CN113933839B - Method, device, system and medium for interpreting polarization-dependent directional diagram of radar - Google Patents
Method, device, system and medium for interpreting polarization-dependent directional diagram of radar Download PDFInfo
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Abstract
The application relates to a method, a device, a system and a medium for interpreting a polarization-dependent directional diagram of a radar, wherein the method comprises the following steps: acquiring a scattering matrix of radar data target pixels and obtaining a target matrix of the scattering matrix; performing unitary transformation on the target matrix, and obtaining a three-dimensional polarization correlation value by using elements of the target matrix after unitary transformation; performing polarization correlation directional diagram visualization processing in a three-dimensional coordinate system according to the three-dimensional polarization correlation value to generate a three-dimensional polarization correlation directional diagram of the radar; three coordinate axes of the three-dimensional polarization correlation pattern are respectively a three-dimensional polarization correlation value, a three-dimensional polarization correlation value and a polarization ellipticity angle of the radar; and extracting features of the three-dimensional polarization related directional diagram to obtain interpretation features for quantitatively identifying scattering mechanisms corresponding to the three-dimensional polarization related directional diagram. The aim of greatly improving the interpretation performance of the target scattering mechanism is effectively fulfilled.
Description
Technical Field
The application relates to the technical field of radar information, in particular to a method, a device, a system and a medium for interpreting a polarization-dependent direction diagram of a radar.
Background
The polarized radar (radar system capable of obtaining multi-polarization data such as polarized synthetic aperture radar and polarized inverse synthetic aperture radar) can obtain a complete polarized scattering matrix of a target by transmitting and receiving a group of orthogonal polarized electromagnetic waves, is favorable for complete description of a scattering mechanism and provides possibility for accurate interpretation of the scattering mechanism. Currently, polarized radars are widely used and become a mainstream sensor in the field of earth remote sensing; through interpretation of the scattering mechanism, the abundant scattering information of the targets in the polarized scattering matrix can be mined and extracted.
Backscatter of radar targets is relatively sensitive to the relative geometry of the target pose and radar line of sight, defined as the diversity of scatter, which presents a number of difficulties in interpretation of radar information. The scattering mechanism of the same target can be obviously different from the radar sight line position, and the corresponding orientation angle is equivalent to the polarization azimuth angle. Polarization dependent direction diagram interpretation tools have been proposed for the interpretation of radar information. However, in the process of implementing the present invention, the inventor has found that the conventional polarization-dependent direction diagram interpretation tool has a technical problem of poor performance of target scattering mechanism interpretation.
Disclosure of Invention
In view of the foregoing, it is desirable to provide a polarization dependent directional diagram interpretation method of a radar, a polarization dependent directional diagram interpretation apparatus of a radar, a radar information interpretation system, and a computer-readable storage medium capable of quantitatively interpreting a scattering mechanism of a target.
In order to achieve the above object, the embodiment of the present invention adopts the following technical scheme:
In one aspect, an embodiment of the present invention provides a method for interpreting a polarization-dependent direction diagram of a radar, including the steps of:
Acquiring a scattering matrix of radar data target pixels and obtaining a target matrix of the scattering matrix; the target matrix comprises a polarization coherence matrix or a polarization covariance matrix;
performing unitary transformation on the target matrix, and obtaining a three-dimensional polarization correlation value by using elements of the target matrix after unitary transformation;
performing polarization correlation directional diagram visualization processing in a three-dimensional coordinate system according to the three-dimensional polarization correlation value to generate a three-dimensional polarization correlation directional diagram of the radar; three coordinate axes of the three-dimensional polarization correlation pattern are respectively a three-dimensional polarization correlation value, a three-dimensional polarization correlation value and a polarization ellipticity angle of the radar;
Extracting features of the three-dimensional polarization related directional diagram to obtain interpretation features for quantitatively identifying scattering mechanisms corresponding to the three-dimensional polarization related directional diagram; the interpretation features include one or more of a maximum correlation value, a minimum correlation value, a maximum curve curvature value, a cross-section maximum correlation value, a cross-section minimum correlation value, a cross-section correlation degree, a cross-section correlation waviness, a correlation difference degree, a normalized correlation difference degree, a cross-section correlation contrast, a cross-section correlation inverse entropy, a maximum gaussian curvature value, a maximum average curvature value, and a maximum dominant curvature value.
