A method and apparatus for modeling electromagnetic scattering properties of a target optical region

Abstract

The application relates to the technical field of radar target scattering characteristic modeling, and discloses a target optical area electromagnetic scattering characteristic modeling method and device, which comprises the following steps: acquiring a multi-view wideband electromagnetic scattering frequency response of a target; calculating one-dimensional scattering center parameter estimators of the target at each view angle by using the multi-view wideband electromagnetic scattering frequency response; acquiring a scattering intensity field of the target in a three-dimensional space by using a RANSAC method and a Parzen window estimation method according to the one-dimensional scattering center parameter estimators; obtaining a rough position of a three-dimensional scattering center in the scattering intensity field by using a three-dimensional spectrum peak search method; and calculating the accurate position of the three-dimensional scattering center by projection, correlation and relocation. In this way, the three-dimensional scattering center of the target can be stably obtained based on the RANSAC and three-dimensional spectrum peak search ideas, and has good consistency with the target structure and scattering principle, so that the electromagnetic scattering characteristics of the target can be accurately reconstructed by using fewer three-dimensional scattering centers.

Description

Technical Field

[0001] This invention relates to the field of radar target scattering characteristic modeling technology, and in particular to a method and apparatus for modeling the electromagnetic scattering characteristics of the target's optical region. Background Technology

[0002] Parametric modeling techniques for the broadband electromagnetic scattering characteristics of radar targets can compress, reconstruct, and generalize target characteristic data, and have been widely applied in radar target detection, identification, imaging, and echo simulation. In recent years, three-dimensional scattering center models based on Geometrical Theory of Diffraction (GTD) have attracted widespread attention due to their excellent ability to fit target scattering characteristics. Both experimental measurements and theoretical calculations show that, in the optical region, the total electromagnetic scattering of a target can be considered as a synthesis of electromagnetic scattering from certain local locations; these scattering sources are called equivalent scattering centers.

[0003] The inverse 3D scattering center modeling method utilizes the multi-view broadband electromagnetic scattering characteristics data of the target to extract a 3D scattering center model, which has low computational complexity and high modeling accuracy. However, existing methods for inverse 3D scattering center modeling of the electromagnetic scattering characteristics of the target's optical region, such as methods based on generalized Hough transform and methods based on Random Sample Consensus (RANSAC), suffer from problems such as difficulty in extracting dominant scattering centers and the generation of a large number of false scattering centers, making them difficult to apply in engineering. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method and apparatus for modeling the electromagnetic scattering characteristics of a target's optical region, which can stably obtain the dominant equivalent three-dimensional scattering center of the target, reduce false scattering centers, and thus accurately reconstruct the electromagnetic scattering characteristics of the target using fewer three-dimensional scattering centers. The specific solution is as follows:

[0005] A method for modeling the electromagnetic scattering characteristics of a target optical region includes:

[0006] Acquire the target's multi-view broadband electromagnetic scattering frequency response;

[0007] Using the obtained multi-view broadband electromagnetic scattering frequency response, a one-dimensional scattering center parameter estimator for the target under each viewpoint is calculated;

[0008] Based on the calculated one-dimensional scattering center parameter estimator, the RANSAC method and Parzen window estimation method are used to obtain the scattering intensity field of the target in three-dimensional space.

[0009] The approximate location of the three-dimensional scattering center is obtained by using a three-dimensional spectral peak search method in the scattering intensity field.

[0010] The precise location of the three-dimensional scattering center is calculated through projection, correlation, and repositioning.

[0011] Preferably, in the target optical region electromagnetic scattering characteristic modeling method provided in the embodiments of the present invention, the step of calculating the one-dimensional scattering center parameter estimator of the target at each viewpoint using the acquired multi-view broadband electromagnetic scattering frequency response includes:

[0012] Using the obtained multi-view broadband electromagnetic scattering frequency response G(f) n ,θ p ,φ q The one-dimensional scattering center parameter estimator Λ of the target is calculated from each viewpoint using a one-dimensional scattering center estimation method. i :

[0013]

[0014] Where f is the frequency of the incident electromagnetic wave of the radar, n = 0,...,N-1 are the numbers of the sampling points for the frequency of the incident electromagnetic wave of the radar; θ is the elevation angle of the incident electromagnetic wave of the radar, p = 0,...,P-1 are the numbers of the sampling points for the elevation angle of the radar line of sight; φ is the azimuth angle of the incident electromagnetic wave of the radar, q = 0,...,Q-1 are the numbers of the sampling points for the azimuth angle of the radar line of sight; Let be the scattering coefficient, type parameter, and distance of the m-th one-dimensional scattering center along the i-th line of sight. Let be the number of one-dimensional scattering centers along the i-th line of sight.

[0015] Preferably, in the target optical region electromagnetic scattering characteristic modeling method provided in the embodiments of the present invention, the step of obtaining the target's scattering intensity field in three-dimensional space using the RANSAC method and the Parzen window estimation method based on the calculated one-dimensional scattering center parameter estimator includes:

[0016] The three-dimensional cube containing the target is divided into a series of spatially resolved units with an interval of Δl.

