A method for calculating the coverage rate of railway terrain deformation scattering points in plain areas considering elevation compensation

Abstract

The present invention relates to a method for calculating the coverage rate of railway object deformation scattering points in plain areas considering elevation compensation, including extracting the railway object scattering point positions based on the microwave scattering characteristics of the railway object; determining the railway ground elevation value and the relative elevation of the railway object scattering point positions relative to the railway ground elevation value based on the digital elevation data of the area along the railway; fitting to obtain the correlation between the offset and the relative elevation; compensating the railway object scattering point positions according to the correlation; extracting the railway object optical position according to the optical remote sensing image of the same area; matching the compensated railway object scattering point positions and the railway object optical positions, obtaining and determining the coverage rate based on the railway object deformation scattering points. The present invention can provide more comprehensive and accurate object deformation information, and can significantly improve the extraction accuracy of railway object deformation scattering points and the accuracy of coverage rate calculation.

Description

Technical Field

[0001] The invention relates to the technical field of satellite-based InSAR detection of railway object deformation, and more specifically to a method for calculating the coverage rate of railway object deformation scattering points in plain areas taking elevation compensation into consideration. Background Art

[0002] With the continuous expansion of my country's railway network and the increase in operating speed, the maintenance and monitoring of railway infrastructure has become particularly important. The shape and position information of railway facilities is the result of the combined effect of environmental factors in the area where the line is located and the impact of railway operation. It is also an intuitive reflection of the service status of railway infrastructure. Monitoring it is a key link to ensure the safe operation of railways.

[0003] At present, satellite-based InSAR technology is mainly used to monitor the deformation of railway objects. The satellite-based InSAR method uses the characteristic scattering of typical railway infrastructure to monitor the deformation of the object. By applying the permanent scatterer interferometry measurement technology of high-resolution images, it can efficiently complete the millimeter-level surface object deformation detection; the result of the time-series InSAR measurement is a point cloud composed of deformation scattering points. Each scattering point contains the time-series deformation information of the object represented by the point. By extracting the time-series deformation information of the microwave scattering points, the deformation of the facility within the time series range can be analyzed.

[0004] Although satellite-based InSAR technology, as a large-scale, non-contact and high-precision ground deformation measurement technology, can obtain the temporal deformation information of surface objects in a large area at one time; however, due to the difference between the side-view observation mode of SAR satellites and the orthographic observation mode of general optical mapping, the original scattering point positions obtained by time-series InSAR are different from the railway facility markings on the map, which affects the extraction and interpretation of railway infrastructure deformation, and directly leads to the inability to obtain effective typical railway facility scattering point coverage, which greatly limits the application and promotion of satellite-based InSAR technology in the railway industry.

[0005] In addition, the complex electromagnetic wave scattering environment formed by artificial structures such as railways and their surrounding scatterers also increases the difficulty of extracting scattering points of typical railway facilities. Summary of the invention

[0006] In view of this, in order to solve the problem of low planar positioning accuracy of facility scattering points in satellite-based InSAR observations of facility deformation on typical railways and the resulting inaccurate calculation of facility coverage, the present invention provides a method for calculating the coverage of railway terrain deformation scattering points in plain areas considering elevation compensation.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] The present invention provides a method for calculating the coverage rate of railway terrain deformation scattering points in plain areas considering elevation compensation, the steps comprising:

[0009] Extract the scattering point position of railway features based on the microwave scattering characteristics of railway features;

[0010] Determine the railway ground elevation value and the relative elevation of the railway ground object scattering point position relative to the railway ground elevation value based on the digital elevation data of the area along the railway;

[0011] Fit the offset and corresponding relative elevation of the local railway feature scattering point positions in the same area to obtain the correlation between the offset and relative elevation;

[0012] Compensate the position of railway feature scattering points based on the correlation between offset and relative elevation;

[0013] Obtain optical remote sensing images of the same area and extract the optical positions of railway features;

[0014] Matching the compensated railway feature scattering point position and the railway feature optical position to obtain the railway feature deformation scattering point;

[0015] Determine coverage based on scatter points.

[0016] Preferably, the microwave scattering characteristics of the railway features include clustering, height and / or spatial position.

[0017] Preferably, the resolution of digital elevation data in the area along the railway is between 3m and 30m, and the buffer range on both sides of the railway line is not less than 200m.

