University of Twente Student Theses


Design and realization of raster-based spatial uncertainty calculus around vector objects

Awasthi, Deepak Raj (2012) Design and realization of raster-based spatial uncertainty calculus around vector objects.

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Abstract:Design and realization of uncertainty is always an important subject matter in geographical information science. Spatial uncertainty can be associated with spatial objects in various ways. Textual description is one of the causes of uncertainty. It is often used in geographical information science during communication or in spatial queries by using named places and spatial relationships. These descriptions provide uncertain or vague information about a locality. Consequently, there always exit spatial uncertainty like positional or extensional uncertainty. Currently, spatial databases and geographic information systems are unable to deal with such spatial uncertainty due to lack of data types and uncertainty functions. There is a need of a mechanism that can represent spatial objects along with their uncertainty and allows a computational facility. In order to solve such problem, a tandem approach is proposed in the project where uncertainty is represented by tiny rasters. The tandem data model uses the combination of two basic data types vector and raster, where vector is deemed as a crisp representation of the object and preserve its identity as point, line string or polygon feature. Raster provides supplementary information about the vector object and describes the possible spatial position of the object using probability theory. This project mainly focuses on the calculation of uncertainty value in every pixel of the raster by using a technique of calculus and subsequently creation of uncertainty raster for tandem data type. PostgreSQL/PostGIS functions are developed to create uncertainty raster and allow computational facility between tandems to approximate the spatial position of the object. Keywords spatial uncertainty representation, tandem approach, spatial database (PostgreSQL/PostGIS) raster support, textual description
Item Type:Essay (Master)
Faculty:ITC: Faculty of Geo-information Science and Earth Observation
Programme:Geoinformation Science and Earth Observation MSc (75014)
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