[0017] The scattering coefficients of the one-dimensional scattering center of the target from various viewpoints are normalized;

[0018] For each of the spatial resolution cells, a cumulative scattering intensity is set and initialized to 0;

[0019] Three lines of sight that are not in the same plane are randomly selected from the radar line of sight and denoted as i1, i2, and i3 respectively.

[0020] Assuming that the m1th scattering center on line of sight i1, the m2th scattering center on line of sight i2, and the m3th scattering center on line of sight i3 all originate from the same three-dimensional scattering center, calculate the coordinates of the three-dimensional scattering center;

[0021] Determine whether the coordinates of the three-dimensional scattering center fall within the target physical space range; if so, determine that the three-dimensional scattering center may be a real scattering center, and update the cumulative scattering intensity of the spatial resolution unit where the coordinates of the three-dimensional scattering center are located; if not, determine that the three-dimensional scattering center is a false scattering center and discard it; repeat the calculation of the coordinates of the three-dimensional scattering center until all possible combinations of m1, m2, m3 are traversed.

[0022] Repeat the steps of randomly selecting lines of sight and determining whether the coordinates of the three-dimensional scattering center fall within the target's physical space until the number of random line-of-sight selections reaches a preset upper limit, and obtain the cumulative amount of scattering intensity of the target in the entire three-dimensional space.

[0023] The cumulative scattering intensity of the target in three-dimensional space is convolved with a three-dimensional Parzen window function with a width of ΔL to obtain the scattering intensity field of the target in three-dimensional space.

[0024] Preferably, in the target optical region electromagnetic scattering characteristic modeling method provided in the embodiments of the present invention, the step of obtaining the approximate location of the three-dimensional scattering center using a three-dimensional spectral peak search method in the scattering intensity field includes:

[0025] A three-dimensional spectral peak search is performed on the acquired scattering intensity field to obtain the highest peak. Each spectral peak;

[0026] The center point of the spatial resolution unit where the spectral peak is located is taken as the approximate location of the three-dimensional scattering center.

[0027] Preferably, in the target optical region electromagnetic scattering characteristic modeling method provided in the embodiments of the present invention, the precise location of the three-dimensional scattering center is calculated by projection, correlation, and repositioning, including:

[0028] For each one-dimensional scattering center on each line of sight, set an association flag F(i,m) with an initial value of 0;

[0029] For each three-dimensional scattering center, associate the one-dimensional scattering centers on each line of sight with it based on the minimum distance criterion; for the i-th line of sight, calculate

[0030]

[0031] Where, δ k (i,m iLet d be the minimum distance difference between the k-th three-dimensional scattering center and the mi-th one-dimensional scattering center under the projection of the i-th line of sight. i Let be the direction vector of the i-th line of sight. The obtained approximate location;

[0032] Determine δ k (i,m i If the distance is greater than a preset distance threshold, then the k-th 3D scattering center is determined to be invisible from the i-th line of sight; otherwise, the m-th scattering center on the i-th line of sight is removed. i Each one-dimensional scattering center is associated with the k-th three-dimensional scattering center, and the association flag F(i,m) = k;

[0033] All I associated with the k-th three-dimensional scattering center k The set Ω is composed of one-dimensional scattering centers. k ;

[0034] According to set Ω k The projected distance of the one-dimensional scattering center is used to estimate the precise location of the k-th three-dimensional scattering center using the least squares method.

[0035] Preferably, in the target optical region electromagnetic scattering characteristic modeling method provided in the embodiments of the present invention, the precise location of the k-th three-dimensional scattering center is estimated using the following formula:

[0036]

[0037]

[0038]

[0039] in, H is the set of real numbers. k This is a matrix composed of the direction vectors of all visible lines of sight from the k-th three-dimensional scattering center. The I-th term represents the k-th three-dimensional scattering center. k The direction vector of the visible line of sight, i k,j For the k-th 3D scattering center and the j-th visible line of sight, The numbering of the one-dimensional scattering center associated with the k-th three-dimensional scattering center under the j-th visible line of sight.

[0040] Preferably, the target optical region electromagnetic scattering characteristic modeling method provided in the embodiments of the present invention further includes:

[0041] Correct the visibility of the three-dimensional scattering center from various viewpoints;

[0042] Estimate the type parameters and scattering coefficients of the three-dimensional scattering center.

[0043] Preferably, in the target optical region electromagnetic scattering characteristic modeling method provided in the embodiments of the present invention, the correction of the visibility of the three-dimensional scattering center at each viewing angle includes:

[0044] Construct a view visibility map for each 3D scattering center;

[0045] A morphological closing operation is performed on the constructed view visibility map to close the small holes in the view visibility map caused by missed scattering centers.

[0046] Preferably, in the target optical region electromagnetic scattering characteristic modeling method provided in the embodiments of the present invention, the estimation of the type parameter and scattering coefficient of the three-dimensional scattering center includes:

[0047] The mode of all type parameter estimators of one-dimensional scattering centers associated with each three-dimensional scattering center is used as the type parameter estimator of the three-dimensional scattering center.

[0048] By taking the type parameter estimator and precise location of the three-dimensional scattering center as true values, the scattering coefficients of all visible three-dimensional scattering centers on each line of sight are estimated using the least squares method.

