應用X-band航海雷達於海岸灘線之量測

Application of X-band Marine Radar on Coastal Shoreline Measurement

莊士賢(Laurence Z.H. Chuang) ； 黃子庭(Zih-Ting Huang) ； 吳立中(Li-Chung Wu) ； 鄭雅云(Ya-Yun Cheng) ； 陳禹儒(Yu-Ru Chen)

《海洋工程學刊》 18卷2期 (2018/08) Pp. 121-140

摘要

海岸變遷現象目前已普遍發生在臺灣的海岸地區，要瞭解海岸變遷的原因，先要觀察與掌握海岸變化的狀況，以避免導致錯誤決策。由於海岸地形侵淤的變化常明顯表現在海岸灘線位置的前進與後退，因此灘線位置的量測便顯得重要。本研究之目的是要利用X-band雷達回波影像來測量灘線位置，根據雷達回波的原理與機制，以雷達回波強度之時間平均統計值可以突顯出海面與陸地所呈現之不同回波訊號特性，因此本文提出一套利用X-band雷達進行灘線位置量測之處理程序，透過邊緣偵測及形態學方法之技術整合，來判別水陸交界線之灘線位置。為證實雷達應用於海岸灘線測繪之可行性，本研究利用無人飛行載具(unmanned aerial vehicle, UAV)拍攝之光學影像與之比較，可發現雷達影像所量測的灘線位置與光學影像中目測辨識的灘線位置相近。以X-band雷達進行海岸灘線監測之優勢是能進行即時且連續地觀測，即使在天候不佳的狀況下，也能提供遠端監控服務，因此能夠長期、持續地自動監測海岸灘線之時空變化，以協助權責單位掌握海岸變遷的現況。

關鍵字

X-band雷達 ； 影像處理與辨識 ； 邊緣偵測 ； 灘線量測

並列摘要

The coast of Taiwan has undergone frequent changes. These coastal changes must be observed and investigated to understand their causes. Because changes in coastal topography often manifest as advances and retreats of shoreline positions, the measurement of shoreline positions is an important task for coastal management. The purpose of this study is to estimate shoreline positions from X-band radar echo images. Based on the principle and mechanism of radar echo signals, the time-averaged statistics of radar echo intensities can highlight the different characteristics of the sea and land. Therefore, this study proposes a set of processing procedures for the measurement of shoreline positions using X-band marine radar. The proposed technique integrates edge detection and a morphological method, which are used to determine the shoreline positions at the land-water interface. In order to assess the feasibility of the proposed method, the obtained shoreline positions are compared with those in an optical image from an unmanned aerial vehicle (UAV). It was found that the shoreline positions measured from radar images agree with those visually identified from UAV orthoimages. The advantage of coastal shoreline monitoring with X-band radar is that can provide real-time and uninterrupted observation, even in bad weather conditions. Therefore, the temporal and spatial variations of a shoreline can be automatically and continuously monitored over the long term to help authorities understand coastal changes.

並列關鍵字

X-band radar ； image processing and recognition ； edge detection ； shoreline measurement