Control method and device for length deformation of coupled elevation and Mercator projection

Abstract

The present disclosure provides a control method and device for coupling elevation and length deformation of Mercator projection, and relates to the technical field of engineering surveying. The method comprises: estimating a first rate of change of projection length deformation caused by Mercator projection in the engineering surveying area according to the latitude distribution of the engineering surveying area; estimating a second rate of change of projection length deformation caused by the height difference according to the height difference distribution of the engineering surveying area; determining the latitude that makes the absolute value of the first rate of change and the absolute value of the second rate of change the same as the standard latitude for Mercator projection in the engineering surveying area; and performing Mercator projection in the engineering surveying area based on the latitude of the standard latitude. Based on this technical solution, the projection deformation of large height difference engineering can be reduced.

Description

Technical Field

[0001] The present disclosure relates to the technical field of engineering measurement, and in particular to a control method and device for coupling elevation and length deformation of Mercator projection. Background Art

[0002] With the development of engineering surveying technology, more and more large-scale projects with large elevation differences are being implemented, and the requirements for the accuracy of engineering construction are becoming higher and higher.

[0003] Usually, in order to facilitate engineering use, in the process of engineering measurement, it is necessary to project the edges on the sphere onto a developable surface, and then unfold it to determine the engineering control points for engineering layout. However, map projection will cause length deformation. In order to ensure the accuracy of the coordinates of the engineering control points, it is necessary to limit the degree of length deformation caused by projection. Especially in projects with large or super-large height differences, the use of traditional Mercator projection or Gauss-Krüger projection cannot meet the requirements of the project for the length deformation of the projection. Generally, engineering measurement requires that the difference between the length of the side directly calculated by the control point coordinates after projection and the length of the side measured on the spot meet the engineering requirements. When the length deformation cannot meet the engineering requirements, some processing methods are needed to improve the length deformation of the side in the engineering measurement area.

[0004] However, it is currently impossible to control the overall projection of the entire project area through a unified reduction benchmark. Therefore, there is an urgent need for a processing method that can quickly obtain projection parameters that meet the projection deformation tolerance requirements of large height difference projects for projection.

[0005] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0006] In order to overcome the problems existing in the related art, the embodiments of the present disclosure provide a method and device for controlling the length deformation of coupled elevation and Mercator projection, which can quickly obtain projection parameters that meet the engineering projection deformation tolerance requirements for projection.

[0007] According to a first aspect of an embodiment of the present disclosure, a method for controlling the length deformation of a coupled elevation and Mercator projection is provided, the method comprising: estimating a first rate of change of projection length deformation caused by Mercator projection in the engineering survey area according to the latitude distribution of the engineering survey area; estimating a second rate of change of projection length deformation caused by the height difference according to the height difference distribution of the engineering survey area; determining a latitude line having the same absolute value of the first rate of change and the same absolute value of the second rate of change as a standard latitude line for Mercator projection in the engineering survey area; and performing Mercator projection in the engineering survey area based on the latitude of the standard latitude line.

[0008] Optionally, based on the latitude of the measurement point in the engineering survey area, the Mercator projection length deformation corresponding to the measurement point in the engineering survey area is estimated; based on the Mercator projection length deformation corresponding to the measurement point in the engineering survey area, the first change rate of the projection length deformation caused by Mercator projection in the engineering survey area is estimated.

[0009] Optionally, based on the latitude of the standard parallel, the latitude of the north end measurement point, the latitude of the south end measurement point and a first preset formula, the Mercator projection length deformation corresponding to the north end measurement point and the Mercator projection length deformation corresponding to the south end measurement point are estimated respectively; the first preset formula includes: ;in, represents the latitude of the standard parallel, Indicates the measuring point The latitude of the location; based on the estimated Mercator projection length deformation corresponding to the north end measurement point, the estimated Mercator projection length deformation corresponding to the south end measurement point, the horizontal distance between the north end measurement point and the south end measurement point, and the second preset formula, the first change rate of the projection length deformation caused by the Mercator projection in the engineering measurement area is estimated; the second preset formula includes: ;in, Indicates the Mercator projection length deformation corresponding to the northern measurement point. Indicates the latitude of the northern measurement point, Indicates the latitude of the southern measurement point, Indicates the Mercator projection length deformation corresponding to the southern measurement point, Indicates the horizontal distance between the north and south measurement points.

[0010] Optionally, based on the latitude of the standard parallel, the latitude of each measuring point and a first preset formula, the Mercator projection length deformation corresponding to each measuring point is estimated respectively; the first preset formula includes: ;in, represents the latitude of the standard parallel, Indicates The latitude of each measuring point; the Mercator projection length deformation corresponding to each measuring point determined based on the first preset formula, and the first change rate of the projection length deformation caused by the Mercator projection in the engineering measurement area is determined by the least squares method.

[0011] Optionally, based on the horizontal distance between the measuring points in the engineering survey area, the mean radius of curvature of the earth, the elevation surface where the average elevation between the measuring points is located, and the elevation difference of a preset side length reduction projection surface, the projection length deformation caused by the elevation difference between the measuring points is estimated; based on the projection length deformation caused by the elevation difference between the measuring points, the second change rate of the projection length deformation caused by the elevation difference between the measuring points is estimated.

[0012] Optionally, based on the horizontal distance between the measuring points, the average radius of curvature of the earth, the elevation difference between the elevation surface where the average elevation between the measuring points is located and the side length reduction projection surface, and a third preset formula, the projection length deformation caused by the elevation difference between the measuring points is estimated; wherein the third preset formula includes: ;in, Indicates The measurement points and The projection length deformation caused by the height difference of the measuring points is Indicates The measurement points and The horizontal distance between the measurement points, represents the mean radius of curvature of the Earth, Indicates the The measurement points and The elevation difference between the elevation surface where the average elevation between the measuring points is located and the projection surface where the side length is calculated.

[0013] Optionally, based on the projection length deformation caused by the height difference between the north and south ends of the engineering measurement area, the horizontal distance between the south end measurement point and the north end measurement point of the engineering measurement area, and a fourth preset formula, a second change rate of the projection length deformation caused by the height difference is estimated; the fourth preset formula includes: ;in, Indicates the projection length deformation caused by the height difference at the southern end of the engineering survey area. Indicates the projection length deformation caused by the height difference at the north end of the engineering survey area. The horizontal distance between the southern and northern measuring points in the engineering survey area. Indicates the elevation of the measuring point at the southern end of the engineering survey area. Indicates the elevation of the measuring point at the north end of the engineering survey area.

