A full polarization scattering feature extraction method, device and computing equipment

Abstract

The application provides a full polarization scattering feature extraction method and device and computing equipment, the method comprising: acquiring an ISAR image of a target to be identified under a preset azimuth central angle; wherein the ISAR image comprises sub-images corresponding to four polarization states; for each group of ISAR images, performing: scattering center extraction is performed on the sub-images in the ISAR image, and at least two amplitude values of scattering centers are obtained; according to the amplitude values extracted from each group of ISAR images, an amplitude matrix corresponding to each scattering center is determined; wherein the amplitude matrix comprises the amplitude value of the scattering center under the preset azimuth central angle; and according to the amplitude matrix, a polarization ratio distribution of the scattering center is obtained. The full polarization scattering feature extraction method provided in the scheme reduces the sensitivity of the polarization scattering matrix to the radar line-of-sight angle and the dependence on the scene, and improves the accuracy of target identification.

Description

Technical Field

[0001] This invention relates to the field of radar technology, and in particular to a method, apparatus, and computing device for extracting fully polarized scattering features. Background Technology

[0002] With the continuous development of radar technology, researchers hope to obtain more effective information about targets for target classification and identification, which is a difficult problem in aerospace defense. Polarization domain information in radar target echo signals is another important feature for target identification, following time domain and frequency domain features.

[0003] There is a mapping relationship between the target polarization characteristics and the target's physical properties such as structure and materials. However, under narrowband conditions, due to the superposition effect of each scattering center, the narrowband polarization characteristics have strong attitude sensitivity and are highly dependent on the actual application scenario. They also cannot reflect the regular mapping between the target's structural properties and polarization characteristics, resulting in the low accuracy of existing aerospace defense target identification. Summary of the Invention

[0004] This invention provides a method, apparatus, and computing device for extracting fully polarimetric scattering features. This method reduces the sensitivity of the polarimetric scattering matrix to the radar line-of-sight angle and its dependence on the scene, thereby improving the accuracy of target recognition.

[0005] In a first aspect, embodiments of the present invention provide a method for extracting fully polarimetric scattering features, including:

[0006] Acquire an ISAR image of the target to be identified at a preset azimuth center angle; wherein, the ISAR image includes sub-images corresponding to four polarization states;

[0007] For each group of ISAR images, the following steps are performed: scattering centers are extracted from all sub-images in the ISAR image to obtain the amplitude values ​​of at least two scattering centers;

[0008] Based on the amplitude values ​​extracted from each group of ISAR images, an amplitude matrix corresponding to each scattering center is determined; wherein, the amplitude matrix includes the amplitude value of the scattering center at the preset azimuth center angle;

[0009] The polarization ratio distribution of the scattering center is obtained based on the amplitude matrix.

[0010] Optionally, acquiring the ISAR image of the target to be identified at a preset azimuth center angle includes:

[0011] Obtain the broadband frequency sweep data of the target to be identified;

[0012] The broadband sweep frequency data is divided into several data segments along the azimuth direction; wherein, the window length of the imaging accumulation angle of each data segment is the same, and the angle sliding window step size of adjacent data segments is the same.

[0013] For each data segment, execute:

[0014] Determine the azimuth center angle of this data segment;

[0015] Two-dimensional imaging focusing processing is performed on this data segment to obtain an ISAR image at the central angle of the stated azimuth;

[0016] The preset azimuth center angle includes the azimuth center angle of each data segment.

[0017] Optionally, the number of segments is determined by the following formula:

[0018] ;

[0019] Wherein, Q represents the number of data segments; L represents the azimuth length of the broadband swept frequency data; N represents the window length of the imaging accumulation angle; and M represents the angle sliding window step size.

[0020] Optionally, a filtered inverse projection algorithm can be used for two-dimensional imaging focusing.

[0021] Optionally, the ISAR image includes sub-images corresponding to four polarization states: HH, HV, VH, and VV; where H represents horizontal polarization, V represents vertical polarization, the first letter indicates the transmission state, and the second letter indicates the reception state.

