What is the main network construction method of the national basic plane control network?

1.Hierarchical network layout, step-by-step control.

China's territory is vast and the terrain is complex, and it is impossible to spread the whole country at once with the highest precision and large density control network. In order to meet the needs of the country's economic construction and national defense construction in a timely manner, it is very necessary to adopt the principle of hierarchical distribution of nets and step-by-step control according to priorities and priorities. That is, the first-class triangular lock with high precision and sparse is quickly distributed throughout the country along the direction of longitude and latitude as much as possible to form a unified backbone earth control network, and then it is laid step by step (or at the same time) in the first-class lock ring.

Second, third, fourth and other control networks.

2.There should be sufficient accuracy.

The accuracy of the control network should be determined according to the need and possibility. As the backbone of the national geodetic control network, the first-class control network should strive for higher accuracy in order to provide reliable data for scientific research.

In order to ensure the accuracy of the national control network, it is necessary to put forward appropriate requirements and regulations for the accuracy of the starting data and observation elements, the size of the graphic angles in the network, etc. These requirements and regulations are set out in the National Specification for Triangulation and Precision Traverse Measurement (hereinafter referred to as the National Code).

3.There should be sufficient density.

The density of the control points is mainly determined by the mapping method and the size of the mapping scale. For example, when using the aerial survey method to create a map, the empirical values of the density requirements are shown in the following table, and the data in the table are mainly based on experience.

4.There should be uniform specifications.

Due to the huge scale of China's triangular lock network, there must be a large number of measurement units and operators to operate at the same time, for this reason, it is necessary for the state to formulate a unified geodetic survey method and operation specification "National Triangulation and Precision Wire Measurement Specification", as the basis for establishing a control network with unified national technical specifications.

Triangulation, precision traverse, trilateration, edge and corner measurement.

There are several main methods to establish a plane control network:

1.Triangle method: A plane control network is established by measuring the inner angles and side lengths of the triangle. This method has high measurement accuracy, but it needs to establish many triangles in the measurement area, and the workload is large.

2.Polygon method: Establish a plane control network by measuring the angle and edge length of a polygon. This method is suitable for complex measurement areas such as buildings and roads, and the number of corners that need to be measured is less to alleviate the disturbance.

3.Zhongyi Nahu Xindian Method: Establish a plane control network by measuring the distance and direction from multiple points to a central point. This method is suitable for sites with large measurement areas, such as cities, forests, etc.

4.Free network method: by establishing some control points in the measurement area, and then randomly laying some measurement points near these control points, and then through calculation and adjustment, the plane control network is established. This method is suitable for sites with large measurement areas and complex terrain.

5.GPS Measurement Method: Establish a plane control network through Global Positioning System (GPS) measurements. This method is suitable for sites with large measurement areas and complex terrain, and can achieve high-precision and high-efficiency measurements.

1. Wire measurement.

Traverse measurement - Divide each control point into a continuous polyline or polygons A and B. The control net formed by this pattern is called a wire network, also known as a wire, and the turning point (control point) is called a wire point. Measure the horizontal angle between adjacent traverse edges and the length of the traverse edge, and calculate the coordinates of each traverse point according to the plane coordinates of the starting point and the azimuth angle of the starting edge, which is called traverse.

2. Triangulation.

Triangulation - each control point is composed of a series of triangles connected to each other, one side of the triangle and the inner angle of all triangles are measured, according to the coordinates of the starting point and the azimuth angle of the starting edge, all the side lengths and azimuth angles are calculated according to the sinusoidal law, so as to calculate the coordinates of each point, the first loss of this work is called triangulation.

3. Three-sided measurement.

Trilateral measurement - refers to the method of determining the horizontal position of the vertices of each triangle by means of edge measurement using a total station electronic tachymeter or photoelectric rangefinder. Trilateral measurement is one of the methods to build a plane control network of Chanqin Youli, and its advantage is that it can better control the error of side length and work efficiency. Trilateration is only to measure the edge length, and there is no verification condition for the single triangulation of the edge.

