Three-dimensional under-ice topography extraction method based on multi-channel ice radar data tomography processing

Abstract

The disclosure provides a three-dimensional subglacial topography extraction method, device and equipment based on multi-channel ice radar data tomography processing and a storage medium. The method comprises the following steps: based on the ray tracing technology, a forward model database two-dimensional table is established by using Snell's law; a two-dimensional tomography output matrix corresponding to the target along the track position coordinates is established according to the multi-channel frequency wavenumber domain migration processing result; the distance and the incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value range are determined according to the two-dimensional tomography output matrix and the normalized spatial frequency; the distance and the incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value range are traversed based on the forward model database two-dimensional table to obtain the two-dimensional subglacial topography across the track direction at the target along the track position coordinates; and the three-dimensional subglacial topography is obtained by traversing the along-track position coordinates based on the two-dimensional subglacial topography across the track direction at the target along the track position coordinates.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of polar ice radar data processing, and particularly relates to a three-dimensional subglacial topography extraction method, device, equipment, medium and program product based on multi-channel ice radar data tomographic processing. BACKGROUND

[0002] The establishment of an ice sheet model is of great significance for understanding global climate change and predicting the rise of sea level, and the ice sheet thickness and subglacial topography provide important reference value for studying the stability of the ice sheet and predicting the evolution of the ice sheet. At present, most of the ice sheet models used to estimate the rise of sea level ignore the dynamic process related to the rapid change observed in Greenland and Antarctica, so it is crucial to develop the next generation of more accurate ice sheet models.

[0003] In the related art, the traditional ice radar data processing algorithm based on f-k (frequency-wavenumber domain migration processing) migration can only measure the two-dimensional subglacial topography under the travel trajectory line, and geographic interpolation is needed to obtain the three-dimensional subglacial topography, but the interpolation accuracy will affect the accuracy of the final three-dimensional topographic map, especially in the area with large ice flow speed, the geographic interpolation scheme will cause the problems of large topographic interpolation error and low cross-track resolution. SUMMARY

[0004] In view of the above problems, the present disclosure provides a three-dimensional subglacial topography extraction method, device, equipment, medium and program product based on multi-channel ice radar data tomographic processing.

[0005] According to a first aspect of the present disclosure, a three-dimensional subglacial topography extraction method based on multi-channel ice radar data tomographic processing is provided, comprising:

[0006] Based on the ray tracing technology, a forward model database two-dimensional table is established using Snell's law, wherein the forward model database two-dimensional table is inputted with ice sheet depth and incident angle and outputted with distance and cross-track position coordinates, and the incident angle represents the angle of incidence from the air to the ice sheet;

[0007] According to the multi-channel frequency-wavenumber domain migration processing result, a two-dimensional tomographic output matrix corresponding to the target along-track position coordinates is established, wherein the multi-channel frequency-wavenumber domain migration processing result is determined according to the target along-track position coordinates and target distance;

[0008] According to the two-dimensional tomographic output matrix and the normalized spatial frequency, the distance and the incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the value range of the normalized spatial frequency are determined;

[0009] Based on the above two-dimensional table of the forward model database, the distance and the incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the above normalized spatial frequency value range are traversed to obtain a two-dimensional cross-track under-ice topography at the target along-track position coordinate;

[0010] Based on the above two-dimensional cross-track under-ice topography at the target along-track position coordinate, the along-track position coordinate is traversed to obtain a three-dimensional under-ice topography.

[0011] According to an embodiment of the present disclosure, the above ray tracing technology is used to establish a two-dimensional table of a forward model database based on Snell's law, including:

[0012] Based on the above ray tracing technology, the above Snell's law is used to determine the refraction angle of the i-th layer in the ice cover according to the refractive index of air and the incident angle, where i is an integer greater than or equal to 1;

[0013] According to the ice layer depth, the refraction angle of the i-th layer, and the dielectric constant corresponding to the i-th layer, the distance and the cross-track position coordinate are determined;

[0014] According to the incident angle, the ice cover depth, the distance, and the cross-track position coordinate, the above two-dimensional table of the forward model database is established.

[0015] According to an embodiment of the present disclosure, the above two-dimensional tomographic output matrix corresponding to the target along-track position coordinate is established according to the multi-channel frequency-wavenumber domain migration processing result, including:

[0016] According to the target distance, the multi-channel ice radar echo signal data of all along-track positions is subjected to distance direction pulse compression processing and frequency-wavenumber domain migration processing to obtain an along-track multi-channel frequency-wavenumber domain migration processing result;

[0017] According to the target along-track position coordinate, a plurality of along-track positions with a fixed interval length and centered on the target along-track position coordinate are continuously set;

[0018] According to the above along-track multi-channel frequency-wavenumber domain migration processing result, the above autocorrelation matrix corresponding to the target along-track position coordinate and the target distance is constructed;

[0019] According to the above autocorrelation matrix, a spatial spectrum function corresponding to the target along-track position coordinate and the target distance is constructed, wherein a row in the above two-dimensional tomographic output matrix is constituted according to the spatial spectrum function corresponding to the target distance;

[0020] Based on the spatial spectrum function corresponding to the target distance, the distance is traversed to establish the two-dimensional tomography output matrix corresponding to the target along-track position coordinate.

[0021] According to an embodiment of the present disclosure, the spatial spectrum function corresponding to the target along-track position and the target distance is constructed according to the autocorrelation matrix, comprising:

[0022] The autocorrelation matrix is subjected to eigenvalue decomposition to obtain a noise eigenvalue and a feature vector corresponding to the noise eigenvalue;

[0023] According to the feature vector corresponding to the noise eigenvalue, a noise subspace is constructed;

[0024] According to the orthogonality between the noise subspace and the directional vector of the normalized spatial frequency, the spatial spectrum function corresponding to the target along-track position coordinate and the target distance is constructed.

[0025] According to an embodiment of the present disclosure, the distance and the incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain are determined according to the two-dimensional tomography output matrix and the normalized spatial frequency, comprising:

[0026] Based on the two-dimensional tomography output matrix, the distance corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain is determined; and

[0027] According to the spatial wave number, the incident angle corresponding to the value in the normalized spatial frequency value domain is determined, wherein the spatial wave number is obtained according to the normalized spatial frequency.

[0028] According to an embodiment of the present disclosure, the distance and the incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain are traversed based on the forward model database two-dimensional table to obtain the two-dimensional cross-track underwater terrain at the target along-track position coordinate.

[0029] The distance and the incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain are traversed to retrieve the corresponding depth and cross-track position coordinate from the forward model database two-dimensional table; and

[0030] According to the corresponding depth and the cross-track position coordinate, the two-dimensional cross-track underwater terrain at the target along-track position coordinate is obtained.

[0031] According to an embodiment of the present disclosure, the two-dimensional cross-track underwater terrain at the target along-track position coordinate is traversed along the along-track position coordinate to obtain a three-dimensional underwater terrain.

[0032] based on the two-dimensional subglacial topography across the along-track position coordinate at the target along-track position coordinate, traverse the along-track position coordinate to obtain the two-dimensional subglacial topography across the along-track position coordinate at all the target along-track position coordinates; and

[0033] obtain the three-dimensional subglacial topography according to the two-dimensional subglacial topography across the along-track position coordinate at all the target along-track position coordinates.

[0034] A second aspect of the present disclosure provides a three-dimensional subglacial topography extraction device based on multi-channel ice radar data tomographic processing, comprising a first establishing module, a second establishing module, a determining module, a first obtaining module and a second obtaining module. The first establishing module is configured to establish a forward model database two-dimensional table based on the ray tracing technique and Snell's law, wherein the forward model database two-dimensional table takes the ice cover depth and the incident angle as input and takes the distance and the across-track position coordinate as output, and the incident angle represents the angle of incidence from the air to the ice cover. The second establishing module is configured to establish a two-dimensional tomographic output matrix corresponding to a target along-track position coordinate according to a multi-channel frequency wavenumber domain migration processing result, wherein the multi-channel frequency wavenumber domain migration processing result is determined according to the target along-track position coordinate and a target distance. The determining module is configured to determine the distance and the incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain according to the two-dimensional tomographic output matrix and the normalized spatial frequency. The first obtaining module is configured to traverse the distance and the incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain based on the forward model database two-dimensional table to obtain the two-dimensional subglacial topography across the along-track position coordinate at the target along-track position coordinate. The second obtaining module is configured to traverse the along-track position coordinate based on the two-dimensional subglacial topography across the along-track position coordinate at the target along-track position coordinate to obtain a three-dimensional subglacial topography.

[0035] A third aspect of the present disclosure provides an electronic device, comprising: one or more processors; a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors execute the above method.

[0036] A fourth aspect of the present disclosure further provides a computer-readable storage medium having stored executable instructions, which, when executed by a processor, cause the processor to execute the above method.

[0037] A fifth aspect of the present disclosure further provides a computer program product comprising a computer program, which, when executed by a processor, implements the above method.