[0022] Optionally, obtaining the polarization ratio distribution of the scattering center based on the amplitude matrix includes:

[0023] For each of the aforementioned scattering centers, the following is performed:

[0024] For each preset azimuth center angle, execute:

[0025] Obtain the amplitude value of the scattering center at the preset azimuth center angle; wherein the amplitude value includes a first amplitude value under HH polarization, a second amplitude value under HV polarization, a third amplitude value under VH polarization, and a fourth amplitude value under VV polarization;

[0026] The polarization ratio is obtained based on the first amplitude value, the second amplitude value, the third amplitude value, and the fourth amplitude value;

[0027] The polarization ratios of each preset azimuth center angle are arranged according to the azimuth direction of the preset azimuth center angle to obtain the polarization ratio distribution of the scattering center.

[0028] Optionally, the polarization ratio includes a first polarization ratio, a second polarization ratio, and a third polarization ratio;

[0029] The first polarization ratio is determined by the following formula:

[0030]

[0031] The second polarization ratio is determined by the following formula:

[0032]

[0033] The third polarization ratio is determined by the following formula:

[0034]

[0035] in, Used to characterize the first polarization ratio; Used to characterize the first amplitude value; Used to characterize the fourth amplitude value; Used to characterize the second polarization ratio; Used to characterize the second amplitude value; Used to characterize the third polarization ratio; Used to characterize the third amplitude value; (x) m ,y m ) is used to characterize the pixel position of the scattering center m in the ISAR image; Used to characterize the i-th preset azimuth center angle.

[0036] Optionally, the step of extracting scattering centers from all sub-images in the ISAR image to obtain amplitude values ​​of at least two scattering centers includes:

[0037] For each sub-image, the following steps are performed: the sub-image is separated and extracted using prior information and the peak-to-maximum method to obtain the amplitude values ​​of at least two scattering centers in the polarization state corresponding to the sub-image.

[0038] Optionally, determining the amplitude matrix corresponding to each scattering center based on the amplitude values ​​extracted from each group of ISAR images includes:

[0039] Based on the scattering center, the amplitude values ​​extracted from each group of ISAR images are classified to obtain an amplitude value group for each scattering center; wherein, the amplitude value group includes the amplitude values ​​of the scattering center corresponding to four polarization states at the preset azimuth center angle;

[0040] The amplitude matrix is ​​obtained by using the amplitude values ​​in the amplitude value group as elements of the amplitude matrix.

[0041] Secondly, embodiments of the present invention also provide a fully polarized scattering feature extraction device, comprising:

[0042] The acquisition module is used to acquire an ISAR image of the target to be identified at a preset azimuth center angle; wherein, the ISAR image includes sub-images corresponding to four polarization states;

[0043] The extraction module is used to perform the following for each group of ISAR images: extract the scattering centers of each sub-image in the ISAR image to obtain the amplitude values ​​of at least two scattering centers;

[0044] The determining module is used to determine the amplitude matrix corresponding to each of the scattering centers based on the amplitude values ​​extracted from each group of ISAR images; wherein, the amplitude matrix includes the amplitude value of the scattering center at the preset azimuth center angle;

[0045] The calculation module is used to obtain the polarization ratio distribution of the scattering center based on the amplitude matrix.

[0046] Thirdly, embodiments of the present invention also provide a computing device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, it implements the fully polarimetric scattering feature extraction method described in any of the above claims.

[0047] Fourthly, embodiments of the present invention also provide a computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, causes the computer to perform the fully polarimetric scattering feature extraction method described in any of the preceding claims.

[0048] This invention provides a method, apparatus, and computing device for extracting fully polarimetric scattering features. The method acquires fully polarimetric ISAR images of a target under different preset azimuth center angles. For each sub-image within a group of fully polarimetric ISAR images under different preset azimuth center angles, scattering centers are extracted to obtain amplitude values ​​of at least two scattering centers. For the amplitude values ​​extracted from each scattering center under different preset azimuth center angles, its amplitude matrix is ​​determined. The polarization ratio distribution of the scattering center is then calculated based on this amplitude matrix. Thus, the type of the target can be determined based on the obtained polarization ratio distribution of the scattering centers. The fully polarimetric scattering feature extraction method provided by this invention reduces the sensitivity of the target polarimetric scattering matrix to the radar line-of-sight angle and its dependence on the scene, improving the universality of polarimetric features in aerospace target identification applications, thereby improving the accuracy of target identification. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is a flowchart of a fully polarimetric scattering feature extraction method provided in an embodiment of the present invention;

[0051] Figure 2 This is a fully polarized RCS anechoic chamber measurement data of the target to be identified at a frequency of 10 GHz, provided by an embodiment of the present invention.

