What is the basic content of surveying and mapping?

The activity of measuring, collecting and expressing the shape, size, spatial position and attributes of natural geographical elements or surface artificial facilities, and processing and providing the obtained data, information and achievements.

In the investigation of basic knowledge, the spatial position of ground points is expressed (determined) by coordinates and elevations. The commonly used coordinates to indicate the plane position of ground points are geographical coordinates and plane rectangular coordinates, and polar coordinates can also be used in a small range; Elevation is the vertical distance from the ground point to the geoid, which is called the absolute elevation of the point, also called elevation.

At present, China takes the average sea level of the Yellow Sea as the geoid. 1985 decided to adopt the newly determined mean sea level of the Yellow Sea as the elevation starting surface of China, which was called "1985 Yellow Sea height system". Previously, China used the average sea level of Dagu Lake in Tianjin as the geoid. Distance, horizontal angle and elevation are three basic geometric features to determine the relative position of ground points, so distance measurement, horizontal angle measurement and elevation measurement are the basic work of measurement.

Combined with the actual work, based on the principle of learning basic knowledge and mastering basic skills, ranging and general leveling (elevation, sight distance and section measurement) are mainly used.

Types of surveying and mapping

1, geodesy. Theories and methods to study and determine the shape and size of the earth, the gravity field of the earth and the geometric position of ground points. Geodesy is the theoretical basis of surveying and mapping disciplines. Its basic task is to establish ground control network and gravity network, accurately determine the three-dimensional position of control points, provide control basis for topographic map, provide basis for various engineering construction, and provide information for studying the shape, size, gravity field and its changes, crustal deformation and earthquake prediction of the earth.

2. Routine measurement. The theory and method of local area control survey and topographic mapping of the earth's surface are studied. Local area means that when surveying and mapping in this area, the curvature of the earth can be ignored and treated as a plane without affecting the accuracy of surveying and mapping.

3. Photogrammetry. This paper studies the theory and method of using camera or other sensors to collect the image information of the measured object, and after processing and analysis, determine the shape, size and position of the measured object and judge its properties.

According to the distance, it can be divided into: aerial photogrammetry, aerial photogrammetry, ground photogrammetry, close-range photogrammetry and microscopic photogrammetry; According to different technical processing methods, it can be divided into analog photogrammetry, analytical photogrammetry and digital photogrammetry.

4. Engineering survey. Study the measurement theory, technology and method in the design, construction and management stages of engineering construction. Provide accurate survey data and large-scale maps for engineering construction, and ensure reasonable site selection, design construction and effective management. In the operation stage of the project, deformation observation and settlement monitoring are carried out to ensure the normal operation of the project.

According to the research object, it can be divided into: architectural engineering survey, hydraulic engineering survey, mine engineering survey, railway engineering survey, highway engineering survey, transmission line and oil pipeline survey, bridge engineering survey, tunnel engineering survey, military engineering survey and so on.

5. Marine mapping. Taking marine water bodies and seabed as objects, it is a discipline that studies the geographical distribution of natural and social confidence, such as marine conditions, determination of marine geoid and average sea surface, seabed and sea surface topography, marine gravity, marine magnetism and marine environment. , as well as the theoretical hunger technology of compiling various charts. It provides guarantee for ship navigation safety and marine engineering construction.