Method and device for reconstructing airborne multi-pass InSAR image

Abstract

The invention discloses an airborne multi-pass InSAR image reconstruction method and device, and belongs to the technical field of synthetic aperture radar interferometry, and the method comprises the steps: obtaining airborne multi-pass InSAR main image data and auxiliary image data; calculating the ground line-of-sight direction of the main image, setting the ground line-of-sight direction of the auxiliary image to be consistent with the main image, and reversely solving the Doppler frequency of the reconstructed auxiliary image; calculating the azimuth pixel resolution of the main image, setting the azimuth pixel resolution of the auxiliary image to be consistent with the main image, and reversely solving the azimuth time resolution of the reconstructed auxiliary image; the range pixel resolution of the reconstructed auxiliary image is set to be consistent with that of the main image; and generating a reconstructed auxiliary image parameter file, establishing a positioning relationship between the auxiliary image and the reconstructed auxiliary image, and re-sampling the auxiliary image to obtain the reconstructed auxiliary image. According to the invention, the problems of inconsistent spatial directions and unmatched spatial scales of the main image and the auxiliary image are solved, so that spatial alignment of the main image and the auxiliary image is realized, and the interference registration precision is remarkably improved.

Description

Technical Field

[0001] The present invention relates to a method and device for reconstructing airborne multi-pass InSAR images, and belongs to the technical field of synthetic aperture radar interferometry (InSAR). Background Art

[0002] As an active imaging sensor, SAR (Synthetic Aperture Radar) can conduct Earth observation around the clock, regardless of natural conditions such as lighting and weather. It has a wide range of applications in terrain mapping, natural resource surveying and monitoring, disaster response, military reconnaissance, and many other fields. Interferometric SAR (InSAR), an extension of SAR technology, leverages the mathematical relationship between interferometric phase and terrain elevation. It is an important remote sensing technology for measuring three-dimensional surface information, particularly surface deformation.

[0003] Airborne multi-pass InSAR is an observation mode that uses repeated airborne SAR flights over the same area to perform interferometric measurements. For long-wavelength SAR, this method overcomes the baseline length limitations of airborne dual- and multi-antenna InSAR systems, enabling three-dimensional surface measurements. It also enables differential interferometry through multiple flights, effectively measuring surface deformation.

[0004] Interferometric registration is a key step in InSAR processing. Achieving high-precision three-dimensional surface inversion requires excellent interferometric registration. Interferometric registration involves using image matching methods to find exact coincident pixels in the interferometric primary and secondary images. This ensures that a pair of pixels in the registered images corresponds to the same surface area, achieving image signal coherence. Interferometric image matching generally employs a window-based correlation function matching method. This method requires that the primary and secondary images be consistent in spatial scale and orientation. Otherwise, matching may fail or result in poor accuracy, preventing the formation of an effective interferometric image and resulting in failure in 3D inversion. Airborne multi-pass InSAR data utilizes repeated flights, resulting in flight paths that are not strictly parallel due to factors such as aircraft flight control and airflow. Furthermore, different Doppler center frequencies are used for imaging during each flight, leading to spatial inconsistencies in the primary and secondary images. Furthermore, variations in flight speed and sampling frequency between flights also lead to spatial scale inconsistencies between the primary and secondary images. Consequently, direct interferometric registration of airborne multi-pass InSAR data can be difficult to achieve ideal results. Therefore, it is necessary to reconstruct the airborne multi-pass InSAR images so that the main and auxiliary images are consistent in spatial scale and direction for subsequent high-precision interferometric registration, thereby achieving high-quality interferometric three-dimensional inversion. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a method and device for reconstructing airborne multi-flyover InSAR images, which can achieve spatial alignment of primary and secondary images and improve the accuracy of interferometric registration.

[0006] The technical solution adopted by the present invention to solve its technical problems is: In a first aspect, an embodiment of the present invention provides a method for reconstructing airborne multi-flyover InSAR images, comprising the following steps: Step S1, obtaining airborne multi-flyover InSAR primary image data and auxiliary image data; Step S2, calculating the main image ground sight line direction according to the main image imaging parameters, setting the auxiliary image ground sight line direction to be consistent with the main image ground sight line direction, and inversely calculating the Doppler frequency of the reconstructed auxiliary image based on the ground sight line direction; Step S3, calculating the azimuth pixel resolution of the primary image based on the azimuth temporal resolution and flight speed of the primary image, setting the azimuth pixel resolution of the secondary image to be consistent with the azimuth pixel resolution of the primary image, and inversely calculating the azimuth temporal resolution of the reconstructed secondary image based on the azimuth pixel resolution and the flight speed of the secondary imaging platform; Step S4, setting the distance pixel resolution of the reconstructed auxiliary image to be consistent with the distance pixel resolution of the main image; Step S5: generating a reconstructed auxiliary image parameter file, establishing a positioning relationship between the auxiliary image and the reconstructed auxiliary image, and resampling the auxiliary image to obtain the reconstructed auxiliary image.