[0052] Figure 3 This is a polarization ratio curve distribution of the target to be identified at a frequency of 10 GHz, provided by an embodiment of the present invention;

[0053] Figure 4 This is a broadband ISAR image of a target to be identified provided in an embodiment of the present invention;

[0054] Figure 5 This is a polarization ratio curve distribution corresponding to the scattering center 1 of the target to be identified, provided in an embodiment of the present invention;

[0055] Figure 6 This is a broadband ISAR image of a target to be identified provided in an embodiment of the present invention;

[0056] Figure 7 This is a polarization ratio curve distribution corresponding to the scattering center 2 of the target to be identified, provided in an embodiment of the present invention;

[0057] Figure 8 This is a broadband ISAR image of a target to be identified provided in an embodiment of the present invention;

[0058] Figure 9 This is a polarization ratio curve distribution corresponding to the scattering center 3 of the target to be identified, provided in an embodiment of the present invention;

[0059] Figure 10 This is a hardware architecture diagram of a computing device provided in an embodiment of the present invention;

[0060] Figure 11 This is a structural diagram of a fully polarized scattering feature extraction device provided in an embodiment of the present invention. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0062] Please refer to Figure 1 This invention provides a method for extracting fully polarimetric scattering features, the method comprising:

[0063] Step 100: Obtain the ISAR image of the target to be identified at the preset azimuth center angle; wherein, the ISAR image includes sub-images corresponding to the four polarization states;

[0064] Step 102: For each group of ISAR images, perform the following: extract the scattering centers of each sub-image in the ISAR image to obtain the amplitude values ​​of at least two scattering centers;

[0065] Step 104: Determine the amplitude matrix corresponding to each scattering center based on the amplitude values ​​extracted from each group of ISAR images; wherein, the amplitude matrix includes the amplitude value of the scattering center at the preset azimuth center angle;

[0066] Step 106: Based on the amplitude matrix, obtain the polarization ratio distribution of the scattering center.

[0067] In this embodiment of the invention, by acquiring fully polarimetric ISAR images of the target under different preset azimuth center angles, scattering centers are extracted from the sub-images within each group of fully polarimetric ISAR images under different preset azimuth center angles, yielding amplitude values ​​of at least two scattering centers. For each scattering center, the amplitude matrix extracted under different preset azimuth center angles is determined, and the polarization ratio distribution of the scattering center is calculated based on this amplitude matrix. Thus, the type of the target can be determined based on the obtained polarization ratio distribution of the scattering centers. The fully polarimetric scattering feature extraction method provided by this invention reduces the sensitivity of the target polarimetric scattering matrix to the radar line-of-sight angle and its dependence on the scene, improving the universality of polarimetric features in aerospace target identification applications, thereby improving the accuracy of target identification.

[0068] It should be noted that Inverse Synthetic Radar (ISAR) uses broadband signals to obtain range resolution and uses the inverse synthetic aperture generated by the moving target relative to the stationary radar to obtain azimuth resolution. High-resolution ISAR images of the target can be obtained through signal processing methods.

[0069] In this invention, the ISAR image includes sub-images corresponding to four polarization states: HH, HV, VH, and VV. Here, H represents horizontal polarization, V represents vertical polarization, the preceding letter indicates the transmission state, and the following letter indicates the reception state. It should be noted that the ISAR sub-images for each of the four polarization states at a preset azimuth center angle constitute a set of ISAR images.

[0070] The following description Figure 1 The execution method of each step is shown.

[0071] First, for step 100, acquire the ISAR image of the target to be identified at a preset azimuth center angle, including:

[0072] Acquire broadband frequency sweep data of the target to be identified;

[0073] The broadband sweep frequency data is divided into several segments along the azimuth direction; the window length of the imaging accumulation angle of each segment is the same, and the angle sliding window step size of adjacent segments is the same.

[0074] For each data segment, execute:

[0075] Determine the azimuth center angle of this data segment;

[0076] Two-dimensional imaging focusing processing is performed on this data segment to obtain an ISAR image at the azimuth center angle;

[0077] The preset azimuth center angle includes the azimuth center angle of each data segment.

[0078] This invention uses ISAR images for scattering center extraction. Compared with directly extracting scattering centers from high-resolution range images (HRRP), ISAR images are two-dimensional range images including the azimuth direction, while HRRP images are one-dimensional range images excluding the azimuth direction. Therefore, the scattering center features obtained using ISAR images are more comprehensive. Experiments have also shown that the polarization ratio distribution of the scattering centers obtained based on ISAR images is more stable, meaning that the target polarization scattering matrix is ​​less sensitive to the radar line-of-sight angle, thus further improving the accuracy of target identification.

