River terrain generation method and device based on coherent difference principle

Abstract

The invention is suitable for the field of water conservancy projects, and discloses a method and a device for generating river topography based on a coherent difference principle, and the method comprises the steps: collecting the L1A-level data of a Gaofen-7 satellite of a river, and carrying out the preprocessing of the data; carrying out optimization processing on stereoscopic image pair data in L1A-level data of the Gaofen-7 satellite of the river channel, and generating initial DSM data of the terrain of the river channel; determining phase information of the river topography by combining initial DSM data of the river topography and an InSAR technology based on the same-period river SAR image data; and converting the phase information of the river topography into elevation information of the river topography, and correcting the elevation information of the river topography in combination with the ground control point to obtain target DSM data of the river topography. According to the method, after two-orbit method InSAR data is introduced for interference analysis, the characteristic of terrain deformation consistency can be effectively identified, the data processing efficiency is improved, the accuracy and reliability of the model are enhanced, and important technical support is provided for river treatment, ecological environment protection and the like.

Description

Technical Field

[0001] This invention relates to the field of water conservancy engineering, and in particular to a method and apparatus for generating river topography based on the principle of coherent difference. Background Technology

[0002] With the development of remote sensing technology, high-precision river topography acquisition based on dual-line array technology has become an emerging technical means. While the regional topographic data acquired by Gaofen-7 using this technology is of high quality, it contains numerous noise points in complex terrain conditions such as river channels, resulting in poor consistency of the extracted river topographic data and a tendency to form local uplifts and reverse slopes, making it difficult to meet the application and research needs of hydrological and hydrodynamic models. Therefore, this invention introduces interferometric analysis using dual-track InSAR data, which can effectively identify the consistency of topographic deformation, and proposes a large-scale river topography generation method based on the principle of coherent difference. Summary of the Invention

[0003] To address the aforementioned issues, this invention provides a method, apparatus, equipment, and medium for generating river topography based on the principle of coherent differential mapping. This method improves data processing efficiency and enhances the accuracy and reliability of the model, providing crucial technical support for river management and ecological environmental protection.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for generating river topography based on the principle of coherent difference, comprising: Collect L1A-level data of the river channel from the Gaofen-7 satellite and preprocess the data; The stereo imagery from the Gaofen-7 satellite L1A-level data of the river channel was optimized and processed to generate initial DSM data of the river channel topography. Based on the contemporaneous river SAR image data, combined with the initial DSM data of the river topography, the phase information of the river topography is determined. The phase information of the river channel topography is converted into the elevation information of the river channel topography. The elevation information of the river channel topography is then corrected by combining it with ground control points to obtain the target DSM data of the river channel topography.

[0005] Furthermore, the stereo imagery from the Gaofen-7 satellite L1A-level data of the river channel was optimized to generate initial DSM data of the river channel topography, including: The first stereo image pair data corresponding to the river channel was obtained from the L1A level data of the Gaofen-7 satellite of the river channel. The first stereo image pair data was optimized to obtain the second stereo image pair data. Based on the second stereo image pair data, an interpolation algorithm was used to generate initial DSM data of the river channel topography.

[0006] Furthermore, the data from the first stereoscopic image is optimized, including: The first stereo image pair corresponding to the river channel was obtained from the L1A level data of the Gaofen-7 satellite. Perform regional adjustment processing on the data of the first stereo image pair to determine the minimum overlap between the front view image and the rear view image of the first stereo image pair. The matching error value of the first stereoscopic image data is processed. Based on the similarity of the matching window images, a quality check is performed on each pixel in the first stereo image data. The optimized first stereo image pair data is used as the second stereo image pair data.

[0007] Furthermore, based on contemporaneous river channel SAR imagery data, combined with initial DSM data of the river channel topography, the phase information of the river channel topography is determined, including: Based on the stereo image pairs in the L1A level data of Gaofen-7 satellite, corresponding reference images and images to be registered are extracted from the river SAR images of the same period to form interferometric image data, and geometric registration processing is performed on the interferometric image data. Interferograms are generated using InSAR technology based on geometrically registered interferometric image data. The generated interferogram is subjected to multi-view processing to remove noise phase from the interferogram; Using the river topographic elevation information from the initial DSM data of the river topography, the topographic phase in the interferogram is removed using the two-track method to obtain the corresponding differential interferogram. The differential interferogram is unwrapped, and geocoding is performed on the phase of the unwrapped differential interferogram to obtain the phase information of the river channel topography in the geographic coordinate system.