[0049] This invention also provides a device for modeling the electromagnetic scattering characteristics of a target optical region, comprising:

[0050] The frequency response acquisition module is used to acquire the multi-view broadband electromagnetic scattering frequency response of the target;

[0051] The parameter estimator calculation module is used to calculate the one-dimensional scattering center parameter estimator of the target from each viewpoint using the acquired multi-view broadband electromagnetic scattering frequency response.

[0052] The scattering intensity field acquisition module is used to obtain the scattering intensity field of the target in three-dimensional space using the RANSAC method and the Parzen window estimation method based on the calculated one-dimensional scattering center parameter estimator.

[0053] A coarse location estimation module is used to obtain the coarse location of the three-dimensional scattering center using a three-dimensional spectral peak search method in the scattering intensity field.

[0054] The precise location calculation module is used to calculate the precise location of the three-dimensional scattering center through projection, correlation, and repositioning.

[0055] As can be seen from the above technical solution, the target optical region electromagnetic scattering characteristic modeling method provided by the present invention includes: obtaining the multi-view broadband electromagnetic scattering frequency response of the target; using the obtained multi-view broadband electromagnetic scattering frequency response, calculating the one-dimensional scattering center parameter estimator of the target at each viewpoint; based on the calculated one-dimensional scattering center parameter estimator, using the RANSAC method and the Parzen window estimation method to obtain the scattering intensity field of the target in three-dimensional space; using the three-dimensional spectral peak search method in the scattering intensity field to obtain the approximate position of the three-dimensional scattering center; and calculating the precise position of the three-dimensional scattering center through projection, correlation, and relocation.

[0056] The target optical region electromagnetic scattering characteristic modeling method provided by this invention, based on RANSAC and three-dimensional spectral peak search, can stably obtain the precise location of the dominant equivalent three-dimensional scattering center of the target. The obtained three-dimensional scattering center has good consistency with the target structure and scattering principle, greatly reducing false scattering centers. Therefore, it can accurately reconstruct a three-dimensional scattering center model with good target scattering characteristic fitting ability using fewer three-dimensional scattering centers, further improving modeling accuracy and reducing computational complexity. Furthermore, this invention also provides a corresponding device for the target optical region electromagnetic scattering characteristic modeling method, further enhancing the practicality of the method. This device has corresponding advantages. Attached Figure Description

[0057] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0058] Figure 1 A flowchart illustrating the method for modeling the electromagnetic scattering characteristics of a target optical region provided in an embodiment of the present invention;

[0059] Figure 2 A three-dimensional view of a three-dimensional CAD model of a cruise missile provided in an embodiment of the present invention;

[0060] Figure 3 A top view of a three-dimensional CAD model of a cruise missile provided in an embodiment of the present invention;

[0061] Figure 4 Left view of a three-dimensional CAD model of a cruise missile provided in an embodiment of the present invention;

[0062] Figure 5 A front view of a three-dimensional CAD model of a cruise missile provided in an embodiment of the present invention;

[0063] Figure 6 A schematic diagram of the multi-view broadband electromagnetic scattering frequency response of a target with a pitch angle of 90°, provided in an embodiment of the present invention;

[0064] Figure 7 A schematic diagram of the multi-view broadband electromagnetic scattering frequency response of a target with a pitch angle of 125°, provided for an embodiment of the present invention;

[0065] Figure 8 A schematic diagram of a multi-view high-resolution range image and a one-dimensional scattering center distribution of a target with a pitch angle of 90°, provided for an embodiment of the present invention;

[0066] Figure 9 A schematic diagram of a multi-view high-resolution range image of a target and a one-dimensional scattering center distribution when the elevation angle is 125°, provided for an embodiment of the present invention;

[0067] Figure 10 This is a schematic diagram of the scattering intensity field of the target in three-dimensional space provided in an embodiment of the present invention;

[0068] Figure 11 This is a schematic diagram showing the location of the three-dimensional scattering center of a cruise missile target provided in an embodiment of the present invention;

[0069] Figure 12 This is one of the modified three-dimensional scattering center view visibility maps provided in the embodiments of the present invention;

[0070] Figure 13 This is the second modified three-dimensional scattering center view visibility map provided in the embodiments of the present invention;

[0071] Figure 14 The third modified three-dimensional scattering center view visibility map provided in the embodiments of the present invention;

[0072] Figure 15 The fourth modified three-dimensional scattering center view visibility map provided in the embodiments of the present invention;

[0073] Figure 16 The correlation coefficient distribution histogram of the original and reconstructed high-resolution range images of the target provided in this embodiment of the invention;

[0074] Figure 17 The original high-resolution range image and reconstructed high-resolution range image of the target with an elevation angle of 90° and an azimuth angle of 120° are provided for embodiments of the present invention.

[0075] Figure 18 The original high-resolution range image and reconstructed high-resolution range image of the target with an elevation angle of 125° and an azimuth angle of 9° are provided for embodiments of the present invention.

[0076] Figure 19The original RCS diagram of the target provided in the embodiments of the present invention;

[0077] Figure 20 The reconstructed RCS diagram of the target provided in the embodiments of the present invention;

[0078] Figure 21 A schematic diagram of the structure of the target optical region electromagnetic scattering characteristics modeling device provided in an embodiment of the present invention. Detailed Implementation

[0079] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0080] This invention provides a method for modeling the electromagnetic scattering characteristics of a target optical region, such as... Figure 1 As shown, it includes the following steps:

[0081] S101. Obtain the target's multi-view broadband electromagnetic scattering frequency response.