[0079] In a preferred embodiment, the number of segment data is determined by the following formula:

[0080]

[0081] Where Q represents the number of segment data; L represents the azimuth length of the broadband swept frequency data; N represents the window length of the imaging accumulation angle; and M represents the angle sliding window step size.

[0082] It should be noted that the number of preset azimuth center angles is the same as the number of segment data.

[0083] Specifically, for example, if the broadband frequency sweep data is the measurement data of 8.5GHz to 10.5GHz with an azimuth angle of -10° to 40°, then L is the azimuth length of -10° to 40°, and L = 50°; when N = 20° and M = 1°, Q = 31, that is, the number of preset azimuth center angles is also 31, and the value range of the preset azimuth center angle is any integer in [0°, 30°]. For the initial segment data, the corresponding azimuth angle range is -10° to 10°, and its initial azimuth center angle is 0°; for the final segment data, the corresponding azimuth angle range is 20° to 40°, and its final azimuth center angle is 30°.

[0084] In a preferred embodiment, a filtered inverse projection algorithm is used for two-dimensional imaging focusing processing.

[0085] Specifically, the preset azimuth center angle is A filtered inverse projection algorithm is used to perform two-dimensional imaging focusing processing on the broadband swept frequency data of the target to be identified, to obtain... The following ISAR images include:

[0086] Under a certain polarization state, the azimuth center angle The corresponding broadband radar swept-frequency complex echo (i.e. The corresponding broadband sweep data of the segment is G(k,θ), where k is the spatial frequency, k = 2f / c, c is the speed of light, f is the frequency range of the broadband sweep data, θ is the azimuth angle, and j is the imaginary unit. Range filtering is applied to G(k,θ) to obtain the high-resolution range profile HRRP.

[0087]

[0088] Where B is the bandwidth of the spatial frequency k; l = ycosθ - xsinθ is the projection line; (x, y) represents the pixel position on the imaging plane; k min =2f min / c,f min is the minimum frequency corresponding to the broadband sweep data; j is the imaginary unit.

[0089] right Azimuth backprojection is performed to obtain high-resolution ISAR images:

[0090]

[0091] Where, θ min for The starting azimuth angle of the corresponding segment data; θ max for The azimuth angle of the corresponding segment data; j is the imaginary unit;

[0092] Using the above formulas (2) and (3), the azimuth center angle is obtained. High-resolution ISAR images under four polarization states—HH, VV, HV, and VH—are denoted as follows: and

[0093] For step 102, scattering centers are extracted from all sub-images in the ISAR image to obtain the amplitude values ​​of at least two scattering centers, including:

[0094] For each sub-image, the following steps are performed: using prior information and the peak-to-maximum method to separate and extract the sub-image, and obtain the amplitude values ​​of at least two scattering centers in the corresponding polarization state of the sub-image.

[0095] Specifically, prior information and the peak-to-maximum method are used to separate and extract scattering centers in ISAR images, obtaining the amplitude value of the m-th scattering center under different polarization states at the current preset azimuth center angle. and Where (x) m ,y m ) represents the position of the m-th scattering center, and |·| represents the modulus operation.

[0096] In step 104, based on the amplitude values ​​extracted from each group of ISAR images, the amplitude matrix corresponding to each scattering center is determined, including:

[0097] Based on the scattering center, the amplitude values ​​extracted from each group of ISAR images are classified to obtain an amplitude value group for each scattering center; wherein, the amplitude value group includes the amplitude values ​​of the scattering center corresponding to the four polarization states at a preset azimuth center angle;

[0098] The amplitude matrix is ​​obtained by using the amplitude values ​​in the amplitude value group as elements of the amplitude matrix.

[0099] Specifically, for the m-th scattering center, the amplitude values ​​extracted from scattering centers at different preset azimuth center angles are correlated based on the minimum distance criterion to obtain an amplitude value group for each scattering center. Each amplitude value group includes 4*Q amplitude values, where 4 represents the four polarization states and Q is the number of preset azimuth center angles. Each amplitude value is used as an element of the amplitude matrix to obtain the fully polarized scattering amplitude matrix. For example, continuing from the previous example, when Q = 31, the amplitude matrix of the m-th scattering center has 124 elements.

