What does topographic survey mean?

Topographic survey is a technique and method used to measure and describe the characteristics of the earth's surface. It grasps the shape and structure of the earth's surface by measuring natural geographical features such as mountains, rivers, islands, lakes and oceans, and is mainly used for geological exploration, map making, urban planning, agricultural investigation and environmental monitoring. Topographic survey can not only provide accurate description of topographic elevation and geomorphological features, but also provide necessary geographic information support for engineering construction and resource development.

There are three main methods of topographic survey: field survey, photogrammetry and satellite remote sensing. Field measurement refers to the direct measurement and observation of the surface by manpower or instruments, such as lofting method, theodolite method and electronic ranging method. Photogrammetry is the use of aerial photographs to measure the terrain, such as aerial photogrammetry, stereo vision measurement and so on. Satellite remote sensing is to measure and shoot remote sensing images by satellite, and then analyze and process the images to obtain various terrain information of the earth's surface.

Topographic survey is a widely used surveying and mapping technology. It plays a great role in social, economic and scientific development. In urban planning and management, topographic survey can help planners design urban planning into a city that is conducive to transportation, ecology and environmental protection. In agriculture and forestry, topographic survey can also provide detailed information about land and help farmers and forestry workers make better use of land resources. In oil and mineral exploration, topographic survey can provide necessary support for finding mineral resources such as oil, metal mines and diamonds. In environmental protection, topographic survey is helpful to grasp the ecological conditions of oceans, lakes and rivers, and find pollution sources and environmental problems.