[0038] The three-dimensional ice-underground terrain extraction method, device, equipment, medium and program product based on multi-channel ice radar data tomographic processing provided according to the present disclosure, according to the multi-channel radar, can obtain the two-dimensional data across the track direction, and according to the two-dimensional tomographic output matrix corresponding to the target along the track direction coordinate established according to the multi-channel frequency wavenumber domain offset processing result, the distance and the incidence angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain are determined, and then the obtained distance and incidence angle are traversed to obtain the corresponding ice cover depth and the cross-track direction position coordinate from the two-dimensional table of the forward model database, so that the two-dimensional ice-underground terrain across the track direction at the target along the track direction coordinate can be obtained, and finally the three-dimensional ice-underground terrain can be obtained by traversing the along-track direction coordinate, so that the ice cover can be detected in a high-resolution, high-precision and strip-shaped manner. BRIEF DESCRIPTION OF DRAWINGS

[0039] The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments of the present disclosure taken in conjunction with the accompanying drawings, in which:

[0040] Figure 1 An application scenario diagram of the three-dimensional ice-underground terrain extraction method, device, equipment, medium and program product based on multi-channel ice radar data tomographic processing according to an embodiment of the present disclosure is schematically shown;

[0041] Figure 2 A flowchart of the three-dimensional ice-underground terrain extraction method based on multi-channel ice radar data tomographic processing according to an embodiment of the present disclosure is schematically shown;

[0042] Figure 3 A diagram showing the relationship between the real part of the dielectric constant and the depth according to an embodiment of the present disclosure is schematically shown;

[0043] Figure 4 A flowchart of establishing the two-dimensional table of the forward model database according to an embodiment of the present disclosure is schematically shown;

[0044] Figure 5 A diagram showing the propagation path of the electromagnetic wave in the multi-layer medium according to the Snell's law applied to the boundary between the adjacent layers in the ice cover based on the ray tracing technology according to an embodiment of the present disclosure is schematically shown;

[0045] Figure 6 A flowchart of establishing the two-dimensional tomographic output matrix corresponding to the target along the track direction coordinate according to an embodiment of the present disclosure is schematically shown;

[0046] Figure 7 A flowchart of constructing the spatial spectrum function corresponding to the target along the track direction coordinate and the target distance according to an embodiment of the present disclosure is schematically shown;

[0047] Figure 8A schematic diagram of the application of the MUSIC algorithm to the two-dimensional tomography output matrix obtained from real data is shown schematically according to an embodiment of the present disclosure;

[0048] Figure 9 A schematic diagram of the geometric relationship between the beam and the electromagnetic wave transmission angle of the ice surface is shown schematically according to an embodiment of the present disclosure;

[0049] Figure 10 A flowchart of obtaining a three-dimensional sub-ice terrain is shown schematically according to an embodiment of the present disclosure;

[0050] Figure 11 A schematic diagram of a point target imaging simulation model suitable for use is shown schematically according to an embodiment of the present disclosure;

[0051] Figure 12 A schematic diagram of the three-dimensional tomography point target simulation effect is shown schematically according to an embodiment of the present disclosure;

[0052] Figure 13 A schematic diagram of the three-dimensional sub-ice terrain result obtained by processing multi-channel ice radar data is shown schematically according to an embodiment of the present disclosure;

[0053] Figure 14 A structural block diagram of a three-dimensional sub-ice terrain extraction device based on multi-channel ice radar data tomography processing is shown schematically according to an embodiment of the present disclosure; and

[0054] Figure 15 A block diagram of an electronic device suitable for implementing a three-dimensional sub-ice terrain extraction method based on multi-channel ice radar data tomography processing is shown schematically according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0055] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood, however, that the description is merely exemplary and is not intended to limit the scope of the present disclosure. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present disclosure. However, it would be apparent to those skilled in the art that one or more embodiments can be practiced without these specific details. In other instances, well-known structures and techniques have been omitted in order to avoid obscuring the concepts of the present disclosure.

[0056] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present disclosure. As used herein, the term "includes" and "comprising" and the like means the inclusion of the stated features, steps, operations, and / or components, but not the exclusion of one or more other features, steps, operations, or components.

[0057] All terms used herein, including technical and scientific terms, have the meanings commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the use of any terms herein should not be interpreted as excluding the use of other terms that have the same or similar meanings unless otherwise defined.

[0058] In the case of using expressions similar to "at least one of A, B, and C, etc.", it should be generally interpreted that the meaning of the expression is at least one of A, B, and C (for example, "a system having at least one of A, B, and C" should include but not be limited to a system having A alone, a system having B alone, a system having C alone, a system having both A and B, a system having both A and C, a system having both B and C, and / or a system having A, B, and C, etc.).

[0059] In the technical solutions of the present disclosure, the collection, storage, use, processing, transmission, provision, disclosure, and application of user personal information comply with relevant laws and regulations, necessary security measures are taken, and do not violate public order and good customs.

[0060] In the technical solutions of the present disclosure, the acquisition, collection, storage, use, processing, transmission, provision, disclosure, and application of data comply with relevant laws and regulations, necessary security measures are taken, and do not violate public order and good customs.

[0061] It is found in the implementation of the present disclosure that, in actual measurement, the mounting platform of the ice radar is usually an airborne platform and a vehicle-mounted platform, wherein the vehicle-mounted multi-channel ice radar with high-precision detection and positioning advantages is suitable for small-range and complex ice-underground structure conditions, can perform strip measurement on the information related to the ice cover surface and the ice cover bottom to obtain a more real ice cover model, and at the same time, the multi-channel ice radar is also helpful to suppress cross-track clutter, improve radar sensitivity, and increase the gain of the transmitting and receiving antennas. At present, the detection and processing of the ice-underground terrain based on the multi-channel vehicle-mounted ice radar are relatively insufficient. In the related art, the traditional ice radar data processing algorithm based on f-k migration can only measure the two-dimensional ice-underground terrain under the running track, and needs geographic interpolation to obtain the three-dimensional ice-underground terrain, but the geographic interpolation scheme causes the problems of large terrain interpolation error and low cross-track resolution.

[0062] To this end, the embodiment of the present disclosure provides a three-dimensional subglacial topography extraction method based on multi-channel ice radar data tomographic processing, comprising: based on a ray tracing technique, a Snell's law is used to establish a forward model database two-dimensional table, wherein the forward model database two-dimensional table is inputted with ice cover depth and incident angle, and outputted with distance and cross-track position coordinates, and the incident angle represents the angle of incidence from the air to the ice cover; a two-dimensional tomographic output matrix corresponding to the target along-track position coordinates is established according to a multi-channel frequency-wavenumber domain migration processing result, wherein the multi-channel frequency-wavenumber domain migration processing result is determined according to the target along-track position coordinates and the target distance; the distance and the incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain are determined according to the two-dimensional tomographic output matrix and the normalized spatial frequency; based on the forward model database two-dimensional table, the distance and the incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain are traversed to obtain the cross-track two-dimensional subglacial topography at the target along-track position coordinates; and based on the cross-track two-dimensional subglacial topography at the target along-track position coordinates, the along-track position coordinates are traversed to obtain the three-dimensional subglacial topography.

[0063] Figure 1 An application scenario diagram of the three-dimensional subglacial topography extraction based on multi-channel ice radar data tomographic processing according to the embodiment of the present disclosure is schematically shown.

[0064] As shown in Figure 1 The application scenario 100 according to the embodiment can include a first terminal device 101, a second terminal device 102, a third terminal device 103, a network 104 and a server 105. The network 104 is a medium for providing a communication link between the first terminal device 101, the second terminal device 102, the third terminal device 103 and the server 105. The network 104 can include various connection types, such as wired, wireless communication links or optical fiber cables, etc.

[0065] A user can use the first terminal device 101, the second terminal device 102, the third terminal device 103 to interact with the server 105 through the network 104 to receive or send messages, etc. Various communication client applications can be installed on the first terminal device 101, the second terminal device 102, the third terminal device 103, such as shopping applications, web browser applications, search applications, instant messaging tools, email clients, social platform software, etc. (only as examples).

[0066] The first terminal device 101, the second terminal device 102, the third terminal device 103 can be various electronic devices with display screens and supporting web browsing, including but not limited to smart phones, tablet computers, laptop computers and desktop computers, etc.

[0067] Server 105 can be a server that provides various services, such as a backend management server that supports websites browsed by users using the first terminal device 101, the second terminal device 102, and the third terminal device 103 (this is just an example). The backend management server can analyze and process data such as received user requests, and feed back the processing results (such as web pages, information, or data obtained or generated according to user requests) to the terminal devices.

[0068] For example, server 105 can use ray tracing technology and Snell's law to establish a two-dimensional table of the forward model database. Based on the multi-channel frequency wavenumber domain offset processing results, a two-dimensional tomographic output matrix corresponding to the target's position coordinates along the trajectory can be established. Then, based on the two-dimensional tomographic output matrix and the normalized spatial frequency, the distance and incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency domain can be determined. Based on the two-dimensional table of the forward model database, the distance and incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency domain can be traversed to obtain the two-dimensional sub-ice terrain across the trajectory at the target's position coordinates along the trajectory. Finally, based on the two-dimensional sub-ice terrain across the trajectory at the target's position coordinates along the trajectory, the position coordinates along the trajectory can be traversed to obtain the three-dimensional sub-ice terrain.