[0100] For step 106, based on the amplitude matrix, the polarization ratio distribution of the scattering center is obtained, including:

[0101] For each scattering center, perform the following:

[0102] For each preset azimuth center angle, execute:

[0103] Obtain the amplitude value of the scattering center at the preset azimuth center angle; wherein, the amplitude value includes a first amplitude value under HH polarization, a second amplitude value under HV polarization, a third amplitude value under VH polarization, and a fourth amplitude value under VV polarization;

[0104] The polarization ratio is obtained based on the first amplitude value, the second amplitude value, the third amplitude value, and the fourth amplitude value;

[0105] The polarization ratios of each preset azimuth center angle are arranged according to the azimuth direction of the preset azimuth center angle to obtain the polarization ratio distribution of the scattering center.

[0106] In a preferred embodiment, the polarization ratio includes a first polarization ratio, a second polarization ratio, and a third polarization ratio;

[0107] The first polarization ratio is determined by the following formula:

[0108]

[0109] The second polarization ratio is determined by the following formula:

[0110]

[0111] The third polarization ratio is determined by the following formula:

[0112]

[0113] in, Used to characterize the first polarization ratio; Used to characterize the first amplitude value; Used to characterize the fourth amplitude value; Used to characterize the second polarization ratio; Used to characterize the second amplitude value; Used to characterize the third polarization ratio; Used to characterize the third amplitude value; (x) m ,y m This is used to characterize the pixel location of the scattering center m in the ISAR image; Used to characterize the i-th preset azimuth center angle.

[0114] In this invention, the polarization ratio distribution calculated by the above formulas (4) to (6) is stable and changes very little with the azimuth angle, or even does not change at all with the azimuth angle. This makes the polarization characteristics of the target to be detected relatively stable and less sensitive to the radar line-of-sight angle, thereby improving the accuracy of target identification.

[0115] Specifically, for example, for the target spherical cone to be identified (such as...) Figure 4 , 6 Or as shown in Figure 8), its corresponding fully polarized RCS anechoic chamber measurement data were obtained at a frequency of 10 GHz (e.g. Figure 2 (as shown) and polarization ratio curve distribution (as shown) Figure 3 (As shown). From Figure 2 and Figure 3 As can be seen, the polarization ratio of narrowband data oscillates significantly with azimuth angle, indicating that narrowband polarization features have strong attitude sensitivity and cannot reflect the regular mapping between target structural properties and polarization features.

[0116] Scattering centers were extracted from the ISAR image of the target, yielding three scattering centers: scattering center 1, scattering center 2, and scattering center 3. Figures 4 to 9 In the ISAR image, the frequency sweep range of the measurement data is 8.5 GHz to 10.5 GHz, the window length of the imaging azimuth accumulation angle is 20°, the azimuth center angle is at 1° interval (i.e., the angle window step size), and the preset azimuth center angle varies uniformly from 0° to 30°. Figure 4 and Figure 5 The broadband ISAR image of the target and the polarization ratio curve distribution corresponding to scattering center 1 are shown respectively. Figure 4 and Figure 5 It can be seen that the amplitude values ​​of the scattering centers of HH polarization and VV polarization are approximately equal, while the magnitudes of cross-polarization and co-polarization differ significantly. Furthermore, the polarization characteristic distribution of the head-oriented spherical structure is stable and hardly changes with the azimuth angle.

[0117] Figure 6 and Figure 7 The polarization ratio curves corresponding to the broadband ISAR image and scattering center 2 are shown respectively. Figure 6 and Figure 7 It can be seen that, due to the geometric relationship between the tail edge orientation and the polarization direction, the amplitude of the tail lateral scattering center in the HH polarization state is greater than that in the VV polarization state; on the tail edge structure, the cross-polarization scattering intensity is approximately equivalent to that in the same polarization. In addition, the polarization characteristic distribution of the tail edge structure is relatively stable and less dependent on the azimuth angle.

[0118] Figure 8 and Figure 9 The polarization ratio curves corresponding to the broadband ISAR image and scattering center 3 are shown respectively. Figure 8 and Figure 9 It can be seen that, because the lateral edge scattering center is formed by splicing a spherical cone and a cylinder, and has a gap structure, multiple scattering occurs, thus the polarization characteristic curve is affected by the azimuth angle to some extent; however, compared to... Figure 2 and Figure 3 The narrow-band RCS shown has a smoother polarization characteristic change in the lateral edge (slot) structure.

