A Least Squares-Based Method for Adjusting the Boundaries of Area Objects

In this paper a least squares-based method is proposed for adjusting the boundaries of area objects in a GIS that is designed particularly for solving inconsistencies between the areas of digitized and registered land parcels. The principle of this approach is taking the size of the registered area of a land parcel as its true value and to adjust the geometric position of the boundaries of the digitized parcel. First, a generic area adjustment model is derived by incorporating the following two categories of constraints: (a) attribute constraint: the size of the true area of the parcel, and (b) geometric constraints: such as, straight lines, right angles and certain distances. Second, the methods used to adjust the areas of the parcels for different cases are presented. Third, the implementation of the proposed model is illustrated using several case studies. The results of the application and the corresponding analysis demonstrate that the proposed approach is able to maintain a consistency between the areas of the digitized and registered parcels. This study has solved one of the most critical problems in developing a land/cadastral information system, and this solution has been adopted in the processing of real world cadastral data in Shanghai and other cities in China.