Classification of ground photogrammetry

Ground photogrammetry is divided into field work and indoor work. Field work includes photography and measurement. Photography is to use phototheodolite or other cameras to shoot both ends of the baseline in a certain way, so as to obtain a stereo image pair of the target. In topographic survey, there are two ways of photography: upright photography and equidistant photography. In the survey work, the photographic baseline is selected first, and then the baseline length, the coordinates and elevation of the baseline endpoint and the inspection point are measured by ordinary survey methods, which provides initial data for indoor photographic processing. Indoor drawing methods are divided into graphic method, simulation method and analytical method. Graphic method is to design a drawing board according to similar triangles relation according to the coordinates of image points and the left and right parallax values measured by stereo coordinate measuring instrument, and to calculate the plane position and elevation of ground points by graphic method. Simulation method is a method of mapping by using ground stereo mapper. Analytic method is to get the spatial coordinates of ground points in its ground auxiliary coordinate system according to a certain mathematical formula, and then convert them into ground coordinates. Analytical method is a common method with strong adaptability and high precision.