[0082] In practical applications, according to GTD theory, the single-station backscattering frequency response of a target when it is irradiated by electromagnetic waves from a given angle can be expressed as:

[0083]

[0084] Where f and f0 are the frequency and initial frequency of the incident electromagnetic wave, respectively; M is the number of scattering centers; a m ,r m ,κ m Let j represent the scattering coefficient, distance, and type parameter of the m-th scattering center, respectively. Equation (1) can be called the one-dimensional scattering center model of GTD. When considering multiple incident angles of electromagnetic waves, the three-dimensional scattering center model can be represented by Equation (2):

[0085]

[0086] Where θ and φ are the elevation and azimuth angles of the radar incident wave, respectively; a m (θ,φ) represents the scattering coefficient of the m-th three-dimensional scattering center. Due to the anisotropy and mutual occlusion of the scattering centers, it is a function of the incident angle; [x m ,y m ,z m ] T It is the location of the m-th three-dimensional scattering center.

[0087] In this invention, the multi-view broadband electromagnetic scattering frequency response G(f) of the target is obtained. n ,θ p ,φ q ), where n = 0,...,N-1 are the sampling points for the radar incident electromagnetic wave frequency; θ is the elevation angle of the radar incident electromagnetic wave, p = 0,...,P-1 are the sampling points for the radar line-of-sight elevation angle; φ is the azimuth angle of the radar incident electromagnetic wave, q = 0,...,Q-1 are the sampling points for the radar line-of-sight azimuth angle. For simplicity, a one-dimensional index value i is used to replace the elevation-azimuth number pair (p,q), where i = (p-1)Q + q. q(i) = mod(i, Q). The direction vector of the i-th radar line of sight is defined as:

[0088] d i =[sinθ p(i) cosφ q(i) sinθ p(i) sinφ q(i) ,sinφ q(i) ] T (3)

[0089] The direction vector di of the i-th radar line of sight mentioned above will be used in subsequent steps.

[0090] It should be noted that there are multiple ways to obtain the above-mentioned multi-view broadband electromagnetic scattering frequency response, such as: obtaining it through electromagnetic simulation based on a high-precision CAD model of the target; obtaining it through microwave anechoic chamber measurement based on a real target or a physical model of the target; and obtaining it through field measurement based on a real target or a physical model of the target.

[0091] In an example of the present invention, with Figures 2 to 5 Taking a cruise missile as an example, electromagnetic simulation can be used to obtain... Figure 6 and Figure 7 The multi-view broadband electromagnetic scattering frequency response of the cruise missile model is shown. The electromagnetic simulation parameters are as follows: frequency sampling f = 10:0.01:10.5 GHz, pitch angle sampling θ = 45:5:135, pitch angle sampling... The electromagnetic wave polarization mode is HH polarization.

[0092] S102. Using the obtained multi-view broadband electromagnetic scattering frequency response, calculate the one-dimensional scattering center parameter estimator of the target from each viewpoint.

[0093] In specific implementation, step S102 utilizes the acquired multi-view broadband electromagnetic scattering frequency response to calculate the one-dimensional scattering center parameter estimator for each viewpoint of the target, which may specifically include:

[0094] Utilizing the acquired target's multi-view broadband electromagnetic scattering frequency response G(f n ,θ p ,φ q The one-dimensional scattering center parameter estimator Λ of the target is calculated from each viewpoint using a one-dimensional scattering center estimation method. i :

[0095]

[0096] in, Let be the scattering coefficient, type parameter, and distance of the m-th one-dimensional scattering center along the i-th line of sight. Let be the number of one-dimensional scattering centers along the i-th line of sight.

[0097] It should be noted that the one-dimensional scattering center parameter estimator can be obtained through super-resolution spectral estimation or generalized likelihood ratio test.

[0098] In an example of this invention, the ESPRIT method for super-resolution spectral estimation is used to obtain a one-dimensional scattering center parameter estimator for a cruise missile target. The distribution of the target's multi-view high-resolution range profile and one-dimensional scattering center is as follows: Figure 8 and Figure 9 As shown.

[0099] S103. Based on the calculated one-dimensional scattering center parameter estimator, use the RANSAC method and the Parzen window estimation method to obtain the scattering intensity field of the target in three-dimensional space.

[0100] Specifically, based on the target's multi-view one-dimensional scattering center parameter estimator Λ i The RANSAC principle and Parzen window estimation method can be used to obtain the scattering intensity field of the target in three-dimensional space.

[0101] In specific implementation, in the target optical region electromagnetic scattering characteristic modeling method provided in the embodiments of the present invention, step S103 uses the RANSAC method and the Parzen window estimation method to obtain the scattering intensity field of the target in three-dimensional space based on the calculated one-dimensional scattering center parameter estimator, which may specifically include the following steps:

[0102] Step 1: Divide the three-dimensional cube containing the target into a series of tiny spatially resolved units with an interval of Δl; let the length, width, and height of the target be L, L, and L, respectively. x L y L z Therefore, the number of spatial resolution units is:

[0103]

[0104] Let the center position of each spatial resolution unit be denoted as Where l = 0,...,K x -1, w = 0,...,K y -1, h = 0,...,K z -1.