[0018] Preferably, determining the railway ground elevation value based on the digital elevation data of the area along the railway includes:

[0019] Based on the digital elevation data of the area along the railway, the surface elevation value within the range d1 around the railway line is extracted;

[0020] The surface elevation values ​​within the range d1 around the railway line are obtained by spatial low-pass filtering and spline interpolation of the surface elevation values.

[0021] Preferably, d1 is not less than 6 times the spatial resolution of microwave remote sensing data.

[0022] Preferably, a linear regression method is used to fit the offset of the local railway feature scattering point position and the corresponding relative elevation in the same area, and the expression is:

[0023] D=a*H+b

[0024] Where D is the offset, H is the relative elevation, and a and b are constants.

[0025] Preferably, after extracting the optical position of the railway feature, the known railway feature position is used for correction and verified in combination with prior information.

[0026] Preferably, when matching the compensated railway feature scattering point positions and the railway feature optical positions, the distance standard deviation of the two sets of coordinates is no more than three times the resolution of the optical remote sensing image.

[0027] Preferably, determining the coverage based on the scattering points comprises,

[0028] The coverage rate of railway feature deformation scattering points is determined based on the ratio of the number of effective deformation scattering points to the number of railway feature points obtained based on optical remote sensing.

[0029] Preferably, the coverage rate of railway terrain deformation scattering points is not greater than 100%.

[0030] Compared with the prior art, the present invention discloses a method for calculating the coverage rate of railway terrain deformation scattering points in plain areas taking into account elevation compensation, and the beneficial effects include:

[0031] (1) Using the height difference between railway facilities and the surrounding ground to correct the plane position can effectively reduce the position error of scattering points caused by the difference between the SAR satellite side-view observation mode and the orthographic observation mode, and improve the plane positioning accuracy of scattering points;

[0032] (2) Optical remote sensing data with high resolution and high ground object positioning accuracy provide a reference for the precise matching of scattering points, thereby further verifying and correcting the positions of scattering points to ensure their accuracy.

[0033] The present invention can provide more comprehensive and accurate information on ground deformation through elevation compensation and combined with optical remote sensing technology, and can significantly improve the accuracy of extraction of railway ground deformation scattering points and coverage calculation, thereby providing more accurate data support for the maintenance and monitoring of railway infrastructure, and helping to ensure the safety and stability of railway operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0035] Figure 1 A flow chart of a method for calculating the coverage rate of railway terrain deformation scattering points in plain areas taking into account elevation compensation according to the present invention;

[0036] Figure 2This is a flowchart of a method for calculating the coverage rate of railway terrain deformation scattering points in plain areas taking into account elevation compensation of the present invention;

[0037] Figure 3 A schematic diagram of the relationship between relative elevation and position deviation of a typical railway feature provided by an embodiment of the present invention;

[0038] Figure 4 A schematic diagram of the original typical railway feature microwave remote sensing scattering points provided by an embodiment of the present invention;

[0039] Figure 5 A schematic diagram of corrected microwave remote sensing scattering points of typical railway features provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] In order to overcome the shortcomings of the prior art and improve the extraction accuracy and coverage accuracy of railway terrain deformation scattering points, the embodiment of the present invention discloses a method for calculating the coverage rate of railway terrain deformation scattering points in plain areas taking into account elevation compensation. The method is mainly used in areas with relatively flat terrain or continuous surface changes. The plane position compensation correction is performed by combining the elevation difference between typical railway facilities and the surrounding ground. By taking advantage of the high resolution and high positioning accuracy of optical remote sensing, the optical remote sensing facility extraction result is used as a standard to extract the corrected scattering point information, thereby finally improving the positioning accuracy of railway terrain scattering points and obtaining a reliable railway terrain scattering point coverage rate.

[0042] This application helps to improve the accuracy and reliability of railway deformation monitoring, ensure the safety of railway operation, and provide a basis for the maintenance of railway facilities.