[0007] As a possible implementation of this embodiment, step S2 includes the following steps: Step S21: Select the center point of the main image, obtain its image coordinates, determine the corresponding platform flight speed based on the azimuth image coordinates, and calculate the main image oblique angle; Step S22: Obtain the slant distance based on the distance image coordinates, calculate the projected length of the slant distance in the orthogonal side view direction, the ground distance, the orthogonal side view direction projected ground distance, and the ground projection slant angle, and determine the ground line of sight direction of the main image in combination with the main image heading azimuth. This step is used to accurately obtain the direction reference of the main image observing the ground. Step S23, using the range-Doppler (RD) model, the geographic coordinates are calculated from the image coordinates of the center point of the primary image combined with the local average elevation, and then the image coordinates of the corresponding auxiliary image point are calculated based on the geographic coordinates. This is to establish a correlation between the primary and auxiliary images in terms of geographic coordinates. In step S24, the ground line of sight of the auxiliary image is set to be consistent with that of the main image. The ground projection slant angle of the auxiliary image is calculated based on its heading azimuth. The Doppler frequency of the reconstructed auxiliary image is inversely calculated based on the flight speed, slant range, and altitude of the auxiliary imaging platform. This ensures that the auxiliary image and the main image are consistent in the ground line of sight, laying the foundation for subsequent spatial alignment.

[0008] As a possible implementation of this embodiment, step S3 includes the following steps: Step S31, using the flight speed of the main imaging platform to calculate the pixel resolution of the main image in azimuth, and to determine the spatial scale of the main image in azimuth; Step S32 , setting the auxiliary image azimuth pixel resolution and the main image azimuth temporal resolution to be consistent, and using the auxiliary image platform flight speed to inversely calculate the auxiliary image azimuth temporal resolution after reconstruction.

[0009] As a possible implementation of this embodiment, step S5 includes the following steps: Step S51, modifying the auxiliary image parameter file, updating the Doppler frequency to the reconstructed frequency, the azimuth time resolution to the reconstructed time resolution, and the range pixel resolution to the set resolution, to generate a reconstructed auxiliary image parameter file, providing an accurate parameter basis for subsequent resampling; Step S52: establishing a geometric positioning model of the auxiliary image and the reconstructed auxiliary image based on the imaging parameters, and clarifying the spatial mapping relationship between the two; In step S53, the reconstructed auxiliary image is initialized according to the auxiliary image size, and the mapping from the reconstructed auxiliary image coordinates to the auxiliary image coordinates is realized pixel by pixel through the positioning model. The pixel values ​​are obtained by the interpolation algorithm, and the resampling is completed to finally obtain the reconstructed auxiliary image aligned with the main image space.

[0010] As a possible implementation of this embodiment, the specific steps of step S2 are as follows: Step S21: Select the center point of the main image and obtain its image coordinates , according to the azimuth image coordinates Determine the flight speed of the corresponding platform , calculate the main image oblique angle ,in, is the main image Doppler frequency, is the radar wavelength; Step S22: according to the distance to the image coordinates Get slope distance , calculate the projection length of the slant distance in the positive side view direction , ground distance , Projected distance from the front and side view directions and ground projection oblique angle , The main image altitude, combined with the main image heading azimuth , determine the ground sight direction of the main image ,The purpose of this step is to accurately obtain the direction reference of the main image observing the ground; Step S23, according to the SAR image geometric positioning model, the image coordinates of the main image center point are Combined with local average elevation Calculating geographic coordinates , and then according to the geographic coordinates Calculate the image coordinates of the corresponding auxiliary image points , which is used to establish the association between the main and auxiliary images in geographic coordinates. The SAR image geometric positioning model adopts the range-Doppler (RD) model: , in, is the observation equation for range imaging conditions, is the Doppler imaging condition observation equation, is the geographic coordinate, is the image coordinate; Step S24: Set the ground sight line direction of the auxiliary image to be the same as the ground sight line direction of the main image. , according to the auxiliary image heading azimuth Calculate the oblique angle of its ground projection , combined with the auxiliary imaging platform flight speed , slope distance Ji Hanggao , inversely calculate the Doppler frequency of the reconstructed auxiliary image , where the auxiliary image oblique angle , the slant distance is projected in the direction of the front side view , the projected distance from the front and side view directions , auxiliary image point distance , in order to ensure that the auxiliary image and the main image are consistent in the ground line of sight direction, laying the foundation for subsequent spatial alignment.

[0011] As a possible implementation of this embodiment, the specific steps of step S3 are as follows: Calculate the pixel resolution of the main image in azimuth: ,in is the flight speed of the main imaging platform, The temporal resolution of the main image in azimuth direction. This calculation can clearly define the spatial scale of the main image in azimuth direction. Set the auxiliary image azimuth pixel resolution to be consistent with the main image azimuth temporal resolution, then the auxiliary image azimuth pixel resolution is , inversely calculate the azimuth time resolution of the reconstructed auxiliary image , The flight speed of the auxiliary imaging platform.

[0012] As a possible implementation of this embodiment, the step S4 is specifically to set the distance pixel resolution of the reconstructed auxiliary image to Pixel resolution in the distance from the main image Consistent, that is , which is used to ensure that the main and auxiliary images remain consistent in the distance spatial scale.

[0013] As a possible implementation of this embodiment, step S5 specifically includes the following steps: Set the Doppler frequency in the auxiliary image parameter file , azimuth time resolution and range pixel resolution Modified to the reconstructed Doppler frequency , azimuth time resolution and range pixel resolution , generate reconstructed auxiliary image parameter file; Establishing a geometric positioning model of the auxiliary image and the reconstructed auxiliary image according to the imaging parameters; Create a reconstructed auxiliary image according to the size of the auxiliary image; then use the image coordinates of the reconstructed auxiliary image points Departure, combined with the local average altitude , calculate geographic coordinates based on the geometric positioning model ; Then by geographic coordinates and local average elevation Calculate the image coordinates of the corresponding auxiliary image points according to the geometric positioning model , according to the image coordinates Interpolate and sample the auxiliary image to obtain pixel values, and fill them into the reconstructed auxiliary image. Image point position; in this way, the reconstructed auxiliary image is positioned and resampled pixel by pixel to obtain the final reconstructed auxiliary image.