[0008] Secondly, the present invention also provides a river topography generation device based on the coherent differential principle, comprising: The collection module is used to collect L1A-level data from the Gaofen-7 satellite in the river channel and to preprocess the data. The generation module is used to optimize the stereo imagery data from the Gaofen-7 satellite L1A-level data of the river channel and generate the initial DSM data of the river channel topography. The determination module is used to determine the phase information of the river topography based on the contemporaneous river SAR image data and the initial DSM data of the river topography. The module is used to convert the phase information of the river topography into the elevation information of the river topography, and to correct the elevation information of the river topography by combining it with ground control points, so as to obtain the target DSM data of the river topography.

[0009] Furthermore, the generation module also includes: The first stereo image pair data corresponding to the river channel was obtained from the L1A level data of the Gaofen-7 satellite of the river channel. The first stereo image pair data was optimized to obtain the second stereo image pair data. Based on the second stereo image pair data, an interpolation algorithm was used to generate initial DSM data of the river channel topography.

[0010] Furthermore, the data from the first stereoscopic image is optimized, including: The first stereo image pair corresponding to the river channel was obtained from the L1A level data of the Gaofen-7 satellite. Perform regional adjustment processing on the data of the first stereo image pair to determine the minimum overlap between the front view image and the rear view image of the first stereo image pair. The matching error value of the first stereoscopic image data is processed. Based on the similarity of the matching window images, a quality check is performed on each pixel in the first stereo image data. The optimized first stereo image pair data is used as the second stereo image pair data.

[0011] Furthermore, the defined module also includes: Based on the stereo image pairs in the L1A level data of Gaofen-7 satellite, corresponding reference images and images to be registered are extracted from the river SAR images of the same period to form interferometric image data, and geometric registration processing is performed on the interferometric image data. Interferograms are generated using InSAR technology based on geometrically registered interferometric image data. The generated interferogram is subjected to multi-view processing to remove noise phase from the interferogram; Using the river topographic elevation information from the initial DSM data of the river topography, the topographic phase in the interferogram is removed using the two-track method to obtain the corresponding differential interferogram. The differential interferogram is unwrapped, and geocoding is performed on the phase of the unwrapped differential interferogram to obtain the phase information of the river channel topography in the geographic coordinate system.

[0012] Thirdly, the present invention also provides an electronic device, comprising: a processor and a memory; The processor is coupled with the memory; The processor is used to read and execute programs or instructions stored in the memory, causing the device to perform the method as described in the first aspect.

[0013] Fourthly, the present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method as described in the first aspect.

[0014] The technical solution provided by this invention has at least the following technical effects or advantages: The technical solution of this invention receives Gaofen-7 satellite data of river channels and optimizes the image data to generate initial DEM (Digital Sounding Model) data of the river channel topography. Combined with contemporaneous SAR (Special Radiation for River Channels) image data, the interferometric registration method in InSAR technology is used to further optimize the quality of the DEM data, ultimately generating a high-resolution river channel topography model. This invention, by introducing two-track InSAR data for interferometric analysis, can effectively identify the consistency of topographic deformation, improve data processing efficiency, and enhance the accuracy and reliability of the model, providing important technical support for river management and ecological environmental protection.

[0015] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating a method for generating river topography based on the principle of coherent difference in an embodiment of the present invention. Figure 2 This is a schematic diagram of a river topography generation device based on the coherent differential principle provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Figure 1 This is a flowchart illustrating a method for generating river topography based on the principle of coherent difference in an embodiment of the present invention. As shown in the figure, the method includes: S101. Collect L1A-level data from the Gaofen-7 satellite of the river channel and preprocess the data; Gaofen-7 is a civilian sub-meter resolution optical transmission stereo mapping satellite that enables three-dimensional observation of the Earth's surface. It is the only satellite in the Gaofen series capable of capturing "3D" stereo images. Gaofen-7 is equipped with one dual-line array camera and one laser altimeter. The dual-line array camera continuously observes and acquires overlapping ground images to obtain stereo images. The dual-line array camera includes a forward-looking camera (+26° tilt) and a rear-looking camera (-5° tilt). The forward-looking camera is mounted on the satellite and captures ground images at a 26° tilt angle, allowing it to acquire ground images from a different perspective than the rear-looking camera. The rear-looking camera captures ground images at a near-vertical (-5° tilt) angle, while the forward-looking camera captures images at a tilt angle. Through the combined observations of both, stereo mapping data can be generated to produce a high-precision digital surface model (DSM).

