本研究之重點是以考慮地表的地形變化、人工建築物存在和相互的遮蔽問題之高解析力衛星中華二號（ROCSAT-2）的影像正射化程序為主要工作，中華二號衛星影像是以Pushbroom的成像方式，故其正射化有別於航照像片，目前適用之衛星影像相關資料無法取得，故需以模擬資料來進行測試。 首先的工作就是模擬出高解析力的衛星影像，這張影像必須是要考慮地表的地形變化、人工建築物的存在和相互的遮蔽問題。模擬衛星影像的程序是利用已經建構好之ROCSAT-2的軌道參數、星曆資料和DSM(Digital Surface Model)以逆轉換模式（Bottom-up）來進行模擬，而模擬影像所要填入的灰度值資訊則是利用經正射、鑲嵌後之數位航空影像來當基準，如此一來模擬的衛星影像才會和真實影像相近。 在模擬衛星影像的工作完成後，接下來就是要進行正射化的工作，在此階段中，利用已經建構好的ROCSAT-2的軌道參數、星曆資料和DSM以逆轉換模式來進行正射化的程序。在完成正射化程序後的衛星影像，將可以修正在衛星影像上因為高差移位效應所呈現之傾斜人工建築物及地形至正確的影像位置上。 The focus of this investigation is the geometric correction for the ROCSAT-2 high resolution satellite images. We correct satellite images using digital surface model (DSM) that includes building and terrain information. Unlike frame photography, where all pixels in the image are exposed simultaneously, each line of a high resolution satellite image is collected in a pushbroom fashion at a different instant of time. Due to unavailability of test data, we need to simulate a high resolution satellite image which considers that the terrain and the building may be hidden each other test, due to we don’t have a applicable data. First of all, we used a satellite-orbit-model of ROCSAT-2, including coordinate-transformation-model, satellite-fly-model, simulation-model and on-board-data-model, and DSM to simulate a high resolution satellite images by Bottom-up approach. In addition, the bases of the simulated image are orthorectified aerial images to minimize differences between the simulate image and the true image. Once imaging simulation had completed, we will use a satellite-orbit-model of ROCSAT-2 and DSM to orthorectify the simulated high resolution satellite's image by Bottom-up.
