Projection parameter determination method and device, computer device, and storage medium

Abstract

The application relates to a projection parameter determination method and device, computer equipment and a storage medium. The method comprises the following steps: acquiring coordinate data of a target area in a standard coordinate system, and configuring a central meridian at a central position of the target area; acquiring multiple groups of projection parameters, and projecting the coordinate data according to each group of projection parameters to obtain multiple groups of sample projection data of the target area; calculating the mean square error of the meridian deformation amount of each group of sample projection data according to the deformation amount of each meridian in each group of sample projection data; and taking the group of projection parameters corresponding to the group of sample projection data with the minimum mean square error of the meridian deformation amount as target projection parameters. The target projection parameters determined based on the method can improve the accuracy of the projection data, and the high-precision projection data can be used to construct a city independent coordinate system, thereby improving the construction precision of the city independent coordinate system.

Description

Technical Field

[0001] This application relates to the field of geodesy technology, and in particular to a method, apparatus, computer equipment, storage medium, and computer program product for determining projection parameters. Background Technology

[0002] With the accelerating pace of urbanization, urban areas are expanding rapidly from hundreds of square kilometers to thousands or even tens of thousands of square kilometers. Meanwhile, the influx of large numbers of people into cities necessitates strengthened urban infrastructure, placing new demands on urban coordinate systems in the engineering field. Projecting using the national 6° or 3° zone method and the national reference ellipsoid as the reduction surface results in increased projection distortion in the east-west direction as the distance from the central meridian increases. In larger cities, this distortion is insufficient for engineering construction needs. Therefore, it is necessary to establish an independent coordinate system for each city to facilitate production and daily life. The purpose of establishing a local independent coordinate system is to ensure that the results of surveying control networks in urban areas or engineering construction areas (such as mines and reservoirs) not only meet the needs of 1:500 scale mapping but also the needs of general engineering layout. It is necessary to minimize the impact of elevation normalization and projection distortion, controlling them within a small range so that calculated lengths do not require any recalculation during practical use (such as engineering layout).

[0003] With rapid urban development, expanding urban areas, and numerous urban construction projects, existing coordinate systems and control networks can no longer meet the demands. Consequently, various cities have established their own independent coordinate systems to facilitate production and daily life. Furthermore, with the adoption of the CGCS2000 geocentric coordinate system, independent urban coordinate systems must be linked to the CGCS2000 system, thus giving new meaning to the construction of independent urban coordinate systems.

[0004] Most current urban independent coordinate systems are established using Gauss-Kruger projection, also known as conformal transverse cylindrical projection. While this can reduce the projection distortion at the central meridian to zero, the distortion on both sides of the central meridian is significant, resulting in uneven control of the distortion and low accuracy of the constructed urban independent coordinate system. Summary of the Invention

[0005] Therefore, it is necessary to provide a method, apparatus, computer equipment, computer-readable storage medium, and computer program product for determining projection parameters that can improve the accuracy of constructing an independent coordinate system for a city, in order to address the aforementioned technical problems.

[0006] Firstly, this application provides a method for determining projection parameters. The method includes:

[0007] Obtain the coordinate data of the target area in the standard coordinate system, and place the central meridian at the center of the target area;

[0008] Multiple sets of projection parameters are obtained, and the coordinate data is projected according to each set of projection parameters to obtain multiple sets of sample projection data of the target area.

[0009] Based on the deformation of each meridian in each set of sample projection data, calculate the mean square error of the meridian deformation of each set of sample projection data.

[0010] The set of projection parameters corresponding to the set of sample projection data with the smallest mean square error of meridian deformation is taken as the target projection parameters.

[0011] In one embodiment, positioning the central meridian at the center of the target area includes:

[0012] The coordinate data is subjected to a 3-degree Gaussian-Kruger projection to obtain the Gaussian projection data of the target area.

[0013] Obtain the deformation of each meridian in the Gaussian projection data. If the deformation of a meridian is greater than the preset deformation, determine the center position of the target area.

[0014] Move the central meridian so that it passes through the center of the target area.

[0015] In one embodiment, the projection parameters include q and K, and multiple sets of projection parameters are obtained, including:

[0016] Configure the first initial value for q and the second initial value for K respectively, and configure the first step distance for q and the second step distance for K;

[0017] Transform q according to the first initial value and the first step distance, and transform K according to the second initial value and the second step distance to obtain multiple combinations of q and K, and use each combination of q and K as a set of projection parameters.

[0018] In one embodiment, the method further includes:

[0019] The coordinate data is projected based on the target projection parameters to obtain the target projection data of the target area.

[0020] Establish a planar coordinate system for the target area based on the target projection data;

[0021] Based on the coordinate data, a regional ellipsoid for the target area is established, and the coordinate data in the plane coordinate system is mapped to the regional ellipsoid.

[0022] A coordinate transformation is performed on the regional ellipsoid to obtain an independent coordinate system for the target region.

[0023] In one embodiment, establishing a planar coordinate system for the target region based on target projection data includes:

[0024] Determine a target location within the target area and use that target location as the origin of the planar coordinate system;

[0025] Orient the plane coordinate system according to the standard coordinate system to determine the direction of the coordinate axes of the plane coordinate system;

[0026] Determine the correspondence between the target location and the target projection data, and establish a planar coordinate system based on the correspondence, the origin, and the coordinate axis directions.

[0027] In one embodiment, a regional ellipsoid of the target region is established based on coordinate data, including:

[0028] The number of reference points is determined based on the size of the target area.