[0014] Optionally, based on the third preset formula, the second change rate of the projection length deformation caused by the height difference is determined by the least square method: ;in, The vector representing the height difference between each measurement point and the projection surface in the engineering measurement area. A vector representing the deformation of the projection length of each measuring point in the engineering measurement area due to the height difference.

[0015] Optionally, the latitude of the latitude line in the engineering measurement area where the absolute value of the first change rate is equal to the absolute value of the second change rate is: .

[0016] According to a second aspect of an embodiment of the present disclosure, a control device for length deformation of coupled elevation and Mercator projection is provided, and the control device for length deformation of coupled elevation and Mercator projection comprises: a length change rate estimation module, a standard latitude determination module and a projection module; the length change rate estimation module is used to estimate a first change rate of projection length deformation caused by Mercator projection of the engineering survey area according to the latitude distribution of the engineering survey area, and to estimate a second change rate of projection length deformation caused by the height difference according to the height difference distribution of the engineering survey area; the standard latitude determination module is used to determine the latitude that makes the absolute value of the first change rate and the absolute value of the second change rate the same as the standard latitude for Mercator projection of the engineering survey area; the projection module is used to perform Mercator projection in the engineering survey area based on the latitude of the standard latitude.

[0017] Optionally, the length change rate estimation module is specifically used to: estimate the Mercator projection length deformation corresponding to the measurement point in the engineering measurement area based on the latitude of the measurement point in the engineering measurement area; and estimate the first change rate of the projection length deformation caused by Mercator projection in the engineering measurement area based on the Mercator projection length deformation corresponding to the measurement point in the engineering measurement area.

[0018] Optionally, the length change rate estimation module is specifically used to respectively estimate the Mercator projection length deformation corresponding to the north end measurement point and the Mercator projection length deformation corresponding to the south end measurement point based on the latitude of the standard parallel, the latitude of the north end measurement point, the latitude of the south end measurement point and a first preset formula; the first preset formula includes: ;in, represents the latitude of the standard parallel, Indicates The latitude of the measuring point; based on the estimated Mercator projection length deformation corresponding to the northern measuring point, the estimated Mercator projection length deformation corresponding to the southern measuring point, the horizontal distance between the northern measuring point and the southern measuring point, and the second preset formula, the first change rate of the projection length deformation caused by the Mercator projection in the engineering survey area is estimated; the second preset formula includes: ;in, Indicates the Mercator projection length deformation corresponding to the northern measurement point. Indicates the latitude of the northern measurement point, Indicates the latitude of the southern measurement point, Indicates the Mercator projection length deformation corresponding to the southern measurement point, Indicates the horizontal distance between the north and south measurement points.

[0019] Optionally, the length change rate estimation module is specifically used to estimate the Mercator projection length deformation corresponding to each measuring point based on the latitude of the standard parallel, the latitude of each measuring point and a first preset formula; the first preset formula includes: ;in, represents the latitude of the standard parallel, Indicates The latitude of each measuring point; the Mercator projection length deformation corresponding to each measuring point determined based on the first preset formula, and the first change rate of the projection length deformation caused by the Mercator projection in the engineering measurement area is determined by the least squares method.

[0020] Optionally, the length change rate estimation module is specifically used to: estimate the projection length deformation caused by the elevation difference between the measuring points based on the horizontal distance between the measuring points in the engineering measurement area, the average radius of curvature of the earth, the elevation surface where the average elevation between the measuring points is located, and the elevation difference of the preset side length reduction projection surface; based on the projection length deformation caused by the elevation difference between the measuring points, estimate the second change rate of the projection length deformation caused by the elevation difference between the measuring points.

[0021] Optionally, the length change rate estimation module is specifically used to estimate the projection length deformation caused by the height difference between the measuring points based on the horizontal distance between the measuring points, the average curvature radius of the earth, the height difference between the elevation surface where the average elevation between the measuring points is located and the side length reduction projection surface, and a third preset formula; wherein the third preset formula includes: ;in, Indicates The measurement points and The projection length deformation caused by the height difference of the measuring points is Indicates The measurement points and The horizontal distance between the measuring points, represents the mean radius of curvature of the Earth, Indicates The measurement points and The elevation difference between the elevation surface where the average elevation between the measuring points is located and the projection surface where the side length is calculated.

[0022] Optionally, the length change rate estimation module is specifically used to estimate the second change rate of the projection length deformation caused by the height difference between the north and south ends of the engineering measurement area, based on the projection length deformation caused by the height difference between the south and north ends of the engineering measurement area, the horizontal distance between the south end measurement point and the north end measurement point of the engineering measurement area, and a fourth preset formula; the fourth preset formula includes: ;in, Indicates the projection length deformation caused by the height difference at the southern end of the engineering survey area. Indicates the projection length deformation caused by the height difference at the north end of the engineering survey area. The horizontal distance between the southern and northern measuring points in the engineering survey area. Indicates the elevation of the measuring point at the southern end of the engineering survey area. Indicates the elevation of the measuring point at the north end of the engineering survey area.

[0023] Optionally, the length change rate estimation module is specifically used to: determine, based on a third preset formula, using a least squares method, a second change rate of the projection length deformation caused by the height difference: ;in, The vector representing the height difference between each measurement point and the projection surface in the engineering measurement area. A vector representing the deformation of the projection length of each measuring point in the engineering measurement area due to the height difference.

[0024] Optionally, the latitude of the latitude line in the engineering measurement area where the absolute value of the first change rate is equal to the absolute value of the second change rate is: .

[0025] According to a third aspect of an embodiment of the present disclosure, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the control method for length deformation of coupled elevation and Mercator projection as described in the first aspect is implemented.

[0026] According to a fourth aspect of an embodiment of the present disclosure, a computer device, a memory, a processor, and computer-readable instructions stored in the memory and executable on the processor are provided, wherein the computer-readable instructions, when executed by the processor, implement the control method for length deformation of coupled elevation and Mercator projection as described in the first aspect.

