Research objects and fields of surveying and mapping science

It is a theoretical and technical subject that studies and calculates the geometric position of ground points, the shape of the earth and the gravity field of the earth, measures the natural shape of the earth surface and the geometric distribution of artificial facilities, and combines the geographical distribution of some social and natural information to compile various scale maps and thematic maps of the world and local areas. Also known as measurement. It includes two main contents: measurement and drawing. Surveying and mapping is widely used in economic construction and national defense construction. In urban and rural construction planning, land resources utilization, environmental protection and other work, it is necessary to conduct land survey and map various maps for planning management. In geological exploration, mineral development and water conservancy and traffic construction, geological survey, control survey of various building design and construction, mine survey, route survey and topographic map must be carried out. Marching operations need military maps, as well as accurate geocentric coordinates and gravity field data to ensure that long-range weapons can accurately hit targets.

Surveying and mapping has a long history. Ancient surveying and mapping technology originated from water conservancy and agriculture. Every year after the Nile flooded in ancient Egypt, the land boundary was redrawn and the survey began. In the 2nd/kloc-0th century BC, Yu Xia in China used simple measuring tools to measure distances and heights. In the 3rd century BC, Eratosthenes of Alexandria calculated the circumference of the meridian circle of the earth for the first time by observing the sun shadows of the two places, which was also the original form of arc measurement to measure the size of the earth. In 724, under the guidance of the delegation, Nangong Shuo and others in the Tang Dynasty in China measured the meridian arc length of about 300 kilometers from Huaxian County to Shangcai. The length of the sun shadow at the same moment was measured in hua county, Kaifeng, Fugou and Shangcai, and the meridian arc length of latitude 1 was calculated. This is the first time in the world that arc measurement. 16 17, W. Snell of the Netherlands pioneered the triangle method of arc length measurement, which overcame the difficulty of measuring arc length directly on the ground. 1687 British I Newton proposed that the earth is an ellipsoid with slightly flat poles according to mechanical theory. In 1690, C. Huygens of the Netherlands also proposed that the earth is an oblate sphere with slightly flattened poles. It was later proved by French arc survey in South America and Northern Europe. Ending the debate about the shape of the earth that lasted for half a century. 1743, Frenchman A.C. Clairaux published the theory of the shape of the earth, which laid a theoretical foundation for studying the shape of the earth by physical methods. 1849, sir G. G Stokes put forward the theory of studying the shape of geoid by using the results of ground gravity measurement. 1945, M.S. Ilodensky of the Soviet Union founded the theory of studying the natural surface shape of the earth and put forward the concept of "quasi-geoid".

Surveying and mapping is a technical subject, and its formation and development largely depend on the creation and reform of measuring methods and instruments. Before the17th century, people used simple tools, such as rope rulers and wooden rulers, to measure distances. The telescope was invented at the beginning of17th century. The triangulation method established in 16 17 started angle measurement. 1730, the first theodolite was made in Xisong, England, which promoted the development of triangulation. 1794, German C.F. Gauss invented the least square method, which was not published until 1809. In 1806, A.-M. Legendre of France also proposed the same observation data processing method. 1859, A. Losta of France pioneered the photogrammetry method. At the beginning of the 20th century, due to the development of aviation technology, automatic continuous aerial camera appeared, which can process aerial photos into topographic maps on stereo plotter, thus promoting the development of aerial photogrammetry.

Since 1950s, surveying and mapping technology has developed towards electronization and automation. Since 1948, various electromagnetic wave rangefinders have appeared, which have overcome the difficulty of ranging and made traverse survey valued and applied. Almost at the same time, the appearance of electronic computers accelerated the speed of measurement and calculation, changed measuring instruments and methods, and appeared analytical mapping instruments, which promoted the development of analytical mapping technology. 1957 after the successful launch of the first artificial earth satellite, a new field of satellite geodesy and space photogrammetry was opened up in the field of surveying and mapping. Subsequently, the development of very long interferometry and inertial measurement technology has added new measurement means to surveying and mapping.