[0029] Based on the number of reference points, obtain one or more reference points from the coordinate data;

[0030] Establish a regional ellipsoid for the target area based on one or more benchmarks and the average elevation surface of the target area.

[0031] In one embodiment, a coordinate transformation is performed on the regional ellipsoid to obtain an independent coordinate system for the target region, including:

[0032] Determine the reference coordinate system corresponding to the regional ellipsoid;

[0033] The transformation parameters between the reference coordinate system and the independent coordinate system of the target region are calculated using the seven-parameter method.

[0034] Based on the transformation parameters, the coordinates of the regional ellipsoid are transformed to obtain an independent coordinate system for the target region.

[0035] Secondly, this application also provides a projection parameter determining device. The device includes:

[0036] The acquisition module is used to acquire the coordinate data of the target area in the standard coordinate system and to set the central meridian at the center of the target area.

[0037] The projection module is used to acquire multiple sets of projection parameters and project the coordinate data according to each set of projection parameters to obtain multiple sets of sample projection data of the target area.

[0038] The calculation module is used to calculate the mean square error of the meridian deformation in each set of sample projection data based on the deformation of each meridian in each set of sample projection data.

[0039] The comparison module is used to take the set of projection parameters corresponding to the set of sample projection data with the smallest mean square error of meridian deformation as the target projection parameters.

[0040] Thirdly, this application also provides a computer device. The computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to perform the following steps:

[0041] Obtain the coordinate data of the target area in the standard coordinate system, and place the central meridian at the center of the target area;

[0042] Multiple sets of projection parameters are obtained, and the coordinate data is projected according to each set of projection parameters to obtain multiple sets of sample projection data of the target area.

[0043] Based on the deformation of each meridian in each set of sample projection data, calculate the mean square error of the meridian deformation of each set of sample projection data.

[0044] The set of projection parameters corresponding to the set of sample projection data with the smallest mean square error of meridian deformation is taken as the target projection parameters.

[0045] Fourthly, this application also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program thereon, which, when executed by a processor, performs the following steps:

[0046] Obtain the coordinate data of the target area in the standard coordinate system, and place the central meridian at the center of the target area;

[0047] Multiple sets of projection parameters are obtained, and the coordinate data is projected according to each set of projection parameters to obtain multiple sets of sample projection data of the target area.

[0048] Based on the deformation of each meridian in each set of sample projection data, calculate the mean square error of the meridian deformation of each set of sample projection data.

[0049] The set of projection parameters corresponding to the set of sample projection data with the smallest mean square error of meridian deformation is taken as the target projection parameters.

[0050] Fifthly, this application also provides a computer program product. The computer program product includes a computer program that, when executed by a processor, performs the following steps:

[0051] Obtain the coordinate data of the target area in the standard coordinate system, and place the central meridian at the center of the target area;

[0052] Multiple sets of projection parameters are obtained, and the coordinate data is projected according to each set of projection parameters to obtain multiple sets of sample projection data of the target area.

[0053] Based on the deformation of each meridian in each set of sample projection data, calculate the mean square error of the meridian deformation of each set of sample projection data.

[0054] The set of projection parameters corresponding to the set of sample projection data with the smallest mean square error of meridian deformation is taken as the target projection parameters.

[0055] The aforementioned projection parameter determination method, apparatus, computer equipment, storage medium, and computer program product acquire coordinate data of the target area in a standard coordinate system and place the central meridian at the center of the target area; acquire multiple sets of projection parameters, and project the coordinate data according to each set of projection parameters to obtain multiple sets of sample projection data of the target area; calculate the mean square error of the meridian deformation of each set of sample projection data based on the deformation of each meridian in each set of sample projection data; and take the set of projection parameters corresponding to the set of sample projection data with the smallest mean square error of meridian deformation as the target projection parameters. Acquiring projection data based on target projection parameters can improve the accuracy of projection data, and constructing an independent urban coordinate system based on high-precision projection data can improve the accuracy of the construction of the independent urban coordinate system. Attached Figure Description

[0056] Figure 1 This is a flowchart illustrating a method for determining projection parameters in one embodiment;

[0057] Figure 2 This is a schematic diagram of coordinate transformation using the seven-parameter method in one embodiment;

[0058] Figure 3 This is a structural block diagram of a projection parameter determination device in one embodiment;

[0059] Figure 4 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0061] In one embodiment, such as Figure 1As shown, a method for determining projection parameters is provided. This embodiment illustrates the application of this method to a computer device. It is understood that the computer device can specifically be a terminal or a server. The terminal can be, but is not limited to, various personal computers, laptops, smartphones, tablets, IoT devices, and portable wearable devices. IoT devices can be smart speakers, smart TVs, smart air conditioners, smart medical devices, etc. Portable wearable devices can be smartwatches, smart bracelets, head-mounted devices, etc. The server can be a standalone server or a server cluster composed of multiple servers. In this embodiment, the method includes the following steps:

[0062] Step 102: Obtain the coordinate data of the target area in the standard coordinate system and set the central meridian at the center of the target area.

[0063] The standard coordinate system refers to either the CGCS2000 coordinate system (China Geodetic Coordinate System 2000) or the WGS-84 coordinate system (World Geodetic System-1984 Coordinate System, an internationally adopted geocentric coordinate system). Coordinate data refers to geographic information data obtained based on a standard coordinate system. The target area can be, but is not limited to, urban areas.