[0020] Collect Gaofen-7 L1A level data of the river channel and preprocess the raw image data of Gaofen-7 L1A level data, including orthorectification and image fusion.

[0021] Orthorectification: Geometric correction is performed on the multispectral and panchromatic images in the original image data to eliminate image distortion and errors caused by factors such as terrain, satellite attitude, orbit, and camera installation, so that images of different bands can be accurately matched in spatial location. Image fusion processing: The multispectral and panchromatic images in the original image data are fused together. The fused image has both the high spatial resolution of the panchromatic image, which can clearly present the details and textures of ground features, and the rich spectral information of the multispectral image, which facilitates the identification and classification of ground features.

[0022] S102. Optimize the stereo imagery from the Gaofen-7 satellite L1A-level data of the river channel and generate initial DSM data of the river channel topography. Because the Gaofen-7 satellite is equipped with dual-line array cameras, the forward-looking camera and the rear-looking camera take pictures of the same area sequentially during the satellite's orbital flight, thus obtaining stereo image pairs of the same area. That is, the forward-looking camera first takes a picture of the ground target to obtain a forward-looking image, and the rear-looking camera takes a picture of the ground target from another angle to obtain a rear-looking image. The forward-looking image and the rear-looking image constitute a stereo image pair of the same ground target.

[0023] The first stereo image pair, consisting of forward-looking and backward-looking images, was obtained from the L1A-level data of the Gaofen-7 satellite of the river channel. This first stereo image pair was then optimized to obtain a high-quality second stereo image pair, specifically including: 1) Perform regional adjustment processing on the data of the first stereo image pair to determine the minimum overlap between the front view image and the rear view image of the first stereo image pair; 2) Processing the matching error value of the first stereo image pair data includes: extracting the feature points to be matched from the front-view and rear-view images; based on the extracted feature points, using feature matching algorithms (such as SIFT, SURF, etc.) to match the front-view and rear-view images, calculating the difference in pixel coordinates for each pair of matched front-view and rear-view feature points, and obtaining the corresponding error value; based on the error value of each pair of front-view and rear-view feature points, calculating the average error, standard deviation, and other statistical indicators corresponding to all matched front-view and rear-view feature points, and then evaluating the overall matching quality of the front-view and rear-view images; if the evaluation result does not meet the quality requirements, geometric correction is performed on the image data and outliers are removed using filtering algorithms, and feature points are reselected for rematching until the quality requirements are met. A smaller matching error value improves the reliability of the image data and reduces mismatches; a larger matching error value helps capture details but may cause excessive mismatches. Therefore, the matching error value processing for the first stereo image pair data can be adjusted according to the actual situation. 3) Based on the similarity of the matching window images, a quality check is performed on each pixel in the first stereo image data, which helps to improve the accuracy of pixels located at feature edges; 4) The optimized first stereo image pair data is identified as the high-quality second stereo image pair data.

[0024] Based on high-quality second stereo imagery, point cloud data corresponding to the river channel was generated using remote sensing image processing tools. Outliers and noise were removed from the point cloud data, and surface and non-surface points were identified using filtering algorithms to classify and segment the point cloud. The point cloud data was interpolated into a regular raster grid using the triangular mesh interpolation algorithm to generate initial DSM data for the river channel topography. Elevation correction was performed on the initial DSM data using ground control points (GCPs) to correct systematic errors, and the grid surface was smoothed using smoothing techniques (such as Gaussian filtering) to preserve topographic details. Further refinement of elevation information was achieved based on the classification results, and non-surface points (such as buildings or vegetation points) were removed to make the initial DSM data for the river channel topography more accurate.