In another aspect, there is also provided a polarization dependent directional diagram interpretation apparatus of a radar, including:
the data acquisition module is used for acquiring a scattering matrix of radar data target pixels and obtaining a target matrix of the scattering matrix; the target matrix comprises a polarization coherence matrix or a polarization covariance matrix;
the unitary transformation module is used for performing unitary transformation processing on the target matrix and obtaining a three-dimensional polarization correlation value by using elements of the target matrix after unitary transformation;
The three-dimensional visual module is used for carrying out polarization correlation directional diagram visual processing in a three-dimensional coordinate system according to the three-dimensional polarization correlation value to generate a three-dimensional polarization correlation directional diagram of the radar; three coordinate axes of the three-dimensional polarization correlation pattern are respectively a three-dimensional polarization correlation value, a three-dimensional polarization correlation value and a polarization ellipticity angle of the radar;
The feature extraction module is used for extracting features of the three-dimensional polarization related directional diagram to obtain interpretation features for quantitatively identifying scattering mechanisms corresponding to the three-dimensional polarization related directional diagram; the interpretation features include one or more of a maximum correlation value, a minimum correlation value, a maximum curve curvature value, a cross-section maximum correlation value, a cross-section minimum correlation value, a cross-section correlation degree, a cross-section correlation waviness, a correlation difference degree, a normalized correlation difference degree, a cross-section correlation contrast, a cross-section correlation inverse entropy, a maximum gaussian curvature value, a maximum average curvature value, and a maximum dominant curvature value.
In yet another aspect, there is provided a radar information interpretation system comprising a memory storing a computer program and a processor implementing the steps of the polarization dependent direction diagram interpretation method of any one of the above radars when the computer program is executed.
In yet another aspect, there is also provided a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the polarization dependent directional diagram interpretation method of any one of the radars described above.
One of the above technical solutions has the following advantages and beneficial effects:
According to the method, the device, the system and the medium for interpreting the polarization-dependent directional diagram of the radar, the three-dimensional polarization-dependent value is obtained through unitary transformation after the scattering matrix of the radar data target pixel is obtained, the three-dimensional polarization-dependent value is displayed in the three-dimensional coordinate system, the three-dimensional polarization-dependent directional diagram of the radar is constructed and visualized, and further, feature extraction is carried out on the three-dimensional polarization-dependent directional diagram, interpretation features of a scattering mechanism can be obtained, quantitative efficient interpretation of the polarization-dependent directional diagram of the radar is completed, the aim of greatly improving the interpretation performance of the target scattering mechanism is effectively achieved, and the subsequent target detection and classification efficiency of the radar is improved.
