Change detection for urban spatial databases using remote sensing and GIS

The aim of this study was to establish a preferred methodology for updating of the spatial database and monitoring the changes of a settlement in Tanzania. In summary, change detection problems can be viewed as the consequence of an increased desire for up-to-date information about the development and changes in a GIS environment to guide urban planners, urban decision-makers, and managers. Two methods that have been used for change detection are: semiautomatic change detection using on-screen digitizing and digital classification and segmentation methods. On-screen digitising of changes shows that (as a pilot study covered only one aerial photograph) this method is fast, convenient, and (depend to the application) complete. The result of segmentation and classification for finding the changes in the settlements Dar es Salaam, shows 73% accuracy when the result of on-screen digitizing is used as a reference map for evaluation and by using existing knowledge such as roads and object geometry contained in the GIS database. Classification and segmentation can be used to derive information from an aerial photograph. The nature, variety and usefulness of such an information would have to be considered according to the project at hand, i.e., the structure of the area, the type of available aerial photograph, and the type of information to be extracted.