根据数字近景摄影测量的特点,针对建筑物三维建模的需要,提出了基于灰度投影的影像匹配算法。该算法将影像行、列两个方向上的一维灰度投影,拓展为行、列、主对角线和次对角线四个方向上的一维灰度投影,计算左右影像的四个一维投影向量间的相似性测度的加权平均值作为最后的匹配测度。利用相对定向线性变换(RLT)算法来确定同名核线,以改进的动态定界法来控制待匹配点序列中后续点沿核线匹配的搜索范围,以减少匹配的搜索空间并提高匹配的准确度。利用该算法对建筑物数字近景摄影影像进行了实验,结果表明该算法具有较高的匹配速度和匹配准确率。

For the purposes of three-dimensional modeling of buildings, a new stereo image matching algorithm based on the gray-scale projection is advanced considering the characteristics of the digital close-range photogrammetry. The algorithm extends the one-dimensional gray-scale projection from two directions to four directions. The gray-scale projections in the column, row, major diagonal and secondary diagonal directions are calculated simultaneously. The weighted average of similarity measure of these four one-dimensional projection vectors between the left image and right image is computed for the final matching decision. Homonymous epipolar lines are found by using the relative orientation linear transformation (RLT). To decrease the searching scope and improve the matching accuracy, an improved dynamic bounding approach is proposed to control the searching scope of sequential points in the point list to be matched along the homonymy epipolar-line. The new algorithm is applied to actual stereo images of a building taken by a digital close-range photogrammetric system and the experimental result shows that the algorithm has a higher matching speed and matching accuracy than the pyramid image matching algorithm.