[0027] The technical solution provided by the embodiments of the present disclosure may have the following beneficial effects:

[0028] In the disclosed embodiment, first, a first rate of change of projection length deformation caused by Mercator projection in the engineering survey area is estimated; based on the height difference distribution in the engineering survey area, a second rate of change of projection length deformation caused by the height difference is estimated; the latitude that makes the absolute value of the first rate of change and the absolute value of the second rate of change the same is determined as the standard latitude for Mercator projection in the engineering survey area; based on the latitude of the standard latitude, Mercator projection is performed in the engineering survey area. On the one hand, since the length deformation estimation is jointly performed based on the projection length deformation caused by the Mercator projection estimated based on the latitude distribution and the projection length deformation caused by the height difference distribution, the positive length change caused by the height difference can be offset by the negative length change generated by the Mercator projection. When the absolute value of the first change rate of the projection length deformation caused by the Mercator projection and the absolute value of the second change rate of the length deformation caused by the height difference are the same, the negative and positive length deformations are the same. The latitudes with the same absolute value of the length deformation change rate are selected as the standard latitudes for Mercator projection. Compared with the method in the related art that requires multiple sets of coordinate systems to be projected for estimating the projection length deformation, the processing speed is fast and the complexity is low, which can improve the speed of determining the engineering coordinates. On the other hand, in the embodiment of the present disclosure, the latitude of each measuring point within the latitude range is concerned, and there is no need to introduce the longitude for deformation estimation. The calculation complexity is low, the accuracy is high, and it is closer to the real deformation. The difference between the side length directly inverted based on the control point coordinates after projection and the side length obtained by field measurement can meet the requirements of large height difference and super-large height difference projects, which can ensure the accuracy of the project control grid coordinates, facilitate the project layout, and improve the accuracy of the layout.

[0029] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0031] Figure 1 A schematic diagram of the system architecture of a method for controlling length deformation of coupled elevation and Mercator projection provided in an embodiment of the present disclosure.

[0032] Figure 2 A flow chart of a method for controlling length deformation of a coupled elevation and Mercator projection provided in an embodiment of the present disclosure.

[0033] Figure 3 A schematic diagram of length deformation caused by a Mercator projection provided in an embodiment of the present disclosure.

[0034] Figure 4A schematic diagram of projection length deformation caused by height difference provided in an embodiment of the present disclosure.

[0035] Figure 5 A hardware structure diagram of a computer device in which a control device for coupling elevation and length deformation of Mercator projection is located in an embodiment of the present disclosure.

[0036] Figure 6 A schematic diagram of the structure of a control device for coupling elevation and length deformation of Mercator projection provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0037] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0038] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. The singular forms of "a", "said" and "the" used in this disclosure and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0039] It should be understood that although the terms first, second, third, etc. may be used in the present disclosure to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present disclosure, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0040] Next, the embodiments of the present disclosure are described in detail.

[0041] Figure 1 A schematic diagram of the system architecture of a method for controlling length deformation of coupled elevation and Mercator projections to which an embodiment of the present disclosure can be applied is shown.

[0042] like Figure 1As shown, the system architecture 100 may include one or more of terminal devices such as a smart phone 101, a portable computer 102, a desktop computer 103, a network 104, and a server 105. The network 104 is used to provide a medium for a communication link between the terminal device and the server 105. The network 104 may include various connection types, such as wired, wireless communication links, or optical fiber cables, etc.

[0043] The terminal device may be any electronic device with data processing function, which has a display screen for displaying the latitude of the measurement point, the measured area, the projection result based on the determined standard latitude, etc. to the user. The electronic device includes but is not limited to the above-mentioned desktop computer, portable computer, smart phone, tablet computer, etc.

[0044] It should be understood that Figure 1 The number of terminal devices, networks and servers in the embodiment is only for illustration. Any number of terminal devices, networks and servers may be provided according to implementation requirements.

[0045] The control method for coupling the elevation and the length deformation of the Mercator projection provided in the embodiment of the present disclosure can be executed by the terminal device, and accordingly, the control device for coupling the elevation and the length deformation of the Mercator projection can be set in the terminal device. However, it is easy for those skilled in the art to understand that the control method for coupling the elevation and the length deformation of the Mercator projection provided in the embodiment of the present disclosure can also be executed by the server 105, and accordingly, the control device for coupling the elevation and the length deformation of the Mercator projection can also be set in the server 105, which is not particularly limited in this exemplary embodiment.

[0046] The disclosed embodiment limits the deformation of the side length by coupling the deformation change rate of the side length caused by the height difference and the deformation change rate of the side length caused by the Mercator projection, providing a more scientific and accurate calculation method for engineering measurement. The method is suitable for projects with high requirements for the projection deformation of the side length in large height differences and super-large height differences, such as reservoir projects, hydropower stations, pumped storage power stations, large bridge and tunnel projects, etc., and can effectively meet the construction requirements of large or super-large elevation projects.

[0047] like Figure 2 As shown, Figure 2 A flow chart of a method for controlling length deformation of coupled elevation and Mercator projection provided by an embodiment of the present disclosure includes the following S201 to S204:

[0048] S201. Estimate a first rate of change of projection length deformation caused by Mercator projection in the engineering survey area according to the latitude distribution of the engineering survey area.

[0049] For example, the latitude range of the engineering survey area and each measurement point may be determined first.

[0050] Usually, for the layout of some projects with large or super-large height differences, such as the layout of large reservoirs and hydropower stations, the requirements for the deformation value of the project side length projection are relatively high. The height difference will cause the deformation of the length after projection. The greater the height difference, the greater the deformation, that is, the greater the deviation after subsequent projection, resulting in lower accuracy of the layout based on the projection results.

[0051] The measurement points include the southern and northern endpoints of the latitude range of the engineering measurement area, as well as other measurement points at different latitudes between the southern and northern endpoints. The elevations of the various measurement points are not necessarily the same.

[0052] It should be noted that the deformation of the Mercator projection (here refers to the Orthotropic Mercator projection) is generally related to latitude but not longitude.

[0053] It should be noted that in the embodiment of the present disclosure, the length deformation of the Mercator projection of each measuring point can be estimated based on the latitude distribution. The length deformation of the Mercator projection is a variable related to the selection of the standard latitude. Therefore, the determined length deformation of the Mercator projection is a deformation relationship related to the standard latitude and the latitude of the measuring point.

[0054] Figure 3 A schematic diagram of the length deformation of a Mercator projection provided by an embodiment of the present disclosure, such as Figure 3 As shown in , taking the earth as a sphere as an example, the center of the earth O is on the central axis of the cylinder, and the latitude range of the engineering survey area is [ B S , B N ]. Among them, the latitude value is B S Edge L S Projected onto the cylinder as the edge , the side length is negatively deformed; the latitude value is B i1 Edge L i1 Projected onto the cylinder as the edge , the side length is negatively deformed; the latitude value is B 0 (standard latitude) L 0 is projected onto the cylinder as an edge , the side length is not deformed; the latitude value is B i2 Edge L i2 Projected onto the cylinder as the edge , the side length undergoes positive deformation; the latitude value is B N Edge LN Projected onto the cylinder as the edge , the side length undergoes positive deformation.

[0055] S202. Estimate a second rate of change of length deformation caused by the height difference according to the height difference distribution in the engineering measurement area.