[0025] S103. Based on the concurrent river SAR image data and combined with the initial DSM data of the river topography, determine the phase information of the river topography. River SAR imagery data contemporaneous with the Gaofen-7 satellite L1A-level data was collected. Initial DSM data of the river topography contained high-precision optical stereo mapping data. The SAR imagery data contained corresponding radar signal phase information. Based on the stereo image pairs from the Gaofen-7 L1A-level data, corresponding reference and registration images were extracted from the contemporaneous river SAR images to form an interferometric image. Geometric registration was performed on the interferometric image data. After geometric registration, the influence of topographic phase on the interferometric phase was removed by combining the initial DSM data of the river topography. The initial DSM provides topographic elevation information for the interferometric image, simulating changes in the radar signal propagation path and obtaining the phase difference caused by deformation. Since radar signal phase is periodic, entanglement may occur, affecting the accurate extraction of deformation information. Phase unwrapping processing was performed on the interferogram generated from the interferometric image. Methods such as the minimum cost flow algorithm with masking were used to unwrap the entangled phase, thus obtaining the correct deformation phase. After topographic phase removal and phase unwrapping processing, the resulting interferometric phase map only contained the surface deformation phase, i.e., the topographic deformation information of the river channel.

[0026] S1031. Based on stereo image pairs from L1A-level data of the Gaofen-7 satellite, corresponding reference images and images to be registered are extracted from contemporaneous river SAR images to form interferometric image data. Geometric registration processing is then performed on the interferometric image data. Interferometric registration, also known as coarse registration, includes coarse and fine registration. This ensures alignment between images and minimizes geometric distortion caused by factors such as orbital differences and sensor parameter variations.

[0027] The main purpose of coarse registration is to initially align images, eliminating significant geometric offsets caused by factors such as satellite orbit differences and sensor parameter variations, ensuring that the two images roughly overlap, and laying the foundation for accuracy. In the coarse registration process, initial DSM data of the river channel topography is used as external auxiliary data. Using the elevation values ​​in the DSM, each pixel in the image is projected onto a statistical geographic coordinate system, thus providing approximate spatial alignment. The DSM can provide accurate topographic information and surface elevation references to reduce the error range of geometric offsets. In this scheme, the initial DSM data of the river channel topography is generated from L1A-level data from the Gao7min satellite, possessing high resolution and high accuracy, which can significantly improve the reliability and efficiency of coarse registration.

[0028] The coarse registration process is as follows: (1) Select the reference image and the image to be registered; Based on stereo image pairs from the L1A-level data of the Gaofen-7 satellite, interferometric images were constructed by extracting corresponding reference and registration images from contemporaneous river SAR images. The extraction process was based on the temporal attributes and degree of change of the images. The reference image was selected as the earlier-captured master image, as it typically more closely resembles the original state of the land surface and possesses greater stability. The registration image was selected as the later-captured secondary image, as it needed to be aligned with the reference image to reflect changes in the land surface over time. When selecting the reference and registration images, image pairs with shorter time intervals were prioritized to minimize the impact of surface changes and atmospheric interference on registration accuracy. Furthermore, the overlap in spatial coverage between the reference and registration images reached a certain standard (e.g., not less than 55%) to ensure sufficient common areas for matching. Initial DSM data of the river channel topography was used as auxiliary data to provide a geometrical reference for the images. Using the elevation values ​​in the DSM, each pixel in the image was projected onto a unified geographic coordinate system, thus providing approximate spatial alignment. By performing initial alignment, the range of geometric offset between images is reduced, making subsequent cross-correlation calculations more efficient and accurate.

[0029] (2) Match and align pixel positions based on the cross-correlation relationship between the reference image and the image to be registered; Based on the image resolution and terrain features, matching windows of the same size are selected in both the reference image and the image to be registered. A matching window is a small region centered on the current pixel in one image, used to search for its corresponding pixel in another image. The size of the matching window is usually defined as a fixed pixel size (e.g., 3x3, 5x5, 7x7, etc.), where pixels refer to the raster size in the image.