[0014] In a second aspect, an embodiment of the present invention provides an airborne multi-flyover InSAR image reconstruction device, comprising: Data acquisition module, used to obtain airborne multi-pass InSAR primary image data and auxiliary image data; A Doppler frequency reconstruction module is used to calculate the ground sight line direction of the main image based on the imaging parameters of the main image, set the ground sight line direction of the auxiliary image to be consistent with the ground sight line direction of the main image, and reversely calculate the Doppler frequency of the reconstructed auxiliary image based on the ground sight line direction; The azimuth parameter reconstruction module is used to calculate the azimuth pixel resolution of the main image based on the azimuth temporal resolution and flight speed of the main image, set the azimuth pixel resolution of the auxiliary image to be consistent with the azimuth pixel resolution of the main image, and reversely calculate the azimuth temporal resolution of the reconstructed auxiliary image based on the azimuth pixel resolution and the flight speed of the auxiliary imaging platform; The distance parameter setting module is used to set the distance pixel resolution of the reconstructed auxiliary image to be consistent with the distance pixel resolution of the main image; The resampling module is used to generate a reconstructed auxiliary image parameter file, establish a positioning relationship between the auxiliary image and the reconstructed auxiliary image, and resample the auxiliary image to obtain the reconstructed auxiliary image.

[0015] As a possible implementation of this embodiment, the Doppler frequency reconstruction module includes: The main image parameter calculation module is used to select the center point of the main image, obtain its image coordinates, determine the corresponding platform flight speed based on the azimuth image coordinates, and calculate the main image oblique angle; The main image ground sight direction determination module is used to obtain the slant distance based on the distance to image coordinates, calculate the projected length of the slant distance in the orthographic side view direction, the ground distance, the orthographic side view direction projected ground distance and the ground projection slant angle, and determine the main image ground sight direction in combination with the main image heading azimuth; The auxiliary image coordinate calculation module is used to calculate the geographic coordinates of the main image center point by combining the image coordinates of the local average elevation using the range-Doppler (RD) model, and then calculate the image coordinates of the corresponding auxiliary image point based on the geographic coordinates; The Doppler frequency inversion module for reconstructing the auxiliary image is used to set the ground line of sight direction of the auxiliary image to be consistent with that of the main image, calculate the ground projection slant angle of the auxiliary image according to its heading azimuth, and inversely calculate the Doppler frequency of the reconstructed auxiliary image based on the flight speed, slant range and altitude of the auxiliary imaging platform.

[0016] As a possible implementation of this embodiment, the azimuth parameter reconstruction module includes: The main image resolution calculation module is used to calculate the pixel resolution of the main image in azimuth using the flight speed of the main imaging platform, and to clarify the spatial scale of the main image in azimuth; The auxiliary image temporal resolution inversion module is used to set the auxiliary image azimuth pixel resolution to be consistent with the main image azimuth temporal resolution, and use the auxiliary image platform flight speed to inversely calculate the reconstructed auxiliary image azimuth temporal resolution.

[0017] As a possible implementation of this embodiment, the resampling module includes: The parameter file generation module is used to modify the auxiliary image parameter file, update the Doppler frequency to the reconstructed frequency, the azimuth time resolution to the reconstructed time resolution, and the range pixel resolution to the set resolution, and generate a reconstructed auxiliary image parameter file; A positioning model building module is used to establish a geometric positioning model of the auxiliary image and the reconstructed auxiliary image based on imaging parameters, and to clarify the spatial mapping relationship between the two; The interpolation sampling module is used to initialize the reconstructed auxiliary image according to the auxiliary image size, realize the mapping from the reconstructed auxiliary image coordinates to the auxiliary image coordinates pixel by pixel through the positioning model, obtain the pixel value by the interpolation algorithm, complete the resampling, and finally obtain the reconstructed auxiliary image aligned with the main image space.

[0018] In a third aspect, an embodiment of the present invention provides an electronic device, comprising a processor, a memory, and a bus, wherein the memory stores machine-readable instructions executable by the processor. When the electronic device is running, the processor communicates with the memory via the bus, and the processor executes the machine-readable instructions to perform the steps of any of the above-mentioned airborne multi-pass InSAR image reconstruction methods.

[0019] In a fourth aspect, an embodiment of the present invention provides a storage medium having a computer program stored thereon, which, when executed by a processor, executes the steps of any of the above-mentioned airborne multi-pass InSAR image reconstruction methods.

[0020] The beneficial effects of the technical solutions of the embodiments of the present invention are as follows: The present invention reconstructs the Doppler frequency of the auxiliary image to make the ground line of sight of the primary and auxiliary images consistent, thus solving the problem of inconsistent spatial directions between the two; by unifying the azimuth and range pixel resolutions of the primary and auxiliary images, the problem of spatial scale mismatch is solved, thereby achieving spatial alignment of the primary and auxiliary images and significantly improving the accuracy of interferometric registration; based on the physical imaging model, the reconstruction parameters are inversely calculated to ensure the accuracy and reliability of the reconstruction process, laying a solid foundation for subsequent high-quality interferometric processing and three-dimensional information inversion.