[0056] Figure 4 A schematic diagram of projection length deformation caused by height difference provided in an embodiment of the present disclosure, such as Figure 4 As shown in , taking the earth as a sphere as an example, is the actual earth surface, which contains topographic relief; The projection surface for side length calculation and the elevation surface for the project are generally the average elevation of the project area (for example, the average elevation of the upper reservoir and the lower reservoir of the pumped storage power station). is the reference ellipsoid; the engineering measurement area is Click to The area between the points, and Due to the height difference, the projection length will be deformed; for and The horizontal distance between for The projection on the side length reduction projection plane, for Projection on the side length reduction projection surface; express and The distance between and The distance between projections on the projection surface calculated by side length. For The plumb line and the side length are calculated from the projection surface The intersection of For The plumb line and the side length are calculated from the projection surface When the side length is short, the side length can be converted to the projection surface and approximately regarded as a horizontal plane, then and The horizontal distance between Can be equal to and The length between Figure 4 It can be seen that and The distance between and The distance between and The length between is greater than and The projection length on the projection surface is calculated by the side length, that is, the height difference causes the projection length to be deformed.

[0057] S203, determining the latitude that makes the absolute value of the first change rate and the absolute value of the second change rate the same as the standard latitude for Mercator projection of the engineering survey area.

[0058] It should be noted that in the embodiment of the present disclosure, the orthoaxial Mercator projection is used in the engineering projection. Before projection, the standard latitude with the smallest overall length deformation of the Mercator projection is determined, that is, the association between the projection deformation and the standard latitude. Therefore, before the map projection (i.e., Mercator projection) is performed, the estimated Mercator projection length deformation of each measuring point in the engineering survey area is a variable, which is related to the latitude of the standard latitude that needs to be determined. The latitude of the latitude with the smallest total length deformation when the Mercator projection is performed can be estimated based on the Mercator projection length deformation of each measuring point and the projection deformation caused by the elevation of each measuring point.

[0059] It should be noted that according to the estimation, two latitudes can be obtained, one in the southern hemisphere and one in the northern hemisphere. The latitudes corresponding to the latitudes within the project latitude range are determined as standard latitudes.

[0060] It should be noted that when the cylindrical surface selected by the Mercator projection is tangent to the earth, there is only one standard parallel with a latitude of 0°, and the projection length deformation in the rest of the latitude range is positive deformation; when the cylindrical surface selected by the Mercator projection is intersecting with the earth, there are two standard parallels, one in the southern and northern hemispheres, and the projection length deformation is negative between the standard parallels (between the standard parallels refers to the area corresponding to the latitude circle), and positive outside the standard parallels. In general, the measurement area includes only one standard parallel. Taking the northern hemisphere as an example, the projection length deformation in the measurement area south of the standard parallel is negative, and the projection length deformation in the measurement area north of the standard parallel is positive.

[0061] The smaller the deformation of the estimated total length after Mercator projection, the more accurate the subsequent engineering calculations based on the determined standard parallel projection will be, so that projects with large elevation differences can be accurately laid out.

[0062] S204. Perform Mercator projection in the engineering survey area based on the latitude of the standard parallel.

[0063] It should be noted that in the embodiments of the present disclosure, after estimating the standard parallel, Mercator projection in the engineering survey area can be performed based on the standard parallel. Since the standard parallel is the parallel with the smallest deformation of the total length of the Mercator projection estimated based on the latitude distribution and elevation difference distribution in the engineering survey area, after obtaining the standard parallel, performing Mercator projection based on the standard parallel can minimize the deformation of the projection of projects with large elevation differences and long distances, make the layout more accurate, and ensure that the accuracy of the coordinates of the engineering control points is higher during actual construction.

[0064] It should be noted that in projects with large elevation differences and a north-south orientation, the deformation caused by the Mercator projection is large, and the deformation caused by the elevation difference is large. By coupling the negative deformation caused by the Mercator projection and the positive deformation caused by the elevation difference, the standard latitude for minimum deformation during projection in projects with large elevation differences and a long length and a north-south orientation can be determined, and then the Mercator projection can be performed based on this standard latitude.

[0065] The disclosed embodiment provides a method for controlling the length deformation of coupled elevation and Mercator projection. First, a first change rate of projection length deformation caused by Mercator projection in an engineering survey area is estimated; a second change rate of projection length deformation caused by the elevation difference is estimated based on the elevation difference distribution in the engineering survey area; a latitude line that makes the absolute value of the first change rate and the absolute value of the second change rate the same is determined as the standard latitude line for Mercator projection in the engineering survey area; and Mercator projection is performed in the engineering survey area based on the latitude of the standard latitude line. On the one hand, since the length deformation estimation is jointly performed based on the projection length deformation caused by the Mercator projection estimated based on the latitude distribution and the projection length deformation caused by the height difference distribution, the positive length change caused by the height difference can be offset by the negative length change generated by the Mercator projection. When the absolute value of the first change rate of the projection length deformation caused by the Mercator projection and the absolute value of the second change rate of the length deformation caused by the height difference are the same, the negative and positive length deformations are the same. The latitudes with the same absolute value of the length deformation change rate are selected as the standard latitudes for Mercator projection. Compared with the method in the related art that requires multiple sets of coordinate systems to be projected for estimating the projection length deformation, the processing speed is fast and the complexity is low, which can improve the speed of determining the engineering coordinates. On the other hand, in the embodiment of the present disclosure, the latitude of each measuring point within the latitude range is concerned, and there is no need to introduce the longitude for deformation estimation. The calculation complexity is low, the accuracy is high, and it is closer to the real deformation. The difference between the side length directly inverted based on the control point coordinates after projection and the side length obtained by field measurement can meet the requirements of large height difference and super-large height difference projects, which can ensure the accuracy of the project control grid coordinates, facilitate the project layout, and improve the accuracy of the layout.

[0066] Optionally, in the control method for coupling elevation and Mercator projection length deformation provided in the embodiment of the present disclosure, the above S201 may be implemented by the following S201a and S201b:

[0067] S201a. Based on the latitude of the measurement point in the engineering survey area, estimate the Mercator projection length deformation corresponding to the measurement point in the engineering survey area.

[0068] S201b, based on the Mercator projection length deformation corresponding to the measurement point in the engineering measurement area, estimating a first change rate of the length deformation caused by Mercator projection in the engineering measurement area.

[0069] It can be understood that the more measurement points there are, the more accurate the estimation of the total length deformation of the Mercator projection will be, and the closer it will be to the actual projection deformation.

[0070] Based on this scheme, the Mercator projection length deformation of the measuring point can be estimated first, and then based on the estimated Mercator projection length deformation of the measuring point, the first change rate of the length deformation caused by the Mercator projection in the engineering measurement area can be estimated, so that the estimated change is more consistent with the actual length deformation change.