[0119] It should be noted that, Figures 2 to 9 The targets to be identified in the samples are all the same, and all are spherical cone targets.

[0120] In summary, this invention, for broadband high-resolution observation conditions, separates the scattering centers of the cone-shaped head, cone-shaped edges, and cone-shaped tail fins of aerospace targets using a scattering center extraction method. This allows for more effective differentiation of the polarization characteristics of various components and scattering types within the target to be identified, providing a new dimension of input for aerospace target component identification, model identification, and authenticity identification. It should be noted that aerospace targets include various types of aircraft and spacecraft.

[0121] like Figure 10 , Figure 11 As shown, this embodiment of the invention provides a fully polarimetric scattering feature extraction device. The device embodiment can be implemented through software, hardware, or a combination of both. From a hardware perspective, as... Figure 10 The diagram shown is a hardware architecture diagram of a computing device containing a fully polarimetric scattering feature extraction device according to an embodiment of the present invention. (Except for...) Figure 10 In addition to the processor, memory, network interface, and non-volatile memory shown, the computing device in the embodiment may also include other hardware, such as a forwarding chip responsible for processing packets. Taking software implementation as an example, such as... Figure 11 As shown, as a logical device, it is formed by the CPU of its computing device reading the corresponding computer program from the non-volatile memory into the memory for execution. This embodiment provides a fully polarimetric scattering feature extraction device, including: an acquisition module 1100, an extraction module 1102, a determination module 1104, and a calculation module 1106;

[0122] The acquisition module 1100 is used to acquire the ISAR image of the target to be identified at a preset azimuth center angle; wherein, the ISAR image includes sub-images corresponding to four polarization states;

[0123] The extraction module 1102 is used to perform the following for each group of ISAR images: extract the scattering centers of each sub-image in the ISAR image to obtain the amplitude values ​​of at least two scattering centers;

[0124] The determination module 1104 is used to determine the amplitude matrix corresponding to each scattering center based on the amplitude values ​​extracted from each group of ISAR images; wherein, the amplitude matrix includes the amplitude value of the scattering center at a preset azimuth center angle;

[0125] The operation module 1106 is used to obtain the polarization ratio distribution of the scattering center based on the amplitude matrix.

[0126] In some specific implementations, the acquisition module 1100 can be used to perform the above step 100, the extraction module 1102 can be used to perform the above step 102, the determination module 1104 can be used to perform the above step 104, and the calculation module 1106 can be used to perform the above step 106.

[0127] In some specific implementations, the ISAR image includes sub-images corresponding to four polarization states: HH, HV, VH, and VV. Here, H represents horizontal polarization, V represents vertical polarization, the first letter indicates the transmission state, and the second letter indicates the reception state.

[0128] In some specific implementations, the acquisition module 1100 is used to perform the following operations:

[0129] Acquire broadband frequency sweep data of the target to be identified;

[0130] The broadband sweep frequency data is divided into several data segments along the azimuth direction; the window length of the imaging accumulation angle of each data segment is the same, and the angle sliding window step size of adjacent data segments is the same.

[0131] The number of data segments is determined by the following formula:

[0132] ;

[0133] Where Q represents the number of segment data; L represents the azimuth length of the broadband swept frequency data; N represents the window length of the imaging accumulation angle; and M represents the angle sliding window step size.

[0134] For each data segment, execute:

[0135] Determine the azimuth center angle of this data segment;

[0136] Two-dimensional imaging focusing processing is performed on this data segment to obtain an ISAR image at the azimuth center angle;

[0137] The preset azimuth center angle includes the azimuth center angle of each data segment.

[0138] In some specific implementations, a filtered inverse projection algorithm is used for two-dimensional imaging focusing.

[0139] In some specific implementations, the extraction module 1102 is used to perform the following operations:

[0140] For each sub-image, the following steps are performed: using prior information and the peak-to-maximum method to separate and extract the sub-image, and obtain the amplitude values ​​of at least two scattering centers in the corresponding polarization state of the sub-image.

[0141] In some specific implementations, the determining module 1104 is used to perform the following operations:

[0142] Based on the scattering center, the amplitude values ​​extracted from each group of ISAR images are classified to obtain an amplitude value group for each scattering center; wherein, the amplitude value group includes the amplitude values ​​of the scattering center corresponding to the four polarization states at a preset azimuth center angle;

[0143] The amplitude matrix is ​​obtained by using the amplitude values ​​in the amplitude value group as elements of the amplitude matrix.