[0021] This invention spatially aligns primary and secondary airborne multi-pass InSAR images through parameter and image reconstruction, enabling subsequent high-precision interferometric registration and three-dimensional inversion. During SAR image data interferometry processing, this invention reconstructs the secondary images by reconstructing three parameters: Doppler frequency, azimuth temporal resolution, and range pixel resolution. This solves the problem of inconsistent spatial scale and orientation of primary and secondary airborne multi-pass InSAR images, achieving excellent technical results. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a flow chart of a method for reconstructing airborne multi-flyover InSAR images according to an exemplary embodiment; Figure 2 1 is a schematic structural diagram of an airborne multi-flyover InSAR image reconstruction device according to an exemplary embodiment; Figure 3 The figure is a schematic diagram showing a method of inversely reconstructing the Doppler frequency of an auxiliary image based on the ground line of sight direction according to an exemplary embodiment. DETAILED DESCRIPTION

[0023] In order to more clearly illustrate the technical features of the present invention, the present invention is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0024] like Figure 1 As shown, an embodiment of the present invention provides a method for reconstructing airborne multi-flyover InSAR images, comprising the following steps: Step S1, obtaining airborne multi-flyover InSAR primary image data and auxiliary image data; Step S2, calculating the ground sight line direction of the main image according to the imaging parameters of the main image, setting the ground sight line direction of the auxiliary image to be consistent with the main image, and inversely calculating the Doppler frequency of the reconstructed auxiliary image based on the ground sight line direction; Step S3, calculating the azimuth pixel resolution of the primary image based on the azimuth temporal resolution and flight speed of the primary image, setting the azimuth pixel resolution of the secondary image to be consistent with that of the primary image, and inversely calculating the azimuth temporal resolution of the reconstructed secondary image based on the azimuth pixel resolution and the flight speed of the secondary image platform; Step S4, setting the distance pixel resolution of the reconstructed auxiliary image to be consistent with the distance pixel resolution of the main image; Step S5: generating a reconstructed auxiliary image parameter file, establishing a positioning relationship between the auxiliary image and the reconstructed auxiliary image, and resampling the auxiliary image to obtain the reconstructed auxiliary image.

[0025] As a possible implementation of this embodiment, step S2 includes the following steps: Step S21: Select the center point of the main image, obtain its image coordinates, determine the corresponding platform flight speed based on the azimuth image coordinates, and calculate the main image slant angle. This sub-step determines the relevant parameters of the main image center point and calculates the slant angle, providing key angle information for subsequent determination of the ground line of sight direction. Step S22, obtaining the slant distance based on the range image coordinates, calculating the projected length of the slant distance in the orthogonal side view direction, the ground distance, the orthogonal side view direction projected ground distance, and the ground projection slant angle, and combining the main image heading azimuth to determine the main image's ground line of sight direction. This step integrates multiple parameters to accurately obtain the main image's ground observation direction reference; Step S23 uses the range-Doppler (RD) model to calculate the geographic coordinates of the primary image center point in combination with the local average elevation. The image coordinates of the corresponding auxiliary image point are then calculated based on these geographic coordinates. This establishes a geographic coordinate relationship between the primary and auxiliary images, providing a basis for subsequent adjustment of auxiliary image parameters. Step S24 sets the ground line of sight of the auxiliary image to be consistent with that of the primary image. Calculate the ground projection slant angle of the auxiliary image based on its heading azimuth. Combined with the flight speed, slant range, and altitude of the auxiliary imaging platform, inversely calculate the Doppler frequency of the reconstructed auxiliary image. This sub-step ensures that the Doppler frequency of the auxiliary image matches that of the primary image in the ground line of sight, thereby ensuring that the auxiliary image and the primary image are consistent in the ground line of sight, laying the foundation for subsequent spatial alignment.

[0026] As a possible implementation of this embodiment, step S3 includes the following steps: Step S31, using the flight speed of the main imaging platform to calculate the pixel resolution of the main image in azimuth, and to determine the spatial scale of the main image in azimuth; In step S32, the azimuth pixel resolution of the auxiliary image is set to be consistent with the azimuth temporal resolution of the primary image, and the azimuth temporal resolution of the reconstructed auxiliary image is inversely calculated using the flight speed of the auxiliary image platform. Through this step, the azimuth temporal resolution of the auxiliary image is adjusted based on the azimuth pixel resolution of the primary image, achieving the uniformity of the azimuth spatial scale of the two.

[0027] As a possible implementation of this embodiment, step S5 includes the following steps: Step S51: Modify the auxiliary image parameter file by updating the Doppler frequency to the reconstructed frequency, the azimuth time resolution to the reconstructed time resolution, and the range pixel resolution to the set resolution, generating a reconstructed auxiliary image parameter file. This step integrates the previously reconstructed parameters into the parameter file, providing comprehensive and accurate parameter guidance for subsequent resampling. Step S52: establishing a geometric positioning model of the auxiliary image and the reconstructed auxiliary image based on the imaging parameters, and defining the spatial correspondence between each pixel of the auxiliary image and the reconstructed auxiliary image through this model; Step S53, initialize the reconstructed auxiliary image according to the auxiliary image size, realize the mapping from the reconstructed auxiliary image coordinates to the auxiliary image coordinates pixel by pixel through the positioning model, use the interpolation algorithm to obtain the pixel value, complete the resampling, and finally obtain the reconstructed auxiliary image aligned with the main image space. This step resamples the auxiliary image pixel by pixel based on the positioning relationship established previously to generate a reconstructed auxiliary image that meets the spatial alignment requirements.