[0071] It should be noted that the embodiment of the present disclosure provides two different methods for estimating the first change rate of the length deformation of the Mercator projection. Among them, when the number of actual measurement points that can be obtained is limited, the Mercator projection length deformation of the south end measurement point and the Mercator projection length deformation of the north end measurement point can be estimated to determine the first change rate, that is, the estimation method of method one; when enough actual measurement points can be obtained, the Mercator projection length deformation of each measurement point is first estimated, and then based on the Mercator projection length deformation of each measurement point, the method of method two is used to process the matrix composed of the Mercator projection length deformation of each measurement point based on the least squares method to estimate the first change rate of the length deformation caused by the Mercator projection.

[0072] Method 1:

[0073] Optionally, in the control method for coupling elevation and length deformation of Mercator projection provided in the embodiment of the present disclosure, the above S201a can be specifically performed by the following T1:

[0074] T1. Based on the latitude of the standard parallel, the latitude of the northern measurement point, the latitude of the southern measurement point and formula (1), the Mercator projection length deformation corresponding to the northern measurement point and the Mercator projection length deformation corresponding to the southern measurement point are estimated respectively.

[0075] ;Formula (1)

[0076] in, represents the latitude of the standard parallel, Indicates The latitude of the measurement point.

[0077] It should be noted that in the embodiment of the present disclosure, in order to simplify the calculation, the earth ellipsoid is regarded as a sphere, wherein: It can express the projection length ratio at each measurement point on the earth. It represents the distance from the measurement point on the standard parallel to the Mercator projection axis. Indicates latitude B i The distance from the measurement point to the Mercator projection axis, which indicates the central axis of the cylinder used in the Mercator projection. Since the Mercator projection disclosed in this disclosure is the positive Mercator projection, the central axis coincides with the earth's axis. Indicates i Deformation per unit projected length at each measuring point.

[0078] Furthermore, the above S201b can be executed by the following T2:

[0079] T2, based on the estimated Mercator projection length deformation corresponding to the northern measurement point, the estimated Mercator projection length deformation corresponding to the southern measurement point, the horizontal distance between the northern measurement point and the southern measurement point and formula (2), estimate the first change rate of the length deformation caused by Mercator projection in the engineering measurement area.

[0080] ;Formula (2)

[0081] in, The Mercator projection length distortion representing the northern measurement point, Indicates the latitude of the northern measurement point, Indicates the latitude of the southern measurement point, The Mercator projection length distortion representing the southern measurement point, Indicates the horizontal distance between the north and south measurement points.

[0082] Based on this scheme, the first change rate of the length deformation caused by Mercator projection in the engineering measurement area can be determined based on the Mercator projection length deformation of each measuring point. When the latitudes of a small number of actual measuring points can be obtained, the change rate of the unit length deformation of the Mercator projection of the engineering measurement area can be quickly estimated by difference, thereby making the subsequent estimation of the standard latitude faster and the standard latitude can be quickly obtained when the number of measuring points is small.

[0083] Method 2:

[0084] Optionally, in the control method for coupling elevation and length deformation of Mercator projection provided in the embodiment of the present disclosure, the above S201a can be specifically performed by the following T3:

[0085] T3. Based on the latitude of the standard parallel, the latitude of each measurement point and formula (1), estimate the Mercator projection length deformation corresponding to each measurement point.

[0086] Furthermore, the above S201b can be executed by the following T4:

[0087] T4. Based on the Mercator projection length deformation corresponding to each measuring point determined by the first preset formula, a first change rate of the projection length deformation caused by Mercator projection in the engineering measurement area is determined by using the least squares method.

[0088] Based on this scheme, the first change rate of the length deformation caused by Mercator projection in the engineering measurement area can be determined based on the Mercator projection length deformation of each measuring point. When the latitudes of a large number of actual measuring points can be obtained, the more measuring points there are, the more accurately the change rate of the unit length deformation of the Mercator projection of the engineering measurement area can be estimated by the least squares fitting method, thereby making the subsequent estimation of the standard latitude more accurate, and the standard latitude can be obtained more accurately when the number of measuring points is large.

[0089] Optionally, in the control method for coupling elevation and length deformation of Mercator projection provided in the embodiment of the present disclosure, the above S202 can be specifically performed by the following S202a and S202b:

[0090] S202a, estimating the projection length deformation caused by the elevation difference based on the horizontal distance between the measurement points in the engineering measurement area, the average radius of curvature of the earth, the elevation surface where the average elevation between the measurement points is located, and the elevation difference between the preset side length reduction projection surface.

[0091] Among them, the preset side length reduction projection surface is a projection surface of a known elevation given according to the actual situation of the project, and can be set through experience.

[0092] For example, you can choose the average elevation surface of two key areas of the project. For example, in a pumped storage power station project, you can choose the average value of the upper reservoir water level elevation and the lower reservoir water level elevation. You can also make floating adjustments based on the average value according to specific circumstances.

[0093] S202b, based on the length deformation caused by the height difference between the measuring points, estimating a second change rate of the length deformation caused by the height difference between the measuring points.

[0094] Based on this scheme, the projection length deformation caused by the elevation difference between the measuring points can be accurately estimated based on the horizontal distance between the measuring points in the engineering measurement area, the average curvature radius of the earth, the elevation surface where the corresponding average elevation between the measuring points is located, and the elevation difference of the preset side length reduction projection surface. Based on the length deformation caused by the elevation difference between the measuring points, the second change rate of the length deformation caused by the elevation difference between the measuring points can be more accurately estimated, and the length deformation caused by the elevation difference can be truly obtained.

[0095] Optionally, in the control method for coupling elevation and length deformation of Mercator projection provided in the embodiment of the present disclosure, the above S202a can be specifically performed by the following T5:

[0096] T5. Estimate the length deformation caused by the height difference between the measuring points based on the horizontal distance between the measuring points, the mean radius of curvature of the earth, the height difference between the elevation surface where the mean elevation between the measuring points is located and the projection surface of the side length, and formula (3).

[0097] ;Formula (3)

[0098] in, Indicates The measurement points and The projection length deformation caused by the height difference of the measuring points is Indicates The measurement points and The horizontal distance between the measuring points, represents the mean radius of curvature of the Earth, Indicates The measurement points and The elevation difference between the elevation surface where the average elevation between the measuring points is located and the projection surface where the side length is calculated.

[0099] Based on this scheme, when the number of measurement points within the latitude range of the engineering survey area that can be obtained is sufficient, the above-mentioned integral form can be used to quickly and accurately determine the total length deformation of the Mercator projection of the engineering survey area based on the estimated Mercator projection length deformation of each measurement point.

