e-GNSS與GPS相對定位於地籍測量之精度分析

Precision Analysis on Cadastral Surveying by Using e-GNSS and GPS Relative Positioning

在使用GPS靜態相對定位進行施測時，通常需要在控制點架設參考站來進行相對定位，而需要花費較多的測量時間、人力及成本，而近年來國內的衛星基準站已完成佈設於全台灣，或許可將這些衛星基準站視為相對定位的參考站，對此本實驗於臺北及宜蘭的一、二等衛星控制點進行施測，並使用TWD97與TWD97[2010]的衛星基準站資料來進行解算，以探討使用此種方式所得到的成果是否能滿足地籍測量規範之要求。本次研究中使用e-GNSS與靜態相對定位兩種方式來進行施測，e-GNSS在兩地區的平面標準差皆在兩公分以內，台北地區的外部精度均可達到地籍測量實施規則最大誤差6公分之要求，但宜蘭地區平均誤差則需經過坐標轉換後才能達到規範值，但在單筆資料上仍有超過6公分之部分，於使用上仍需注意。靜態定位數據以陽明山衛星追蹤站進行解算時，研究顯示當基線距離大於20公里時使用商業軟體解算偶會發生較大之誤差，若剔除較大誤差之點位，台北地區各點位的平面方向誤差皆能在6公分以內，但宜蘭地區經過坐標轉換後仍有較大的誤差，坐標轉換改正後誤差範圍在4.6~57.4公分之間。 When the GPS static relative positioning is adopted for surveying, the reference stations are required to be setup at control points. Therefore, more time, cost and manpower are required. In recent years, the GPS reference stations have been constructed in Taiwan, these GPS stations may be treated as the reference stations for relative positioning. In this study, the GPS receivers were setup on the satellite controlling points of Taipei and Yilan, and the data from the reference stations with TWD97 and TWD97[2010] coordinates were utilized for data processing. Two approaches of e-GNSS and static relative positioning were adopted, and the standard deviations in horizontal direction in both areas were within 2 cm. When it came to the external precision, the maximum error of positioning precision was within 6 cm, which was in according with the standard of cadastral surveying. However, the positioning results after coordinate transformation were better than 6 cm in Yilan area averagely, there was still parts exceeding 6 cm in singular data. When the GPS data were processed by using the Yangming mountain reference station, the larger errors were occurred by using commercial software when the baselines were longer than 20 km. If the larger errors were excluded, the external precisions in horizontal direction in Taipei area were within 6 cm. On the other hand, the errors after coordinate transformation in Yilan area were 4.6~57.4 cm.

When the GPS static relative positioning is adopted for surveying, the reference stations are required to be setup at control points. Therefore, more time, cost and manpower are required. In recent years, the GPS reference stations have been constructed in Taiwan, these GPS stations may be treated as the reference stations for relative positioning. In this study, the GPS receivers were setup on the satellite controlling points of Taipei and Yilan, and the data from the reference stations with TWD97 and TWD97[2010] coordinates were utilized for data processing. Two approaches of e-GNSS and static relative positioning were adopted, and the standard deviations in horizontal direction in both areas were within 2 cm. When it came to the external precision, the maximum error of positioning precision was within 6 cm, which was in according with the standard of cadastral surveying. However, the positioning results after coordinate transformation were better than 6 cm in Yilan area averagely, there was still parts exceeding 6 cm in singular data. When the GPS data were processed by using the Yangming mountain reference station, the larger errors were occurred by using commercial software when the baselines were longer than 20 km. If the larger errors were excluded, the external precisions in horizontal direction in Taipei area were within 6 cm. On the other hand, the errors after coordinate transformation in Yilan area were 4.6~57.4 cm.