Surveying

Author: Ji Yuhua, Huadian Jun
Publisher:
Publish Date: 2004-06-01
Features: Surveying is a science that studies the shape and size of the Earth and determines the positions of ground points. Its main content includes two parts: measurement and surveying. Measurement refers to the use of surveying instruments and methods to obtain measurement data of ground points through measurement and calculation, or to scale down the terrain of the Earth's surface into topographic maps at a certain ratio for scientific research, national economic construction, and planning design. Surveying (also known as construction layout) involves marking the positions (planar and elevation) of buildings and structures designed on planning drawings on the ground using surveying instruments and methods, serving as a basis for construction. Surveying is divided into several branch disciplines based on the fields of study and service targets:
① Geodesy, which is the science of studying and determining the shape and size of the entire Earth, solving problems such as large-area control surveys and the Earth's gravitational field. Geodesy is further divided into conventional geodesy, astronomical geodesy, gravity geodesy, and satellite geodesy.
② General Surveying, which is the science that studies the theory, techniques, and methods of measuring small areas of the Earth's surface.
③ Photogrammetry, which is the science of studying the determination of the shape and size of objects using remote sensing and photographs. Photogrammetry is further divided into aerial photogrammetry, terrestrial photogrammetry, and satellite remote sensing.
④ Engineering Surveying, which is the science of studying various measurements in the exploration, design, construction, and management stages of engineering projects.
⑤ Cartography, which is the science of studying how to compile and print various maps using various map projection methods based on surveying results.
⑥ Hydrographic Surveying, which is the science of studying the measurement and mapping of oceans and inland waters.
The task of surveying is to determine the positions of ground points using various surveying instruments, techniques, and methods to serve various sectors of the national economy. Surveying information is one of the most important basic information in national economic construction, and surveying science is widely applied in national economic and social development plans. Surveying science has broad applications in civil engineering construction. For example, in the exploration and design stages of urban planning, construction engineering, road and bridge engineering, transportation engineering, and pipeline engineering, topographic maps of various scales are required for planning and design. During the construction stage, surveying instruments and methods must be used to mark the positions (planar and elevation) of buildings, structures, roads, bridges, and pipelines designed on planning drawings on the ground for construction purposes. After the project is completed, as-built surveys are conducted for future maintenance and expansion. Regular deformation monitoring is also required for some large or important buildings and structures to ensure their safety.
Surveying is an ancient science closely related to the Earth on which humans depend for survival. Through the observation of celestial body movement patterns and field surveys of the Earth, humans gradually realized that the Earth is a sphere. In 1687, Newton proposed the theory that the Earth is an ellipsoid based on his law of universal gravitation, indicating that under the effect of centrifugal force, the Earth should be slightly flattened at the poles, with its shape closely resembling a rotating ellipsoid formed by rotating an ellipse around its short axis. China began large-scale astronomical geodesy in 1708, the results of which showed that the higher the latitude, the greater the length of each degree of longitude.