Recently, GIS technology is widely applied in many fields. DEM (Digital elevation model) is one of quite important data for GIS. Many methods were introduced for elevation interpolation from elevation contour data so far. However, every method of them has difficulty to get satisfactory result when the elevation contour forms complicated pattern. The fundamental fault of them is the limitation to take straight line only as reference line for elevation interpolation. Therefore, it cannot be realised suitable interpolation at the blind part of complicated contour line which occurs frequently in actual elevation contour data.
Newly developed elevation interpolation method takes elevation contour plane as elevation potential field. The idea is rather similar to treat electric field which is formed by giving electric potential correspond to elevation value against contour line. This method is realized taking 2-dimensional flexibility of reference line for elevation interpolation. The application of this method enables to get better quality DEM even elevation contour is so complicated. Author call this method as Quasi Potential Method.