[0064] Optionally, in the CGCS2000 coordinate system, acquire the relevant coordinate data of the urban area, and then perform a 3-degree Gauss-Kruger projection on the coordinate data. If the deformation of a meridian within the urban area exceeds a preset deformation, move the central meridian to the center of the urban area. The center can be a center point determined by measurement of the urban area, in which case the central meridian needs to pass through the center point; the center can also be a central area determined by measurement of the urban area, in which case the central meridian needs to pass through the central area; the center can also be a central area determined by measurement of the urban area, in which case the central meridian needs to pass through the central area; the center can also be the north-south centerline determined by measurement of the urban area, in which case the central meridian can be moved to coincide with the centerline.

[0065] Step 104: Obtain multiple sets of projection parameters, and project the coordinate data according to each set of projection parameters to obtain multiple sets of sample projection data of the target area.

[0066] Optionally, the projection parameters include q and K, with a first initial value for q and a second initial value for K configured, as well as a first step distance for q and a second step distance for K configured. q is transformed according to the first initial value and the first step distance, and K is transformed according to the second initial value and the second step distance to obtain multiple combinations of q and K. Each combination of q and K is used as a set of projection parameters, and the coordinate data of the urban area is projected according to each set of q and K to obtain multiple sets of sample projection data of the urban area.

[0067] Step 106: Calculate the mean square error of the meridian deformation in each set of sample projection data based on the deformation of each meridian in each set of sample projection data.

[0068] The mean-square error (MSE) is a measure of the difference between the estimator and the estimated quantity. Let t be an estimator of the population parameter θ determined from the sample. The expected value of (θ-t)² is called the mean-square error of the estimator t. It is equal to σ² + b², where σ² and b are the variance and bias of t, respectively.

[0069] Step 108: Take the set of projection parameters corresponding to the set of sample projection data with the smallest mean square error of meridian deformation as the target projection parameters.

[0070] Optionally, the set of q and K corresponding to the set of sample projection data with the smallest meridian deformation MSE can be used as the target projection parameters.

[0071] In the above method for determining projection parameters, coordinate data of the target area in a standard coordinate system are obtained, and the central meridian is positioned at the center of the target area. Multiple sets of projection parameters are obtained, and the coordinate data are projected based on each set of parameters to obtain multiple sets of sample projection data for the target area. The mean square error of the meridian deformation in each set of sample projection data is calculated based on the deformation of each meridian. The set of projection parameters corresponding to the set of sample projection data with the smallest mean square error of meridian deformation is taken as the target projection parameters. Obtaining projection data based on target projection parameters improves the accuracy of the projection data. Constructing a city-independent coordinate system based on high-precision projection data improves the accuracy of the city-independent coordinate system construction.

[0072] In one embodiment, positioning the central meridian at the center of the target area includes: performing a 3-degree Gauss-Kruger projection on the coordinate data to obtain Gauss projection data of the target area; acquiring the deformation of each meridian in the Gauss projection data; if the deformation of any meridian is greater than a preset deformation, determining the center position of the target area; and moving the central meridian so that it passes through the center position of the target area.

[0073] Furthermore, the projection parameters include q and K. Multiple sets of projection parameters are obtained, including: configuring a first initial value for q and a second initial value for K, and configuring a first step distance for q and a second step distance for K; transforming q according to the first initial value and the first step distance, and transforming K according to the second initial value and the second step distance, obtaining multiple combinations of q and K, and using each combination of q and K as a set of projection parameters. Based on each set of projection parameters, the coordinate data is projected to obtain multiple sets of sample projection data for the target area. Based on the deformation of each meridian in each set of sample projection data, the mean square error of the meridian deformation in each set of sample projection data is calculated. The set of projection parameters corresponding to the set of sample projection data with the smallest mean square error of meridian deformation is used as the target projection parameters.

[0074] Optionally, under the national standard 3° Gaussian projection, when the length deformation value in the urban area is greater than 2.5 cm / km, the central meridian is determined to be at the center of the urban area. With q=0 and K=0 as initial values, and q=0.0005 and K=2 as upper limits, q and K are transformed with step sizes of 0.0001 and 0.5 respectively, and different combinations are performed for projection. The optimal combination of projection parameters that can effectively control the deformation is selected based on the minimum MSE.

[0075] In this embodiment, coordinate data of the target area in a standard coordinate system is obtained, and the central meridian is positioned at the center of the target area to acquire multiple sets of projection parameters. This method is suitable for establishing an independent urban coordinate system and can effectively prevent excessive projection deformation at the edges of urban areas or coordinate systems.

[0076] In one embodiment, the method further includes: projecting coordinate data according to target projection parameters to obtain target projection data of the target area; determining a target location in the target area and using the target location as the origin of a plane coordinate system; orienting the plane coordinate system according to a standard coordinate system to determine the coordinate axis directions of the plane coordinate system; determining the correspondence between the target location and the target projection data, and establishing a plane coordinate system based on the correspondence, the origin, and the coordinate axis directions; determining the number of reference points based on the area size of the target area; obtaining one or more reference points from the coordinate data based on the number of reference points; establishing a regional ellipsoid of the target area based on the one or more reference points and the average elevation surface of the target area, and mapping the coordinate data in the plane coordinate system to the regional ellipsoid; determining the reference coordinate system corresponding to the regional ellipsoid; calculating the transformation parameters between the reference coordinate system and the independent coordinate system of the target area using the seven-parameter method; and performing coordinate transformation on the regional ellipsoid according to the transformation parameters to obtain the independent coordinate system of the target area.