Drawings
FIG. 1 is a schematic diagram of a conventional polarization dependent pattern;
FIG. 2 is a flow diagram of a method for polarization dependent directional diagram interpretation of a radar in one embodiment;
FIG. 3 is a schematic diagram of a 3-D PCP visualization of a dipole in one embodiment; wherein, (a) is a visual characterization result of the 3-D PCP, and (b) is a tangential plane of three-dimensional polarization related patterns under different PEAs;
FIG. 4 is a schematic diagram of a 3-D PCP visualization of four exemplary scatterers in one embodiment; wherein (a 1) is a three-sided 3-D PCP Visual characterization result, (b 1) is 3-D PCP/>, with a triangular faceVisual characterization result, (c 1) is 3-D PCP/>, with a triangular faceVisual characterization of the results, (a 2) is dihedral 3-D PCP/>Visual characterization result, (b 2) is dihedral 3-D PCP/>Visual characterization result, (c 2) is dihedral 3-D PCP/>Visual characterization result, (a 3) is 3-D PCP/>, of dipoleVisual characterization result, (b 3) is 3-D PCP/>, of dipoleVisual characterization result, (c 3) is 3-D PCP/>, of dipoleVisual characterization of the results, (a 4) is the 3-D PCP/>, of the spirocheteVisual characterization result, (b 4) is 3-D PCP/>, of spirocheteVisual characterization result, (c 4) is 3-D PCP/>, of spirocheteVisual characterization results;
FIG. 5 is a graph showing the Gaussian curvature distribution of a typical diffuser in one embodiment; wherein, (a) is the distribution of the value of the Gaussian curvature of the dihedral angle, (b) is the distribution of the value of the Gaussian curvature of the left spiral, (c) is the distribution of the value of the Gaussian curvature of the dihedral angle, and (d) is the distribution of the value of the Gaussian curvature of the dipole;
FIG. 6 is a diagram of measured data Pauli in one embodiment;
FIG. 7 is a schematic diagram of a three-dimensional polarization-dependent pattern of pixels selected from Radasat-2 data in one embodiment;
wherein (a 1) is a 3-D PCP of a ship pixel (B 1) is the 3-D PCP/>, of the ship pixel(C 1) is the 3-D PCP/>, of the ship pixel point(A 2) is the 3-D PCP/>, of the sea pixel point(B 2) is the 3-D PCP/>, of the sea pixel point(C 2) is the 3-D PCP/>, of the sea pixel pointVisual characterization results of (2);
FIG. 8 is a graph showing GC curvature distribution of a measured data pixel 3-D PCP according to one embodiment; wherein (a 1) is a 3-D PCP of a ship pixel (B 1) is the 3-D PCP/>, of the ship pixel point(C 1) is the 3-D PCP/>, of the ship pixel pointGC curvature value distribution of (a 2) is 3-D PCP/>, which is sea pixel point(B 2) is the 3-D PCP/>, of the sea pixel point(C 2) is the 3-D PCP/>, of the sea pixel pointGC curvature value distribution of (2);
Fig. 9 is a schematic block diagram of a polarization dependent pattern interpretation apparatus of a radar in one embodiment.
Detailed Description
The present application will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
In addition, the technical solutions of the embodiments of the present invention may be combined with each other, but it is necessary to be based on the fact that those skilled in the art can implement the technical solutions, and when the technical solutions are contradictory or cannot be implemented, it should be considered that the technical solutions are not combined, and are not within the scope of protection claimed by the present invention.
Please refer to the polarization dependent pattern shown in fig. 1, which is a visual pattern of the polarization dependent pattern interpretation tool proposed in the prior art. The inventor researches and discovers that from the aspect of a geometric descriptor, the complete representation of electromagnetic waves relates to a polarization azimuth angle and a polarization ellipticity angle, so that from the aspects of information completeness and further improvement of a polarization interpretation level and overcoming of a rotation effect of a target, the change of a target polarization-related pattern along with the polarization ellipticity is depicted, and more useful characteristics are hopefully mined, and the polarization interpretation level is improved.
In the prior art, for polarized radars, the definition of the horizontal and vertical polarization basis of the scattering matrix of a target is:
Wherein the subscript HV represents vertical transmission and horizontal reception, HH represents horizontal transmission and horizontal reception, VH represents horizontal transmission and vertical reception, and VV represents vertical transmission and vertical reception. The scattering matrix in any polarization basis (X, Y) can be derived by unitary transformation of the scattering matrix of formula (1) under horizontal and vertical polarization basis (H, V):
S(X,Y)＝U2(θ,τ)TS(H,V)U2(θ,τ) (2)
Where θ is the polarization azimuth, hereinafter denoted by POA, τ is the polarization ellipticity angle, hereinafter denoted by PEA. U 2 (θ, τ) is a unitary transformation matrix, and can be obtained by multiplying a unitary matrix U 2 (θ) containing POA and a unitary matrix U 2 (τ) containing PEA.
