區域性大地起伏最佳曲面擬合之研究──以台中地區為例

The Best Surface Fitting of Regional Geoidal Undulation-A Case Study of Taichung Area

幾何法大地起伏可以由正高及全球導航定位系統的橢球高快速獲得，且其精度較重力法所得到之大地起伏高，因此本研究於不同的曲面模型中尋求最佳的大地起伏擬合曲面，利用此曲面能夠精確的內插出各未知點之大地起伏值，由研究結果顯示在經費及精度上考量以二次曲面為最佳。

The geoidal undulation of points can be derived from orthometric height and GNSS geodetic height. The geometric method can produce geoidal undulation more accurate and faster than gravimetric method in the area with GNSS data and levelling data. In this research, we use different surface models to find out the best fitting surface based on geometric method to interpolate geoidal undulation of unknown point. The result shows quadratic surface method is the best one to solve regional geoidal undulation in terms of both costs and benefits. 幾何法大地起伏可以由正高及全球導航定位系統的橢球高快速獲得，且其精度較重力法所得到之大地起伏高，因此本研究於不同的曲面模型中尋求最佳的大地起伏擬合曲面，利用此曲面能夠精確的內插出各未知點之大地起伏值，由研究結果顯示在經費及精度上考量以二次曲面為最佳。