[0105] Step 2: Normalize the scattering coefficients of the one-dimensional scattering center of the target from each viewpoint to obtain the normalized scattering coefficients.

[0106]

[0107] Step 3: For each spatial resolution cell, set a cumulative scattering intensity U(l,w,h) and initialize it to 0.

[0108] Step 4: Randomly select three lines of sight from the radar lines of sight {1,2,…,PQ}, and denot them as i1, i2, and i3 respectively, ensuring that these three lines of sight are not in the same plane.

[0109] Step 5: Assuming that the m1th scattering center on line of sight i1, the m2th scattering center on line of sight i2, and the m3th scattering center on line of sight i3 all originate from the same three-dimensional scattering center, calculate the coordinates of the three-dimensional scattering center using equations (1)-(3).

[0110]

[0111] Next, determine the coordinates of the three-dimensional scattering center. Does it fall within the target's physical space? If not, the 3D scattering center is determined to be a false scattering center and discarded; if so, the 3D scattering center is determined to be likely a true scattering center and updated. The position of Cumulative scattering intensity of each spatially resolved cell:

[0112]

[0113] in,

[0114]

[0115] The average intensity of this three-dimensional scattering center.

[0116] Repeat step five until all possible combinations of m1, m2, and m3 have been traversed. It should be noted that the average intensity of the three-dimensional scattering centers described above can be the arithmetic or geometric mean of the intensities of the one-dimensional scattering centers.

[0117] Step Six: Repeat the steps of randomly selecting lines of sight and determining whether the coordinates of the three-dimensional scattering center fall within the target's physical space. That is, repeat Steps Four and Five until the number of random line-of-sight selections reaches the preset upper limit N. extr The cumulative scattering intensity of the target in the entire three-dimensional space is obtained as U(l,w,h).

[0118] Step 7: Convolve the cumulative scattering intensity U(l,w,h) of the target in three-dimensional space with a three-dimensional Parzen window function W(l,w,h) of width ΔL to obtain the scattering intensity field V(l,w,h) of the target in three-dimensional space:

[0119] V(l,w,h)=U(l,w,h)⊙W(l,w,h); (10)

[0120] Here, ⊙ represents a three-dimensional convolution operation. It should be noted that the aforementioned three-dimensional Parzen window function W(l,w,h) can be a Gaussian window or a cube window.

[0121] In an example of the present invention, the length L of the target x = 8.5m, width L y = 4.4m, height L z =2.4m, spatial resolution unit size Δl = 0.075m, window length of the 3D Parzen window function ΔL = 0.675m, upper limit N for random line-of-sight sampling. extr =100000, the average intensity of the three-dimensional scattering centers is taken as the arithmetic mean of the intensity of the one-dimensional scattering centers, and the three-dimensional Parzen window function is a Gaussian window. The scattering intensity field of the target in three-dimensional space is as follows: Figure 10 As shown.

[0122] S104. Use the three-dimensional spectral peak search method in the scattering intensity field to obtain the approximate location of the three-dimensional scattering center.

[0123] In a specific implementation, in the target optical region electromagnetic scattering characteristic modeling method provided in the embodiments of the present invention, step S104 uses a three-dimensional spectral peak search method to obtain the approximate location of the three-dimensional scattering center in the scattering intensity field, which may specifically include the following steps:

[0124] First, a three-dimensional spectral peak search is performed on the obtained scattering intensity field V(l,w,h) of the target in three-dimensional space to obtain the highest peak. One significant spectral peak;

[0125] Then, the center point of the spatial resolution unit where the spectral peak is located. As a rough location of the three-dimensional scattering center.

[0126] It should be noted that the selection of the above-mentioned significant spectral peaks can be based on the absolute height of the peak, the relative height of the peak, or a comprehensive index composed of the absolute height, relative height, width, and other characteristics of the peak.

[0127] S105. Calculate the precise location of the three-dimensional scattering center through projection, correlation, and repositioning.

[0128] In a specific implementation, in the target optical region electromagnetic scattering characteristic modeling method provided in the embodiments of the present invention, step S105 processes the obtained coarse position through projection, association, and repositioning to obtain the precise position of the three-dimensional scattering center, which may specifically include the following steps:

[0129] Step 1: For each one-dimensional scattering center along each line of sight, set an association flag F(i,m) with an initial value of 0; where i = 0, ..., PQ-1.

[0130] The second step is to associate each three-dimensional scattering center with the one-dimensional scattering center along each line of sight using the minimum distance as the criterion; for the i-th line of sight, calculate...

[0131]

[0132] Where, δ k (i,m i ) represents the k-th three-dimensional scattering center and its relationship with the m-th scattering center under the projection of the i-th line of sight. i The minimum distance difference between the one-dimensional scattering centers, d i Let be the direction vector of the i-th line of sight. To obtain a rough location;

[0133] Determine δ k (i,m i If the distance is greater than a preset distance threshold δ, then the k-th 3D scattering center is determined to be invisible from the i-th line of sight; otherwise, the m-th scattering center on the i-th line of sight is removed. i Each one-dimensional scattering center is associated with the k-th three-dimensional scattering center, and the association flag is set as follows:

[0134] F(i,m)=k; (12)

[0135] All I associated with the k-th three-dimensional scattering center k The set Ω is composed of one-dimensional scattering centers. k :

[0136]

[0137] Use {i k,j ,mk,j} represents the set Ω k The j-th element.