[0100] Similarly, the embodiments of the present disclosure provide two different methods for estimating the second rate of change of length deformation caused by elevation difference. When the number of actual measurement points that can be obtained is limited, the length deformation caused by the elevation difference between the north and south ends can be estimated, so as to determine the second rate of change caused by the elevation difference, that is, the estimation method of method 1. When a sufficient number of actual measurement points can be obtained, the length deformation caused by the elevation difference between each measurement point is first estimated, and then based on the length deformation caused by the elevation difference of each measurement point, the method of method 2 is used to process the vector composed of the length deformation caused by the elevation difference of each measurement point based on the least squares method to estimate the second rate of change of the length deformation caused by the elevation difference.

[0101] Method 1:

[0102] When the number of measurement points is less than the preset number, the above S202b can be specifically executed through the following T6.

[0103] T6. Based on the projection length deformation caused by the height difference between the north and south ends of the engineering survey area, the horizontal distance between the south and north measuring points of the engineering survey area, and formula (4), the second change rate of the length deformation caused by the height difference is estimated.

[0104] ;Formula (4)

[0105] in, Indicates the projection length deformation caused by the height difference at the southern end of the engineering survey area. Indicates the projection length deformation caused by the height difference at the north end of the engineering survey area. The horizontal distance between the southern and northern measuring points in the engineering survey area. Indicates the elevation of the measuring point at the southern end of the engineering survey area. Indicates the elevation of the measuring point at the north end of the engineering survey area.

[0106] Based on this scheme, when the number of actual measurement points is small, the rate of change of the projection length deformation caused by the elevation difference can be quickly determined based on the length deformation determined by the measurement point at the south end, the length deformation determined by the measurement point at the north end, and the horizontal distance between the measurement points at the south and north ends.

[0107] After estimating the change rate of the length deformation caused by the height difference through the above processing method, the latitude at which the total length deformation of the Mercator projection is the smallest can be determined based on the equality of the above first change rate and the second change rate: .

[0108] It can be understood that in this case, the latitude of the final standard parallel is related to the latitude range of the project, the horizontal distance between the measuring points, and the rate of change of length deformation caused by the elevation difference. That is, when estimating based on this scheme, the standard parallel can be obtained based on the latitude range coupled with the elevation difference, so that the projection deformation caused by the elevation can be compensated by the deformation of the Mercator projection, and the standard latitude with the smallest overall deformation can be determined.

[0109] Method 2:

[0110] When the number of measurement points is greater than the preset number, the above S202b can be specifically executed through the following T7.

[0111] T7. Based on formula (3), the second change rate of length deformation caused by the height difference is determined by the least square method as follows (5).

[0112] ;Formula (5)

[0113] in, The vector representing the height difference between each measurement point and the projection surface in the engineering measurement area. A vector representing the deformation of the projection length of each measuring point in the engineering measurement area due to the height difference.

[0114] The second change rate can be estimated based on the above formula (3) and the least square method to expand the above formula (5). Then, based on a given iteration stop condition (such as the number of iterations is greater than a preset number, or the difference between the two calculations is less than a set threshold), the standard latitude value that makes the length change rate caused by the Mercator projection and the length change rate caused by the height difference in the engineering measurement area the same can be obtained. B 0, so that the standard latitude can be determined to facilitate Mercator projection in the engineering survey area based on the standard latitude, which can minimize the overall length deformation caused by Mercator projection within the latitude range and the length deformation caused by height difference.

[0115] It can be understood that when the number of measuring points is sufficient, the least square method can be used to more accurately determine the change rate of the length deformation caused by the height difference based on the length deformation vector caused by the height difference of each measuring point.

[0116] It can be understood that when there are enough measuring points, the first rate of change of the projection length deformation between the measuring points caused by the Mercator projection and the second rate of change of the projection length deformation between the measuring points caused by the height difference determined above can be combined, the absolute values ​​of both sides are taken respectively, and then expanded for iterative calculation. Based on the least squares method, the latitude value of the standard latitude with the smallest overall projection length deformation value within the latitude range of the engineering measurement area can be quickly found.

[0117] Based on this scheme, in the construction of large and super-large elevation difference projects such as reservoir projects, hydropower stations, pumped storage power stations, large bridge and tunnel projects, if the actual number of measurement points obtained within the latitude range of the engineering measurement area is sufficient, the least squares iterative calculation is performed in the form of the above matrix according to the latitude that can be measured based on a sufficient number of measurement points. If the number of measurement points that can actually be obtained is sufficient, the target latitude value with the smallest overall projection length deformation value within the latitude range of the engineering measurement area can also be quickly found.

[0118] Corresponding to the embodiments of the aforementioned method, the present disclosure also provides embodiments of a control device for coupling elevation and length deformation of Mercator projection and a computer device to which it is applied.

[0119] The embodiment of the control device for coupling the elevation and the length deformation of the Mercator projection disclosed in the present invention can be applied to a computer device, such as a server or a terminal device. The embodiment of the control device for coupling the elevation and the length deformation of the Mercator projection can be implemented by software, or by hardware or a combination of software and hardware. Taking software implementation as an example, as a control device for coupling the elevation and the length deformation of the Mercator projection in a logical sense, it is formed by the processor of the engineering projection in which it is located reading the corresponding computer program instructions in the non-volatile memory into the memory and running them. From the hardware level, if Figure 5 As shown, it is a hardware structure diagram of a computer device where the control device for coupling the height and length deformation of the Mercator projection in the embodiment of the present disclosure is located. Figure 5 In addition to the processor 510, memory 530, network interface 520, and non-volatile memory 540 shown, the server or electronic device where the control method for coupling elevation and length deformation of Mercator projection is located in the embodiment may also include other hardware, usually according to the actual function of the computer device, which will not be described in detail.

[0120] like Figure 6 As shown, Figure 6A schematic diagram of the structure of a control device for length deformation of coupled elevation and Mercator projection provided in an embodiment of the present disclosure, wherein the control device 600 for length deformation of coupled elevation and Mercator projection comprises: a length change rate estimation module 601, a standard latitude determination module 602 and a projection module 603; the length change rate estimation module 601 is used to estimate a first change rate of projection length deformation caused by Mercator projection in the engineering survey area according to the latitude distribution of the engineering survey area; and to estimate a second change rate of projection length deformation caused by the height difference according to the height difference distribution of the engineering survey area; the standard latitude determination module 602 is used to determine the latitude that makes the absolute value of the first change rate and the absolute value of the second change rate the same as the standard latitude for Mercator projection in the engineering survey area; the projection module 603 is used to perform Mercator projection in the engineering survey area based on the latitude of the standard latitude.