[0069] It should be noted that the three-dimensional sub-ice terrain extraction method based on multi-channel ice radar data tomography provided in this embodiment can generally be executed by server 105. Correspondingly, the three-dimensional sub-ice terrain extraction device based on multi-channel ice radar data tomography provided in this embodiment can generally be located in server 105. The three-dimensional sub-ice terrain extraction method based on multi-channel ice radar data tomography provided in this embodiment can also be executed by a server or server cluster that is different from server 105 and can communicate with the first terminal device 101, the second terminal device 102, the third terminal device 103, and / or server 105. Correspondingly, the three-dimensional sub-ice terrain extraction device based on multi-channel ice radar data tomography provided in this embodiment can also be located in a server or server cluster that is different from server 105 and can communicate with the first terminal device 101, the second terminal device 102, the third terminal device 103, and / or server 105.

[0070] It should be understood that Figure 1 The number of terminal devices, networks, and servers shown is merely illustrative. Depending on implementation needs, any number of terminal devices, networks, and servers can be included.

[0071] The following will be based on Figure 1 The described scene, through Figures 2-13 The method for extracting three-dimensional sub-ice terrain based on multi-channel ice radar data tomography according to the disclosed embodiments is described in detail.

[0072] Figure 2 A flowchart of a three-dimensional under-ice terrain extraction method based on multi-channel ice radar data tomographic processing is shown schematically according to an embodiment of the present disclosure.

[0073] As shown in Figure 2 , the method comprises operation S210 to operation S250.

[0074] According to an embodiment of the present disclosure, before operation S210 is performed, some pre-step is further included. Since different radar antenna transceiving signals will cause a part of data segments to be in a blind area, the data applied in the present application has a system delay of 2μs and a sampling window delay of 22.2μs. Since the f-k migration algorithm requires data to start from zero time, it is necessary to use the characteristics of time domain cyclic convolution to equivalently compensate the delay of the sampling window.

[0075] In operation S210, a forward model database two-dimensional table is established based on the ray tracing technology and using Snell's law.

[0076] According to an embodiment of the present disclosure, the forward model database two-dimensional table takes the ice cover depth and the incident angle as input and takes the distance and the cross-track position coordinate as output. The incident angle can represent the angle of incidence from the air to the ice cover.

[0077] According to an embodiment of the present disclosure, the distance can represent the length of the hypotenuse of a right triangle with the ice cover depth and the cross-track position coordinate as the two legs. The distance can represent the track of the electromagnetic wave running in the ice cover interface.

[0078] According to an embodiment of the present disclosure, the forward model database two-dimensional table can take any two data of the ice cover depth, the incident angle, the distance and the cross-track position coordinate as input and output the other two corresponding data.

[0079] In operation S220, a two-dimensional tomographic output matrix corresponding to the target along-track position coordinate is established according to the multi-channel frequency-wavenumber domain migration processing result.

[0080] According to an embodiment of the present disclosure, the multi-channel frequency-wavenumber domain migration processing result is determined according to the target along-track position coordinate and the target distance.

[0081] According to an embodiment of the present disclosure, the target along-track position coordinate can represent a given along-track position coordinate. The target along-track position coordinate can correspond to multiple target distances. According to the target along-track position coordinate and one target distance, one corresponding multi-channel frequency-wavenumber domain migration processing result can be determined. According to the target along-track position coordinate and multiple target distances, a two-dimensional tomographic output matrix corresponding to the target along-track position coordinate can be established.

[0082] According to an embodiment of the present disclosure, the rows of the two-dimensional tomography output matrix can correspond to normalized spatial frequencies, and the columns can correspond to distances. The distance corresponding to the column of the two-dimensional tomography output matrix can represent the cross-track distance of the target along the track position coordinate to the position coordinate.

[0083] In operation S230, distances and incidence angles corresponding to the maximum function values of the spatial spectrum functions corresponding to the values in the value range of the normalized spatial frequencies are determined according to the two-dimensional tomography output matrix and the normalized spatial frequencies.

[0084] According to an embodiment of the present disclosure, the value range of the normalized spatial frequencies is (-0.5, 0.5).

[0085] In operation S240, the distances and the incidence angles corresponding to the maximum function values of the spatial spectrum functions corresponding to the values in the value range of the normalized spatial frequencies are traversed based on the two-dimensional table of the forward model database to obtain the two-dimensional subglacial topography of the cross-track position coordinate of the target along the track position coordinate.

[0086] According to an embodiment of the present disclosure, all the distances and the incidence angles corresponding to the target along the track position coordinate are input into the two-dimensional table of the forward model database, and the corresponding ice cover depth and the cross-track position coordinate can be obtained, and the three-dimensional subglacial topography data of the target along the track position coordinate can be obtained according to all the ice cover depths and the cross-track position coordinates.

[0087] In operation S250, the three-dimensional subglacial topography is obtained by traversing the track position coordinates based on the two-dimensional subglacial topography of the cross-track position coordinate of the target along the track position coordinate.

[0088] According to an embodiment of the present disclosure, the two-dimensional subglacial topographies corresponding to each track position coordinate can be obtained by traversing the track position coordinates and performing operations S220-S240 for each track position coordinate, and the three-dimensional subglacial topography data of the vehicle-mounted multi-channel ice radar detection can be obtained according to all the two-dimensional subglacial topographies.

[0089] According to an embodiment of the present disclosure, according to the multi-channel radar, the two-dimensional data of the cross-track can be obtained, and the two-dimensional tomography output matrix corresponding to the target along the track position coordinate is established according to the multi-channel frequency wavenumber domain offset processing result, the distances and the incidence angles corresponding to the maximum function values of the spatial spectrum functions corresponding to the values in the value range of the normalized spatial frequencies are determined, and the obtained distances and the incidence angles are traversed to obtain the corresponding ice cover depth and the cross-track position coordinate from the two-dimensional table of the forward model database, so that the two-dimensional subglacial topography of the cross-track position coordinate of the target along the track position coordinate can be obtained, and finally the three-dimensional subglacial topography can be obtained by traversing the track position coordinates, so that the high-resolution, high-precision, and strip-shaped detection of the ice cover can be realized.

[0090] Figure 3 A diagram showing the relationship between the real part of the dielectric constant and the depth is shown schematically according to an embodiment of the present disclosure.

[0091] As shown in Figure 3 , the real part of the dielectric constant corresponding to different ice cover depths can be obtained. In the diagram showing the relationship between the real part of the dielectric constant and the depth, the horizontal axis is the depth (m), and the vertical axis is the real part of the dielectric constant.

[0092] According to an embodiment of the present disclosure, in the depth range of 0-250 m, as the depth increases, the corresponding value of the real part of the dielectric constant also increases rapidly, but in the depth range of 250 m-3500 m, as the depth increases, the corresponding value of the real part of the dielectric constant does not change significantly.

[0093] Figure 4 A flowchart of establishing a two-dimensional table of the forward model database is shown schematically according to an embodiment of the present disclosure.

[0094] As shown in Figure 4 , the method includes operation S410 to operation S430.

[0095] In operation S410, based on the ray tracing technique, the Snell's law is used to determine the refraction angle of the i-th layer in the ice cover according to the refractive index of air and the incident angle.

[0096] According to an embodiment of the present disclosure, i is an integer greater than or equal to 1. The Snell's law can characterize the law of refraction.

[0097] Figure 5 A diagram showing the propagation path of electromagnetic waves in a multi-layer medium according to the Snell's law applied to the boundary between adjacent layers in the ice cover is shown schematically according to an embodiment of the present disclosure.

[0098] As shown in Figure 5 , the x-axis can represent the along-track direction, the y-axis can represent the cross-track direction, and the z-axis can represent the along-ice cover depth direction.

[0099] According to an embodiment of the present disclosure, it is assumed that the ice layer is homogeneous, linear, non-dissipative, and isotropic medium. In each Δd i , the ice cover is divided into layers, and the refractive index of each layer medium is respectively named n1, n2…n m , and the corresponding angle between the electromagnetic wave and the normal is respectively named θ1, θ2…θ m . Assuming that the interval of each layer is small enough, the real part of the dielectric constant in each layer remains unchanged, and the real part of the dielectric constant of the multiple layer media is respectively named ε1, ε2…ε m . In the ice cover, the trajectory of the electromagnetic wave running in each layer interface is respectively named d1, d2…d mThe layers are named sequentially, with propagation speeds within each layer in the order v1, v2…v m The electromagnetic waves are named sequentially, with the distances they travel across the trajectory at each layer interface denoted as y1, y2, ... y3. m Named sequentially, with the delay of each layer expressed in t. d1 t d2 …t dm They are named sequentially. Here, m can represent dividing the ice sheet into m layers, where m is an integer greater than or equal to 1, and i is an integer greater than or equal to 1 and less than or equal to m.

[0100] According to embodiments of this disclosure, such as Figure 5 As shown, point a can represent the position where the air refracts with the first layer, and point b can represent the position where the first layer refracts with the second layer. Then, line segment ab can represent the trajectory of the electromagnetic wave in the first layer interface, i.e., d1.

[0101] According to Snell's law, if two media have different refractive indices, refraction will occur. The incident wave and the refracted wave are in the same plane, called the incident plane, and the angle between the incident wave and the interface normal satisfies a certain relationship, which can be expressed as the following formula (1).

