設計一種機動有效的蒐集空中攝影影像為本研究之主要動機，因此設計了以氣球為載具，裝載數位攝影機之航空攝影方式。載具中包含電視(CCD)攝影機與數位攝影機，前者用來監視攝影地區，可即時無線傳輸影像，呈現於地面之LCD監視螢幕上。地面線控之氣球升空後，經由監視螢幕，得知CCD與數位兩台攝影機之視場，故可調整氣球並移動至預定之攝影位置，在預定攝影地區呈現於LCD螢幕時，即遙控啟動數位攝影機之快門裝置。 成像經過正射糾正鑲嵌後，與其他現有地圖影像資料一同用來分析與比較，評估檢核點之後，得知成像可達次像元之精度，而與現有1/1000比例尺之數值地形圖比較，亦可見對位情況良好，本研究所採用之航空攝影方式，對小地區之大比例尺製圖而言，確為可行且有效之方式。 本研究曾選定一段小流域面積之河川實驗區，利用分類後比較方式偵測研究區之變遷，分類圖與伴隨之自至(from-to)資訊明顯表露河川實驗區在不同時期之變遷情況。 Using a flexible and efficient way to obtain aerial images has been the primary purpose of this study. The balloon platform was used to take aerial images. A video camera and a digital camera were fixed together in a durable plastic box, and hung on the balloon. The video camera was used to monitor the ground view, and its image could be telemetered remotely and displayed on a LCD monitor arranged on the ground. Once monitoring the area of interest shown on the LCD, the shutter button of the digital camera was then pushed remotely and the interested image was taken. The resultant images were ortho-rectified for analysis and comparison. The accuracy of aerial images was examined by check points. The results showed that the images achieved sub-pixel accuracy and were well-matched with the 1/1000 digital topographic maps. This expressed that it was really a useful and efficient method of taking large-scale images for a small research area. At last, post-classification comparison method was introduced to detect change of the ortho-rectified images which were taken in three different periods. The classification maps and the from-to change class information clearly indicated the change of river way among various periods.