What do you mainly study in engineering survey? We are studying engineering drawing now, but what if I can't learn three-dimensional thinking? Yes, professional engineering.

The survey work in the planning and design stage is mainly to provide large-scale topographic maps. The main methods used are ground manual mapping and photogrammetry mapping. ① Manual mapping on the ground. According to the principle from the whole to the part, the plane and elevation control points are established in the survey area (see engineering control survey), and then the features and landforms are measured according to the control points. In recent years, with the development of electronic rapid measuring instrument and computer-aided mapping system, the three-dimensional coordinate data of feature points of ground objects and landforms can be obtained by using multifunctional integrated or combined electronic rapid measuring system, and input into the mapping system for automatic mapping. ② Photogrammetry mapping. It is to shoot the ground, interpret, measure and process the photos in order to obtain the required information. The first application is ground photogrammetry, that is, using phototheodolite to take photos of the investigation area on the ground to make maps. Later, it developed into aerial photogrammetry, which became the most important and effective method for mapping topographic maps. In recent years, with the improvement of photographic equipment and surveying and mapping instruments, in addition to analog surveying and mapping methods, analytical surveying and mapping methods have been developed, that is, photogrammetry is analyzed by using stereo coordinate measuring instruments to obtain topographic data. Analytic mapping instrument can not only map like ordinary analog stereo mapping instrument, but also encrypt regional network points, carry out digital mapping and obtain digital map. The digital expression of ground morphology is called "digital ground model", which can be used to solve the problems of drawing section and calculating earthwork in engineering design.

The engineering survey in the construction stage is mainly to establish the construction control network according to the requirements of design and construction, and then set out the positions of various parts of buildings and production equipment at the scene with appropriate accuracy according to the control network as the basis for construction and installation. The lofting work includes plane position lofting and elevation lofting. Plane position lofting usually adopts polar coordinate method, rectangular coordinate method and intersection method. Elevation lofting is usually carried out by leveling method according to elevation control network points. In recent years, laser measuring instruments have been applied in construction survey, such as laser collimator, laser vertical instrument, laser plane instrument, laser theodolite, laser levels and so on. (See engineering measuring instruments). This not only improves the accuracy and speed of measurement, but also helps to realize automation.

The survey work in the management stage is mainly to monitor the present situation of engineering buildings and ensure safe operation. Including vertical displacement (settlement), horizontal displacement, inclination, deflection, wind vibration, sunshine and other deformation observation items, which is characterized by the need to establish a high-precision deformation observation control network and a stable benchmark. Due to the different requirements of each project, the accuracy requirements and methods of observation are also very different. After the completion of field observation, after adjustment calculation and preliminary arrangement, the reliability of deformation observation results is analyzed by statistical test, and the regularity of deformation is discussed by regression analysis. Vertical displacement (settlement) observation usually adopts precise leveling method. Using static leveling method, the elevation change of liquid level can be converted into inductance output, which is beneficial to realize observation automation. The observation methods of horizontal displacement of buildings are different because of their different stress conditions and displacement directions. For displacement observation in any direction, the pre-angle intersection method is often used, and for displacement observation in a specific direction, the baseline method is often used. The reference plane can be established by using the line of sight of theodolite, tension steel wire or laser beam. The deviation value of the observation point relative to the datum can be observed manually or automatically by photoelectric sensing technology. In addition to geodesy, close-range photogrammetry can also be used to observe the displacement, inclination, deflection and instantaneous deformation of buildings (see observation of building deformation).