[0102] n air sinθ air =n1sinθ1=n2sinθ2=n i sinθ i (1)

[0103] Among them, such as Figure 5 As shown, n air θ can represent the refractive index of air. air The angle of incidence from air into the ice sheet can be represented by n1, θ1 can represent the refractive index of the first layer in the ice sheet, or the angle of refraction from the first layer to the second layer, and n2 can represent the refractive index of the second layer in the ice sheet, and θ2 can represent the angle of refraction from the first layer to the second layer. i θ can represent the refractive index of the i-th layer in the ice sheet. i It can represent the angle of refraction of the i-th layer in the ice sheet, or the angle of incidence from the i-th layer to the (+1)-th layer.

[0104] According to formula (1), the refraction angle θ at the th layer is obtained. i It can be expressed as the following formula (2).

[0105]

[0106] In operation S420, the distance and cross-track position coordinates are determined based on the ice depth, the refraction angle of the first layer, and the dielectric constant corresponding to the first layer.

[0107] According to embodiments of this disclosure, the depth Δd of each layer is obtained. i It can be expressed as the following formula (3).

[0108] Δd i =t q *v i / twenty three)

[0109] Among them, t q This can represent the sampling time for acquiring depth data at each layer, with t corresponding to each layer. q They are the same, t q = ts / A, where A can represent a value determined based on the amount of data collected, and A is an integer greater than or equal to 0; ts = 1 / fs, where fs can represent the sampling frequency.

[0110] According to embodiments of this disclosure, for example, let t q = ts / 100, t q The smaller ts value reduces the time required for each layer of electromagnetic waves to travel and increases the number of refractions of electromagnetic waves within the ice sheet. This improves the accuracy of the data obtained and makes the data in the two-dimensional tables of the positive model database more accurate.

[0111] According to embodiments of this disclosure, ice sheet depth can be characterized. Electromagnetic waves propagate two ways through ice sheets. Ice depth can be characterized by the depth Δd of each layer. i .

[0112] According to embodiments of this disclosure, the trajectory d of the electromagnetic wave at each layered interface is obtained. i It can be expressed as the following formula (4).

[0113] d i =2Δd i / cosθ i (4)

[0114] According to embodiments of this disclosure, the propagation velocity v within each layer is obtained. i It can be expressed as the following formula (5).

[0115]

[0116] Where c can represent the propagation speed of electromagnetic waves in free space, ε i It can be expressed as according to Figure 3 The real part of the dielectric constant corresponding to the i-th layer is obtained.

[0117] According to embodiments of this disclosure, the time delay t of each layer is obtained based on function (4) and formula (5). diIt can be expressed as the following formula (6).

[0118] t di =d i / v i =ts / cosθ i (6)

[0119] According to the embodiments of this disclosure, the total latency obtained by summing the latency of each layer interface can be expressed as the following formula (7).

[0120]

[0121] According to embodiments of this disclosure, based on the depth Δd of the i-th layer i and the angle of incidence θ i The cross-trajectory distance y of the i-th layer is obtained. i This can be expressed as the following formula (8)

[0122] y i =Δd i *tanθ i (8)

[0123] According to the embodiments of this disclosure, the cross-trajectory distance within each layer is accumulated to obtain the corresponding cross-trajectory position coordinates, which can be expressed as the following formula (9).

[0124]

[0125] According to embodiments of this disclosure, based on the obtained ice sheet depth Δd and total time delay t d Cross-trajectory position coordinates and incident angle θ air You can get the corresponding distance.

[0126] When operating the S430, a two-dimensional table of the forward model database is established based on the incident angle, ice sheet depth, distance, and cross-track position coordinates.

[0127] According to embodiments of this disclosure, based on the aforementioned incident angle, ice sheet depth, and the distance and cross-track position coordinates corresponding to the incident angle and ice sheet depth, a two-dimensional table of a forward model database can be established, with the incident angle and ice sheet depth as input and the distance and cross-track position coordinates as output, for subsequent use to obtain the corresponding ice sheet depth and cross-track position coordinates based on the distance and incident angle.

[0128] Figure 6 The flowchart illustrating the creation of a two-dimensional tomographic output matrix corresponding to the position coordinates of the target along the trajectory, according to an embodiment of the present disclosure, is shown.

[0129] like Figure 6 As shown, the method includes operations S610 to S650.

[0130] At operation S610, according to the target distance, the multi-channel ice radar echo signal data along the track direction is subjected to range direction pulse compression processing and frequency-wavenumber domain migration processing to obtain a multi-channel frequency-wavenumber domain migration processing result along the track direction.

[0131] According to an embodiment of the present disclosure, according to a given target distance p, the propagated vehicle-mounted multi-channel ice radar echo signal data is demodulated to a baseband and subjected to range direction pulse compression processing, and then the multi-channel data along all track direction positions is simultaneously subjected to frequency-wavenumber domain migration processing to realize track focusing. The multi-channel can include N channels, where N is an integer greater than or equal to 1. The N-channel radar is placed along the cross-track direction.

[0132] According to an embodiment of the present disclosure, the multi-channel ice radar echo signal data is in the time domain, and the frequency-wavenumber domain migration processing of the multi-channel ice radar echo signal data is to convert it from the time domain to the frequency domain.

[0133] According to an embodiment of the present disclosure, in the frequency-wavenumber domain, when the ice cover depth is h, the multi-channel frequency-wavenumber domain migration processing result can be expressed as the following formula (10).

[0134]

[0135] where Δi can represent the ice layer depth corresponding to each layering in the range direction, Π can represent a multiplication symbol, x can represent a beam along the track direction, j can represent an imaginary factor, z can represent a beam along the ice cover depth direction, and ω can represent a frequency. h can represent the ice cover depth, and h can represent the ice cover being divided into layers. (x, z, h) can represent the multi-channel frequency-wavenumber domain migration processing result in the frequency-wavenumber domain when the ice cover depth is h. (x, z = 0) can represent the multi-channel frequency-wavenumber domain migration processing result in the frequency-wavenumber domain when the ice cover depth is 0.

[0136] According to an embodiment of the present disclosure, the inverse transform corresponding to x can be expressed as the following formula (11).

[0137]

[0138] where (x, z, h) can represent the track direction position coordinates, (x, z, h = 0) can represent the multi-channel ice radar echo signal at time 0 in the time domain, and t can represent time.

[0139] At operation S610, according to the target track direction position coordinates, a plurality of track direction positions with a fixed length and centered on the target track direction position coordinates are continuously set.

[0140] According to an embodiment of the present disclosure, according to the given target along-track position coordinates, a plurality of interval fixed length along-track positions can be continuously arranged to be centered on the target along-track position.

[0141] According to an embodiment of the present disclosure, the radar scanning range is conical, and a plurality of interval fixed length along-track positions are symmetrically arranged with the target along-track position coordinates as the center.

[0142] In operation S630, according to the along-track multi-channel frequency-wavenumber domain migration processing result, a self-correlation matrix corresponding to the target along-track position and the target distance is constructed.

[0143] According to an embodiment of the present disclosure, the constructed self-correlation matrix Can be expressed as the following formula (12).

[0144]

[0145] Wherein, The observation matrix Can be constructed by the frequency-wavenumber domain migration processing results of the channels corresponding to the along-track interval fixed length positions, Can represent the conjugate transpose of the observation matrix

[0146] According to an embodiment of the present disclosure, in the case of =5, 5 along-track positions can be obtained, and the along-track position coordinates can be represented as -2, -1, +1 and +2 respectively, and the observation matrix Can be expressed as the following formula (13).

[0147]

[0148] Wherein, The frequency-wavenumber domain migration processing results from the channels can be represented as The frequency-wavenumber domain migration processing results from the channels can be represented as

[0149] According to an embodiment of the present disclosure, the along-track multi-channel frequency-wavenumber domain migration processing result can include

[0150] In operation S640, according to the self-correlation matrix, a spatial spectrum function corresponding to the target along-track position coordinates and the target distance is constructed.

[0151] According to an embodiment of the present disclosure, a row in the two-dimensional tomographic output matrix is constructed according to the spatial spectrum function corresponding to the target along-track position coordinates and the target distance.

[0152] In operation S650, based on the spatial spectrum function corresponding to the target distance, the distance is traversed to establish a two-dimensional tomographic output matrix corresponding to the target along-trajectory position coordinate.

[0153] According to an embodiment of the present disclosure, the spatial spectrum function corresponding to the target distance can constitute a row in the two-dimensional tomographic output matrix, and then the distance is traversed to perform operations S610-S640 for each distance corresponding to the target along-trajectory position coordinate, so as to obtain the spatial spectrum function corresponding to each distance, and the two-dimensional tomographic output matrix corresponding to the target along-trajectory position coordinate can be obtained according to all the obtained spatial spectrum functions.

[0154] According to an embodiment of the present disclosure, according to the along-trajectory position and the multi-channel radar, the two-dimensional data across the trajectory can be obtained, and according to the target along-trajectory position coordinate and the target distance, the spatial spectrum function corresponding to the target along-trajectory position coordinate and the target distance can be constructed, so as to obtain a row in the two-dimensional tomographic output matrix, and then the distance corresponding to the target along-trajectory position coordinate is traversed, so as to obtain the two-dimensional tomographic output matrix corresponding to the target along-trajectory position coordinate.

