The Identification and Monitoring of Objects with Fuzzy Spatial Extent

The determination of the spatial extent of geo-objects is generally approached through the boundaries or more precisely through the position of the boundary points. The analysis of the geometric uncertainty of the objects is therefore often based on accuracy models for the coordinates of these points. The accuracy evaluation in land surveying and photogrammetry generally refers to the mapping of crisp objects. In many other survey disciplines objects are mapped that are not crisp, in that case the geometric uncertainty is not only a matter of coordinate accuracy, but also a problem of object definition and thematic vagueness. It can not be handled by only a geometric approach such as epsilon band method. This paper proposes an approach to map the spatial extent of the objects and their uncertainties when objects are measured from field observation data. The effects of the uncertainties on geometric change detection are investigated. Several measures for fuzzy change detection are presented to evaluate the change processes of the objects, through a practical example of dynamics of sediments along Dutch coast.