[0138] Step 3: Based on set Ω k The projected distance of the one-dimensional scattering center is used to estimate the precise location of the k-th three-dimensional scattering center using the least squares method.

[0139] In practical implementation, the precise location of the k-th three-dimensional scattering center can be estimated using the following formula:

[0140]

[0141] Among them, matrix

[0142]

[0143]

[0144] in, H is the set of real numbers. k This is a matrix composed of the direction vectors of all visible lines of sight from the k-th three-dimensional scattering center. The I-th term represents the k-th three-dimensional scattering center. k The direction vector of the visible line of sight, i k,j For the k-th 3D scattering center and the j-th visible line of sight, The numbering of the one-dimensional scattering center associated with the k-th three-dimensional scattering center under the j-th visible line of sight.

[0145] In an example of the present invention, the precise location of the three-dimensional scattering center of the cruise missile target is as follows: Figure 11 As shown. By Figure 11 It can be seen that the target has eight main three-dimensional scattering centers, which are distributed on the warhead, main wing and tail fin of the cruise missile.

[0146] Furthermore, in a specific implementation, the target optical region electromagnetic scattering characteristic modeling method provided in the above embodiment of the present invention may further include, after executing step S105: correcting the visibility of the three-dimensional scattering center at each viewing angle; estimating the type parameters and scattering coefficient of the three-dimensional scattering center.

[0147] In specific implementation, in the target optical region electromagnetic scattering characteristic modeling method provided in the embodiments of the present invention, the above steps of correcting the visibility of the three-dimensional scattering center at each viewpoint may specifically include the following steps:

[0148] First, construct a view visibility map for each 3D scattering center. If there exists a one-dimensional scattering center on the i-th line of sight that is associated with the k-th three-dimensional scattering center, let S k(p(i),q(i))=1; otherwise, let S k (p(i),q(i))=0;

[0149] Then, the constructed view visibility graph S k Perform morphological closing operations to bridge small holes in the spectral visibility map caused by missed scattering centers:

[0150] S k ←morph_close(S k ,SE); (17)

[0151] SE is the structuring element for performing morphological operations.

[0152] In an example of the present invention, the angular visibility diagram of the three-dimensional scattering center of the cruise missile target is as follows: Figures 12 to 15 As shown.

[0153] In specific implementation, in the target optical region electromagnetic scattering characteristic modeling method provided in the embodiments of the present invention, the estimation of the type parameter and scattering coefficient of the three-dimensional scattering center in the above steps may specifically include the following steps:

[0154] First, the mode of the type parameter estimators of all one-dimensional scattering centers associated with each three-dimensional scattering center is taken as the type parameter estimator of the three-dimensional scattering center, that is:

[0155]

[0156] Then, record all lines visible from the i-th line. A set of three-dimensional scattering centers

[0157]

[0158] Use k i,j Represents set Ψ i The j-th element. The type parameter estimator of the three-dimensional scattering center. and precise location Treating them as true values, the least squares method is used to estimate the scattering coefficients of all visible three-dimensional scattering centers along the i-th line of sight.

[0159]

[0160]

[0161]

[0162]

[0163]

[0164] in, For the target at pitch angle θ p(i) Azimuth The raw electromagnetic scattering data corresponding to the lower frequency point f0.

[0165] An implementation example based on electromagnetic simulation data of cruise missile targets shows that the three-dimensional scattering center model of the target obtained using the method proposed in this invention can well represent the broadband electromagnetic scattering characteristics of the target. Substituting the estimated three-dimensional scattering center parameters into formula (2) yields the reconstructed broadband electromagnetic scattering characteristics of the target. The correlation coefficient between the reconstructed high-resolution range image and the original high-resolution range image is used to evaluate the fitting effect of the three-dimensional scattering center model. For all radar lines of sight, the histogram of the correlation coefficient distribution is as follows: Figure 16 As shown. A comparison between the original high-resolution range image and the reconstructed high-resolution range image of the target at a given angle. Figure 17 and Figure 18 As shown, the comparison between the original RCS and the reconstructed RCS of the target is as follows: Figure 19 and Figure 20 As shown, the average correlation coefficient between the reconstructed high-resolution range image and the original high-resolution range image is 0.92, and the proportion of correlation coefficients exceeding 0.8 is 88%.

[0166] In the target optical region electromagnetic scattering characteristic modeling method provided in the embodiments of the present invention, based on RANSAC and the three-dimensional spectral peak search approach, the precise position of the dominant equivalent three-dimensional scattering center of the target can be stably obtained. The obtained three-dimensional scattering center has good consistency with the target structure and scattering principle, greatly reducing false scattering centers, and thus enabling the accurate reconstruction of the target's electromagnetic scattering characteristics using fewer three-dimensional scattering centers.