[0155] Figure 7 A flowchart for constructing the spatial spectrum function corresponding to the target along-trajectory position coordinate and the target distance according to an embodiment of the present disclosure is schematically shown.

[0156] As shown in Figure 7 , the method includes operations S710-S730.

[0157] In operation S710, eigenvalue decomposition is performed on the autocorrelation matrix to obtain a noise eigenvalue and an eigenvector corresponding to the noise eigenvalue.

[0158] According to an embodiment of the present disclosure, eigenvalue decomposition is performed on the autocorrelation matrix constructed according to operation S630 above, and three matrices can be obtained, and the eigenvalues and the eigenvectors corresponding to the eigenvalues can be obtained according to the three matrices, wherein the second matrix can represent the eigenvalue matrix. The eigenvalues can include noise eigenvalues and signal eigenvalues, and the eigenvectors can include eigenvectors corresponding to the noise eigenvalues and eigenvectors corresponding to the signal eigenvalues. According to an embodiment of the present disclosure, the obtained eigenvalues are sorted according to the numerical value, and the signal eigenvalues and the noise eigenvalues are screened out. For example, the number of eigenvalues is 8, and the 8 eigenvalues are sorted according to the numerical value, and in the case of needing 2 signal eigenvalues, the two eigenvalues with the largest numerical value in the 8 eigenvalues are selected as the signal eigenvalues, and the remaining 6 eigenvalues are selected as the noise eigenvalues.

[0159] ​

[0160] At operation S720, a noise subspace is constructed according to the eigenvectors corresponding to the noise eigenvalues.

[0161] According to an embodiment of the present disclosure, a noise subspace can be constructed according to the eigenvectors corresponding to the noise eigenvalues. A signal subspace can be constructed according to the eigenvectors corresponding to the signal eigenvalues. The noise subspace can be composed of the eigenvectors corresponding to the noise eigenvalues in the autocorrelation matrix. The signal subspace can be composed of the eigenvectors corresponding to the signal eigenvalues in the autocorrelation matrix.

[0162] At operation S730, a spatial spectrum function corresponding to the target along the track position coordinate and the target distance is constructed according to the orthogonality between the noise subspace and the direction vector of the normalized spatial frequency.

[0163] According to an embodiment of the present disclosure, for a multi-channel ice radar with a channel number of M, the direction vector corresponding to the normalized spatial frequency can be expressed as formula (14) as follows.

[0164] s = [1, exp(j2πF), …, exp(j(M-1)2πF) T (14)

[0165] According to an embodiment of the present disclosure, by using the orthogonality between the noise subspace and the direction vector of the normalized spatial frequency, the construction of the spatial spectrum function corresponding to the target along the track position coordinate and the target distance can be expressed as formula (15) as follows.

[0166]

[0167] wherein N can represent the number of expected targets, i.e., the number of targets to be detected, M can represent the channel number, may represent the mth eigenvector, may also represent the direction vector corresponding to the normalized spatial frequency, may represent the conjugate transpose of.

[0168] According to an embodiment of the present disclosure, M channels can obtain M signals. In the case of M being 8, 8 signals can be obtained, wherein the signal eigenvalues can be 2, i.e., the number of targets to be detected is 2, and the eigenvectors corresponding to the noise eigenvalues are from the 3rd eigenvector. According to an embodiment of the present disclosure, by performing eigenvalue decomposition on the autocorrelation matrix, noise eigenvalues and eigenvectors corresponding to the noise eigenvalues can be obtained, and a noise subspace can be constructed according to the noise eigenvalues and the eigenvectors corresponding to the noise eigenvalues. By using the orthogonality between the noise subspace and the direction vector of the normalized spatial frequency, a spatial spectrum function can be constructed, which can be used for subsequent establishment of a two-dimensional tomographic output matrix.

[0169] According to an embodiment of the present disclosure, the distance corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain and the incident angle corresponding to the value in the normalized spatial frequency value domain are determined according to the two-dimensional tomography output matrix and the normalized spatial frequency, comprising: determining the distance corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain based on the two-dimensional tomography output matrix; and determining the incident angle corresponding to the value in the normalized spatial frequency value domain according to the spatial wave number, wherein the spatial wave number is obtained according to the normalized spatial frequency.

[0170] Figure 8 A schematic diagram of the two-dimensional tomography output matrix obtained by applying the MUSIC algorithm to the measured data according to an embodiment of the present disclosure is schematically shown.

[0171] As shown in Figure 8 , by using the MUSIC (Multiple Signal Classification) algorithm, a schematic diagram of the two-dimensional tomography output matrix obtained according to the measured data obtained by the above method 600 is shown as Figure 8 . The horizontal coordinate can represent the value domain of the normalized spatial frequency, the horizontal coordinate is set in the range of (-0.6, 0.6) with an interval of 0.2, and the vertical coordinate can represent the distance.

[0172] According to an embodiment of the present disclosure, the value domain of the normalized spatial frequency F is all values in (-0.5, 0.5). For all values in the normalized spatial frequency value domain (-0.5, 0.5), find the maximum function value of the corresponding spatial spectrum function in the corresponding column of the two-dimensional tomography output matrix, record the corresponding distance, and determine the distance corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain. Each value in the normalized spatial frequency value domain can find a column corresponding to the value in the normalized spatial frequency value domain in Figure 8 , and the maximum function value of the corresponding spatial spectrum function corresponding to the value in the normalized spatial frequency value domain exists in each column. The distance corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain can represent the distance corresponding to the brightest position in the corresponding column, and the brightest position can represent the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain.

[0173] Figure 9 A schematic diagram of the geometric relationship between the beam and the electromagnetic wave transmission angle of the ice surface according to an embodiment of the present disclosure is schematically shown.

[0174] As shown in Figure 9 , the present method applies 8 channels. The geometric relationship between the spatial beam k y and the electromagnetic wave transmission angle θ of the ice surface can be represented by the following formula (16).

[0175]

[0176] wherein k y may represent a beam in the y direction.

[0177] According to an embodiment of the present disclosure, k y The relationship with the normalized spatial frequency F can be represented as formula (17) as follows.

[0178]

[0179] wherein Δ y may represent an antenna element spacing, Δ y may represent the spacing between two adjacent channels.

[0180] According to an embodiment of the present disclosure, the beam can be represented as formula (18) as follows.

[0181] k = 2π / λ = 2π(n snow f c ) / c (18)

[0182] wherein λ may represent the working wavelength of the radar transmitted signal, f c may represent the radar working center frequency, n snow may represent the refractive index of the ice cover surface snow layer, and may represent the propagation speed of the electromagnetic wave in free space.

[0183] According to an embodiment of the present disclosure, according to formula (16) to formula (18), the relationship between the normalized spatial frequency F and the corresponding ice surface electromagnetic wave transmission angle (incident angle) can be represented as formula (19) as follows.

[0184]

[0185] According to an embodiment of the present disclosure, according to formula (19), the incident angle corresponding to the value in the normalized spatial frequency value domain can be obtained.

[0186] According to an embodiment of the present disclosure, according to the two-dimensional tomography output matrix, the distance corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain can be determined, and by using the relationship between the spatial wave number and the ice surface electromagnetic wave incident angle, the incident angle corresponding to the value in the normalized spatial frequency value domain can be determined, so that all distances of the target along the trajectory position coordinates and the incident angles corresponding to the distances can be obtained.

[0187] According to embodiments of this disclosure, based on a two-dimensional table in a forward model database, the distance and incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency range are traversed to obtain the two-dimensional sub-ice terrain across the trajectory direction at the target's position coordinates along the trajectory direction. This includes: traversing the distance and incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency range, retrieving the corresponding depth and cross-trajectory position coordinates from the two-dimensional table in the forward model database; and obtaining the two-dimensional sub-ice terrain across the trajectory direction at the target's position coordinates along the trajectory direction based on the corresponding depth and cross-trajectory position coordinates.

[0188] According to embodiments of this disclosure, by inputting all the obtained distances and the corresponding incident angles into a two-dimensional table of the forward model database, the corresponding ice sheet depth and cross-track position coordinates can be obtained.

[0189] According to embodiments of this disclosure, through a two-dimensional table in the forward model database, the corresponding ice sheet depth and cross-track position coordinates can be obtained based on the distance and incident angle. Based on the corresponding ice sheet depth and cross-track position coordinates, the two-dimensional sub-ice terrain across the track direction at the target's track-direction position coordinates can be obtained.

[0190] According to embodiments of this disclosure, a three-dimensional sub-ice terrain is obtained by traversing the position coordinates along the trajectory direction based on the two-dimensional sub-ice terrain spanning the trajectory direction at the target's position coordinates along the trajectory direction. This includes: traversing the position coordinates along the trajectory direction based on the two-dimensional sub-ice terrain spanning the trajectory direction at the target's position coordinates along the trajectory direction to obtain all two-dimensional sub-ice terrain spanning the trajectory direction at the position coordinates along the trajectory direction; and obtaining the three-dimensional sub-ice terrain based on all two-dimensional sub-ice terrain spanning the trajectory direction at the position coordinates along the trajectory direction.