On the basis of satisfying the reciprocity principle S HV＝SVH, the Pauli vectors k P and Lexicographic (dictionary order) k L are expressed as:
The coherence matrix T and covariance matrix C can be expressed as:
Wherein the superscript H represents the conjugate transpose and the symbol </SUB > represents the unit average. According to the definition of the prior document, the mathematical expression of the polarization dependent pattern of the radar is shown as the following formula (8), in which For the conjugate of s 2, the numbers 1 and 2 represent different polarization channels.
Aiming at the technical problems that the traditional polarization dependent direction diagram interpretation tool is not fully utilized with the information of the dimension of the polarization ellipticity angle and the interpretation performance of a target scattering mechanism is poor, the invention provides a novel radar polarization dependent direction diagram interpretation method, which comprises a visual construction method of a three-dimensional polarization dependent direction diagram, extracts various types of characteristics from the three-dimensional polarization dependent direction diagram and is used for quantitatively distinguishing and identifying different types of scattering mechanisms. The basic conception is as follows: introducing the polarization ellipticity angle into a polarization correlation direction diagram, constructing a three-dimensional polarization correlation direction diagram, describing the polarization correlation direction diagram under different polarization ellipticity angles, and more intuitively reflecting the differences of different scattering types by constructing the three-dimensional polarization correlation direction diagram; based on the geometrical structure of the three-dimensional polarization-dependent pattern of a typical scatterer and the variability in the numerical features, various types of features are defined and extracted for identifying the type of scattering.
Referring to fig. 2, in one aspect, the present invention provides a method for interpreting a polarization dependent direction diagram of a radar, including steps S12 to S18 as follows:
s12, acquiring a scattering matrix of radar data target pixels and obtaining a target matrix of the scattering matrix; the target matrix comprises a polarization coherence matrix or a polarization covariance matrix;
S14, unitary transformation processing is carried out on the target matrix, and three-dimensional polarization correlation values are obtained by using elements of the target matrix after unitary transformation;
s16, performing polarization correlation directional diagram visualization processing in a three-dimensional coordinate system according to the three-dimensional polarization correlation value to generate a three-dimensional polarization correlation directional diagram of the radar; three coordinate axes of the three-dimensional polarization correlation pattern are respectively a three-dimensional polarization correlation value, a three-dimensional polarization correlation value and a polarization ellipticity angle of the radar;
S18, extracting features of the three-dimensional polarization related directional diagram to obtain interpretation features for quantitatively identifying scattering mechanisms corresponding to the three-dimensional polarization related directional diagram; the interpretation features include one or more of a maximum correlation value, a minimum correlation value, a maximum curve curvature value, a cross-section maximum correlation value, a cross-section minimum correlation value, a cross-section correlation degree, a cross-section correlation waviness, a correlation difference degree, a normalized correlation difference degree, a cross-section correlation contrast, a cross-section correlation inverse entropy, a maximum gaussian curvature value, a maximum average curvature value, and a maximum dominant curvature value.
It can be understood that the radar data target pixel refers to the pixel data of the target in the data output after the target is detected by the polarized radar, and the pixel data contains complete polarized scattering matrix information of the target. The target matrix may comprise a polarization coherence matrix or a polarization covariance matrix, and may comprise other forms of matrices derived from the scattering matrix by mathematical operations. The three-dimensional coordinate system may be a cylindrical coordinate system or a Cartesian coordinate system. On the basis of visual representation of the three-dimensional polarization correlation directional diagram, concepts such as Gaussian curvature, average curvature, principal curvature and the like in differential geometry are introduced, so that each interpretation characteristic is defined and obtained, and the method is used for distinguishing and quantitatively representing different scattering types in the three-dimensional polarization correlation directional diagram.
The specific feature types of the interpretation features can be selected according to actual application requirements, wherein according to different sections selected in actual application, the maximum correlation value, the minimum correlation value, the correlation degree, the fluctuation degree, the correlation difference degree, the normalized correlation difference degree, the correlation contrast degree and the inverse entropy of the correlation of the sections can derive more features, so that the interpretation of a target scattering mechanism with higher performance can be realized.
