The core problem of digital photogrammetry is

The core problem of digital photogrammetry is image matching. Image matching is the key difference between digital photogrammetry and analog or analytical photogrammetry. Digital photogrammetry is a measurement method that uses the basic principle of photogrammetry to extract the geometric and physical information of the subject by computer technology and express it in digital form. Through image matching, that is, images taken from different perspectives or times are corresponding and registered, which can realize three-dimensional reconstruction, topographic survey, deformation monitoring and other applications. The accuracy and stability of image matching are very important to the quality of digital photogrammetry results.