[0144] In some specific implementations, the arithmetic module 1106 is used to perform the following operations:

[0145] For each scattering center, perform the following:

[0146] For each preset azimuth center angle, execute:

[0147] Obtain the amplitude value of the scattering center at the preset azimuth center angle; wherein, the amplitude value includes a first amplitude value under HH polarization, a second amplitude value under HV polarization, a third amplitude value under VH polarization, and a fourth amplitude value under VV polarization;

[0148] The polarization ratio is obtained based on the first amplitude value, the second amplitude value, the third amplitude value, and the fourth amplitude value;

[0149] The polarization ratio includes the first polarization ratio, the second polarization ratio, and the third polarization ratio;

[0150] The first polarization ratio is determined by the following formula:

[0151]

[0152] The second polarization ratio is determined by the following formula:

[0153]

[0154] The third polarization ratio is determined by the following formula:

[0155]

[0156] in, Used to characterize the first polarization ratio; Used to characterize the first amplitude value; Used to characterize the fourth amplitude value; Used to characterize the second polarization ratio; Used to characterize the second amplitude value; Used to characterize the third polarization ratio; Used to characterize the third amplitude value; (x)m ,y m This is used to characterize the pixel location of the scattering center m in the ISAR image; Used to characterize the i-th preset azimuth center angle;

[0157] The polarization ratios of each preset azimuth center angle are arranged according to the azimuth direction of the preset azimuth center angle to obtain the polarization ratio distribution of the scattering center.

[0158] It is understood that the structures illustrated in the embodiments of the present invention do not constitute a specific limitation on a fully polarimetric scattering feature extraction device. In other embodiments of the present invention, a fully polarimetric scattering feature extraction device may include more or fewer components than illustrated, or combine some components, split some components, or have different component arrangements. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0159] The information interaction and execution process between the modules in the above-mentioned device are based on the same concept as the method embodiment of the present invention, and the specific details can be found in the description of the method embodiment of the present invention, and will not be repeated here.

[0160] This invention also provides a computing device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements a fully polarimetric scattering feature extraction method according to any embodiment of this invention.

[0161] This invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform a fully polarimetric scattering feature extraction method according to any embodiment of this invention.

[0162] Specifically, a system or apparatus equipped with a storage medium may be provided, on which software program code implementing the functions of any of the embodiments described above is stored, and the computer (or CPU or MPU) of the system or apparatus may read and execute the program code stored in the storage medium.

[0163] In this case, the program code read from the storage medium can itself implement the function of any of the above embodiments, and therefore the program code and the storage medium storing the program code constitute part of the present invention.

[0164] Examples of storage media used to provide program code include floppy disks, hard disks, magneto-optical disks, optical disks (such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW), magnetic tapes, non-volatile memory cards, and ROMs. Alternatively, program code can be downloaded from a server computer via a communication network.

[0165] Furthermore, it should be clear that not only can the program code read by the computer be executed, but also the operating system or other components operating on the computer can be instructed based on the program code to perform some or all of the actual operations, thereby realizing the function of any of the embodiments described above.

[0166] Furthermore, it is understood that the program code read from the storage medium is written to the memory set in the expansion board inserted into the computer or to the memory set in the expansion module connected to the computer. Then, based on the instructions of the program code, the CPU or other components installed on the expansion board or expansion module execute some and all of the actual operations, thereby realizing the function of any of the above embodiments.

[0167] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0168] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media that can store program code, such as ROM, RAM, magnetic disk, or optical disk.