After a scattering matrix of radar data target pixels is obtained, a three-dimensional polarization correlation value is obtained through unitary transformation, and then the three-dimensional polarization correlation value is displayed in a three-dimensional coordinate system, so that three-dimensional polarization correlation pattern construction and visualization of the radar are realized, and further feature extraction is carried out from the three-dimensional polarization correlation pattern, and the interpretation features of a scattering mechanism can be obtained, so that quantitative efficient interpretation of the polarization correlation pattern of the radar is completed, the aim of greatly improving the interpretation performance of the target scattering mechanism is effectively achieved, and the subsequent target detection and classification efficiency of the radar is also improved.
In one embodiment, the process of unitary transformation processing on the polarized coherent matrix is implemented by the following conversion method:
T(θ,τ)＝U3p(θ,τ)TU3p(θ,τ)H (9)
wherein T (θ, τ) represents a polarization coherence matrix after unitary transformation, U 3p (θ, τ) represents a unitary transformation matrix, T represents a polarization coherence matrix before unitary transformation, θ represents a polarization azimuth angle, τ represents a polarization ellipticity angle, and upper right corner mark H represents a conjugate transpose.
Specifically, on the basis of obtaining the scattering matrix S (X,Y) of the target and the corresponding polarization coherence matrix T, the unitary transformation formula for the polarization coherence matrix T is redefined. With the elements in S (X,Y), the vector k P (θ, τ) under arbitrary polarization can be expressed as:
The relationship between vector k P (θ, τ) and Pauli vector k P can be further deduced:
The unitary transformation formula thus re-derived is:
U3p(θ,τ)＝U3p(τ)U3p(θ) (12)
Where U 3p (τ) represents a unitary matrix containing the polarization ellipticity angle, and U 3p (θ) represents a unitary matrix containing the polarization azimuth angle. The polarization coherence matrix T is defined as Therefore, the above-described conversion formula (9) exists.
In one embodiment, the unitary transformation processing of the polarization covariance matrix is implemented by the following conversion method:
C(θ,τ)＝UT-CT(θ,τ)U-1 T-C (13)
Wherein,
Wherein C (θ, τ) represents a polarization covariance matrix after unitary transformation, U T-C represents a special unitary matrix, T (θ, τ) represents a polarization coherence matrix after unitary transformation, θ represents a polarization azimuth angle, and τ represents a polarization ellipticity angle.
Specifically, the unitary transformation of the covariance matrix C under any polarization basis can be implemented by transforming the polarization coherence matrix T (θ, τ) after the unitary transformation, where the transformation matrix is a special unitary matrix U T-C, and the formulas are shown in the above formula (13) and formula (14), respectively.
In one embodiment, the three-dimensional polarization dependent pattern proposed by the present application can be written asIt is defined as
It will be appreciated that in the general case of non-given polar groups, there areThe three-dimensional polarization correlation value can be derived under any polarization base, wherein s 1 and s 2 can be: pauli vector/>And Lexicographic vector/>The subscripts X and Y are used to denote any two different polarizations, respectively.
Preferably, s 1 and s 2 may be Pauli vectors when defined under horizontal and vertical polarization basesAnd Lexicographic vector/>Any element in the above list. It will be appreciated that when defined under horizontal and vertical polarization, the subscript X in the two aforementioned vectors is correspondingly replaced with H (to correspondingly represent horizontal polarization) and the subscript Y is correspondingly replaced with V (to correspondingly represent vertical polarization).