[0030] For each matching window, calculate the cross-correlation matrix between the reference image and the image to be registered. It can be calculated using the following formula:

[0031] in, and These are the pixel values ​​of the reference image and the image to be registered, respectively. `i` is the row index of the pixel matrix, and `j` represents the column index of the pixel matrix. and is the average value within the matching window, N and M are the width and height of the matching window, and u and v are the offsets of the image to be registered relative to the reference image.

[0032] Find the location of the maximum value in the cross-correlation matrix. The offset (u,v) corresponding to this location is the optimal offset of the image to be registered relative to the reference image. Based on the obtained optimal offset (u,v), adjust each pixel of the image to be registered to align it with the reference image.

[0033] Fine registration is a process that further improves registration accuracy based on coarse registration. It primarily focuses on sub-pixel level correction to ensure high consistency between the two images at the pixel level. Fine registration is crucial for reducing noise in interferograms and improving interferometric coherence and phase quality, thus enabling more accurate extraction of surface deformation information. Fine registration mainly employs enhanced spectral diversity (ESD) technology, which utilizes the transformation relationship between time-domain delay and frequency-domain phase slope to obtain relevant parameters. This algorithm considers the phase consistency of overlapping regions between adjacent images, using this as an iterative standard to eliminate phase jumps in overlapping areas. Finally, due to the relatively steep phase slope of the Doppler centroid, azimuth spectrum deskewing is required.

[0034] S1032. Based on the geometrically registered interferometric image data, an interferogram is generated using InSAR technology. The interferogram is calculated from the phase difference between images and includes a comprehensive representation of information such as topography, deformation, flat-bottom effect, and noise.

[0035] In the process of producing interferograms, the differential interferometric phase between images in the interferometric image data is extracted using the two-track method. The two-track method is a technique used in InSAR (Interferometric Synthetic Aperture Radar) processing to extract the interferometric phase between images. It involves analyzing the phase difference between two SAR images acquired at different times but on the same orbit to calculate the surface features or dynamic changes of the target area. The interferometric phase is calculated from the phase difference between the two SAR images for the same target point. The formula for calculating the interferometric phase is as follows:

[0036] In the formula, It is the interference phase; It is the radar wavelength; It represents the change in the radar propagation path of the target point in the two SAR images.

[0037] The changes in the interference phase mainly originate from the following factors: flat phase Phase component caused by Earth's curvature and flat-surface effects; topographic phase The phase is caused by changes in the radar propagation path due to terrain undulations at the target point; deformation phase. The change in the propagation path of the target point due to surface deformation reflects the dynamic changes of the surface in the radar line-of-sight direction; noise error. The combined effects of atmospheric disturbances, systematic errors, and random noise. Therefore, the interference phase can be expressed as: .

[0038] S1033. Perform multi-view processing on the generated interferogram to remove noise phase from the interferogram; To reduce the interference of random noise on the interferometric phase, multi-view processing is performed on the generated interferogram. This effectively reduces the impact of noise while preserving the main components of the interferometric phase (such as terrain phase, deformation phase, and flat terrain phase). The interferometric phase after multi-view processing can be represented as follows: .

[0039] Multi-Looking is a method for reducing noise and improving the signal-to-noise ratio in interferograms. It reduces the impact of phase noise by averaging pixels in specific directions (such as azimuth and range) of the image, resulting in a smoother interferogram suitable for subsequent processing. Azimuth: In the horizontal direction, the phase values ​​are averaged in windows of 10 consecutive pixels, i.e., along the scanning direction of the radar imaging, averaging every 10 pixels to reduce the impact of noise on horizontal resolution. Range: In the vertical direction, the phase values ​​are averaged in windows of 2 consecutive pixels, i.e., along the range direction of radar wave propagation, averaging every 2 pixels to reduce the impact of noise on vertical resolution.

[0040] Let the original phase value of the interferogram be... Where x is the azimuth pixel and y is the range pixel, the phase after multi-view processing can be expressed as:

[0041] In the formula, Orientation window size (10 pixels in this example); : Distance to window size (2 pixels in this example); The original phase value of each pixel within the window; Phase value after multi-view processing.