[0191] According to embodiments of this disclosure, by traversing the position coordinates along the trajectory, it is possible to obtain all two-dimensional sub-ice terrain at the position coordinates along the trajectory that span the trajectory, and based on the obtained two-dimensional sub-ice terrain at the position coordinates along the trajectory that span the trajectory, it is possible to obtain three-dimensional sub-ice terrain.

[0192] Figure 10 A flowchart illustrating the process of obtaining three-dimensional subglacial topography according to an embodiment of the present disclosure is shown.

[0193] like Figure 10 As shown, the method includes operations S1001 to S1012.

[0194] When operating S1001, based on ray tracing technology and using Snell's law, a two-dimensional table of forward model database is established.

[0195] In operation S1002, all vehicle-mounted multi-channel ice radar echo signal data propagated along the trajectory are subjected to range pulse compression processing.

[0196] In operation S1003, according to the target distance, frequency-wavenumber domain migration processing is performed on all the multi-channel ice radar echo signal data along the track-to-position, to obtain a track-to multi-channel frequency-wavenumber domain migration processing result.

[0197] In operation S1004, according to the target track-to-position coordinates, a plurality of track-to-positions with a fixed length interval are sequentially arranged with the target track-to-position coordinates as the center.

[0198] In operation S1005, according to the track-to multi-channel frequency-wavenumber domain migration processing result, a self-correlation matrix corresponding to the target track-to-position and the target distance is constructed.

[0199] In operation S1006, eigenvalue decomposition is performed on the self-correlation matrix to obtain a noise eigenvalue and a feature vector corresponding to the noise eigenvalue, and a noise subspace is constructed according to the feature vector corresponding to the noise eigenvalue.

[0200] In operation S1007, according to the noise subspace obtained from the self-correlation matrix and the direction vector of the normalized spatial frequency being orthogonal, a spatial spectrum function corresponding to the target track-to-position coordinates and the target distance is constructed.

[0201] In operation S1008, based on the spatial spectrum function corresponding to the target distance, the distance is traversed to establish a two-dimensional tomographic output matrix corresponding to the target track-to-position coordinates.

[0202] In operation S1009, based on the two-dimensional tomographic output matrix, the distance corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain is determined.

[0203] In operation S1010, according to the spatial beam, the incident angle corresponding to the value in the normalized spatial frequency value domain is determined.

[0204] In operation S1011, based on the forward model database two-dimensional table, the distance and the incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value domain are traversed to obtain a two-dimensional cross-track ice undersea terrain at the target track-to-position coordinates.

[0205] In operation S1012, based on the two-dimensional cross-track ice undersea terrain at the target track-to-position coordinates, the track-to-position coordinates are traversed to obtain a three-dimensional ice undersea terrain.

[0206] Figure 11 A point target imaging simulation model diagram applicable according to an embodiment of the present disclosure is schematically shown.

[0207] As Figure 11As shown, the x-axis can represent the direction along the trajectory, the y-axis can represent the direction across the trajectory, and the z-axis can represent the direction along the depth of the ice sheet.

[0208] According to embodiments of this disclosure, the method of this disclosure is verified using simulation data obtained from a point target imaging simulation model. A point target imaging simulation model suitable for vehicle-mounted multi-channel ice radar is as follows: Figure 11 As shown, ignoring signal propagation losses and receiver noise in various media, a coordinate system is established with the vertical projection of the point target detected by the vehicle-mounted multi-channel ice radar onto the ice surface as the origin. The vehicle-mounted radar system moves at a constant velocity v along the azimuth direction (x-axis). Two point targets at different depths under the ice and across the trajectory are simulated according to the parameters of the vehicle-mounted ice radar. The position information of the two point targets in the (y,z) coordinate system is as follows: Figure 11 As shown.

[0209] Table 1 shows the simulation parameter data of the point target imaging simulation model.

[0210] Table 1

[0211]

[0212]

[0213] According to embodiments of this disclosure, the radar platform's scanning range is conical, intersecting the ice-rock interface at two points on the positive and negative y-axis in a two-dimensional profile. The position information of the two point targets in the coordinate system obtained from simulation is as follows: Figure 11 As shown, the position information of the left point target in the coordinate system can be represented as approximately 2020m in depth along the z-axis and approximately -20m in position across the trajectory along the y-axis; the position information of the right point target in the coordinate system can be represented as approximately 2000m in depth along the z-axis and approximately 284.3m in position across the trajectory along the y-axis.

[0214] Figure 12 The illustration shows a schematic diagram of the simulation effect of a three-dimensional tomographic point target according to an embodiment of the present disclosure.

[0215] like Figure 12 As shown, the horizontal axis can represent the position coordinates across the trajectory, and the vertical axis can represent the ice sheet depth. The position information of the two point targets obtained by actual measurement according to the method of this disclosure can be represented as (-20.2, 2019.9) and (282.2, 2000.2), respectively.

[0216] According to embodiments of this disclosure, Figure 11 The position information of the two point targets shown is obtained from the point target imaging simulation model. Figure 12The position information of the two point targets obtained by the method according to the present disclosure is shown, and it can be seen that the position information of the two point targets obtained by the method according to the present disclosure is consistent with the position information of the two point targets obtained by model simulation.

[0217] Figure 13 A schematic diagram of a three-dimensional sub-ice terrain result obtained by processing multi-channel ice radar data according to an embodiment of the present disclosure is schematically shown.

[0218] As shown in Figure 13 , a three-dimensional sub-ice terrain schematic diagram obtained by the method according to the present disclosure can be seen. According to the multi-channel radar, it is possible to obtain two-dimensional data in the three-dimensional sub-ice terrain across the track direction. The obtained three-dimensional sub-ice terrain across the track direction has a strip of about 1000m.

[0219] Based on the three-dimensional sub-ice terrain extraction method based on multi-channel ice radar data tomographic processing described above, the present disclosure further provides a three-dimensional sub-ice terrain extraction device based on multi-channel ice radar data tomographic processing. The device will be described in detail below. Figure 14 .

[0220] Figure 14 A structural block diagram of a three-dimensional sub-ice terrain extraction device based on multi-channel ice radar data tomographic processing according to an embodiment of the present disclosure is schematically shown.

[0221] As shown in Figure 14 , the three-dimensional sub-ice terrain extraction device based on multi-channel ice radar data tomographic processing 1400 of this embodiment includes a first establishing module 1410, a second establishing module 1420, a determining module 1430, a first obtaining module 1440 and a second obtaining module 1450.

[0222] The first establishing module 1410 is configured to establish a forward model database two-dimensional table based on a ray tracing technique and Snell's law, wherein the forward model database two-dimensional table is inputted with ice cover depth and incident angle and outputted with distance and cross-track direction position coordinates, and the incident angle represents the angle of incidence from the air to the ice cover. In an embodiment, the first establishing module 1410 can be configured to perform the operation S210 described above, and details are not repeated here.

[0223] The second establishing module 1420 is configured to establish a two-dimensional tomographic output matrix corresponding to the target along-track direction position coordinates according to the multi-channel frequency-wavenumber domain migration processing result, wherein the multi-channel frequency-wavenumber domain migration processing result is determined according to the target along-track direction position coordinates and target distance. In an embodiment, the second establishing module 1420 can be configured to perform the operation S220 described above, and details are not repeated here.

[0224] The determining module 1430 is configured to determine the distance and the incidence angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value range according to the two-dimensional tomography output matrix and the normalized spatial frequency. In an embodiment, the determining module 1430 can be configured to perform the operation S230 described above, and details are not repeated here.

[0225] The first obtaining module 1440 is configured to traverse the distance and the incidence angle corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency value range based on the two-dimensional table of the forward model database to obtain the two-dimensional cross-track under-ice topography at the target along-track position coordinate. In an embodiment, the first obtaining module 1440 can be configured to perform the operation S240 described above, and details are not repeated here.

[0226] The second obtaining module 1450 is configured to traverse the along-track position coordinate based on the two-dimensional cross-track under-ice topography at the target along-track position coordinate to obtain the three-dimensional under-ice topography. In an embodiment, the second obtaining module 1450 can be configured to perform the operation S250 described above, and details are not repeated here.

[0227] According to an embodiment of the present disclosure, the first establishing module 1410 includes a first determining unit, a second determining unit, and a first establishing unit.

[0228] The first determining unit is configured to determine the refraction angle of the i-th layer of the ice cover based on the Snell's law according to the refractive index of air and the incidence angle by using the ray tracing technology, where i is an integer greater than or equal to 1.

[0229] The second determining unit is configured to determine the distance and the cross-track position coordinate according to the ice layer depth, the refraction angle of the i-th layer, and the dielectric constant corresponding to the i-th layer.

[0230] The first establishing unit is configured to establish the two-dimensional table of the forward model database according to the incidence angle, the ice cover depth, the distance, and the cross-track position coordinate.

[0231] According to an embodiment of the present disclosure, the second establishing module 1420 includes a processing unit, a setting unit, a first constructing unit, a second constructing unit, and a second establishing unit.

[0232] The processing unit is configured to perform the range direction pulse compression processing and the frequency wavenumber domain migration processing on all the along-track position multi-channel ice radar echo signal data to obtain the along-track multi-channel frequency wavenumber domain migration processing result according to the target distance.

[0233] The setting unit is configured to continuously set a plurality of along-track positions with a fixed length interval and taking the target along-track position coordinate as the center according to the target along-track position coordinate.