The embodiment of the invention takes the case of horizontal and vertical polarization as an example, and three typical three-dimensional polarization related patterns are derived. Referring to fig. 3 and 4, the three-dimensional polarization dependent patterns include a first three-dimensional polarization dependent pattern, a second three-dimensional polarization dependent pattern, and a third three-dimensional polarization dependent pattern;
The first three-dimensional polarization-dependent pattern is
The second three-dimensional polarization-dependent pattern is
The third three-dimensional polarization-dependent pattern is
Where θ represents the polarization azimuth angle, τ represents the polarization ellipticity angle, s HH (θ, τ) represents the scattering matrix elements of the horizontally transmitted and horizontally received polarization channels,Conjugation of scattering matrix element s HV (θ, τ) representing the polarization channels of vertical transmission and horizontal reception,/>The conjugate of the scattering matrix element s VV (θ, τ) representing the vertically-transmitted and vertically-received polarized channels, s HH+VV (θ, τ) representing the sum of the scattering matrix elements of the horizontally-transmitted and horizontally-received polarized channels and the vertically-transmitted and vertically-received polarized channels, s HH-VV (θ, τ) representing the difference of the scattering matrix elements of the horizontally-transmitted and horizontally-received polarized channels and the vertically-transmitted and vertically-received polarized channels,/>Representing the conjugate of s HH-VV (θ, τ). For the three-dimensional polarization dependent patterns proposed above, each pattern can be used to derive a series of eigenvalues.
Specifically, a three-dimensional image corresponding to the expression is drawn in a three-dimensional coordinate system (hereinafter, a cylindrical coordinate system is taken as an example for convenience of description), wherein coordinate axes are respectively: polarization correlation valuePolarization correlation value/>And the ellipticity angle τ, thus resulting in a three-dimensional polarization dependent pattern, which may be represented by a 3-D PCP hereinafter. In three-dimensional polarization dependent pattern/>, of dipolesFor example, the visual representation is shown in fig. 3, wherein (a) is the visual representation of the 3-D PCP result and (b) is the tangential plane of the three-dimensional polarization-dependent pattern at different PEAs.
For typical scatterers such as dihedral angles, dipoles and spirals, the scattering matrix elements [ S HH SHV SVH SVV ] are [ 100 1], [1 0-1 ], [ 1000 ] and 1/2 x [1 j j-1 ], respectively, under horizontal and vertical polarization, in this embodiment the first, second and third three-dimensional polarization dependent patterns described above are exemplified, and the visualized 3-D-PCP is shown in FIG. 4, respectively. In FIG. 4, the letters a, b and c in the reference numerals of each column of subgraphs respectively represent different 3-D-PCPsAnd/>The numbers in the numbers of each row of subgraphs represent typical scatterers: 1 denotes a dihedral angle, 2 denotes a dihedral angle, 3 denotes a dipole, and 4 denotes a helix.
In one embodiment, the extraction process of the maximum gaussian curvature value is:
calculating Gaussian curvature values of the three-dimensional polarization correlation values under a parameter space of a polarization azimuth angle and a polarization ellipticity angle;
Extracting the maximum value in the absolute values of the Gaussian curvature values as the maximum Gaussian curvature value;
The extraction process of the maximum average curvature value comprises the following steps:
calculating an average curvature value of the three-dimensional polarization correlation value under a parameter space of a polarization azimuth angle and a polarization ellipticity angle;
Extracting the maximum value in the absolute values of the average curvature values as the maximum average curvature value;
The extraction process of the maximum principal curvature value comprises the following steps:
Calculating two principal curvature values of the three-dimensional polarization related value under a parameter space about a polarization azimuth angle and a polarization ellipticity angle;
taking the maximum value of the absolute values of the two main curvature values as the maximum main curvature value;
The maximum Gaussian curvature value, the maximum average curvature value and the maximum dominant curvature value are used for identifying the surface curvature degree of the three-dimensional polarization related pattern and the three-dimensional polarization related value, and follow the change degree of the polarization azimuth angle and the polarization ellipticity angle.
Specifically, the various types of features provided by the application at least comprise the three features. Wherein:
Maximum gaussian curvature value GC max: the characteristic reflects the bending degree of the three-dimensional surface in the three-dimensional polarization related directional diagram and the change degree of the three-dimensional polarization related value along with the parameters POA and PEA, and the characteristic has the maximum value when the curved surface is bent in all directions. Therefore, the feature extraction method is as follows: first, three-dimensional polarization correlation value is calculated Regarding the gaussian curvature values GC under POA and PEA parameter space, the maximum gaussian curvature value GC max is defined as GC max =max (|gc|).