[0042] S1034. Using the river topographic elevation information from the initial DSM data of the river topography, the topographic phase in the interferogram is removed by the two-track method to obtain the corresponding differential interferogram. Since the topographic phase in the interferogram affects the accuracy of the final generated river channel topography, it is necessary to remove the topographic phase to improve the accuracy of the final generated river channel topography. The initial DSM data of the river channel topography can provide topographic elevation information for the interferometric image. This elevation information is used to simulate the phase changes caused by topographic undulations in the radar signal propagation path, obtaining the phase error caused by deformation, i.e., the deformation information of the river channel surface in the interferogram. Based on the phase error caused by deformation, the topographic phase in the interferogram is removed using the two-track method to obtain the corresponding differential interferogram. The phase of the differential interferogram... It can be represented as:

[0043] In the formula, For deformation phase, Residual terrain phase introduced by external DSM phase error; This refers to the orbital error phase introduced during the processing. The phase difference is caused by atmospheric errors. This is noise error.

[0044] Residual terrain phase: refers to the phase error caused by terrain that was not completely eliminated during the terrain phase removal process. This phase error is mainly affected by the DSM elevation accuracy introduced from the Gaofen-7 satellite. and vertical baseline The impact; The role of phase error: to provide a basis for error correction for the accurate extraction of subsequent deformation information; The impact of DSM elevation accuracy: The initial DSM data accuracy for river topography is 2 meters, referring to the error range between the elevation data in the DSM and the actual terrain, usually expressed as root mean square error (RMSE). Its function is to provide an elevation reference for simulating terrain phase and to eliminate the influence of terrain phase in interferograms. The impact of the vertical baseline: This is the vertical distance between the orbits of two satellites, which affects the difference in the propagation path length of radar waves; The residual terrain phase can be represented as:

[0045] For wavelength, The distance from the sensor to the target. The external DEM uses a digital elevation model with a resolution of 12.5 meters to represent the radar incident angle.

[0046] S1035. Unwrap the differential interferogram and perform geocoding based on the phase of the unwrapped differential interferogram to obtain the phase information of the river topography in the geographic coordinate system. Typically, because the phase of a radar wave is a periodic function, its value ranges from 0 to 2π (or... (π to π). When the terrain phase change exceeds this range, phase entanglement occurs, causing the phase value to repeat within a complete cycle. This severely affects the resolution of the interferogram and the accuracy of the final result. Therefore, to improve the accuracy of elevation information, phase unwrapping processing is required before "converting phase information into deformation information".

[0047] The entangled differential interferogram phase is the differential interferogram phase obtained by removing the topographic phase from the initial interferogram phase. The phase information varies periodically within the range of (-π, π). Phase values ​​exceeding π or below... The π portion is folded back into this range, resulting in phase entanglement. A minimum cost flow algorithm with masking is used to untangle the differential interferogram phase and calculate the integer ambiguity. The untangled differential interferogram phase is converted into the actual deformation map phase, and the deformation map phase is geocoded into the WGS84 coordinate system. That is, the deformation information along the radar line of sight is mapped to the geographic coordinate system, giving the deformation data geospatial significance. The output generated after geocoding is a phase information map in the geographic coordinate system, which contains the spatial distribution information of surface deformation, i.e., the phase information of river channel topography.

[0048] S104. Convert the phase information of the river topography into the elevation information of the river topography, and correct the elevation information of the river topography by combining it with ground control points to obtain the target DSM data of the river topography.

[0049] The phase information of the interferometrically processed river channel topography is converted into the river channel's elevation information and further calibrated using ground control points (GCPs). Through precise error correction, the final high-resolution digital surface model (DSM), i.e., the target DSM data of the river channel, is generated to accurately represent the river channel's topographic features. Specifically: The phase information of the river channel topography is converted into elevation information using the following formula, which is expressed as: h=

[0050] In the formula, h represents the change or difference in surface elevation; It is the wavelength of the radar wave; It is the radar's angle of incidence, that is, the angle between the radar wave and the normal to the Earth's surface. It refers to the phase change after correction, which is the phase information obtained after topographic phase removal and phase unwrapping. This phase information has been removed from the influence of various non-deformation-related factors, and only the part related to the actual deformation of the surface is retained.

