精進e-GNSS即時動態定位系統三維坐標轉換模型精度之研究

A study on improving the accuracy of 3D coordinate transformation on e-GNSS real-time kinematic positioning system

內政部國土測繪中心e-GNSS即時動態定位系統（簡稱e-GNSS系統）自103年起提供三維坐標轉換服務，透過RTCM 3.1 Type 1021及Type 1023之資料格式，分別將坐標轉換七參數，殘差網格修正模型與網格內插計算方法傳送給使用者，讓使用者在外業測量現場可即時將e-GNSS系統測量成果轉換至法定坐標系統，轉換精度在平面分量約5公分，高程分量約10公分。考量在部分共同點分布較稀疏，無法完全修正板塊與地殼變動影響量之地區，其轉換結果會有些微系統誤差存在，轉換精度略低於其他地區。本研究藉由e-GNSS系統更新e-GNSS[2021]坐標時，一併辦理735點基本控制點測量工作，並計算基本控制點e-GNSS[2021]坐標，期望透過增加轉換模型共同點密度之方式，提升轉換模型精度，並解決部分地區存在系統誤差之問題。

The e-GNSS real-time kinematic positioning system of the National Land Surveying and Mapping Center (e-GNSS) provided 3D coordinate transformation service for users to determine the legal coordinates from e-GNSS coordinates easily by RTCM3.1 Type1021 and Type1023 since 2014, the accuracy of e-GNSS after transformed by 3D coordinate transformation service was about 5cm in horizontal and 10cm in vertical. Consideration of the systematic errors in some area where were not enough common points, we tried to improve the transformation accuracy and solve the systematic errors of transformation model by considering the distribution and using more common points for transformation mode.