[0043] In one embodiment:

[0044] A method for calculating the coverage rate of railway terrain deformation scattering points in plain areas considering elevation compensation is disclosed, the steps are as follows: Figure 1 As shown, including:

[0045] Extract the scattering point position of railway features based on the microwave scattering characteristics of railway features;

[0046] Determine the railway ground elevation value and the relative elevation of the railway ground object scattering point position relative to the railway ground elevation value based on the digital elevation data of the area along the railway line;

[0047] Fit the offset and corresponding relative elevation of the local railway feature scattering point positions in the same area to obtain the correlation between the offset and relative elevation;

[0048] Compensate the position of railway feature scattering points based on the correlation between offset and relative elevation;

[0049] Obtain optical remote sensing images of the same area and extract the optical positions of railway features;

[0050] Matching the compensated railway feature scattering point position and the railway feature optical position to obtain the railway feature deformation scattering point;

[0051] Determine coverage based on scatter points.

[0052] It should be noted that extracting the railway feature scattering point position, determining the railway ground elevation value, and extracting the railway feature optical position can be performed simultaneously, and this embodiment does not limit the execution order.

[0053] Reference Figure 2 , Figure 2 A block diagram representation of the flow of the calculation method for the coverage rate of railway terrain deformation scattering points in plain areas considering elevation compensation;

[0054] In one embodiment, the location of the railway feature scattering point is extracted based on the microwave scattering characteristics of the railway feature;

[0055] In this embodiment, cluster analysis is performed based on the microwave scattering characteristics of typical railway features, and point clusters are extracted from the PS-InSAR processing results, so as to obtain the location XI of the typical railway features in the InSAR observation results. Preferably, manual detection is performed on XI to eliminate non-railway features.

[0056] The PS-InSAR results of the railway area contain deformation information of railway facilities and other features. Typical railway features have specific distribution characteristics such as height, spatial position and clustering. The scattering points of typical railway features are extracted through these characteristics, and their positions represent the positions of typical railway features in the PS-InSAR results. As a preference, the scattering information of non-railway features is further eliminated in combination with prior information.

[0057] In one embodiment, the railway ground elevation value and the relative elevation of the railway ground feature scattering point position relative to the railway ground elevation value are determined based on the digital elevation data of the area along the railway;

[0058] In this application, the digital elevation data of the area along the railway shall have a spatial resolution of not less than 30m and not more than 3m, and the buffer range on both sides of the railway line shall not be less than 200m.

[0059] After the preliminary processing is completed, the elevation change pattern of the surface in the area can be revealed. The resolution of the extracted strip surface elevation LL1 is consistent with the spatial resolution of D1. The resolution of the equivalent railway ground elevation L1 should be consistent with the optical remote sensing spatial resolution used for object identification in the area, which is generally sub-meter level, with a resolution of 0.5m being appropriate.

[0060] In this embodiment, the surface elevation value LL1 within the range d1 around the railway line position A1 is firstly extracted from the DEM data D1 of the area along the railway. LL1 includes the elevation information of the ground, railway features and other structures in the area.

[0061] The equivalent railway ground elevation value L1 within the range d1 around A1 is obtained by performing spatial low-pass filtering and spline interpolation on LL1; the specific steps include:

[0062] Based on the digital elevation data of the area along the railway, the surface elevation value within the range d1 around the railway line is extracted;

[0063] The surface elevation values ​​within the range d1 around the railway line are obtained by spatial low-pass filtering and spline interpolation of the surface elevation values.

[0064] Low-pass filtering can remove the surface undulations caused by small-scale objects. Using spline interpolation, the surface deformation information after low-pass filtering is subjected to cubic spline interpolation to obtain equivalent railway ground elevation information consistent with the resolution of optical object extraction, that is, the equivalent railway ground elevation value L1 suitable for microwave remote sensing scattering point height correction, which is used to more carefully characterize the changes in equivalent railway ground elevation and quantitatively depict its impact on the InSAR monitoring results of typical railway facilities.

[0065] Preferably, d1 is not less than 6 times the spatial resolution of microwave remote sensing data, preferably 200m.

[0066] Further, the relative elevation of the railway feature scattering point position relative to the railway ground elevation value is determined;

[0067] The PS-InSAR results contain the elevation information of the scattering points, that is, both the ground scattering points and the railway feature scattering points contain elevation information. The height of typical railway features relative to the ground can be calculated through the elevation difference.

[0068] In one embodiment, the height h0 of a typical railway feature is used as constraint information to verify the validity of the relative elevation.