[0028] As a possible implementation of this embodiment, the specific steps of step S2 are as follows: Step S21: Select the center point of the main image and obtain its image coordinates , according to the azimuth image coordinates Determine the flight speed of the corresponding platform , calculate the main image oblique angle ,in, is the main image Doppler frequency, is the radar wavelength; Step S22: according to the distance to the image coordinates Get slope distance , calculate the projection length of the slant distance in the positive side view direction , ground distance , Projected distance from the front and side view directions and ground projection oblique angle , The main image altitude, combined with the main image heading azimuth , determine the ground sight direction of the main image ,The purpose of this step is to accurately obtain the direction reference of the main image observing the ground; Step S23, according to the SAR image geometric positioning model, the image coordinates of the main image center point are Combined with local average elevation Calculating geographic coordinates , and then according to the geographic coordinates Calculate the image coordinates of the corresponding auxiliary image points , which is used to establish the association between the main and auxiliary images in geographic coordinates. The SAR image geometric positioning model adopts the range-Doppler (RD) model: , in, is the observation equation for range imaging conditions, is the Doppler imaging condition observation equation, is the geographic coordinate, is the image coordinate; Step S24: Set the ground sight line direction of the auxiliary image to be the same as the ground sight line direction of the main image. , according to the auxiliary image heading azimuth Calculate the oblique angle of its ground projection , combined with the auxiliary imaging platform flight speed , slope distance Ji Hanggao , inversely calculate the Doppler frequency of the reconstructed auxiliary image , where the auxiliary image oblique angle , the slant distance is projected in the direction of the front side view , the projected distance from the front and side view directions , auxiliary image point distance , in order to ensure that the auxiliary image and the main image are consistent in the ground line of sight direction, laying the foundation for subsequent spatial alignment.

[0029] As a possible implementation of this embodiment, the specific steps of step S3 are as follows: Calculate the pixel resolution of the main image in azimuth: ,in is the flight speed of the main imaging platform, The temporal resolution of the main image in azimuth direction. This calculation can clearly define the spatial scale of the main image in azimuth direction. Set the auxiliary image azimuth pixel resolution to be consistent with the main image azimuth temporal resolution, then the auxiliary image azimuth pixel resolution is , inversely calculate the azimuth and temporal resolution of the reconstructed auxiliary image , The flight speed of the auxiliary imaging platform.

[0030] As a possible implementation of this embodiment, the step S4 is specifically to set the distance pixel resolution of the reconstructed auxiliary image to Pixel resolution in the distance from the main image Consistent, that is The setting is simple and direct, ensuring the consistency of the distance spatial scale of the main and auxiliary images, without the need for complex calculation processes, and intuitively and effectively improving the image matching foundation.

[0031] As a possible implementation of this embodiment, step S5 specifically includes the following steps: Set the Doppler frequency in the auxiliary image parameter file , azimuth time resolution and range pixel resolution Modified to the reconstructed Doppler frequency , azimuth time resolution and range pixel resolution , generate reconstructed auxiliary image parameter file; Establishing a geometric positioning model of the auxiliary image and the reconstructed auxiliary image according to the imaging parameters; Create a reconstructed auxiliary image according to the size of the auxiliary image; then use the image coordinates of the reconstructed auxiliary image points Departure, combined with the local average altitude , calculate geographic coordinates based on the geometric positioning model ; Then by geographic coordinates and local average elevation Calculate the image coordinates of the corresponding auxiliary image points according to the geometric positioning model , according to the image coordinates Interpolate and sample the auxiliary image to obtain pixel values, and fill them into the reconstructed auxiliary image. Image point position; in this way, the reconstructed auxiliary image is positioned and resampled pixel by pixel to obtain the final reconstructed auxiliary image.

[0032] like Figure 2 As shown, an embodiment of the present invention provides an airborne multi-flyover InSAR image reconstruction device, comprising: Data acquisition module, used to obtain airborne multi-pass InSAR main image data and auxiliary image data; A Doppler frequency reconstruction module is used to calculate the ground sight line direction of the main image based on the imaging parameters of the main image, set the ground sight line direction of the auxiliary image to be consistent with the main image, and reversely calculate the Doppler frequency of the reconstructed auxiliary image based on the ground sight line direction; The azimuth parameter reconstruction module is used to calculate the azimuth pixel resolution of the main image based on the azimuth temporal resolution and flight speed of the main image, set the azimuth pixel resolution of the auxiliary image to be consistent with the main image, and reversely calculate the azimuth temporal resolution of the reconstructed auxiliary image based on the azimuth pixel resolution and the flight speed of the auxiliary imaging platform; The distance parameter setting module is used to set the distance pixel resolution of the reconstructed auxiliary image to be consistent with the distance pixel resolution of the main image; The resampling module is used to generate a reconstructed auxiliary image parameter file, establish a positioning relationship between the auxiliary image and the reconstructed auxiliary image, and resample the auxiliary image to obtain the reconstructed auxiliary image.