[0167] Based on the same inventive concept, this embodiment of the invention also provides a target optical region electromagnetic scattering characteristic modeling device. Since the principle of this device in solving the problem is similar to the aforementioned target optical region electromagnetic scattering characteristic modeling method, the implementation of this device can refer to the implementation of the target optical region electromagnetic scattering characteristic modeling method, and the repeated parts will not be described again.

[0168] In specific implementation, the target optical region electromagnetic scattering characteristic modeling device provided in this embodiment of the invention, such as... Figure 21 As shown, it specifically includes:

[0169] Frequency response acquisition module 11 is used to acquire the multi-view broadband electromagnetic scattering frequency response of the target;

[0170] The parameter estimator calculation module 12 is used to calculate the one-dimensional scattering center parameter estimator of the target from each viewpoint using the acquired multi-view broadband electromagnetic scattering frequency response.

[0171] The scattering intensity field acquisition module 13 is used to acquire the scattering intensity field of the target in three-dimensional space based on the calculated one-dimensional scattering center parameter estimator, using the RANSAC method and the Parzen window estimation method.

[0172] The coarse location estimation module 14 is used to obtain the coarse location of the three-dimensional scattering center in the scattering intensity field using a three-dimensional spectral peak search method.

[0173] The precise position calculation module 15 is used to process the obtained coarse position through projection, association, and repositioning to obtain the precise position of the three-dimensional scattering center.

[0174] In the target optical region electromagnetic scattering characteristic modeling device provided in the embodiments of the present invention, the precise position of the dominant equivalent three-dimensional scattering center of the target can be stably obtained through the interaction of the above five modules. The obtained three-dimensional scattering center has good consistency with the target structure and scattering principle, greatly reducing false scattering centers, and thus enabling the accurate reconstruction of the target's electromagnetic scattering characteristics using fewer three-dimensional scattering centers.

[0175] In specific implementations, the target optical region electromagnetic scattering characteristic modeling device provided in the embodiments of the present invention may further include:

[0176] The visibility correction module is used to correct the visibility of the 3D scattering center from various viewpoints;

[0177] The parameter estimation module is used to estimate the type parameters and scattering coefficients of the three-dimensional scattering center.

[0178] For more detailed information on the working process of each of the above modules, please refer to the relevant content disclosed in the foregoing embodiments, which will not be repeated here.

[0179] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0180] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0181] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0182] Finally, 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.

[0183] The above provides a detailed description of the target optical region electromagnetic scattering characteristic modeling method and apparatus provided by the present invention. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for modeling the electromagnetic scattering characteristics of a target's optical region, characterized in that, include: Acquire the target's multi-view broadband electromagnetic scattering frequency response; Using the obtained multi-view broadband electromagnetic scattering frequency response, a one-dimensional scattering center parameter estimator for the target under each viewpoint is calculated; Based on the calculated one-dimensional scattering center parameter estimator, the RANSAC method and Parzen window estimation method are used to obtain the scattering intensity field of the target in three-dimensional space. The approximate location of the three-dimensional scattering center is obtained by using a three-dimensional spectral peak search method in the scattering intensity field. For each one-dimensional scattering center along each line of sight, set an association flag with an initial value of 0. ; For each three-dimensional scattering center, associate it with the one-dimensional scattering center on each line of sight using the minimum distance criterion; for the... Line of sight, calculation: ； in, For the first The three-dimensional scattering center at the th in the ... The projection of the line of sight with the first The smallest distance difference between the one-dimensional scattering centers For the first The direction vector of the line of sight, The obtained approximate position; judge Is the distance greater than the preset threshold? If so, then determine from the first Observe the first line of sight The third three-dimensional scattering center is not visible; otherwise, the third... The first line of sight The one-dimensional scattering center and the first The three-dimensional scattering centers are associated, and the association marker is set. ; All and the Associated with three-dimensional scattering centers A set of one-dimensional scattering centers ; According to the set The projected distance to the one-dimensional scattering center is estimated using the least squares method. The precise location of each three-dimensional scattering center.

2. The method for modeling the electromagnetic scattering characteristics of the target optical region according to claim 1, characterized in that, The step of calculating the one-dimensional scattering center parameter estimator of the target from each viewpoint using the acquired multi-view broadband electromagnetic scattering frequency response includes: Using the obtained multi-view broadband electromagnetic scattering frequency response The one-dimensional scattering center parameter estimator of the target under various viewing angles is calculated using the one-dimensional scattering center estimation method. : ； in, The frequency of the incident electromagnetic wave for radar. This refers to the numbering of the sampling points for the frequency of the incident electromagnetic wave from the radar. The elevation angle of the incident electromagnetic wave on the radar. The numbering of the radar line-of-sight elevation angle sampling points; The azimuth angle of the incident electromagnetic wave on the radar. This refers to the numbering of the radar line-of-sight azimuth sampling points; The first The first line of sight The scattering coefficient, type parameter, and distance of a one-dimensional scattering center For the first The number of one-dimensional scattering centers along the line of sight.