[0121] Optionally, the length change rate estimation module 601 is specifically used to: estimate the Mercator projection length deformation corresponding to the measurement point in the engineering measurement area based on the latitude of the measurement point in the engineering measurement area; and estimate the first change rate of the projection length deformation caused by Mercator projection in the engineering measurement area based on the Mercator projection length deformation corresponding to the measurement point in the engineering measurement area.

[0122] Optionally, the length change rate estimation module 601 is specifically used to respectively estimate the Mercator projection length deformation corresponding to the north end measurement point and the Mercator projection length deformation corresponding to the south end measurement point based on the latitude of the standard parallel, the latitude of the north end measurement point, the latitude of the south end measurement point and a first preset formula; the first preset formula includes: ;in, represents the latitude of the standard parallel, Indicates The latitude of the measuring point; based on the estimated Mercator projection length deformation corresponding to the northern measuring point, the estimated Mercator projection length deformation corresponding to the southern measuring point, the horizontal distance between the northern measuring point and the southern measuring point, and the second preset formula, the first change rate of the projection length deformation caused by the Mercator projection in the engineering survey area is estimated; the second preset formula includes: ;in, Indicates the Mercator projection length deformation corresponding to the northern measurement point. Indicates the latitude of the northern measurement point, Indicates the latitude of the southern measurement point, Indicates the Mercator projection length deformation corresponding to the southern measurement point, Indicates the horizontal distance between the north and south measurement points.

[0123] Optionally, the length change rate estimation module 601 is specifically used to estimate the Mercator projection length deformation corresponding to each measuring point based on the latitude of the standard parallel, the latitude of each measuring point and a first preset formula; the first preset formula includes: ; in, represents the latitude of the standard parallel, Indicates The latitude of each measuring point; the Mercator projection length deformation corresponding to each measuring point determined based on the first preset formula, and the first change rate of the projection length deformation caused by the Mercator projection in the engineering measurement area is determined by the least squares method.

[0124] Optionally, the length change rate estimation module 601 is specifically used to: estimate the projection length deformation caused by the elevation difference between the measuring points based on the horizontal distance between the measuring points in the engineering measurement area, the average radius of curvature of the earth, the elevation surface where the average elevation between the measuring points is located, and the elevation difference of the preset side length reduction projection surface; based on the projection length deformation caused by the elevation difference between the measuring points, estimate the second change rate of the projection length deformation caused by the elevation difference between the measuring points.

[0125] Optionally, the length change rate estimation module 601 is specifically used to estimate the projection length deformation caused by the height difference between the measuring points based on the horizontal distance, the average curvature radius of the earth, the height difference between the elevation surface where the average elevation between the measuring points is located and the side length reduction projection surface, and a third preset formula; wherein the third preset formula includes: ;in, Indicates The measurement points and The projection length deformation caused by the height difference of the measuring points is Indicates The measurement points and The horizontal distance between the measuring points, represents the mean radius of curvature of the Earth, Indicates The measurement points and The elevation difference between the elevation surface where the average elevation between the measuring points is located and the projection surface where the side length is calculated.

[0126] Optionally, the length change rate estimation module 601 is specifically used to estimate the second change rate of the projection length deformation caused by the height difference between the north and south ends of the engineering measurement area, based on the projection length deformation caused by the height difference between the south and north ends of the engineering measurement area, the horizontal distance between the south end measurement point and the north end measurement point of the engineering measurement area, and a fourth preset formula; the fourth preset formula includes: ;in, Indicates the projection length deformation caused by the height difference at the southern end of the engineering survey area. Indicates the projection length deformation caused by the height difference at the north end of the engineering survey area. The horizontal distance between the southern and northern measuring points in the engineering survey area. Indicates the elevation of the measuring point at the southern end of the engineering survey area. Indicates the elevation of the measuring point at the north end of the engineering survey area.

[0127] Optionally, the latitude of the latitude line in the engineering measurement area where the absolute value of the first change rate is equal to the absolute value of the second change rate is: .

[0128] Optionally, the length change rate estimation module 601 is specifically used to: determine, based on a third preset formula, by using the least squares method, a second change rate of the projection length deformation caused by the height difference: ;in, The vector representing the height difference between each measurement point and the projection surface in the engineering measurement area. A vector representing the deformation of the projection length of each measuring point in the engineering measurement area due to the height difference.

[0129] The control device for coupling elevation and length deformation of Mercator projection provided by the embodiment of the present disclosure first estimates a first change rate of projection length deformation caused by Mercator projection in an engineering survey area; estimates a second change rate of projection length deformation caused by elevation difference according to the elevation difference distribution in the engineering survey area; determines the latitude that makes the absolute value of the first change rate and the absolute value of the second change rate the same as the standard latitude for Mercator projection in the engineering survey area; and performs Mercator projection in the engineering survey area based on the latitude of the standard latitude. On the one hand, since the length deformation estimation is jointly performed based on the projection length deformation caused by the Mercator projection estimated based on the latitude distribution and the projection length deformation caused by the height difference distribution, the positive length change caused by the height difference can be offset by the negative length change generated by the Mercator projection. When the absolute value of the first change rate of the projection length deformation caused by the Mercator projection and the absolute value of the second change rate of the length deformation caused by the height difference are the same, the negative and positive length deformations are the same. The latitudes with the same absolute value of the length deformation change rate are selected as the standard latitudes for Mercator projection. Compared with the method in the related art that requires multiple sets of coordinate systems to be projected for estimating the projection length deformation, the processing speed is fast and the complexity is low, which can improve the speed of determining the engineering coordinates. On the other hand, in the embodiment of the present disclosure, the latitude of each measuring point within the latitude range is concerned, and there is no need to introduce the longitude for deformation estimation. The calculation complexity is low, the accuracy is high, and it is closer to the real deformation. The difference between the side length directly inverted based on the control point coordinates after projection and the side length obtained by field measurement can meet the requirements of large height difference and super-large height difference projects, which can ensure the accuracy of the project control grid coordinates, facilitate the project layout, and improve the accuracy of the layout.

[0130] Correspondingly, the present disclosure also provides a control device for coupling the length deformation of elevation and Mercator projection, the control device for coupling the length deformation of elevation and Mercator projection includes a processor; a memory for storing instructions executable by the processor; wherein the processor is configured to: estimate a first change rate of projection length deformation caused by Mercator projection in an engineering survey area; estimate a second change rate of projection length deformation caused by elevation difference according to the elevation difference distribution in the engineering survey area; determine the latitude that makes the absolute value of the first change rate and the absolute value of the second change rate the same as the standard latitude for Mercator projection in the engineering survey area; and perform Mercator projection in the engineering survey area based on the latitude of the standard latitude.