[0033] As a possible implementation of this embodiment, the Doppler frequency reconstruction module includes: The main image parameter calculation module is used to select the center point of the main image, obtain its image coordinates, determine the corresponding platform flight speed based on the azimuth image coordinates, and calculate the main image oblique angle; The main image ground sight direction determination module is used to obtain the slant distance based on the distance to image coordinates, calculate the projected length of the slant distance in the orthographic side view direction, the ground distance, the orthographic side view direction projected ground distance and the ground projection slant angle, and determine the main image ground sight direction in combination with the main image heading azimuth; The auxiliary image coordinate calculation module is used to calculate the geographic coordinates of the main image center point by combining the image coordinates of the local average elevation using the range-Doppler (RD) model, and then calculate the image coordinates of the corresponding auxiliary image point based on the geographic coordinates; The Doppler frequency inversion module for reconstructing the auxiliary image is used to set the ground sight line direction of the auxiliary image to be consistent with the main image, calculate the ground projection slant angle of the auxiliary image according to its heading azimuth, and inversely calculate the Doppler frequency of the reconstructed auxiliary image based on the flight speed, slant range and altitude of the auxiliary imaging platform.

[0034] As a possible implementation of this embodiment, the azimuth parameter reconstruction module includes: The main image resolution calculation module is used to calculate the pixel resolution of the main image in azimuth using the flight speed of the main imaging platform, and to clarify the spatial scale of the main image in azimuth; The auxiliary image temporal resolution inversion module is used to set the auxiliary image azimuth pixel resolution to be consistent with the main image azimuth temporal resolution, and use the auxiliary image platform flight speed to inversely calculate the reconstructed auxiliary image azimuth temporal resolution.

[0035] As a possible implementation of this embodiment, the resampling module includes: The parameter file generation module is used to modify the auxiliary image parameter file, update the Doppler frequency to the reconstructed frequency, the azimuth time resolution to the reconstructed time resolution, and the range pixel resolution to the set resolution, and generate a reconstructed auxiliary image parameter file; A positioning model building module is used to establish a geometric positioning model of the auxiliary image and the reconstructed auxiliary image based on imaging parameters, and to clarify the spatial mapping relationship between the two; The interpolation sampling module is used to initialize the reconstructed auxiliary image according to the auxiliary image size, realize the mapping from the reconstructed auxiliary image coordinates to the auxiliary image coordinates pixel by pixel through the positioning model, obtain the pixel value by the interpolation algorithm, complete the resampling, and finally obtain the reconstructed auxiliary image aligned with the main image space.

[0036] The specific process of reconstructing airborne multi-flyover InSAR images using the technical solution of the present invention is as follows.

[0037] Step 1: Acquire airborne multi-flyover InSAR primary and auxiliary image data.

[0038] Acquire multiple airborne InSAR data for a specific area, including raw data and imaging parameters (radar wavelength, altitude, flight speed, Doppler frequency, azimuth / range resolution, etc.) for both primary and secondary images. This step provides the foundational data for the entire reconstruction process and is a prerequisite for subsequent processing. Different flyover image data carries information about the target area from different perspectives and times, and this data is required for subsequent analysis and processing to achieve image reconstruction.

[0039] Step 2: Calculate the ground sight line direction of the main image based on the imaging parameters of the main image, set the ground sight line direction of the auxiliary image to be consistent with the main image, and inversely calculate the Doppler frequency of the reconstructed auxiliary image based on the ground sight line direction.

[0040] Take the center point of the main image, its image coordinates , according to the azimuth image coordinates Get the corresponding platform flight speed , then calculate the oblique angle : , in, is the main image Doppler frequency, is the radar wavelength; According to the distance to the image coordinates Get slope distance , calculate the projection length of the slant distance in the positive side view direction ; Calculate ground distance , Main image altitude; calculate the projected ground distance in the positive and side view directions ; Calculate the ground projection oblique angle Calculate the ground sight direction of the main image , is the heading azimuth of the main image; According to the SAR image geometric positioning model, the image coordinates of the center point of the main image Combined with local average elevation , calculate geographic coordinates ; Then according to the geometric positioning model, and Calculate the image coordinates of the auxiliary image point ; The range-Doppler (RD) model is used as the geometric positioning model, and the positioning model equation can be expressed as: , in, is the observation equation for range imaging conditions, is the Doppler imaging condition observation equation, is the geographic coordinate, is the image coordinate; Set the auxiliary image ground sight direction to be consistent with the main image , calculate the ground projection oblique angle according to the ground line of sight direction , The heading azimuth of the auxiliary image; according to the azimuth image coordinates Get the platform speed corresponding to the auxiliary image , according to the distance to the image coordinates Get slope distance , calculate the auxiliary image point distance , The auxiliary image altitude; calculate the projection ground distance in the positive and side view directions ; Calculate the projection length of the slant distance in the positive side view direction , calculate the auxiliary image oblique angle , and finally inversely calculate the Doppler frequency of the reconstructed auxiliary image ,like Figure 3 As shown; The ground line of sight direction of the main image determines the radar's observation angle of the ground. By setting the auxiliary image to be the same, the two can be unified in observation direction; inverse Doppler frequency is the key parameter for adjusting the auxiliary image to match the observation characteristics of the main image, providing directional consistency for subsequent interference processing.

[0041] Step 3: Calculate the azimuth pixel resolution of the main image based on the azimuth temporal resolution and flight speed of the main image, set the azimuth pixel resolution of the auxiliary image to be consistent with the azimuth pixel resolution of the main image, and inversely calculate the azimuth temporal resolution of the reconstructed auxiliary image based on the azimuth pixel resolution and the flight speed of the auxiliary image platform.