[0234] The first construction unit is configured to construct a self-correlation matrix corresponding to the target along-track position coordinate and the target distance according to the result of the offset processing along the track to the multi-channel frequency wavenumber domain.

[0235] The second construction unit is configured to construct a spatial spectrum function corresponding to the target along-track position coordinate and the target distance according to the self-correlation matrix, wherein a row in the two-dimensional tomographic output matrix is formed according to the spatial spectrum function corresponding to the target distance.

[0236] The second construction unit is configured to construct a spatial spectrum function corresponding to the target along-track position coordinate and the target distance according to the self-correlation matrix, wherein a row in the two-dimensional tomographic output matrix is formed according to the spatial spectrum function corresponding to the target distance.

[0237] According to an embodiment of the present disclosure, the second construction unit includes an obtaining subunit, a constructing subunit and a constructing subunit.

[0238] The obtaining subunit is configured to perform eigenvalue decomposition on the self-correlation matrix to obtain a noise eigenvalue and a feature vector corresponding to the noise eigenvalue.

[0239] The constructing subunit is configured to construct a noise subspace according to the feature vector corresponding to the noise eigenvalue.

[0240] The constructing subunit is configured to construct a spatial spectrum function corresponding to the target along-track position coordinate and the target distance according to the orthogonality between the noise subspace and the direction vector of the normalized spatial frequency.

[0241] According to an embodiment of the present disclosure, the determining module 1430 includes a third determining unit and a fourth determining unit.

[0242] The third determining unit is configured to determine a distance corresponding to a maximum function value of a spatial spectrum function corresponding to a value in a normalized spatial frequency value domain based on the two-dimensional tomographic output matrix.

[0243] The fourth determining unit is configured to determine an incidence angle corresponding to a value in a normalized spatial frequency value domain according to a spatial wavenumber, wherein the spatial wavenumber is obtained according to the normalized spatial frequency.

[0244] According to an embodiment of the present disclosure, the first obtaining module 1440 includes a first traversal unit and a first obtaining unit.

[0245] The first traversal unit is configured to traverse the distance and the incidence angle corresponding to the value in the normalized spatial frequency value domain to retrieve a corresponding depth and a cross-track position coordinate from the forward model database two-dimensional table.

[0246] The first obtaining unit is configured to obtain a two-dimensional subglacial topography across the track at the target along-track position coordinate according to the corresponding depth and the cross-track position coordinate.

[0247] According to an embodiment of the present disclosure, the second obtaining module 1450 comprises a second traversing unit and a second obtaining unit.

[0248] The second traversing unit is configured to traverse the along-track position coordinates based on the cross-track two-dimensional subglacial topography at the along-track position coordinates, to obtain the cross-track two-dimensional subglacial topography at all the along-track position coordinates.

[0249] The second obtaining unit is configured to obtain the three-dimensional subglacial topography according to the cross-track two-dimensional subglacial topography at all the along-track position coordinates.

[0250] According to an embodiment of the present disclosure, any of the first establishing module 1410, the second establishing module 1420, the determining module 1430, the first obtaining module 1440 and the second obtaining module 1450 can be combined in one module for implementation, or any of the modules can be split into multiple modules. Alternatively, at least part of the functions of one or more of the modules can be combined with at least part of the functions of other modules, and implemented in one module. According to an embodiment of the present disclosure, at least one of the first establishing module 1410, the second establishing module 1420, the determining module 1430, the first obtaining module 1440 and the second obtaining module 1450 can be at least partially implemented as a hardware circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), a system on chip, a system on board, a system on package, an application specific integrated circuit (ASIC), or any other reasonable manner of hardware or firmware that can be integrated or packaged with a circuit, or implemented in any one of software, hardware and firmware or in a proper combination of any of the above. Alternatively, at least one of the first establishing module 1410, the second establishing module 1420, the determining module 1430, the first obtaining module 1440 and the second obtaining module 1450 can be at least partially implemented as a computer program module that can perform corresponding functions when the computer program module is run.

[0251] Figure 15 A block diagram of an electronic device suitable for implementing the three-dimensional subglacial topography extraction method based on multi-channel ice radar data tomographic processing according to an embodiment of the present disclosure is schematically shown.

[0252] As Figure 15As shown, the electronic device 1500 according to embodiments of the present disclosure includes a processor 1501 that can perform various appropriate actions and processes according to programs stored in a read only memory (ROM) 1502 or loaded from a storage section 1508 into a random access memory (RAM) 1503. The processor 1501 can include, for example, a general purpose microprocessor (e.g., a CPU), an instruction set processor, and / or a related chip set, and / or a dedicated microprocessor (e.g., an application specific integrated circuit (ASIC)), and so on. The processor 1501 can also include an on-board memory for cache use. The processor 1501 can include a single processing unit or multiple processing units for executing different actions of the method processes according to embodiments of the present disclosure.

[0253] In the RAM 1503, various programs and data required for the operation of the electronic device 1500 are stored. The processor 1501, the ROM 1502, and the RAM 1503 are connected to each other via a bus 1504. The processor 1501 performs various operations of the method processes according to embodiments of the present disclosure by executing the programs in the ROM 1502 and / or the RAM 1503. Note that the programs can also be stored in one or more memories other than the ROM 1502 and the RAM 1503. The processor 1501 can also perform various operations of the method processes according to embodiments of the present disclosure by executing the programs stored in the one or more memories.

[0254] According to embodiments of the present disclosure, the electronic device 1500 can further include an input / output (I / O) interface 1505, which is also connected to the bus 1504. The electronic device 1500 can further include one or more of the following components connected to the I / O interface 1505: an input section 1506 including a keyboard, a mouse, etc.; an output section 1507 including a display such as a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 1508 including a hard disk, etc.; and a communication section 1509 including a network interface card such as a LAN card, a modem, etc. The communication section 1509 performs communication processing via a network such as the Internet. A drive 1510 is also connected to the I / O interface 1505 as necessary. A removable medium 1511 such as a magnetic disk, a magneto-optical disk, a semiconductor memory, etc. is attached to the drive 1510 as necessary, so that a computer program read out therefrom is installed into the storage section 1508 as necessary.

[0255] The present disclosure also provides a computer readable storage medium, which can be included in the device / apparatus / system described in the above embodiments, or exist separately without being assembled into the device / apparatus / system. The above computer readable storage medium carries one or more programs, which, when executed, implement the method according to the embodiments of the present disclosure.

[0256] According to the embodiments of the present disclosure, the computer readable storage medium can be a non-volatile computer readable storage medium, which can include, but is not limited to, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any appropriate combination thereof. In the present disclosure, the computer readable storage medium can be any tangible medium that contains or stores a program, which can be used by or in connection with an instruction execution system, apparatus, or device. For example, according to the embodiments of the present disclosure, the computer readable storage medium can include the ROM 1502 and / or the RAM 1503 described above, and / or one or more memories other than the ROM 1502 and the RAM 1503.

[0257] The embodiments of the present disclosure also include a computer program product, which includes a computer program containing program codes for executing the methods shown in the flowcharts. When the computer program product is run in a computer system, the program codes are used to make the computer system implement the item recommendation method provided by the embodiments of the present disclosure.

[0258] The above functions defined in the system / apparatus of the embodiments of the present disclosure are performed when the computer program is executed by the processor 1501. According to the embodiments of the present disclosure, the system, apparatus, module, unit, etc. described above can be implemented by computer program modules.

[0259] In one embodiment, the computer program can rely on a tangible storage medium such as an optical storage device, a magnetic storage device, etc. In another embodiment, the computer program can also be transmitted, distributed, and downloaded in the form of a signal via a network medium, and be downloaded and installed through the communication part 1509 and / or installed from the detachable medium 1511. The program codes contained in the computer program can be transmitted via any appropriate network medium, including but not limited to wireless, wired, etc., or any appropriate combination thereof.

[0260] In such embodiments, the computer program can be downloaded and installed from the network through the communication part 1509, and / or installed from the detachable medium 1511. When the computer program is executed by the processor 1501, the above-described functions defined in the system of the embodiments of the present disclosure are executed. According to the embodiments of the present disclosure, the system, device, apparatus, module, unit, and the like described above can be implemented by computer program modules.

[0261] According to the embodiments of the present disclosure, the program code for executing the computer program provided by the embodiments of the present disclosure can be written in any combination of one or more programming languages, and specifically, these computer programs can be implemented using high-level procedural and / or object-oriented programming language, and / or assembly / machine language. The programming language includes, but is not limited to, such as Java, C++, python, "C" language or similar programming language. The program code can be executed entirely on the user computing device, partially on the user device, partially on a remote computing device, or entirely on a remote computing device or server. In the case involving a remote computing device, the remote computing device can be connected to the user computing device through any kind of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computing device (for example, connected through the Internet by using an Internet service provider).

[0262] The flowcharts and block diagrams in the drawings illustrate the possible architectural, functional, and operational scenarios of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowcharts or block diagrams can represent a module, a program segment, or a portion of code that contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions noted in the blocks can occur in different orders than that shown in the figures. For example, two blocks that are shown in succession can actually be executed substantially concurrently, or they can sometimes be executed in reverse order, depending on the functionality involved. It should also be noted that each block in the flowcharts or block diagrams, and combinations of blocks in the flowcharts or block diagrams, can be implemented by dedicated hardware-based systems that perform the specified functions or operations, or can be implemented by a combination of dedicated hardware and computer instructions.