[0069] In one embodiment, the offset and the corresponding relative elevation of the local railway feature scattering point positions in the same area are fitted to obtain the correlation between the offset and the relative elevation;

[0070] That is, the height h0 of typical railway features is obtained through prior information, and its relative elevation H0 relative to the ground elevation L1 is calculated; the selection of typical railway features must evenly cover the entire line; and include features in different sections of the line and features at different heights, so as to form the most parameterized solution for the entire line.

[0071] Then, the position offset D0 of typical railway facilities at different local elevations is obtained through the InSAR results in the same area; the linear regression method is used to fit the offset and corresponding relative elevation of the local railway feature scattering point position in the same area, and the least squares linear fitting is used to obtain the target area height compensation function, which is then extrapolated to the elevation compensation of the area along the railway; the compensation function expression is:

[0072] D=a*H+b

[0073] Where D is the offset, H is the relative elevation, and a and b are constants.

[0074] It should be noted that the fitted relationship is only valid within the same region. Figure 3 shown.

[0075] In one embodiment, the position of the railway feature scattering point is compensated according to the correlation between the offset and the relative elevation.

[0076] In one embodiment, the deviation compensation DA value of other typical railway facilities in the test area is first determined based on the correlation between the offset and the relative elevation.

[0077] Then, according to the plane coordinate compensation amount DA of the railway feature and the position XI of the typical railway feature, the microwave remote sensing real position XW of the typical railway feature within the observation range is obtained;

[0078] In this embodiment, the typical railway feature microwave remote sensing scattering points before position compensation correction are as follows: Figure 4 As shown, the plane position of the corrected microwave remote sensing scattering point is as follows Figure 5 As shown, relative to Figure 4 Elevation deviation correction improves the consistency between the scattering point positions of typical railway features and the results of optical feature extraction, providing effective support for the interpretation of railway facility deformation.

[0079] In one embodiment, optical remote sensing images of the same area are obtained to extract the optical position of railway features; in this embodiment, optical position information XD of typical railway features is obtained based on high-resolution optical remote sensing images;

[0080] In one embodiment, high-resolution optical remote sensing images used to extract typical railway features need to be processed and spliced ​​to properly cover the railway line;

[0081] First, extract the preliminary optical position of the railway feature.

[0082] The preliminary position is corrected by evenly setting position correction points along the line to obtain the refined position of typical railway features to ensure the image positioning accuracy of the area along the railway.

[0083] And the optical position information XD of the typical railway features is obtained by combining the prior information for verification, that is, the typical features are selected to verify the extraction and positioning accuracy to obtain the real position information XD of the typical railway features.

[0084] In one embodiment, the compensated railway feature scattering point positions and the corresponding railway feature optical positions are matched to obtain railway feature deformation scattering points, and an intersection X, X∈XD is formed accordingly.

[0085] XW is the coordinate of the microwave remote sensing scattering point after elevation correction, including the location information of typical railway facilities and other objects; XD of the optical position of typical railway objects is used as the standard for registration.

[0086] In one embodiment, a spatial distance threshold Y1 is set, and when the distance between the microwave remote sensing real positions XW and XD of the corresponding positions is less than Y1, the registration is successful and they are regarded as the same point;

[0087] In this embodiment, the distance threshold is set based on the distance standard deviation corresponding to the two sets of coordinates, and the threshold should not be greater than 3 times the resolution of the optical remote sensing data.

[0088] This embodiment combines the advantages of high spatial resolution of optical remote sensing and microwave scatterer deformation analysis method, and corrects the microwave scatterer positioning result by quantifying the relationship between the elevation difference between typical railway facilities and the surrounding ground and the offset of their scattering points, thereby improving the accuracy of positioning typical railway scatterers. At the same time, the natural connection between the microwave scatterer of the same railway object and the optical imaging result is used to collect the scattering point data of typical railway objects, further correct the position of the scattering point, and ensure the accuracy of the scattering point position. This invention method effectively improves the positioning accuracy of synthetic aperture radar deformation observation in railway line deformation interpretation.

[0089] In another embodiment, the coverage is determined based on the scatter points, including:

[0090] The coverage rate of railway feature deformation scattering points is determined according to the ratio of the number of effective deformation scattering points n1 to the number of railway feature points n2 acquired based on optical remote sensing.

[0091] Among them, n1 is not greater than n2, that is, the PS-InSAR scattering point coverage of typical railway features is not greater than 100%.