[0169] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for extracting fully polarimetric scattering features, characterized in that, include: Acquire an ISAR image of the target to be identified at a preset azimuth center angle; wherein, the ISAR image includes sub-images corresponding to four polarization states; the ISAR image is obtained from broadband frequency sweep data; For each group of ISAR images, the following steps are performed: scattering centers are extracted from all sub-images in the ISAR image to obtain the amplitude values ​​of at least two scattering centers; the ISAR image includes sub-images corresponding to four polarization states: HH, HV, VH, and VV; where H represents horizontal polarization, V represents vertical polarization, the first letter indicates the transmission state, and the second letter indicates the reception state. Based on the amplitude values ​​extracted from each group of ISAR images, an amplitude matrix corresponding to each scattering center is determined; wherein, the amplitude matrix includes the amplitude value of the scattering center at the preset azimuth center angle; Based on the amplitude matrix, the polarization ratio distribution of the scattering center is obtained; The step of determining the amplitude matrix corresponding to each scattering center based on the amplitude values ​​extracted from each group of ISAR images includes: Based on the scattering center, the amplitude values ​​extracted from each group of ISAR images are classified to obtain an amplitude value group for each scattering center; wherein, the amplitude value group includes the amplitude values ​​of the scattering center corresponding to four polarization states at the preset azimuth center angle; The amplitude matrix is ​​obtained by using the amplitude values ​​in the amplitude value group as elements of the amplitude matrix; The step of obtaining the polarization ratio distribution of the scattering center based on the amplitude matrix includes: For each of the aforementioned scattering centers, the following is performed: For each preset azimuth center angle, execute: Obtain the amplitude value of the scattering center at the preset azimuth center angle; wherein the amplitude value includes a first amplitude value under HH polarization, a second amplitude value under HV polarization, a third amplitude value under VH polarization, and a fourth amplitude value under VV polarization; The polarization ratio is obtained based on the first amplitude value, the second amplitude value, the third amplitude value, and the fourth amplitude value; The polarization ratios of each preset azimuth center angle are arranged according to the azimuth direction of the preset azimuth center angle to obtain the polarization ratio distribution of the scattering center.

2. The method according to claim 1, characterized in that, The acquisition of the ISAR image of the target to be identified at a preset azimuth center angle includes: Acquire the broadband frequency sweep data of the target to be identified; The broadband sweep frequency data is divided into several data segments along the azimuth direction; wherein, the window length of the imaging accumulation angle of each data segment is the same, and the angle sliding window step size of adjacent data segments is the same. For each data segment, execute: Determine the azimuth center angle of this data segment; Two-dimensional imaging focusing processing is performed on this data segment to obtain an ISAR image at the central angle of the stated azimuth; The preset azimuth center angle includes the azimuth center angle of each data segment.

3. The method according to claim 2, characterized in that, The number of data segments is determined by the following formula: ； in, Used to represent the number of segments of data; L Used to characterize the azimuth length of the broadband sweep frequency data; N The window length is used to characterize the imaging accumulation angle; M is used to characterize the angle sliding window step size.

4. The method according to claim 2, characterized in that, A filtered inverse projection algorithm is used for two-dimensional imaging focusing.

5. The method according to claim 1, characterized in that, The polarization ratio includes a first polarization ratio, a second polarization ratio, and a third polarization ratio; The first polarization ratio is determined by the following formula: ； The second polarization ratio is determined by the following formula: ； The third polarization ratio is determined by the following formula: ； in, Used to characterize the first polarization ratio; Used to characterize the first amplitude value; Used to characterize the fourth amplitude value; Used to characterize the second polarization ratio; Used to characterize the second amplitude value; Used to characterize the third polarization ratio; Used to characterize the third amplitude value; (x) m ,y m ) is used to characterize the pixel position of the scattering center m in the ISAR image; Used to characterize the i-th preset azimuth center angle.

6. The method according to any one of claims 1 to 5, characterized in that, The step of extracting scattering centers from all sub-images in the ISAR image to obtain amplitude values ​​of at least two scattering centers includes: For each sub-image, the following steps are performed: the sub-image is separated and extracted using prior information and the peak-to-maximum method to obtain the amplitude values ​​of at least two scattering centers in the polarization state corresponding to the sub-image.

7. A device for extracting fully polarized scattering features, characterized in that, For implementing the method as described in any one of claims 1 to 6, comprising: The acquisition module is used to acquire an ISAR image of the target to be identified at a preset azimuth center angle; wherein, the ISAR image includes sub-images corresponding to four polarization states; The extraction module is used to perform the following for each group of ISAR images: extract the scattering centers of each sub-image in the ISAR image to obtain the amplitude values ​​of at least two scattering centers; The determining module is used to determine the amplitude matrix corresponding to each of the scattering centers based on the amplitude values ​​extracted from each group of ISAR images; wherein, the amplitude matrix includes the amplitude value of the scattering center at the preset azimuth center angle; The calculation module is used to obtain the polarization ratio distribution of the scattering center based on the amplitude matrix.

8. A computing device comprising a memory and a processor, wherein the memory stores a computer program, and the processor, when executing the computer program, implements the method as described in any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, causes the computer to perform the method of any one of claims 1-6.

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