LSA for validation of digitized rectangular and straight-line features

The quality of digitized spatial databases directly affects many mapping ap plications and decision-making processes in geographic information systems (GIS). Because all information in GIS is, to some extent, related to spatia l data, spatial accuracy plays a very important role. A large number of fea tures in digitized databases contain rectangular and straight-line segment components. This is especially true for urban GIS databases, where rectangl es and straight lines are the most common basic features. Automatic validat ion of such digitized components and features is part of the approach towar d applying a quality control process before the databases are used in appli cations. This paper introduces a least squares adjustment (LSA) method for validating digitized rectangular and straight-line features. The method can be seamlessly implemented in digitizing software so that the digitized fea tures can be automatically checked and corrected, and the spatial quality i s enhanced. In addition, the overall digitizing quality indicator estimated from the validation procedure can be used to represent the spatial quality of the digitized features, although it is only an internal or relative qua lity measure. Such a quality measure is also critical to the uncertainty mo deling in GIS. The results of an experiment using this validation method ar e given.