利用已知控制点，通过空间后方交会求得像片的外方位元素，并利用求得的外方位元素，通过前方交会求出像点的地面摄影测量坐标，并判断外方位元素的精度是否达标。(By using the known control points, the exterior orientation elements of the photo are obtained through the space resection. The ground photogrammetric coordinates of the image points are obtained through the forward intersection, and the accuracy of the exterior orientation elements is determined.)