travel possibilities and path selection options in these dynamic and uncertain settings. The goal of this research is a better understanding of the impact of dynamic and uncertain environments on wayfinding travel possibilities. An integrated spatio-temporal framework, populated with barriers and requirements, models wayfinding scenarios by generating four travel possibility partitions based on the wayfinder's maximum travel speed. Using these partitions, wayfinders …
Modeling Multiple Granularities Of Spatial Objects, Chitra Ramalingam
Modeling Multiple Granularities Of Spatial Objects, Chitra Ramalingam
Electronic Theses and Dissertations
People conceptualize objects in an information space over different levels of details or granularities and shift among these granularities as necessary for the task at hand. Shifting among granularities is fundamental for understanding and reasoning about an information space. In general, shifting to a coarser granularity can improve one's understanding of a complex information space, whereas shifting to a more detailed granularity reveals information that is otherwise unknown. To arrive at a coarser granularity. objects must be generalized. There are multiple ways to perform generalization. Several generalization methods have been adopted from the abstraction processes that are intuitively carried out …
Modeling Intersections Of Geospatial Lifelines, Ramaswam Hariharan
Modeling Intersections Of Geospatial Lifelines, Ramaswam Hariharan
Electronic Theses and Dissertations
Modeling moving objects involves spatio-temporal reasoning. The continuous movements of objects in space-time captured as discrete samples form geospatial lifelines. Existing lifeline models can represent the movement of objects between samples from most likely location to all possible locations. This thesis builds on a model called lifeline bead and necklace that captures all the possible locations of moving objects. Beads are 3-dimensional representations of an object's movements and a series of beads form a necklace. The extent of finding the possible locations is constrained by the speed of movement of the objects. Intersections of lifelines occur when two or more …
Using Raster Sketches For Digital Image Retrieval, James Carswell
Using Raster Sketches For Digital Image Retrieval, James Carswell
Electronic Theses and Dissertations
This research addresses the problem of content-based image retrieval using queries on image-object shape, completely in the raster domain. It focuses on the particularities of image databases encountered in typical topographic applications and presents the development of an environment for visual information management that enables such queries. The query consists of a user-provided raster sketch of the shape of an imaged object. The objective of the search is to retrieve images that contain an object sufficiently similar to the one specified in the query. The new contribution of this work combines the design of a comprehensive digital image database on-line …