The task of photogrammetry

Photogrammetry is a method to determine the shape, size, nature, spatial position and relationship of objects by using photographic image information (optical or digital). Its main research contents include: obtaining the image of the target, processing the image, and expressing the obtained results with graphics, images or numbers.

One of the characteristics of photogrammetry is that images represent rich information and are objective and true. The main work is carried out indoors, and the image is measured and interpreted without touching the target object itself, so it is rarely limited by natural and environmental conditions. All kinds of images are the true reflection of the objective target object, and the image information is rich and vivid, from which people can obtain a lot of geometric and physical information of the studied object. It can take instantaneous images of dynamic objects and complete the measurement work that is difficult to achieve by conventional methods; Suitable for large-scale topographic mapping, with fast mapping speed and high efficiency; The products have various forms, and can produce paper topographic maps, digital line drawings, digital elevation models, digital orthophoto maps, etc.

The main task of photogrammetry is mapping topographic maps of various scales, establishing digital ground models, and providing basic data for various geographic information systems and land information systems. The two major problems to be solved in photogrammetry are geometric positioning and image interpretation. Geometric positioning is to determine the size, shape and spatial position of the object being photographed. Image interpretation is to determine the attributes of the object corresponding to the image.