3. The method for modeling the electromagnetic scattering characteristics of the target optical region according to claim 2, characterized in that, The step of obtaining the scattering intensity field of the target in three-dimensional space using the RANSAC method and the Parzen window estimation method based on the calculated one-dimensional scattering center parameter estimator includes: by The three-dimensional cube containing the target is divided into a series of spatially resolved units at intervals; The scattering coefficients of the one-dimensional scattering center of the target from various viewpoints are normalized; For each of the spatial resolution cells, a cumulative scattering intensity is set and initialized to 0; Three lines of sight that are not on the same plane are randomly selected from the radar line of sight and denoted as follows: ; Assuming line of sight The first Individual, line of sight The first Individual, line of sight The first Each one-dimensional scattering center originates from the same three-dimensional scattering center; calculate the coordinates of the three-dimensional scattering center. Determine whether the coordinates of the three-dimensional scattering center fall within the target's physical space. If so, determine that the three-dimensional scattering center is likely a true scattering center, and update the cumulative scattering intensity of the spatial resolution unit where the coordinates of the three-dimensional scattering center are located. If not, determine that the three-dimensional scattering center is a false scattering center and discard it. Repeat the calculation of the coordinates of the three-dimensional scattering centers until all three-dimensional scattering centers have been traversed. All possible combinations; Repeat the steps of randomly selecting lines of sight and determining whether the coordinates of the three-dimensional scattering center fall within the target's physical space until the number of random line-of-sight selections reaches a preset upper limit, and obtain the cumulative amount of scattering intensity of the target in the entire three-dimensional space. The cumulative scattering intensity of the target in three-dimensional space is multiplied by the width. The scattering intensity field of the target in three-dimensional space is obtained by performing convolution operation on the three-dimensional Parzen window function.

4. The method for modeling the electromagnetic scattering characteristics of the target optical region according to claim 3, characterized in that, The step of obtaining the approximate location of the three-dimensional scattering center using a three-dimensional spectral peak search method in the scattering intensity field includes: A three-dimensional spectral peak search is performed on the acquired scattering intensity field to obtain the highest peak. Each spectral peak; The center point of the spatial resolution unit where the spectral peak is located is taken as the approximate location of the three-dimensional scattering center.

5. The method for modeling the electromagnetic scattering characteristics of the target optical region according to claim 4, characterized in that, Estimate the number using the following formula Precise location of each three-dimensional scattering center: ； ； ； in, For the set of real numbers, For the first A matrix composed of the direction vectors of the visible lines of sight under all three-dimensional scattering centers. Indicates the first The third three-dimensional scattering center A visible line-of-sight direction vector, For the first The third three-dimensional scattering center One visible line of sight, For the first The three-dimensional scattering center at the th in the ... The number of one-dimensional scattering centers associated with the visible line of sight.

6. The method for modeling the electromagnetic scattering characteristics of the target optical region according to claim 5, characterized in that, Also includes: Correct the visibility of the three-dimensional scattering center from various viewpoints; Estimate the type parameters and scattering coefficients of the three-dimensional scattering center.

7. The method for modeling the electromagnetic scattering characteristics of the target optical region according to claim 6, characterized in that, The correction of the visibility of the three-dimensional scattering center at various viewpoints includes: Construct a view visibility map for each 3D scattering center; A morphological closing operation is performed on the constructed view visibility map to close the small holes in the view visibility map caused by missed scattering centers.

8. The method for modeling the electromagnetic scattering characteristics of the target optical region according to claim 7, characterized in that, The estimated type parameters and scattering coefficients of the three-dimensional scattering center include: The mode of all type parameter estimators of one-dimensional scattering centers associated with each three-dimensional scattering center is used as the type parameter estimator of the three-dimensional scattering center. By taking the type parameter estimator and precise location of the three-dimensional scattering center as true values, the scattering coefficients of all visible three-dimensional scattering centers on each line of sight are estimated using the least squares method.

9. A device for modeling the electromagnetic scattering characteristics of a target optical region, characterized in that, include: The frequency response acquisition module is used to acquire the multi-view broadband electromagnetic scattering frequency response of the target; The parameter estimator calculation module is used to calculate the one-dimensional scattering center parameter estimator of the target from each viewpoint using the acquired multi-view broadband electromagnetic scattering frequency response. The scattering intensity field acquisition module is used to obtain the scattering intensity field of the target in three-dimensional space using the RANSAC method and the Parzen window estimation method based on the calculated one-dimensional scattering center parameter estimator. A coarse location estimation module is used to obtain the coarse location of the three-dimensional scattering center using a three-dimensional spectral peak search method in the scattering intensity field. The precise location calculation module is used to set an association flag with an initial value of 0 for each one-dimensional scattering center along each line of sight. ; For each three-dimensional scattering center, associate it with the one-dimensional scattering center on each line of sight using the minimum distance criterion; for the... Line of sight, calculation: ； in, For the first The three-dimensional scattering center at the th in the ... The projection of the line of sight with the first The smallest distance difference between the one-dimensional scattering centers For the first The direction vector of the line of sight, To obtain the approximate position; determine Is the distance greater than the preset threshold? If so, then determine from the first Observe the first line of sight The third three-dimensional scattering center is not visible; otherwise, the third... The first line of sight The one-dimensional scattering center and the first The three-dimensional scattering centers are associated, and the association marker is set. All related to the first Associated with three-dimensional scattering centers A set of one-dimensional scattering centers According to the set The projected distance to the one-dimensional scattering center is estimated using the least squares method. The precise location of each three-dimensional scattering center.

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