Combining Regional GPS Height Transformation

In survey engineering, height anomalies must be known in order to convert GPS ellipsoidal heights into normal heights. There are many transformation models, such as polynomial, BP neural network and multi-quadrics fitting. Because the quasi-geoid is an irregular geometric object, every method has both advantages and disadvantages, and is appropriate to different transformation patterns. It is difficult to identify which transformation model is the most suitable for a particular area. In order to obtain a more precise and reliable analytical result, the combined model based on the combining forecast theory is adopted. As a result, the fitting ability of single models is significantly improved. The combined model still possesses the same important features as the single models. An example is presented and the results are analyzed in detail to demonstrate the efficiency of the proposed methodology.