Automatic Extraction of Image Tie Points for Aerial Digital Frame Imagery with Large Overlap

For the aerial digital frame imagery with large overlap,we propose an automatic transferring point scheme composed of image matching in image-space-free network adjustment-image matching in object-space.Firstly,more accurately exterior orientation elements of images were obtained by image matching in image-space and free network adjustment,which provide approximate values for the image matching in object-space.Secondly,the collinearity geometric constraints were introduced to image matching in object-space,which enables the multi-photo geometrically constrained least squares matching to consider the errors in the image exterior orientation elements flexibly.Finally,the multiple images were simultaneously matched and the reliability and success rate of image are improved.Experimental results show that the proposed method can acquire the image tie points successfully for the images with large overlap,which can meet the demand for automatic point transferring in aerial triangulation,and improve the height accuracy of the photogrammetric points significantly.