[0051] After obtaining the preliminary elevation data, ground control points (GCPs) are used for correction to improve the accuracy of the data. The correction formula is as follows:

[0052] In the formula, It is the elevation value after correction by ground control points; These are the uncorrected, original elevation values; It is the elevation error calculated from the ground control points, reflecting the elevation difference between the ground control points (GCP) and satellite data.

[0053] Ground control points are points on the ground with known, precise coordinates, typically obtained through high-precision surveying techniques such as GPS positioning. Their primary purpose is to provide a reference point when matching remotely sensed images with actual geographical locations, thereby improving accuracy and reducing errors.

[0054] Based on the corrected elevation information of the river channel, a high-precision digital surface model of the river channel topography is generated, which yields the target DSM data of the river channel topography.

[0055] The technical solutions in the embodiments of the present invention have at least the following technical effects or advantages: The technical solution of this invention collects Gaofen-7 satellite data of river channels and optimizes the image data to generate initial DEM (Digital Sounding Model) data of the river channel topography. Combined with contemporaneous SAR image data of the river channel, the interferometric registration method in InSAR technology is used to further optimize the quality of the DEM data, ultimately generating a high-resolution river channel topography model. This invention, by introducing two-track InSAR data for interferometric analysis, can effectively identify the consistency of topographic deformation, improve data processing efficiency, and enhance the accuracy and reliability of the model, providing important technical support for river management and ecological environmental protection.

[0056] Figure 2 This is a schematic diagram of a river topography generation device based on the coherent differential principle provided in an embodiment of the present invention. As shown in the figure, the device includes... The collection module is used to collect L1A-level data from the Gaofen-7 satellite in the river channel and to preprocess the data. The generation module is used to optimize the stereo imagery data from the Gaofen-7 satellite L1A-level data of the river channel and generate the initial DSM data of the river channel topography. The determination module is used to determine the phase information of the river topography based on the contemporaneous river SAR image data and the initial DSM data of the river topography. The module is used to convert the phase information of the river topography into the elevation information of the river topography, and to correct the elevation information of the river topography by combining it with ground control points, so as to obtain the target DSM data of the river topography.

[0057] It should be noted that, for ease of explanation, Figure 2 For example, only the main modules of the river topography generation device structure based on the coherent differential principle are shown. In practical applications, the system may also include modules or components not shown in the figure; the system is not limited to the above module structure, and may also be other module structures that implement the above method embodiments.

[0058] Figure 3 The present invention provides a schematic diagram of the structure of an electronic device, as shown in the figure. The electronic device includes a processor and a memory. The processor is used to read and execute programs and instructions stored in the memory, causing the electronic device to perform the above-described method embodiments.

[0059] It should be noted that, for ease of explanation, Figure 3 For illustrative purposes only, the main components of the electronic device are shown. In practical applications, the electronic device may also include components or parts not shown in the figures.

[0060] The present invention also provides a computer-readable storage medium storing a program or instructions, which, when read and executed by a computer, causes the computer to perform the above-described method embodiments.

