DGPS與PPP於空載光達解算定位精度成果之研究

空載光達點雲精度深受GPS定位精度影響。空載光達施測時，於台灣部份已是人煙罕至高山區域架設地面參考基站，這是一項挑戰不可能的任務。因此，本研究嘗試運用精密單點定位（PPP）定位解算，作為不易架設地面基站區域之替代方案可能性。PPP主要是以IGS公告衛星精密星曆及精密時鐘差修正資料，輔助以單點無差分方式進行定位，可達成後處理高精度的定位成果。本研究分別以差分定位（DGPS）與PPP兩種解算方式，在6條空載光達掃瞄航線中選出調查區塊進行比較。首先，比較兩種解算方式產出之航跡差異。再以DGPS及PPP各別解算航跡產出光達離散點雲LASer（LAS）成果，以對應時間戳記比較平差前、後點雲兩種解算方式差量。另外，以結合DGPS及PPP各別產出LAS平差成果與僅DGPS解算產出LAS平差成果比較，試瞭解在難以設置地面基站作業區域中PPP替代DGPS可能性。本研究結論DGPS及PPP兩種解算方式於不同大地基準情況下，PPP產出之航帶點雲能有效利用航帶平差作業方式，達成結合DGPS及PPP兩種解算點雲之成果。

關鍵字

GPS時間戳記；航帶平差；資料合併；地面參考站；光達點雲

並列摘要

The positioning accuracy of airborne LiDAR point clouds is mainly originated from GPS positioning. In general, DGPS method is used in Taiwan for solving the position of GPS rover on the air-plane with a ground base station within 20 km. However, part of the high mountains in Taiwan is inaccessible, where suitable site for installing ground reference stations is almost impossible. It is important to know the potential of applying Precise Point Positioning(PPP). PPP by using IGS GPS satellite precise ephemeris and clock anywhere in the world can achieve real-time or post processing for high-precision positioning. In this study, a test is carried out by using both conventional DGPS and PPP methods for a block of 6 selected flight strips of LiDAR scans. Results of LAS data generated by both methods are compared by the TIMESTAMP of point clouds for both before and after strip adjustment. In addition, results of adjustment of strips combined from both DGPS and PPP are compared with those of all strips of DGPS and, thus, to understand the possibility of using PPP instead of DGPS for the area not accessible for installing continuous GPS stations. It is concluded that though there is a datum difference between DGPS and PPP, strips of point clouds generated by PPP can be effectively merged into strip adjustment combining both strips of point clouds by DGPS and PPP.

並列關鍵字

GPS timestamp ； strip adjustment ； data merge ； base station ； LiDAR LAS

國際替代計量

DGPS與PPP於空載光達解算定位精度成果之研究

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