[0077] Optionally, first, determine the city's plane coordinate system. The orientation of the city's plane coordinate system is used to determine the starting azimuth of the entire coordinate system, consistent with the orientation of the national coordinate system. The origin of the city coordinate system is generally chosen at the center of the urban area or a stable and reliable high-level control point that is easy to preserve. A constant can be added to the coordinates of the origin; this constant should be chosen to ensure that all coordinate values ​​in the city's plane coordinate system are positive.

[0078] Furthermore, the regional ellipsoid is determined. For large-area cities, a multi-point method is used, while for small-area cities, a single-point method is used to ensure that the regional ellipsoid is sufficiently close to the average elevation surface of the city. Then, the target projection data is reduced to the ellipsoid surface, and the values ​​of the surface are then reduced to the Gaussian plane.

[0079] Finally, perform coordinate transformation. If the WGS-84 ellipsoid was used as the reference ellipsoid when determining the new ellipsoid elements, convert all coordinates from WGS-84 to the new coordinate system. If CGCS2000 coordinates were used when determining the ellipsoid elements, first convert them to WGS-84 coordinates, and then to city-independent coordinates. When converting city-independent coordinates to CGCS2000 or WGS-84 coordinates, the seven-parameter method can be used to solve for the transformation parameters.

[0080] The method for solving the transformation parameters using the seven-parameter method is as follows: Figure 2 As shown, there are seven transformation parameters between coordinate systems A and B—three translation parameters, three rotation parameters, and one scale parameter. For example, coordinate system A is the CGCS2000 coordinate system, and coordinate system B is a city-independent coordinate system.

[0081] If: (X) A Y A Z A ) T Let be the spatial rectangular coordinates of a point in coordinate system A;

[0082] (X B Y B Z B ) T The coordinates of the point in coordinate system B are the spatial rectangular coordinates.

[0083] (ΔX0 ΔY0 ΔZ0) T These are the translation parameters for transforming coordinate system A to coordinate system B;

[0084] (ω x ω y ω z ) T The rotation parameters are used to transform coordinate system A to coordinate system B;

[0085] m is the scale parameter for transforming from coordinate system A to coordinate system B.

[0086] The transformation relationship from coordinate system A to coordinate system B is as follows:

[0087]

[0088] in:

[0089]

[0090]

[0091]

[0092] General ω x ω y and ω z Since both are small angles, expanding cosω and sinω into Taylor series and retaining only the first-order terms, we have:

[0093] cosω≈1

[0094] sinω≈ω (5)

[0095] Then we have:

[0096]

[0097] Without knowing the transformation parameters, the transformation parameters can be solved in reverse by using two sets of coordinates of three or more known points, as follows.

[0098] Equation (1) can be written as:

[0099]

[0100] In the formula, a = 1 + m, b = (1 + m)ω z c=(1+m)ω y d=(1+m)ω x .

[0101] Equation (7) is transformed to obtain:

[0102]

[0103] If we treat the coordinates in coordinate system A as accurate values ​​and the coordinates in coordinate system B as observed values, then we can derive the error equation:

[0104]

[0105] When there are three or more points, nine or more equations can be formulated, with only seven parameters. In this case, the indirect adjustment method should be used according to the least squares principle to solve the problem. As for the transformation of plane coordinates, the transformation parameters can be solved using the similarity transformation method based on the projection results of the old and new coordinates of the same point. The similarity transformation formula is as follows:

[0106]

[0107] In the formula, X A Y A The coordinates are in the original planar coordinate system; X B Y B ΔX0 and ΔY0 are the coordinates in the independent coordinate system; ΔX0 and ΔY0 are the translation amounts of the original planar coordinates to the planar coordinates in the independent coordinate system; m and α are the scaling factor and rotation angle of the original planar coordinates to the independent coordinate system, respectively.

[0108] For ease of processing, equation (10) can be simplified to:

[0109]

[0110] In the formula,

[0111] In this embodiment, the coordinate data is projected according to the target projection parameters to obtain the target projection data of the target area; a planar coordinate system of the target area is established based on the target projection data; a regional ellipsoid of the target area is established based on the coordinate data, and the coordinate data in the planar coordinate system is mapped to the regional ellipsoid; coordinate transformation is performed on the regional ellipsoid to obtain the independent coordinate system of the target area. This allows for the acquisition of the optimal combination of projection parameters to balance the projection deformation at different longitudes, reduce projection deformation, effectively prevent the projection deformation at the edges of urban areas or coordinate systems from exceeding limits, and improve the construction accuracy of the city's independent coordinate system.

[0112] In one embodiment, a method for determining projection parameters includes:

[0113] Obtain the coordinate data of the target area in the standard coordinate system, and perform a 3-degree Gauss-Kruger projection on the coordinate data to obtain the Gauss projection data of the target area; obtain the deformation of each meridian in the Gauss projection data, and if the deformation of a meridian is greater than the preset deformation, determine the center position of the target area; move the central meridian so that the central meridian passes through the center position of the target area.

[0114] Configure the first initial value for q and the second initial value for K, as well as the first step distance for q and the second step distance for K. Transform q according to the first initial value and the first step distance, and transform K according to the second initial value and the second step distance to obtain multiple combinations of q and K. Each combination of q and K is used as a set of projection parameters. Project the coordinate data according to each set of projection parameters to obtain multiple sets of sample projection data for the target area. Calculate the mean square error of the meridian deformation in each set of sample projection data based on the deformation of each meridian. Use the set of projection parameters corresponding to the set of sample projection data with the smallest mean square error of meridian deformation as the target projection parameters.

