Ground photogrammetry analysis

Indoor mapping methods of ground stereo photogrammetry can be divided into analytical method, graphic method and mapping method using ground stereo mapper. Its principle is shown in figure 1 (the corresponding side view is shown on the right). The analytical method of indoor mapping is to measure the abscissa x 1 and ordinate z 1 and the left-right parallax p(p=x 1-x2) of a point m on the left photo m 1 with the coordinate origin of the left camera station S 1 and the baseline direction as the X axis according to the following formula. For real photography:

Where f is the main distance of the camera; B is the horizontal length of the photographic baseline. For isochromatic photography (Figure 2):

In the formula, the deviation angles are equal, which is positive when it deviates to the right and negative when it deviates to the left. The abscissa on the right is X2. The graphic method of indoor mapping is to design the drawing board according to similar triangles relation according to the values of x 1, z 1 and P measured by three-dimensional coordinate measuring instrument, and to calculate the plane position and elevation of ground points by graphic method. This method has played a role in the development of ground photogrammetry. The surveying and mapping method of ground stereo mapper is the main method used in production practice at present.