[0263] Those skilled in the art can understand that the features described in various embodiments of the present disclosure and / or claims can be combined or / and integrated, even if such combinations or integrations are not explicitly described in the present disclosure. In particular, the features described in various embodiments of the present disclosure and / or claims can be combined and / or integrated in various combinations, without departing from the spirit and teachings of the present disclosure. All such combinations and / or integrations are within the scope of the present disclosure.

[0264] The above described embodiments of the present disclosure. However, these embodiments are merely for illustrative purposes, and are not intended to limit the scope of the present disclosure. Although each embodiment is described above separately, this does not mean that the measures in each embodiment cannot be advantageously used in combination. The scope of the present disclosure is defined by the appended claims and their equivalents. Those skilled in the art can make various substitutions and modifications without departing from the scope of the present disclosure, and all such substitutions and modifications shall fall within the scope of the present disclosure.

Claims

1. A method for extracting three-dimensional sub-ice terrain based on multi-channel ice radar data tomography, comprising: Based on ray tracing technology and using Snell's law, a two-dimensional table of the forward model database is established. The two-dimensional table of the forward model database takes ice sheet depth and incident angle as input and distance and cross-track position coordinates as output. The incident angle represents the angle of incidence from the air into the ice sheet. Based on the multi-channel frequency wavenumber domain migration processing results, a two-dimensional tomographic output matrix corresponding to the target's position coordinates along the trajectory is established. This includes: performing range-direction pulse compression and frequency wavenumber domain migration processing on all multi-channel ice radar echo signal data along the trajectory based on the target distance, obtaining the multi-channel frequency wavenumber domain migration processing results along the trajectory; continuously setting multiple trajectory-direction positions with fixed intervals centered on the target's trajectory-direction position coordinates based on the target's trajectory-direction position coordinates; constructing an autocorrelation matrix corresponding to the target's trajectory-direction position coordinates and the target distance based on the multi-channel frequency wavenumber domain migration processing results along the trajectory; constructing a spatial spectrum function corresponding to the target's trajectory-direction position coordinates and the target distance based on the autocorrelation matrix, wherein one row in the two-dimensional tomographic output matrix is ​​constructed based on the spatial spectrum function corresponding to the target distance; and traversing the distances based on the spatial spectrum function corresponding to the target distance to establish the two-dimensional tomographic output matrix corresponding to the target's trajectory-direction position coordinates; wherein the multi-channel frequency wavenumber domain migration processing results are determined based on the target's trajectory-direction position coordinates and the target distance. Based on the two-dimensional tomography output matrix and the normalized spatial frequency, determine the distance and angle of incidence corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency range; Based on the two-dimensional table of the forward model database, the distance and incident angle corresponding to the maximum function value of the spatial spectral function corresponding to the values ​​in the normalized spatial frequency range are traversed to obtain the two-dimensional sub-ice terrain across the trajectory direction at the target's position coordinates along the trajectory; and Based on the two-dimensional sub-ice terrain at the target's position coordinates along the trajectory, the three-dimensional sub-ice terrain is obtained by traversing the position coordinates along the trajectory.

2. The method according to claim 1, wherein, The method, based on ray tracing technology and utilizing Snell's law, establishes a two-dimensional table for the forward model database, including: Based on the aforementioned ray tracing technology and utilizing Snell's law, the refractive index of air and the incident angle are used to determine the first... The angle of refraction of the layer, where, It is an integer greater than or equal to 1; According to the ice sheet depth, the first The refraction angle of the layer and the first The dielectric constant corresponding to the layer is used to determine the distance and the cross-trajectory position coordinates; A two-dimensional table for the forward model database is established based on the incident angle, the ice sheet depth, the distance, and the cross-trajectory position coordinates.

3. The method according to claim 1, wherein, The step of constructing a spatial spectral function corresponding to the target's position coordinates along the trajectory and the target distance based on the autocorrelation matrix includes: The autocorrelation matrix is ​​decomposed into eigenvalues ​​to obtain noise eigenvalues ​​and eigenvectors corresponding to the noise eigenvalues. Based on the feature vectors corresponding to the noise feature values, a noise subspace is constructed; Based on the fact that the direction vector of the noise subspace is orthogonal to the normalized spatial frequency, a spatial spectrum function corresponding to the target's position coordinates along the trajectory and the target distance is constructed.

4. The method according to claim 1, wherein, The step of determining the distance and angle of incidence corresponding to the maximum function value of the spatial spectral function corresponding to the value in the normalized spatial frequency range based on the two-dimensional tomography output matrix and the normalized spatial frequency includes: Based on the two-dimensional tomography output matrix, determine the distance corresponding to the maximum function value of the spatial spectral function corresponding to the value in the normalized spatial frequency range; and The incident angle corresponding to the value in the normalized spatial frequency range is determined based on the spatial wavenumber, wherein the spatial wavenumber is obtained based on the normalized spatial frequency.

5. The method according to claim 1, wherein, The method involves iterating through the two-dimensional table of the forward model database, traversing the distance and incident angle corresponding to the maximum function value of the spatial spectral function corresponding to the values ​​in the normalized spatial frequency range, to obtain the two-dimensional subglacial terrain across the trajectory direction at the target's position coordinates along the trajectory, including: The distance and incident angle corresponding to the maximum function value of the spatial spectral function corresponding to the values ​​in the normalized spatial frequency range are traversed, and the corresponding depth and cross-trajectory position coordinates are retrieved from the two-dimensional table of the forward model database; and Based on the corresponding depth and the cross-track position coordinates, the two-dimensional sub-ice terrain of the target at the cross-track position coordinates is obtained.

6. The method according to claim 1, wherein, The method of obtaining a three-dimensional subglacial terrain by traversing the trajectory coordinates of the target's position along the trajectory direction, based on the two-dimensional subglacial terrain across the trajectory direction, includes: Based on the two-dimensional sub-ice terrain spanning the trajectory direction at the target's position coordinates along the trajectory direction, the position coordinates along the trajectory direction are traversed to obtain all the two-dimensional sub-ice terrain spanning the trajectory direction at the target's position coordinates along the trajectory direction; and The three-dimensional subglacial terrain is obtained based on the two-dimensional subglacial terrain at all the position coordinates along the trajectory.

7. A three-dimensional sub-ice terrain extraction device based on multi-channel ice radar data tomography, comprising: The first module is used to establish a two-dimensional table of a forward model database based on ray tracing technology and using Snell's law. The two-dimensional table of the forward model database takes ice sheet depth and incident angle as input and distance and cross-track position coordinates as output. The incident angle represents the angle of incidence from the air into the ice sheet. The second module is used to establish a two-dimensional tomography output matrix corresponding to the target's position coordinates along the trajectory, based on the multi-channel frequency wavenumber domain migration processing results. The multi-channel frequency wavenumber domain migration processing results are determined based on the target's position coordinates along the trajectory and the target distance. The second establishment module includes a processing unit, a setting unit, a first construction unit, a second construction unit, and a second establishment unit. The processing unit is used to perform range pulse compression processing and frequency wavenumber domain offset processing on all multi-channel ice radar echo signal data along the trajectory direction according to the target distance, so as to obtain the multi-channel frequency wavenumber domain offset processing result along the trajectory direction. The setting unit is used to continuously set multiple trajectory-oriented positions with fixed intervals, centered on the trajectory-oriented position coordinates of the target, according to the trajectory-oriented position coordinates of the target. The first construction unit is used to construct an autocorrelation matrix corresponding to the target's position coordinates along the trajectory and the target distance, based on the multi-channel frequency wavenumber domain offset processing result along the trajectory. The second construction unit is used to construct a spatial spectrum function corresponding to the target's position coordinates along the trajectory and the target distance based on the autocorrelation matrix, wherein one row of the two-dimensional tomography output matrix is ​​constructed based on the spatial spectrum function corresponding to the target distance; The second establishment unit is used to establish the two-dimensional tomography output matrix corresponding to the target's position coordinates along the trajectory by traversing the distance based on the spatial spectrum function corresponding to the target distance; The determination module is used to determine the distance and angle of incidence corresponding to the maximum function value of the spatial spectrum function corresponding to the value in the normalized spatial frequency range, based on the two-dimensional tomography output matrix and the normalized spatial frequency. The first acquisition module is used to traverse the distance and incident angle corresponding to the maximum function value of the spatial spectrum function corresponding to the values ​​in the normalized spatial frequency range, based on the two-dimensional table of the forward model database, to obtain the two-dimensional sub-ice terrain across the trajectory direction at the target's position coordinates along the trajectory direction; and The second acquisition module is used to traverse the position coordinates along the trajectory of the target along the trajectory to obtain the three-dimensional sub-ice terrain based on the two-dimensional sub-ice terrain across the trajectory direction at the target's position coordinates.

8. An electronic device, comprising: One or more processors; Storage device for storing one or more programs. Wherein, when the one or more programs are executed by the one or more processors, the one or more processors perform the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having stored thereon executable instructions that, when executed by a processor, cause the processor to perform the method according to any one of claims 1 to 6.

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