What's the difference between photogrammetry and ordinary surveying? What are the advantages?

Photogrammetry needs photo interpretation, and the accuracy is slightly poor. Compared with traditional measurement, photogrammetry has the advantages of high efficiency, fast update and labor saving.

Photogrammetry refers to the technology of measuring the shape, size and spatial position of the target by combining camera and film. It obtains the shape, size, position, characteristics and their relationship of the object after processing the photos obtained by the optical camera. It focuses on the measurement information of geometric quantities (position, size and shape of objects, etc.). Its main task is to draw topographic maps of various scales, establish digital ground models, and provide 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. The basic principle of geometric positioning comes from the forward intersection method of surveying, which is based on two known photographic stations and two known photographic direction lines, and intersects the three-dimensional coordinates of the undetermined ground points that constitute these two photographic rays. Image interpretation is to determine the attributes of the object corresponding to the image.

A basic survey conducted in a small area. Use basic measuring instruments: theodolite, level, tape measure, rangefinder, total station, etc. Carry out distance measurement, angle measurement, elevation measurement, alignment measurement, topographic survey and construction lofting of general engineering buildings, including data processing and drawing.