Imu/dgps-supported Automatic Image Measuring

Automatic image measuring is to identify and to measure conjugate points in two or more overlapping photographs automatically. In digital photogrammetry, this process is done by image matching. A straightforward way to make image matching well-posed is to restrict the space of possible solutions and provide good initial parallax. Initial parallax is related to the searching space. The better the initial parallax, the smaller the searching space. So in image matching, the initial parallax should be determined firstly. Since IMU/DGPS system can get exterior orientation (EO) parameters of the image, using the EO parameters and the corresponding elevation to predict the location of conjugate points can get a better initial parallax. Thus, the limitation of traditional method in deciding initial parallax, such as gaining incorrect initial parallax, large searching space, etc, may be hopefully improved. Then the operator's interference in automatic image measuring will reduce and the efficiency, reliability of image matching will increase. This paper studies the use of IMU/DGPS data in automatic image measuring. Using IMU/DGPS data to decide the initial parallax can avoid the dependence of image condition. So the parallax decided will be better than that of the gray-correlation's which is depended on image condition. In this paper, two methods are introduced to decide the initial parallax. They are gray-correlation and IMU/DGPS data supported. Experiments are carried out to evaluate the applicability and strongpoint of IMU/DGPS -supported automatic image measuring.