利用七參數進行TWD67、TWD97與e-GPS定位坐標之轉換－－以中壢地區為例

Coordinate Transformation Between TWD67、TWD97 and e-GPS By Using Seven Parameters Method：case study on Jhongli

內政部國土測繪中心業已完成全台e-GPS 系統之建置，並已逐步推廣到地方政府的測量工作中；然e-GPS 所量測之坐標，與台灣現行的TWD67 及TWD97 之間仍存有一系統性誤差，應可利用七參數坐標轉換法來修正。本研究在中壢觀音地區，選取了20 點TWD67 控制點與55 點TWD97 控制點來進行測試，並將量測成果與政府公告值相比較。經過七參數坐標轉換之後，e-GPS 定位坐標與TWD67 公告值之差異，在N 方向上由203.84 公尺降低為2.8 公分，E 方向上由829.93 公尺降低為5.7 公分。若比較e-GPS 與TWD97 之差異，在N 方向上由4.1 公分降低為1.6 公分，E 方向由2.7 公分降低為1.6 公分。證實了只要經過適當的坐標轉換，不論在單筆資料或平均值上，可將e-GPS 應用於TWD97 控制點地籍測量。 National Land Surveying and Mapping Center of Taiwan already constructed the e-GPSsystem, and this system is widely adopted by the cadastral survey. However, there is a systematicerror existed between the TWD67, TWD97 and e-GPS, and this kind of error can be eliminated byusing seven parameters transformation. In this study, 20 TWD67 and 55 TWD97 controlling points inJhongli were measured by e-GPS and the measured coordinates were compared with the announcedvalues by government. After coordinate transformation of seven parameters, the error betweenTWD67 and e-GPS was from 203.84 m to 2.8 cm in N direction; and that was from 829.93 m to 5.7cm in E direction. Moreover, the error between TWD97 and e-GPS was from 4.1 cm to 1.6 cm in Ndirection; and that was from 2.7 cm to 1.6 cm in E direction. It will be okay to use e-GPS technologyin TWD97 cadastral survey when proper coordinate transformation is employed.

National Land Surveying and Mapping Center of Taiwan already constructed the e-GPSsystem, and this system is widely adopted by the cadastral survey. However, there is a systematicerror existed between the TWD67, TWD97 and e-GPS, and this kind of error can be eliminated byusing seven parameters transformation. In this study, 20 TWD67 and 55 TWD97 controlling points inJhongli were measured by e-GPS and the measured coordinates were compared with the announcedvalues by government. After coordinate transformation of seven parameters, the error betweenTWD67 and e-GPS was from 203.84 m to 2.8 cm in N direction; and that was from 829.93 m to 5.7cm in E direction. Moreover, the error between TWD97 and e-GPS was from 4.1 cm to 1.6 cm in Ndirection; and that was from 2.7 cm to 1.6 cm in E direction. It will be okay to use e-GPS technologyin TWD97 cadastral survey when proper coordinate transformation is employed.