[0042] The flight speed of the main imaging platform calculated using step 2 , calculate the pixel resolution of the main image in the azimuth direction , The temporal resolution of the main image in azimuth direction; Set the pixel resolution of the auxiliary image to be the same as that of the main image. , using the auxiliary imaging platform flight speed calculated in step 2 , inversely calculate the azimuth time resolution of the reconstructed auxiliary image ; Step 3 unifies the spatial scales of the primary and secondary images in azimuth, ensuring that the actual ground distances represented by the azimuth pixels of the two images are consistent, which helps to improve the accuracy of image matching and interferometric processing.

[0043] Step 4: Set the distance pixel resolution of the reconstructed auxiliary image to be consistent with the distance pixel resolution of the main image.

[0044] Set the distance pixel resolution of the reconstructed auxiliary image and main image distance pixel resolution Consistent, that is This setting ensures that the spatial scale of the primary and secondary images is unified in the distance dimension, making the images comparable in the distance dimension and laying the foundation for subsequent image fusion and interference operations.

[0045] Step 5: Generate a reconstructed auxiliary image parameter file, establish a positioning relationship between the auxiliary image and the reconstructed auxiliary image, resample the auxiliary image, and obtain the reconstructed auxiliary image.

[0046] Modify the Doppler frequency in the auxiliary image parameter file , azimuth time resolution and range pixel resolution , modified to the reconstructed 、 Range pixel resolution , generate the reconstructed auxiliary image parameter file. Establish the geometric positioning model of the auxiliary image and the reconstructed auxiliary image according to the imaging parameters; Create a reconstructed auxiliary image according to the auxiliary image size; then use the image coordinates of the reconstructed auxiliary image points Departure, combined with the local average altitude , calculate geographic coordinates based on the geometric positioning model ; then by and Calculate the image coordinates of the corresponding auxiliary image points according to the geometric positioning model , according to the image coordinates Interpolate and sample the auxiliary image to obtain pixel values, and fill them into the reconstructed auxiliary image. Image point position; thus, the reconstructed auxiliary image is positioned and resampled pixel by pixel to obtain the final reconstructed auxiliary image; The reconstructed auxiliary image parameter file integrates the parameters obtained in the previous steps to provide a basis for image resampling; establishing a positioning relationship clarifies the correspondence between the new and old images; and the resampling process resamples the auxiliary image according to the new parameters to generate a reconstructed auxiliary image that matches the main image in both spatial scale and orientation.

[0047] An embodiment of the present invention provides an electronic device, including a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the electronic device is running, the processor and the memory communicate via the bus, and the processor executes the machine-readable instructions to perform the steps of any of the above-mentioned airborne multi-pass InSAR image reconstruction methods.

[0048] Specifically, the above-mentioned memory and processor can be general-purpose memory and processor, which are not specifically limited here. When the processor runs the computer program stored in the memory, the above-mentioned airborne multi-flyover InSAR image reconstruction method can be executed.

[0049] Corresponding to the method for starting the above-mentioned application, an embodiment of the present invention further provides a storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the above-mentioned method for reconstructing any airborne multi-pass InSAR image are executed.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for reconstructing airborne multi-flyover InSAR images, characterized in that: The steps include: Step S1, obtaining airborne multi-flyover InSAR primary image data and auxiliary image data; Step S2, calculating the ground sight line direction of the main image according to the imaging parameters of the main image, setting the ground sight line direction of the auxiliary image to be consistent with the main image, and inversely calculating the Doppler frequency of the reconstructed auxiliary image based on the ground sight line direction; Step S3, calculating the azimuth pixel resolution of the primary image based on the azimuth temporal resolution and flight speed of the primary image, setting the azimuth pixel resolution of the secondary image to be consistent with the azimuth pixel resolution of the primary image, and inversely calculating the azimuth temporal resolution of the reconstructed secondary image based on the azimuth pixel resolution and the flight speed of the secondary imaging platform; Step S4, setting the distance pixel resolution of the reconstructed auxiliary image to be consistent with the distance pixel resolution of the main image; Step S5: generating a reconstructed auxiliary image parameter file, establishing a positioning relationship between the auxiliary image and the reconstructed auxiliary image, and resampling the auxiliary image to obtain the reconstructed auxiliary image.

2. The method for reconstructing airborne multi-flyover InSAR images according to claim 1, characterized in that: The step S2 comprises the following steps: Step S21: Select the center point of the main image, obtain its image coordinates, determine the corresponding platform flight speed based on the azimuth image coordinates, and calculate the main image oblique angle; Step S22, obtaining the slant distance according to the distance image coordinates, calculating the projected length of the slant distance in the orthogonal side view direction, the ground distance, the orthogonal side view direction projected ground distance, and the ground projection slant angle, and determining the ground line of sight direction of the main image in combination with the heading azimuth of the main image; Step S23, using the range-Doppler model, the geographical coordinates are calculated from the image coordinates of the center point of the main image combined with the local average elevation, and then the image coordinates of the corresponding auxiliary image point are calculated based on the geographical coordinates; Step S24 , setting the ground sight line direction of the auxiliary image to be consistent with the ground sight line direction of the main image, calculating the ground projection slant angle of the auxiliary image based on its heading azimuth, and inversely calculating the Doppler frequency of the reconstructed auxiliary image based on the auxiliary image platform's flight speed, slant range, and altitude.

3. The method for reconstructing airborne multi-flyover InSAR images according to claim 1, characterized in that: The step S3 comprises the following steps: Step S31, using the flight speed of the main imaging platform to calculate the pixel resolution of the main image in azimuth, and to determine the spatial scale of the main image in azimuth; Step S32 , setting the auxiliary image azimuth pixel resolution and the main image azimuth temporal resolution to be consistent, and using the auxiliary image platform flight speed to inversely calculate the auxiliary image azimuth temporal resolution after reconstruction.

