Area calculations are based on cadastral measurements. At present, the tool used for area measurement is mainly the acre measurement instrument. The acre measurement instrument is based on the analytical data and the cadastral map of the coordinates of the boundary point, the length of the edge, and the appropriate method is used to calculate the area. Area measurement should also be carried out in accordance with the principle of controlling from the whole to the local level and checking step by step in order to eliminate errors and improve accuracy. Air Purifier,Air Purifier Filters,Multifunctional Air Purifier,Home Hepa Air Purifier Leeyo Pilot Electric Technology Co., Ltd , https://www.nbleeyo-pilot.com
Area measurement refers to the calculation of horizontal area, which mainly includes the calculation of land area and land use area.
The method of area measurement is usually divided into analysis method and graphic method, and partial analysis method is a combination of the two. The data used by the analytical method is analytical coordinates or analytical side lengths, calculated using a strict analytical formula. The calculated data obtained from the figure is the graphic method, including the planimeter method, grid method, and dot method. Geometry law is divided into analytical or graphical methods according to the method of obtaining product elements. So far, there is no strict classification method. Each area calculation method has its own characteristics and scope of application. In actual work, it can be selected according to the situation and considered comprehensively, without being tied to a method.
In urban areas and rural settlements, the unit of measurement for the area is m2, which is one decimal place; the area for rural areas is calculated in acres, and two decimal places are used. The land area of ​​each tenement unit in the consolidated land is calculated based on the proportion of the total land area of ​​each tenement unit. The area measurement work program is divided into three steps: control area measurement, broken area measurement, and summary statistics.
Control area measurement: The area of ​​the lower administrative units is controlled by the area of ​​the higher administrative units, and the lower control area is under the control of the upper control area. The map theory area of ​​a map is the most basic control of the area of ​​each level. Streets or neighborhoods and villages generally have the final control area of ​​urban and rural areas.
Fragment area calculation: the area of ​​the individual spots measured within the control area of ​​this level. The area of ​​the broken parts should be adjusted according to the upper control area, and the sum of the area after adjustment should be equal to the controlled area.
Aggregate statistics: first calculate the area of ​​parcels or land area of ​​each administrative unit by maps, and then summarize the statistics of each frame. When summarizing, verification should be carried out. The sum of the area of ​​all levels should be consistent with the control area at the previous level to prevent mistakes.
1 Land area measurement method The area measurement method is divided into analytical method and graphic method. The method of calculating the land area based on the measured data is called analytical method, including analytical coordinate area calculation method and geometric figure area calculation method, which is commonly used by towns. The digital cadastral measurement uses the analytical coordinate area calculation method. Its calculation formula is: 
In the formula, P - parcel area, m2;
Xi, yi - the coordinates of the i-th boundary site in the parcel, m;
n - The number of parcel boundary points.
The geometric area calculation method is a method of calculating the land area based on the distance from the field. The principle is to divide the polygon area into a number of basic geometric shapes (such as rectangles, trapezoids, or triangles, etc.), calculate the areas and add them, so as to obtain the required polygon area. The length of the side used in the calculation of the area is calculated to cm. Small towns that generally do not have digital mapping conditions use this method. The so-called graphical method is to directly measure the area on the cadastral map or measure the quadrature element on the cadastral map, and then use the formula to calculate the method. Including photoelectric area measuring instrument method, planimeter method, graphical coordinate method, geometric method and.
2 The calculation of land area requires that the Regulations for Survey of Urban Cadastries stipulate that no matter what method is used to measure the area, it should be carried out independently twice. When measuring on the map, the difference between the two measurements is taken within the tolerance. When analytical methods are used to perform surveys, the area of ​​each parcel should be calculated using the coordinate area calculation method, and independent verification should be performed twice. Regardless of the method used to measure the area, two separate calculations should be made for verification. The digital cadastre uses the coordinate analysis method to calculate the area, and its two calculations should be consistent. When using the partial analytical method for cadastral measurement, the area of ​​each neighborhood should be determined by analytical method, and the area of ​​each parcel within the neighborhood should be controlled by the number of neighborhoods. When the error in the area of ​​the parcels and the size of the neighborhood is less than 1/200, the error is distributed to each parcel in proportion, and the parcel area after adjustment is obtained. However, the length measurement data can be unchanged. The parcel area of ​​the regular graph calculated entirely from the measured data may not be involved in the adjustment.
3 Digital mapping area calculation and summary For the digital cadastral, since the parcels have the analytical coordinates of field measurements, the area of ​​each parcel is automatically calculated by the computer, such as the simultaneous input. For the number of floors in the parcel, the mapping system will automatically calculate the building footprint and the building area of ​​each parcel, as well as the building density and the building volume ratio. At the same time, the area calculations and summary results can be output in print format in a prescribed format. Its report types mainly include:
(1) Settlements point results table. The content includes the boundary point number and the coordinates of the boundary point, such as the elevation measured in the field, and the elevation of the individual site. Output range: parcels, neighborhoods.
(2) The parcel area calculation table. The content includes site number, coordinates, side lengths, and the building footprint, building area, building density, and building volume ratio in each parcel. Output range: parcels, neighborhoods.
(3) Summary of parcel area. The content includes the cadastral number, land number, land type code, and area. Output range: streets, neighborhoods.
(4) Statistical tables of geographical areas. The content includes various types of area and summary results according to the classification of urban land in the output range. Output range: neighborhoods, streets, districts, cities. When generating a report, labor only needs to specify the scope and area, street, and neighborhood number of the report output, and then all calculations and aggregations are automatically completed by the mapping system, avoiding many manual errors.
4 Conclusion In summary, the measurement of land area is an important part of cadastral surveys. Through the calculation of land area, we can obtain the total area of ​​all levels of administrative jurisdiction, the area of ​​parcels of each unit of ownership, and the data of each classified land area. Based on these data, we can scientifically carry out urban planning and construction to meet the needs of the general public. And housing requirements.