[0115] The coordinate data is projected based on the target projection parameters to obtain the target projection data of the target area.

[0116] A target location is determined within the target area, and this target location is used as the origin of a plane coordinate system. The plane coordinate system is then oriented according to a standard coordinate system to determine the direction of its coordinate axes. The correspondence between the target location and the target projection data is established, and a plane coordinate system is created based on this correspondence, the origin, and the coordinate axis directions. The number of reference points is determined based on the area of ​​the target region. One or more reference points are obtained from the coordinate data based on this number. A regional ellipsoid for the target region is established based on the one or more reference points and the average elevation surface of the target region, and the coordinate data from the plane coordinate system is mapped onto the regional ellipsoid. A reference coordinate system corresponding to the regional ellipsoid is determined. The transformation parameters between the reference coordinate system and the independent coordinate system of the target region are calculated using the seven-parameter method. The regional ellipsoid is then transformed according to these transformation parameters to obtain the independent coordinate system of the target region.

[0117] For example, using measured data from a certain city as research data, the city's overall area lies between 120°55' and 122°16' east longitude and 28°51' and 30°33' north latitude, within the 40th zone of the nationally unified 3° latitude zone (the central meridian is at 120°). Therefore, the entire urban area of ​​the city is located west of the central meridian. Calculations show that the westernmost point of the city is 91 km from the central meridian, and the easternmost point is 204 km away. The data used in this experiment are 106 control points of various levels evenly distributed throughout the city, using the CGCS2000 coordinate system. The city's average elevation is approximately 53.65 m, and its average radius of curvature is taken as 6371 km. The central meridian is moved to the city center, with a central longitude of 121.53°. A reference point gj18 (29.8119545, 121.4822751, 16.9) is selected. With the central meridian moved to the city center, the initial values ​​of the projection parameters q and K are set to 0 and 0, respectively. The values ​​of q and K are then transformed in increments of 0.0001 and 0.5, respectively, and different combinations are explored. The optimal solution is selected based on the minimum mean squared error (MSE). The results showed that if the national standard three-dimensional zone projection was used, the projection deformation at all 106 control points could not meet the requirements of the urban surveying specifications due to the large distance between the city and the central meridian. When only the central meridian was moved to the city center, the overall projection deformation at 66 points met the requirements of the urban surveying specifications. In addition, after multiple combinations, it was found that the change in the q value had a greater impact on the results than the change in the K value, and the effect of controlling deformation was best when the q value was on the order of 10 to the power of negative fourth and the K value was 0.0001 with K=1.

[0118] The calculation results using Gaussian projection and those using projection parameters q = 0.0001, K = 1 are compared, as shown in Tables 1 and 2. It can be seen that the double meridian secant elliptic cylindrical projection using q = 0.0001, K = 1 places the double meridian at approximately ±0.8° from the central meridian. This projection method can more uniformly limit deformation and prevent excessive projection deformation at the city's edge (or at locations far from the central meridian). This demonstrates that moving the central meridian to the city center and establishing a city-independent coordinate system using the projection parameters q = 0.0001, K = 1 can more effectively suppress projection deformation.

[0119] Table 1. Deformation of a certain area in a city when q = 0

[0120] 29 0.0000000 0.0000047 0.0000187 0.0000422 0.0000750 0.0001171 29.2 0.0000000 0.0000047 0.0000187 0.0000420 0.0000747 0.0001167 29.4 0.0000000 0.0000046 0.0000186 0.0000418 0.0000744 0.0001162 29.6 0.0000000 0.0000046 0.0000185 0.0000417 0.0000741 0.0001157 29.8 0.0000000 0.0000046 0.0000184 0.0000415 0.0000738 0.0001153 30 0.0000000 0.0000046 0.0000184 0.0000413 0.0000735 0.0001148 30.2 0.0000000 0.0000046 0.0000183 0.0000412 0.0000732 0.0001144 30.4 0.0000000 0.0000046 0.0000182 0.0000410 0.0000729 0.0001139 30.6 0.0000000 0.0000045 0.0000181 0.0000408 0.0000726 0.0001134 30.8 0.0000000 0.0000045 0.0000181 0.0000407 0.0000723 0.0001129 31 0.0000000 0.0000045 0.0000180 0.0000405 0.0000720 0.0001125

[0121] Table 1. Deformation of a certain area in a city when q = 0

[0122] 29 -0.0000765 -0.0000718 -0.0000578 -0.0000343 -0.0000016 0.0000406 29.2 -0.0000762 -0.0000715 -0.0000575 -0.0000342 -0.0000015 0.0000404 29.4 -0.0000759 -0.0000713 -0.0000573 -0.0000341 -0.0000015 0.0000403 29.6 -0.0000756 -0.0000710 -0.0000571 -0.0000339 -0.0000015 0.0000401 29.8 -0.0000753 -0.0000707 -0.0000569 -0.0000338 -0.0000015 0.0000400 30 -0.0000750 -0.0000704 -0.0000566 -0.0000337 -0.0000015 0.0000398 30.2 -0.0000747 -0.0000701 -0.0000564 -0.0000335 -0.0000015 0.0000396 30.4 -0.0000744 -0.0000698 -0.0000562 -0.0000334 -0.0000015 0.0000395 30.6 -0.0000741 -0.0000696 -0.0000559 -0.0000333 -0.0000015 0.0000393 30.8 -0.0000738 -0.0000693 -0.0000557 -0.0000331 -0.0000015 0.0000391 31 -0.0000735 -0.0000690 -0.0000555 -0.0000330 -0.0000015 0.0000390

[0123] Table 2. Deformation of the city area when q = 0.0001 and K = 1

[0124] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0125] Based on the same inventive concept, this application also provides a projection parameter determining apparatus for implementing the projection parameter determining method described above. The solution provided by this apparatus is similar to the implementation described in the above method; therefore, the specific limitations in one or more projection parameter determining apparatus embodiments provided below can be found in the limitations of the projection parameter determining method described above, and will not be repeated here.

