What coordinate system is commonly used in photogrammetry? How to define each coordinate system?

(1) image plane coordinate system is used to indicate the position of an image point on the image plane. Usually, the right-handed coordinate system is adopted, and the selection of xy axis depends on needs. In analytical photogrammetry and digital photogrammetry, the image plane coordinate system is often determined according to the frame, which is called the frame coordinate system.

(2) Image space coordinate system, in order to facilitate the transformation of space coordinates, it is necessary to establish a coordinate system that describes the position of image points in image space, that is, image space coordinate system. Taking the photography center S as the coordinate origin, the xy axis is parallel to the xy axis of the image plane coordinate system, and the z axis coincides with the main optical axis to form the right-handed rectangular coordinate system s-xyz in the image space.

(3) Image space auxiliary coordinate system. The image space coordinates of image points can be obtained directly from the image plane coordinates, but the point of this coordinate is that the image space coordinate system of each photo is not uniform, which brings difficulties to calculation. Therefore, it is necessary to establish a relatively unified coordinate system, called image space auxiliary coordinate system, which is expressed by s-XYZ. The origin of this coordinate system is still selected in the photography center. The choice of S coordinate system depends on the need.