在數值攝影測量中進行相對方位計算之前，必須先量測立體影像對中連結點的位 置。一般最常用的方法是以最小二乘匹配法求取立體影像對中的共軛點位置，但實際上常因 為影像旋轉、曝光不均或者因地物高度不同產生遮蔽效應及陰影的影響，而造成匹配失敗。 本文嘗試以 Hough 轉換偵測影像中房屋邊緣的直線段之位置，再求其交點當作屋角點。 為 了避免房屋陰影之影響，我們提出一判斷原則以偵測出真正的屋角點。本文最後以一實際之 航測立體影像對來作實驗，以測試本文所提方法之可行性，所得結果證實此方法確實可以在 有陰影干擾時代取代最小二乘匹配法來量測正確的屋角點位置。

　　　　　In developing an automatic process to recover the relative orientation, tie points in each pair of stereo images should be identified. The least-square matching (LSM) has been widely used in the past few years but the fact that it tends to fail to match locally different images. Difficulties arise due to the influence of the image rotation and unequal exposures. The purpose of this study is to remedy the drawbacks of LSM. For identifying conjugate image points, we detect the line segment of building roof using the Hough transform and compute the intersections of the lines to obtain the building corners. The result will be invariant with respect to the size and rotation of the image. In order to solve the occlusion problem, a simple criterion is proposed to match conjugate building corners. In order to test the practicability of this method, some experiments on a pair of real stereo image are processed with this method. The results are compared with the numbers obtained by using LSM. The comparisions show that this method is more robust to the effect of local changes in the images. We therefore conclude that this method can be a backup of LSM in image matching.