本研究之目的為針對EROS A衛星影像建立幾何改正模式,主要工作包含軌道修正及影像正射化兩個部份。研究中將使用衛星載體資料並配合地面控制點進行軌道修正,依修正後之軌道配合數值地形模型進行影像正射化。在軌道修正方面,分別提出光束法及載體參數修正法兩種模式。在影像正射化方面,使用逆轉換模式建立物空間及像空間之對應關係,為提昇逆轉換模式之運算效率,使用網格化方式將影像分成區塊進行處理。實驗結果顯示,就飛行弧長比大於13之EROS A單張像幅而言,軌道修正時檢核點之均方根誤差為2至2.5個像元之精度。在影像正射化部份,以逆轉換模式所產生之正射影像,其檢核點均方根誤差在像平面上亦達2至2.5個像元之精度。
The objective of this investigation is to build up a geometric correction model for EROS A satellite images. The major works comprise orbit modeling and orthorectification. In addition to the Bundle Adjustment and On-board Data Correction Method in orbit modeling, we include least squares filtering technique to compensate for the local systematic errors. Considering the indirect approach in orthorectification, a Point-by-point Backprojection Method is developed. We also propose Patch Backprojection Method to minimize the computation load without significantly losing accuracy. Experimental results indicate that the proposed scheme may reach an accuracy of 2.5 pixels in orbit modeling for an image with an asynchronous ratio of 13. The accuracy of the generated orthoimage is equivalent to the one for orbit modeling.