[0092] In order to improve the accuracy of railway object deformation scattering point coverage, the present invention introduces elevation compensation to correct the plane position of the scattering points, and combines the high-resolution optical remote sensing object extraction results as a basis to carry out railway object deformation scattering point coverage calculation, providing a more reliable means for microwave remote sensing railway facility observation efficiency evaluation.

[0093] Specifically, by combining the advantages of accurate positioning of the ground height difference compensation method for railway facilities and high resolution and high positioning accuracy of optical remote sensing, the plane position correction is made by using the height difference between typical railway facilities and the surrounding ground, and the positioning accuracy of the facilities is improved with the help of optical remote sensing. The corrected scattering point information is extracted using the extraction results of optical remote sensing facilities as a standard, and finally the scattering point coverage efficiency of railway features is obtained. This method introduces elevation compensation information and effectively improves the calculation accuracy of the scattering point coverage rate of railway feature deformation in plain areas. It can effectively solve the problem of low plane positioning accuracy of the scattering point rate of facilities in satellite-based InSAR observations of facility deformation on typical railways, which affects the calculation of coverage rate, especially the problem of plane position offset of scattering points caused by the height difference of the ground.

[0094] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0095] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for calculating the coverage rate of railway terrain deformation scattering points in plain areas considering elevation compensation, characterized in that: Extract the scattering point position of railway features based on the microwave scattering characteristics of railway features; Determine the railway ground elevation value and the relative elevation of the railway ground object scattering point position relative to the railway ground elevation value based on the digital elevation data of the area along the railway; Determining the ground elevation value of the railway based on the digital elevation data of the area along the railway includes: extracting the surface elevation value within the range d1 around the railway line based on the digital elevation data of the area along the railway; performing spatial low-pass filtering and spline interpolation on the surface elevation value to obtain the surface elevation value within the range d1 around the railway line; Fit the offset and corresponding relative elevation of the local railway feature scattering point positions in the same area to obtain the correlation between the offset and relative elevation; Compensate the position of railway feature scattering points based on the correlation between offset and relative elevation; Obtain optical remote sensing images of the same area and extract the optical positions of railway features; Matching the compensated railway feature scattering point position and the railway feature optical position to obtain the railway feature deformation scattering point; Determine coverage based on scatter points.

2. The method for calculating the coverage rate of railway feature deformation scattering points in plain areas according to claim 1 is characterized in that: The microwave scattering characteristics of railway objects include clustering, height and / or spatial location.

3. The method for calculating the coverage rate of railway feature deformation scattering points in plain areas according to claim 1 is characterized in that: The resolution of digital elevation data in the area along the railway is between 3m and 30m, and the buffer range on both sides of the railway line is not less than 200m.

4. The method for calculating the coverage rate of railway feature deformation scattering points in plain areas according to claim 1 is characterized in that: d1 shall not be less than 6 times the spatial resolution of microwave remote sensing data.

5. The method for calculating the coverage rate of railway feature deformation scattering points in plain areas according to claim 1 is characterized in that: The linear regression method is used to fit the offset and corresponding relative elevation of the local railway feature scattering point position in the same area. The expression is: D=a*H+b Where D is the offset, H is the relative elevation, and a and b are constants.

6. The method for calculating the coverage rate of railway feature deformation scattering points in plain areas according to claim 1 is characterized in that: After extracting the optical position of the railway features, the known positions of the railway features are used for correction and verified in combination with prior information.

7. The method for calculating the coverage rate of railway feature deformation scattering points in plain areas according to claim 1 is characterized in that: When matching the compensated railway feature scattering point positions and railway feature optical positions, the standard deviation of the distance between the two sets of coordinates shall not be greater than three times the resolution of the optical remote sensing image.

8. The method for calculating the coverage rate of railway feature deformation scattering points in plain areas according to claim 1 is characterized in that: Determining coverage based on scatter points includes: The coverage rate of railway feature deformation scattering points is determined based on the ratio of the number of effective deformation scattering points to the number of railway feature points obtained based on optical remote sensing.

9. The method for calculating the coverage rate of railway feature deformation scattering points in plain areas according to claim 8 is characterized in that: The coverage rate of railway terrain deformation scattering points shall not exceed 100%.

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