[0126] In one embodiment, such as Figure 3 As shown, a projection parameter determination device 300 is provided, including: an acquisition module 301, a projection module 302, a calculation module 303, and a comparison module 304, wherein:

[0127] The acquisition module 301 is used to acquire the coordinate data of the target area in the standard coordinate system and to set the central meridian at the center of the target area.

[0128] The projection module 302 is used to acquire multiple sets of projection parameters and project the coordinate data according to each set of projection parameters to obtain multiple sets of sample projection data of the target area.

[0129] The calculation module 303 is used to calculate the mean square error of the meridian deformation of each set of sample projection data based on the deformation of each meridian in each set of sample projection data.

[0130] The comparison module 304 is used to take the set of projection parameters corresponding to the set of sample projection data with the smallest mean square error of meridian deformation as the target projection parameters.

[0131] In one embodiment, the acquisition module 301 is further configured to perform a 3-degree Gauss-Kruger projection on the coordinate data to obtain Gauss projection data of the target area; acquire the deformation of each meridian in the Gauss projection data; if the deformation of a meridian is greater than a preset deformation, determine the center position of the target area; and move the central meridian so that the central meridian passes through the center position of the target area.

[0132] In one embodiment, the projection module 302 is further configured to configure a first initial value corresponding to q and a second initial value corresponding to K, and to configure a first step distance corresponding to q and a second step distance corresponding to K; to transform q according to the first initial value and the first step distance, and to transform K according to the second initial value and the second step distance, to obtain multiple combinations of q and K, and to use each combination of q and K as a set of projection parameters.

[0133] In one embodiment, the apparatus further includes:

[0134] The construction module 305 is used to project the coordinate data according to the target projection parameters to obtain the target projection data of the target area; establish a planar coordinate system of the target area according to the target projection data; establish a regional ellipsoid of the target area according to the coordinate data, and map the coordinate data in the planar coordinate system to the regional ellipsoid; and perform coordinate transformation on the regional ellipsoid to obtain an independent coordinate system of the target area.

[0135] In one embodiment, the construction module 305 is further configured to determine a target location in the target area and use the target location as the origin of the plane coordinate system; orient the plane coordinate system according to the standard coordinate system to determine the coordinate axis direction of the plane coordinate system; determine the correspondence between the target location and the target projection data, and establish the plane coordinate system according to the correspondence, the origin and the coordinate axis direction.

[0136] In one embodiment, the construction module 305 is further configured to determine the number of reference points based on the area size of the target region; obtain one or more reference points from the coordinate data according to the number of reference points; and establish a regional ellipsoid of the target region based on the one or more reference points and the average elevation surface of the target region.

[0137] In one embodiment, the construction module 305 is further configured to determine the reference coordinate system corresponding to the regional ellipsoid; calculate the transformation parameters between the reference coordinate system and the independent coordinate system of the target region using the seven-parameter method; and perform coordinate transformation on the regional ellipsoid according to the transformation parameters to obtain the independent coordinate system of the target region.

[0138] The modules in the aforementioned projection parameter determination device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0139] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 4 As shown, the computer device includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The input / output interface is used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When executed by the processor, the computer program implements a projection parameter determination method. The display unit is used to form a visually visible image and can be a display screen, a projection device, or a virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the computer device, or external keyboards, touchpads, or mice, etc.

[0140] Those skilled in the art will understand that Figure 4 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0141] In one embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to perform the following steps: acquiring coordinate data of a target area in a standard coordinate system and placing the central meridian at the center of the target area; acquiring multiple sets of projection parameters and projecting the coordinate data according to each set of projection parameters to obtain multiple sets of sample projection data of the target area; calculating the mean square error of the meridian deformation of each set of sample projection data according to the deformation of each meridian in each set of sample projection data; and taking the set of projection parameters corresponding to the set of sample projection data with the smallest mean square error of meridian deformation as the target projection parameters.

[0142] In one embodiment, when the processor executes the computer program, it further performs the following steps: performing a 3-degree Gauss-Kruger projection on the coordinate data to obtain Gauss projection data of the target area; obtaining the deformation of each meridian in the Gauss projection data; if the deformation of a meridian is greater than a preset deformation, determining the center position of the target area; and moving the central meridian so that the central meridian passes through the center position of the target area.

[0143] In one embodiment, when the processor executes the computer program, it further performs the following steps: configuring a first initial value corresponding to q and a second initial value corresponding to K, and configuring a first step distance corresponding to q and a second step distance corresponding to K; transforming q according to the first initial value and the first step distance, and transforming K according to the second initial value and the second step distance, obtaining multiple combinations of q and K, and using each combination of q and K as a set of projection parameters.

[0144] In one embodiment, when the processor executes the computer program, it further performs the following steps: projecting coordinate data according to target projection parameters to obtain target projection data of the target area; establishing a planar coordinate system of the target area according to the target projection data; establishing a regional ellipsoid of the target area according to the coordinate data, and mapping the coordinate data in the planar coordinate system to the regional ellipsoid; and performing coordinate transformation on the regional ellipsoid to obtain an independent coordinate system of the target area.