[0131] The present disclosure also provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the various steps in the embodiment of the control method for length deformation of coupled elevation and Mercator projection are implemented.

[0132] The present disclosure also provides a computer device, which includes a memory, a processor, and computer-readable instructions stored in the memory and executable on the processor, wherein the computer-readable instructions, when executed by the processor, implement the various steps in the above-mentioned control method embodiment of the length deformation of the coupled elevation and Mercator projection.

[0133] The implementation process of the functions and effects of each module in the above-mentioned device is specifically described in the implementation process of the corresponding steps in the above-mentioned method, which will not be repeated here.

[0134] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, wherein the modules described as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical modules, that is, they may be located in one place, or they may be distributed on multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the disclosed solution. A person of ordinary skill in the art can understand and implement it without paying creative labor.

[0135] The above describes specific embodiments of the present disclosure. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0136] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the inventions claimed herein. The present disclosure is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art that are not claimed in the present disclosure. The description and examples are to be considered exemplary only, and the true scope and spirit of the present disclosure are indicated by the following claims.

[0137] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

[0138] The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the scope of protection of the present disclosure.

Claims

1. A method for controlling the length deformation of coupled elevation and Mercator projection, characterized in that: The method comprises: According to the latitude of the standard parallel, the latitude of the measurement point in the engineering measurement area and a first preset formula, the Mercator projection length deformation corresponding to the measurement point in the engineering measurement area is estimated respectively; the first preset formula includes: ;in, represents the latitude of the standard parallel, Indicates The latitude of the measurement point; estimating a first rate of change of projection length deformation caused by Mercator projection in the engineering survey area based on the Mercator projection length deformation corresponding to the measurement point in the engineering survey area; Based on the horizontal distance between the measuring points in the engineering measurement area, the average radius of curvature of the earth, the elevation difference between the elevation surface where the average elevation between the measuring points is located and the preset side length reduction projection surface, and a third preset formula, the projection length deformation caused by the elevation difference between the measuring points is estimated; the third preset formula includes: ;in, Indicates The measurement points and The projection length deformation caused by the height difference of the measuring points is Indicates the measurement points and the The horizontal distance between the measuring points, represents the mean radius of curvature of the Earth, Indicates the measurement points and the The elevation difference between the elevation surface where the average elevation of the measuring points is located and the projection surface calculated by the side length; estimating a second rate of change of the projection length deformation caused by the height difference based on the projection length deformation caused by the height difference between the measuring points; Determine the latitude line at which the absolute value of the first rate of change is equal to the absolute value of the second rate of change as the standard latitude line for Mercator projection of the engineering survey area; Based on the latitude of the standard parallel, a Mercator projection is performed on the engineering survey area.

2. The method according to claim 1, characterized in that The method of estimating the Mercator projection length deformation corresponding to the measurement point in the engineering survey area according to the latitude of the standard parallel, the latitude of the measurement point in the engineering survey area and the first preset formula includes: Based on the latitude of the standard parallel, the latitude of the north end measurement point, the latitude of the south end measurement point and the first preset formula, respectively estimate the Mercator projection length deformation corresponding to the north end measurement point and the Mercator projection length deformation corresponding to the south end measurement point; The estimating a first rate of change of projection length deformation caused by Mercator projection in the engineering survey area based on the Mercator projection length deformation corresponding to the measurement point in the engineering survey area includes: Based on the estimated Mercator projection length deformation corresponding to the north end measurement point, the estimated Mercator projection length deformation corresponding to the south end measurement point, the horizontal distance between the north end measurement point and the south end measurement point, and a second preset formula, a first change rate of the projection length deformation caused by Mercator projection in the engineering measurement area is estimated; the second preset formula includes: ;in, Indicates the Mercator projection length deformation corresponding to the northern measurement point, represents the latitude of the northernmost measurement point, represents the latitude of the southern measurement point, Indicates the Mercator projection length deformation corresponding to the southern measurement point, Indicates the horizontal distance between the north end measurement point and the south end measurement point.

3. The method according to claim 1, characterized in that The estimating a first rate of change of projection length deformation caused by Mercator projection in the engineering survey area based on the Mercator projection length deformation corresponding to the measurement point in the engineering survey area includes: Based on the Mercator projection length deformation corresponding to each measuring point determined by the first preset formula, a first change rate of the projection length deformation caused by Mercator projection in the engineering measurement area is determined by using the least squares method.

4. The method according to claim 1, characterized in that The estimating a second rate of change of the projection length deformation caused by the height difference between the measuring points based on the projection length deformation caused by the height difference between the measuring points comprises: Based on the projection length deformation caused by the height difference between the north and south ends of the engineering measurement area, the horizontal distance between the south end measurement point and the north end measurement point of the engineering measurement area, and a fourth preset formula, a second change rate of the projection length deformation caused by the height difference is estimated; The fourth preset formula includes: ; in, Indicates the projection length deformation caused by the height difference at the southern end of the engineering survey area. Indicates the projection length deformation caused by the height difference of the measuring point at the north end of the engineering measurement area. The horizontal distance between the southern and northern measuring points of the engineering survey area, Indicates the elevation of the southern end of the survey area of ​​the project. Indicates the elevation of the measuring point at the north end of the engineering survey area.

5. The method according to claim 1, characterized in that The estimating a second rate of change of the projection length deformation caused by the height difference between the measuring points based on the projection length deformation caused by the height difference between the measuring points comprises: Based on the third preset formula, the least square method is used to determine the second change rate of the projection length deformation caused by the height difference: ; in, A vector representing the height difference between each measurement point in the engineering measurement area and the projection surface, A vector representing the projection length deformation of each measuring point in the engineering measurement area due to the height difference.

6. The method according to claim 4, characterized in that The latitude of the latitude line in the engineering survey area where the absolute value of the first change rate is equal to the absolute value of the second change rate is: .

7. A control device for coupling elevation and length deformation of Mercator projection, characterized in that: The control device is applied to the method according to claim 1, and the control device for coupling the length deformation of the elevation and Mercator projection comprises: a length change rate estimation module, a standard latitude determination module and a projection module; The length change rate estimation module is used to estimate a first change rate of projection length deformation caused by Mercator projection of the engineering survey area according to the latitude distribution of the engineering survey area, and to estimate a second change rate of projection length deformation caused by the height difference according to the height difference distribution of the engineering survey area; The standard latitude determination module is used to determine the latitude that makes the absolute value of the first change rate and the absolute value of the second change rate the same as the standard latitude for Mercator projection of the engineering survey area; The projection module is used to perform Mercator projection in the engineering survey area based on the latitude of the standard parallel.

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