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The calculation of land area is an important part of land management. It is a concrete means to find out the proportion of land and family land and the proportion of various types of land structures. It is also the basis for adjusting the land use structure and the revision of land use planning. Therefore, grasping the use of area measuring instruments such as area measuring instruments and the calculation of land area are important technical means for accurately grasping land resource data.
The solution to the problems in the calculation of land area 1. Improve the measurement accuracy in the field to avoid the measurement error When measuring the land, firstly avoid the system error, human error, and error factors in the area measurement instrument. In addition, use high-precision control data to comply with Various professional procedures, taking into account external influences, improve the measurement accuracy, so as to ensure the accuracy of land area measurement.
2. The following three methods are used to solve the distortion caused by the map projection: (1) Using the Earth's radius and the distance from the central meridian to establish a mathematical model, plus the projection area correction;
(2) Select the appropriate projection bandwidth. The distortion produced in the map projection varies with the bandwidth. Therefore, when calculating the area, first calculate the maximum length deformation value based on the known area accuracy, and then determine the projection bandwidth from this length deformation value, so as to select the banding;
(3) Use equal-area projection method instead. The distortion produced in the map projection is due to the isometric projection of the Gauss-Krueger projection. When calculating the area, to ensure that the area does not change, consider using the equal-area projection method to calculate, that is, calculate the starting latitude and longitude and the area of ​​the ending latitude and longitude. Since the enclosed area is a trapezoid after Gaussian projection, it is also called a spherical trapezoidal area. Calculations.
3. Oblique surface projection Projection correction to the floor plan The area measuring instrument must properly consider the deformation of the inclined surface projection onto the plane. The tilted surface projection area is related to the inclination of the ground and should be corrected when calculating the actual area of ​​the ground.
The solution to the problems in the calculation of land area 1. Improve the measurement accuracy in the field to avoid the measurement error When measuring the land, firstly avoid the system error, human error, and error factors in the area measurement instrument. In addition, use high-precision control data to comply with Various professional procedures, taking into account external influences, improve the measurement accuracy, so as to ensure the accuracy of land area measurement.
2. The following three methods are used to solve the distortion caused by the map projection: (1) Using the Earth's radius and the distance from the central meridian to establish a mathematical model, plus the projection area correction;
(2) Select the appropriate projection bandwidth. The distortion produced in the map projection varies with the bandwidth. Therefore, when calculating the area, first calculate the maximum length deformation value based on the known area accuracy, and then determine the projection bandwidth from this length deformation value, so as to select the banding;
(3) Use equal-area projection method instead. The distortion produced in the map projection is due to the isometric projection of the Gauss-Krueger projection. When calculating the area, to ensure that the area does not change, consider using the equal-area projection method to calculate, that is, calculate the starting latitude and longitude and the area of ​​the ending latitude and longitude. Since the enclosed area is a trapezoid after Gaussian projection, it is also called a spherical trapezoidal area. Calculations.
3. Oblique surface projection Projection correction to the floor plan The area measuring instrument must properly consider the deformation of the inclined surface projection onto the plane. The tilted surface projection area is related to the inclination of the ground and should be corrected when calculating the actual area of ​​the ground.
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