[0145] In one embodiment, when the processor executes the computer program, it further performs the following steps: determining a target location in the target area and using the target location as the origin of the planar coordinate system; orienting the planar coordinate system according to the standard coordinate system to determine the direction of the coordinate axes of the planar coordinate system; determining the correspondence between the target location and the target projection data, and establishing the planar coordinate system according to the correspondence, the origin, and the direction of the coordinate axes.

[0146] In one embodiment, when the processor executes the computer program, it further performs the following steps: determining the number of reference points based on the area size of the target region; obtaining one or more reference points from coordinate data according to the number of reference points; and establishing a regional ellipsoid of the target region based on the one or more reference points and the average elevation surface of the target region.

[0147] In one embodiment, when the processor executes the computer program, it further performs the following steps: determining the reference coordinate system corresponding to the regional ellipsoid; calculating the transformation parameters between the reference coordinate system and the independent coordinate system of the target region using the seven-parameter method; and performing coordinate transformation on the regional ellipsoid according to the transformation parameters to obtain the independent coordinate system of the target region.

[0148] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, it performs the following steps: acquiring coordinate data of a target area in a standard coordinate system and placing the central meridian at the center of the target area; acquiring multiple sets of projection parameters and projecting the coordinate data according to each set of projection parameters to obtain multiple sets of sample projection data of the target area; calculating the mean square error of the meridian deformation of each set of sample projection data according to the deformation of each meridian in each set of sample projection data; and taking the set of projection parameters corresponding to the set of sample projection data with the smallest mean square error of meridian deformation as the target projection parameters.

[0149] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: performing a 3-degree Gauss-Kruger projection on the coordinate data to obtain Gauss projection data of the target area; obtaining the deformation of each meridian in the Gauss projection data; if the deformation of a meridian is greater than a preset deformation, determining the center position of the target area; and moving the central meridian so that the central meridian passes through the center position of the target area.

[0150] In one embodiment, when the computer program is executed by the processor, it further implements the following steps: configuring a first initial value corresponding to q and a second initial value corresponding to K, and configuring a first step distance corresponding to q and a second step distance corresponding to K; transforming q according to the first initial value and the first step distance, and transforming K according to the second initial value and the second step distance, obtaining multiple combinations of q and K, and using each combination of q and K as a set of projection parameters.

[0151] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: projecting the coordinate data according to the target projection parameters to obtain the target projection data of the target area; establishing a planar coordinate system of the target area according to the target projection data; establishing a regional ellipsoid of the target area according to the coordinate data, and mapping the coordinate data in the planar coordinate system to the regional ellipsoid; performing coordinate transformation on the regional ellipsoid to obtain an independent coordinate system of the target area.

[0152] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: determining a target location in the target area and using the target location as the origin of the planar coordinate system; orienting the planar coordinate system according to the standard coordinate system to determine the direction of the coordinate axes of the planar coordinate system; determining the correspondence between the target location and the target projection data, and establishing the planar coordinate system according to the correspondence, the origin, and the direction of the coordinate axes.

[0153] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: determining the number of reference points based on the area size of the target region; obtaining one or more reference points from the coordinate data according to the number of reference points; and establishing a regional ellipsoid of the target region based on the one or more reference points and the average elevation surface of the target region.

[0154] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: determining the reference coordinate system corresponding to the regional ellipsoid; calculating the transformation parameters between the reference coordinate system and the independent coordinate system of the target region using the seven-parameter method; and performing coordinate transformation on the regional ellipsoid according to the transformation parameters to obtain the independent coordinate system of the target region.

[0155] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, performs the following steps: acquiring coordinate data of a target area in a standard coordinate system and placing the central meridian at the center of the target area; acquiring multiple sets of projection parameters and projecting the coordinate data according to each set of projection parameters to obtain multiple sets of sample projection data of the target area; calculating the mean square error of the meridian deformation of each set of sample projection data based on the deformation of each meridian in each set of sample projection data; and using the set of projection parameters corresponding to the set of sample projection data with the smallest mean square error of meridian deformation as the target projection parameters.

[0156] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: performing a 3-degree Gauss-Kruger projection on the coordinate data to obtain Gauss projection data of the target area; obtaining the deformation of each meridian in the Gauss projection data; if the deformation of a meridian is greater than a preset deformation, determining the center position of the target area; and moving the central meridian so that the central meridian passes through the center position of the target area.

[0157] In one embodiment, when the computer program is executed by the processor, it further implements the following steps: configuring a first initial value corresponding to q and a second initial value corresponding to K, and configuring a first step distance corresponding to q and a second step distance corresponding to K; transforming q according to the first initial value and the first step distance, and transforming K according to the second initial value and the second step distance, obtaining multiple combinations of q and K, and using each combination of q and K as a set of projection parameters.

[0158] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: projecting the coordinate data according to the target projection parameters to obtain the target projection data of the target area; establishing a planar coordinate system of the target area according to the target projection data; establishing a regional ellipsoid of the target area according to the coordinate data, and mapping the coordinate data in the planar coordinate system to the regional ellipsoid; performing coordinate transformation on the regional ellipsoid to obtain an independent coordinate system of the target area.

[0159] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: determining a target location in the target area and using the target location as the origin of the planar coordinate system; orienting the planar coordinate system according to the standard coordinate system to determine the direction of the coordinate axes of the planar coordinate system; determining the correspondence between the target location and the target projection data, and establishing the planar coordinate system according to the correspondence, the origin, and the direction of the coordinate axes.

