A mathematical model for least squares point determination from cadastral data
Transnet possesses approximately 60000 land parcels covering the whole of the South African rail network. These parcels, or polygons, will form the base map in a corporate Geographic Information System (GIS) which will be used for property administration and general railroad operations management. Accuracy requirements are high and unique coordinate values have to be determined for each polygon apex before data are input into the GIS. Railroad property portfolios are characteristically configured in long thin strips. The solution therefore has to cope with poor geometry. The method used to determine apex coordinates must be time and cost efficient, and produce acceptable levels of precision. This study examines the feasibility of using a particular mathematical model with the least squares method in the partial automation of the determination of unique points from sets of differing and, at times, conflicting cadastral data for the creation of a digital cadastral database. The approach is not a mathematically rigorous conventional survey network solution, but a pragmatic application of least squares and network principles, to suit the nature and limitations of the data.
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