無人飛行載具搭載數位相機於地質構造判釋之應用

隨著科技進步，野外地質調查的方法日新月異。結合現代化空間資訊技術的使用，野外資料的取得效率與精度大幅提升。本文將以近石門水庫大漢溪溪床露頭和大甲溪峭壁的三義斷層露頭為例，以無人飛行載具(Unmanned aerial vehicle, UAV)掛載數位相機，結合全球衛星定位系統(Global positioning system, GPS)靜態測量，獲取區域地面控制點坐標，處理所得之正射影像和立面影像，進行地質構造判釋。大漢溪溪床的正射影像中呈現一系列走向N20°E 左移的斷層，及一振幅約90 公尺、半波長約120 公尺的S 形褶皺。980 公尺寬的大甲溪峭壁立面影像中發現三義斷層以至少三條分支的逆斷層帶出現，由西往東分別為斷層F1、 F2 和 F3。F1 切穿現代礫石層，判定為最活躍的斷層；F2 並無切穿上覆約70 公尺的階地堆積層，西側未再出現早於四百萬年形成的桂竹林層青灰色砂岩，研判為具最大錯移量的分支；F3 上盤為為青灰色砂岩組成之桂竹林層，下盤為階地堆積層，近地表為風化層及植被所覆蓋。以上的地質構造判釋，皆得利於UAV 所提供的影像，地面取樣距離(Ground sample distance, GSD)達4cm/pixel；GPS 靜態觀測，經解算與平差後，地面控制點的平面精度達0.5 公分，高程精度約為1 公分內；數值地表模型(Digitalsurface model, DSM)的精度約莫為公分等級，足見UAV 影像測繪搭配高精度地面控制點的高實用性，為未來地質調查不可或缺的工具。

關鍵字

三義斷層；構造地質；野外地質調查；攝影測量； UAV 影像測繪；無人飛行載具

並列摘要

Taking advantage of spatial information technology, the efficiency of collecting data in the field and the data accuracy have been dramatically enhanced for geologists nowadays. In this research, by using UAVs (unmanned aerial vehicles) with a digital camera, and ultra-high accuracy ground control points, we produce ortho- and elevation images in order to recognize and analyze geological structures. We take a 750-meter-wide Dahan River riverbed near the Shihmen reservoir and a Dajia River cliff outcrop of the Sanyi active fault as examples to illustrate the usefulness of UAV for geologists. At the Dahan Riverbed, there are a series of left-lateral sense faults with orientation of N20°E. Furthermore, an S-shaped fold has been recognized with a 50-meter amplitude and 200-meter half-wavelength in the orthoimage. At the Dajia River cliff, a 980-meter-long elevation image has been produced. At least three fault branches can be recognized on the elevation image. They are labelled as F1, F2 and F3 from west to east in this Sanyi fault zone. F1 cutting into the modern gravelly layer has been acknowledged as the most active branch fault in the research area. F2 did not cut into the overlaid 70-meter-high terrace layer. It may be the fault branch with a maximum separation because the greenish grey sandstone of Kueichulin formation formed earlier than 4 million ago is not exposed west of F2 on the cliff. The hanging wall of F3 is composed of the greenish grey sandstone of Kueichulin formation and the footwall of F3 is composed of gravelly layer formed after 2 million years ago. The F3 is overlaid with regolith and vegetation. The results of the geologically structural analyze above all benefit from the images taken via UAV. Moreover, the GSD (ground sample distance) of the high-quality models presented in this study reaches 4 cm/pixel. With the accuracy of static GPS (global positioning system) reaches about 0.5cm in horizontal and 1cm in elevation. DSM accuracy is about in centimeters. To sum up, UAV-based photogrammetry with high accuracy ground control points, showing a high efficiency and high flexibility indispensable technology in the field survey for geologists.

並列關鍵字

Sanyi fault ； geological field survey ； structural geology ； photogrammetry ； UAV mapping and unmanned aerial vehicle (UAV)

國際替代計量

無人飛行載具搭載數位相機於地質構造判釋之應用

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