[0160] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: determining the number of reference points based on the area size of the target region; obtaining one or more reference points from the coordinate data according to the number of reference points; and establishing a regional ellipsoid of the target region based on the one or more reference points and the average elevation surface of the target region.

[0161] In one embodiment, when the computer program is executed by the processor, it further performs the following steps: determining the reference coordinate system corresponding to the regional ellipsoid; calculating the transformation parameters between the reference coordinate system and the independent coordinate system of the target region using the seven-parameter method; and performing coordinate transformation on the regional ellipsoid according to the transformation parameters to obtain the independent coordinate system of the target region.

[0162] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data shall comply with the relevant laws, regulations and standards of the relevant countries and regions.

[0163] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0164] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0165] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for determining projection parameters, characterized in that, The method includes: Obtain the coordinate data of the target area in the standard coordinate system, and place the central meridian at the center of the target area; Multiple sets of projection parameters are obtained, and the coordinate data is projected according to each set of projection parameters to obtain multiple sets of sample projection data of the target area; Based on the deformation of each meridian in each set of sample projection data, calculate the mean square error of the meridian deformation of each set of sample projection data. The set of projection parameters corresponding to the set of sample projection data with the smallest mean square error of the meridian deformation is taken as the target projection parameters; the mean square error is the sum of the variance of the meridian deformation and the square of the bias. The projection parameters include q and K, and obtaining multiple sets of projection parameters includes: Configure the first initial value corresponding to q and the second initial value corresponding to K respectively, and configure the first step distance corresponding to q and the second step distance corresponding to K; the first step distance is on the order of 10 to the power of negative 4 and is smaller than the second step distance; Transform q according to the first initial value and the first step distance, and transform K according to the second initial value and the second step distance to obtain multiple combinations of q and K, and use each combination of q and K as a set of projection parameters.

2. The method according to claim 1, characterized in that, The step of placing the central meridian at the center of the target area includes: Perform a 3-degree Gaussian-Kruger projection on the coordinate data to obtain the Gaussian projection data of the target area; Obtain the deformation of each meridian in the Gaussian projection data. If the deformation of a meridian is greater than a preset deformation, determine the center position of the target area. Move the central meridian so that it passes through the center of the target area.

3. The method according to claim 1, characterized in that, The method further includes: The coordinate data is projected according to the target projection parameters to obtain the target projection data of the target area; Based on the target projection data, establish a planar coordinate system for the target area; Based on the coordinate data, a regional ellipsoid of the target area is established, and the coordinate data in the planar coordinate system is mapped onto the regional ellipsoid. A coordinate transformation is performed on the regional ellipsoid to obtain an independent coordinate system for the target region.

4. The method according to claim 3, characterized in that, The step of establishing a planar coordinate system for the target region based on the target projection data includes: A target location is determined within the target area, and this target location is used as the origin of a planar coordinate system. Orient the planar coordinate system according to the standard coordinate system to determine the direction of the coordinate axes of the planar coordinate system; The correspondence between the target position and the target projection data is determined, and the planar coordinate system is established based on the correspondence, the origin, and the coordinate axis directions.

5. The method according to claim 3, characterized in that, The step of establishing a regional ellipsoid for the target region based on the coordinate data includes: The number of reference points is determined based on the area of ​​the target region; Based on the number of reference points, obtain one or more reference points from the coordinate data; Based on the one or more reference points and the average elevation surface of the target area, a regional ellipsoid of the target area is established.

6. The method according to claim 3, characterized in that, The coordinate transformation of the regional ellipsoid to obtain an independent coordinate system for the target region includes: Determine the reference coordinate system corresponding to the regional ellipsoid; The transformation parameters between the reference coordinate system and the independent coordinate system of the target region are calculated using the seven-parameter method. The coordinates of the regional ellipsoid are transformed according to the transformation parameters to obtain an independent coordinate system for the target region.

7. A projection parameter determining device, characterized in that, The device includes: The acquisition module is used to acquire coordinate data of the target area in the standard coordinate system and to set the central meridian at the center of the target area. The projection module is used to acquire multiple sets of projection parameters and project the coordinate data according to each set of projection parameters to obtain multiple sets of sample projection data of the target area. The calculation module is used to calculate the mean square error of the meridian deformation in each set of sample projection data based on the deformation of each meridian in each set of sample projection data. The comparison module is used to take the set of projection parameters corresponding to the set of sample projection data with the smallest mean square error of the meridian deformation as the target projection parameters; the mean square error is the sum of the variance of the meridian deformation and the square of the bias. The projection module is further configured to configure a first initial value corresponding to q and a second initial value corresponding to K, and to configure a first step distance corresponding to q and a second step distance corresponding to K; the first step distance is on the order of 10 to the power of negative 4 and is less than the second step distance; q is transformed according to the first initial value and the first step distance, and K is transformed according to the second initial value and the second step distance to obtain multiple combinations of q and K, and each combination of q and K is used as a set of projection parameters.

8. The apparatus according to claim 7, characterized in that, The acquisition module is further configured to perform a 3-degree Gauss-Kruger projection on the coordinate data to obtain Gauss projection data of the target area; acquire the deformation of each meridian in the Gauss projection data; if the deformation of a meridian is greater than a preset deformation, determine the center position of the target area; and move the central meridian so that the central meridian passes through the center position of the target area.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

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