4. The method for reconstructing airborne multi-flyover InSAR images according to claim 1, characterized in that: The step S5 comprises the following steps: Step S51, modifying the auxiliary image parameter file, updating the Doppler frequency to the reconstructed frequency, the azimuth time resolution to the reconstructed time resolution, and the range pixel resolution to the set resolution, to generate a reconstructed auxiliary image parameter file; Step S52: establishing a geometric positioning model of the auxiliary image and the reconstructed auxiliary image based on the imaging parameters, and clarifying the spatial mapping relationship between the two; In step S53, the reconstructed auxiliary image is initialized according to the auxiliary image size, and the mapping from the reconstructed auxiliary image coordinates to the auxiliary image coordinates is realized pixel by pixel through the positioning model. The pixel values ​​are obtained by the interpolation algorithm, and the resampling is completed to finally obtain the reconstructed auxiliary image aligned with the main image space.

5. An airborne multi-flyover InSAR image reconstruction device, characterized in that: include: Data acquisition module, used to obtain airborne multi-pass InSAR main image data and auxiliary image data; A Doppler frequency reconstruction module is used to calculate the ground sight line direction of the main image based on the imaging parameters of the main image, set the ground sight line direction of the auxiliary image to be consistent with the ground sight line direction of the main image, and reversely calculate the Doppler frequency of the reconstructed auxiliary image based on the ground sight line direction; The azimuth parameter reconstruction module is used to calculate the azimuth pixel resolution of the main image based on the azimuth temporal resolution and flight speed of the main image, set the azimuth pixel resolution of the auxiliary image to be consistent with the azimuth pixel resolution of the main image, and reversely calculate the azimuth temporal resolution of the reconstructed auxiliary image based on the azimuth pixel resolution and the flight speed of the auxiliary imaging platform; The distance parameter setting module is used to set the distance pixel resolution of the reconstructed auxiliary image to be consistent with the distance pixel resolution of the main image; The resampling module is used to generate a reconstructed auxiliary image parameter file, establish a positioning relationship between the auxiliary image and the reconstructed auxiliary image, and resample the auxiliary image to obtain the reconstructed auxiliary image.

6. The airborne multi-flyover InSAR image reconstruction device according to claim 5, characterized in that: The Doppler frequency reconstruction module includes: The main image parameter calculation module is used to select the center point of the main image, obtain its image coordinates, determine the corresponding platform flight speed based on the azimuth image coordinates, and calculate the main image oblique angle; The main image ground sight direction determination module is used to obtain the slant distance based on the distance to image coordinates, calculate the projected length of the slant distance in the orthographic side view direction, the ground distance, the orthographic side view direction projected ground distance and the ground projection slant angle, and determine the main image ground sight direction in combination with the main image heading azimuth; The auxiliary image coordinate calculation module is used to calculate the geographic coordinates of the main image center point by combining the image coordinates of the local average elevation using the range-Doppler model, and then calculate the image coordinates of the corresponding auxiliary image point based on the geographic coordinates; The Doppler frequency inversion module for reconstructing the auxiliary image is used to set the ground line of sight direction of the auxiliary image to be consistent with that of the main image, calculate the ground projection slant angle of the auxiliary image according to its heading azimuth, and inversely calculate the Doppler frequency of the reconstructed auxiliary image based on the flight speed, slant range and altitude of the auxiliary imaging platform.

7. The airborne multi-flyover InSAR image reconstruction device according to claim 5, characterized in that: The azimuth parameter reconstruction module includes: The main image resolution calculation module is used to calculate the pixel resolution of the main image in azimuth using the flight speed of the main imaging platform, and to clarify the spatial scale of the main image in azimuth; The auxiliary image temporal resolution inversion module is used to set the auxiliary image azimuth pixel resolution to be consistent with the main image azimuth temporal resolution, and use the auxiliary image platform flight speed to inversely calculate the reconstructed auxiliary image azimuth temporal resolution.

8. The airborne multi-flyover InSAR image reconstruction device according to claim 5, characterized in that: The resampling module comprises: The parameter file generation module is used to modify the auxiliary image parameter file, update the Doppler frequency to the reconstructed frequency, the azimuth time resolution to the reconstructed time resolution, and the range pixel resolution to the set resolution, and generate a reconstructed auxiliary image parameter file; A positioning model building module is used to establish a geometric positioning model of the auxiliary image and the reconstructed auxiliary image based on imaging parameters, and to clarify the spatial mapping relationship between the two; The interpolation sampling module is used to initialize the reconstructed auxiliary image according to the auxiliary image size, realize the mapping from the reconstructed auxiliary image coordinates to the auxiliary image coordinates pixel by pixel through the positioning model, obtain the pixel value by the interpolation algorithm, complete the resampling, and finally obtain the reconstructed auxiliary image aligned with the main image space.

9. An electronic device, characterized in that: The electronic device comprises a processor, a memory and a bus, wherein the memory stores machine-readable instructions executable by the processor. When the electronic device is running, the processor and the memory communicate via the bus, and the processor executes the machine-readable instructions to perform the steps of the method for reconstructing airborne multiple-flyover InSAR images as described in any one of claims 1 to 4.

10. A storage medium, characterized in that: The storage medium stores a computer program, which, when executed by a processor, executes the steps of the method for reconstructing airborne multi-flyover InSAR images according to any one of claims 1 to 4.

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