[0061] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A river channel topography generating method based on a coherent difference principle, characterized by, The application relates to a method for generating river terrain DSM data. The method comprises the following steps: collecting high-resolution satellite L1A data of a river course and pre-processing the data; optimizing stereo image pair data in the high-resolution satellite L1A data of the river course and generating initial DSM data of the river terrain; based on synchronous river SAR image data, combining the initial DSM data of the river terrain, determining phase information of the river terrain; 2. The river course terrain generating method based on the coherent difference principle according to claim 1, characterized by, converting the phase information of the river terrain into elevation information of the river terrain, correcting the elevation information of the river terrain by combining ground control points, and obtaining target DSM data of the river terrain. The method for optimizing the stereo image pair data in the high-resolution satellite L1A data of the river course and generating the initial DSM data of the river terrain comprises the following steps: acquiring first stereo image pair data corresponding to the river course from the high-resolution satellite L1A data of the river course, optimizing the first stereo image pair data, and obtaining second stereo image pair data; 3. The river course terrain generating method based on the coherent difference principle according to claim 2, characterized by, based on the second stereo image pair data, generating the initial DSM data of the river terrain by using an interpolation algorithm. The method for optimizing the first stereo image pair data comprises the following steps: acquiring the first stereo image pair data corresponding to the river course from the high-resolution satellite L1A data of the river course; performing regional adjustment processing on the first stereo image pair data to determine the minimum overlap between the forward-looking image and the rear-looking image of the first stereo image pair; performing matching error value processing on the first stereo image pair data; based on the similarity of the matching window image, performing quality inspection on each pixel in the first stereo image pair data; 4. The method according to any one of claims 1 to 3, wherein determining the optimized first stereo image pair data as the second stereo image pair data. The method for determining the phase information of the river terrain based on the synchronous river SAR image data and combining the initial DSM data of the river terrain comprises the following steps: based on the stereo image pair data in the high-resolution satellite L1A data, extracting corresponding reference images and to-be-registered images from the synchronous river SAR images to form interference image data, and performing geometric registration processing on the interference image data; based on the geometrically registered interference image data, generating an interference graph by using InSAR technology; performing multi-view processing on the generated interference graph to remove noise phases in the interference graph; by using the river terrain elevation information of the initial DSM data of the river terrain, removing terrain phases in the interference graph by using a two-track method to obtain corresponding differential interference graphs; 5. A river topography generation device based on the principle of coherent difference, characterized in that, performing unwrapping processing on the differential interference graphs, and based on the unwrapped differential interference graph phases, performing geographic coding processing to obtain the phase information of the river terrain in a geographic coordinate system. The application further discloses a method for generating river terrain DSM data. The method comprises the following steps: a collecting module for collecting high-resolution satellite L1A data of a river course and pre-processing the data; a generating module for optimizing stereo image pair data in the high-resolution satellite L1A data of the river course and generating initial DSM data of the river terrain; a determining module for determining phase information of the river terrain based on synchronous river SAR image data and combining the initial DSM data of the river terrain. The obtaining module is configured to convert phase information of the river channel terrain into elevation information of the river channel terrain, correct the elevation information of the river channel terrain in combination with ground control points, and obtain target DSM data of the river channel terrain.

6. The river course topography generating apparatus based on the coherent difference principle according to claim 5, wherein The generating module further includes: The first stereo image pair data corresponding to the river channel is obtained from the high-resolution satellite L1A-level data of the river channel, and the first stereo image pair data is processed to obtain second stereo image pair data. Based on the second stereo image pair data, an interpolation algorithm is used to generate initial DSM data of the river channel terrain.

7. The river course topography generating apparatus based on the coherent difference principle according to claim 6, wherein The first stereo image pair data is processed to obtain the second stereo image pair data, including: The first stereo image pair data corresponding to the river channel is obtained from the high-resolution satellite L1A-level data of the river channel; The first stereo image pair data is processed to determine the minimum overlap between the forward-looking image and the rear-looking image of the first stereo image pair data; The first stereo image pair data is processed to determine the minimum overlap between the forward-looking image and the rear-looking image of the first stereo image pair data; Based on the similarity of the matching window image, the quality of each pixel in the first stereo image pair data is checked; The optimized first stereo image pair data is determined as the second stereo image pair data.

8. The river course topography generating apparatus based on the coherent difference principle according to any one of claims 5 to 7, characterized by The determining module further includes: Based on the stereo image pair data in the high-resolution satellite L1A-level data, corresponding reference images and to-be-registered images are extracted from the river channel SAR images of the same period to form interferometric image data, and the interferometric image data is processed for geometric registration; Based on the geometrically registered interferometric image data, an interferogram is generated using InSAR technology; The generated interferogram is processed for multi-view processing to remove noise phases in the interferogram; The river channel terrain elevation information of the initial DSM data of the river channel terrain is used to remove terrain phases in the interferogram using a two-track method to obtain corresponding differential interferograms; The differential interferograms are processed for unwrapping, and the unwrapped differential interferogram phases are processed for geocoding to obtain phase information of the river channel terrain in a geographic coordinate system.

9. An electronic device, comprising: It includes: A processor and a memory; The processor is coupled to the memory; The processor is configured to read and execute programs or instructions stored in the memory, so that the device executes the method of any one of claims 1-4.

10. A computer-readable storage medium, characterized in that, A computer program is stored, and the program is executed by the processor to implement the method of any one of claims 1-4.

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