4. GPS measurement.

GPS GPS Surveying - GPS is a new generation of satellite navigation and positioning system with all-round real-time 3D navigation and congratulatory positioning capabilities in the sea, land and air. With its remarkable characteristics of all-weather, high precision, automation, and high efficiency, GPS has been successfully applied to engineering control measurement, such as the third bridge of the Yangtze River in Nanjing, the 18km Qinling Tunnel of the Xikang railway line, and line control measurement.

Summary. The task of plane control measurement is to measure the angle and distance elements between control points with precision instruments and precision methods, and calculate the coordinates of each control point according to the plane coordinates and azimuth angles of known points. The methods of establishing a plane control network include traverse measurement, triangulation, trilateration measurement, GPS measurement, etc.

With the development of electromagnetic wave ranging technology, traverse measurement has become the main method of plane control measurement.

What are the ways to build a plane control network? What are the advantages and disadvantages of each?

Pro: Thank you for your patience, here for you to find the patient, the square ant bridge method of the construction of the mu fierce plane control network has traverse method, small triangulation method and angle front intersection method. Among them, the advantage of traverse measurement method is that it can easily measure areas with complex distribution of ground objects and many obstructions in sight. The advantages of triangulation are excellent, I hope mine can help you, thank you for your consultation.

The methods for establishing a plane control network include traverse, triangulation and angular front intersection. Among them, the advantage of traverse measurement method is that it can easily measure the distribution of ground objects, complex mountains and miscellaneous areas, and there are many visual obstructions. The advantage of the small triangulation method is that the chain is better than the tunnel and bridge area in the mountainous and hilly areas; The angular front intersection shed sensitivity method is better than that of areas with a high density of measurement control points.

The task of plane control measurement is to measure the angle and distance elements between control points with precision instruments and precision methods, and calculate the coordinates of each control point according to the plane coordinates and azimuth angles of known points. The methods of establishing a plane control network include traverse difference measurement, triangular pin spike measurement, trilateral measurement, GPS measurement, etc. With the development of electromagnetic wave ranging technology, traverse measurement has become the main method of plane control measurement.

The principle of laying out the national basic plane control network is that it should be adapted to local conditions, starting from the current needs and giving due consideration to development.

A control network established throughout the country is called the National Control Network. It is a national scale of all kinds.

Basic control of mapping and provides research information for determining the shape and size of the Earth. The national control network is established by precision measuring instruments and methods according to the measurement accuracy according to the first, second, third, and fourth grades, and its low-level points are controlled by the high-level points step by step. The conventional method of establishing a national plane control network is triangulation.

and precision wire measurements.

The foundation plane control network is suitable for the new 250 350km h high-speed railway engineering survey, and the new 200km h ballastless and track railway engineering survey can be carried out with reference.

1. The CPI control network should be established in the initial test stage, and it should be completed before the final test when it is difficult, and the whole line (section) should be laid out at one time, unified measurement, and overall adjustment.

2 The CPI control network shall be laid along the line direction as required and attached to the CPO control network. The control point should be located within 50 1000rn from the center of the line, which is not easy to be damaged by construction, stable and reliable, and convenient for Peibu measurement. The point layout should take into account the requirements of the construction control network of bridges, tunnels and other large-scale buildings (structures), and bury stones according to the regulations.

After the burial of the marker stone is completed, the point description should be filled in on the spot, the distance from the marker stone to the obvious ground object should be measured, the schematic diagram of the point should be drawn, and the point mark should be made as required.

3 CP I should be constructed by edge connection to form a ribbon network composed of triangles or earth quadrilaterals. **The starting point and end point of the road survey design or the connection with other railway plane control networks must have 2 or more CP I control points overlapping, and the relationship between them must be reflected in the survey results. The CPI control network should be tested in conjunction with a known leveling point nearby.

4 CPI control network should be measured with the national or city along the third class and above plane control points, generally every 50km should be a plane control point, the total number of plane control points of the whole line (section) should not be less than 3, under special circumstances shall not be less than 2 travel. When the number of joint measurement points is 2 matching ears, they should be distributed at both ends of the network as much as possible; When the number of joint measurement points is 3 or more, it is advisable to distribute them evenly in the network.

5. The CPI control network should be measured according to the requirements of second-class GPS measurement.