Maximum average curvature value MC max: the characteristic reflects the degree of curvature of the three-dimensional surface in the three-dimensional polarization dependent pattern and the degree of variation of the three-dimensional polarization dependent value with the parameters POA and PEA. Therefore, the feature extraction method is as follows: first, three-dimensional polarization correlation value is calculatedRegarding the average curvature value MC at POA and PEA parameter space, the maximum average curvature value MC max is defined as MC max =max (|mc|).
Maximum principal curvature value PC max: the characteristic reflects the degree of curvature of the three-dimensional surface in the three-dimensional polarization dependent pattern and the degree of variation of the three-dimensional polarization dependent value with the parameters POA and PEA. Therefore, the feature extraction method is as follows: first, three-dimensional polarization correlation value is calculatedRegarding the two principal curvature values κ 1 and κ 2 in the POA and PEA parameter spaces, the maximum principal curvature value PC max is defined as PC max＝max(|κ1|,|κ2 |).
In one embodiment, the maximum correlation value is a maximum value of three-dimensional polarization correlation values in the three-dimensional polarization correlation pattern, and the minimum correlation value is a minimum value of three-dimensional polarization correlation values in the three-dimensional polarization correlation pattern.
Specifically, the maximum correlation valueWhich is defined as the maximum value in the 3-D-PCP. Minimum correlation value/>Which is defined as the minimum value in the 3-D-PCP.
In one embodiment, the extraction process of the maximum curve curvature value is:
And extracting a section of the three-dimensional polarization related directional diagram at a set polarization azimuth angle or a set polarization ellipticity angle, calculating curve curvature values of all the curves in the section, and taking the maximum value of the curve curvature values as the maximum curve curvature value.
Specifically, the maximum curve curvature valueFirst, a specific value of POA or PEA is given, where α represents POA or PEA and β represents the given specific value (i.e., the set polarization azimuth or polarization ellipticity angle). Then extracting a cross section under the condition of alpha=beta in the three-dimensional polarization related directional diagram, calculating curve curvature values CC at all parts of the curve in the cross section, and calculating the maximum curve curvature value/>Defined as/>A schematic of the cross section is shown in fig. 3 (b).
The extraction process of the maximum correlation value of the section is as follows:
and calculating the maximum value in the three-dimensional polarization correlation values under the section as the section maximum correlation value.
Specifically, the maximum correlation value of the cross sectionFirst, a specific value of POA or PEA is given, where α represents POA or PEA and β represents the given specific value (i.e., the set polarization azimuth or polarization ellipticity angle). And then extracting a cross section under the condition of alpha=beta in the three-dimensional polarization correlation directional diagram, and calculating the maximum value in the three-dimensional polarization correlation value under the cross section to obtain the maximum correlation value of the cross section. A schematic of the cross section is shown in fig. 3 (b).
The extraction process of the section minimum correlation value comprises the following steps:
And calculating the minimum value in the three-dimensional polarization correlation values under the section as the section minimum correlation value.
Specifically, the cross-section minimum correlation valueFirst, a specific value of POA or PEA is given, where α represents POA or PEA and β represents the given specific value (i.e., the set polarization azimuth or polarization ellipticity angle). And then extracting a cross section under the condition of alpha=beta in the three-dimensional polarization correlation directional diagram, and calculating the minimum value in the three-dimensional polarization correlation value under the cross section to obtain the minimum correlation value of the cross section. A schematic of the cross section is shown in fig. 3 (b).
The extraction process of the cross section correlation degree comprises the following steps:
And calculating an average value of the three-dimensional polarization correlation values under the section as the section correlation degree.
Specifically, cross-section correlationFirst, a specific value of POA or PEA is given, where α represents POA or PEA and β represents the given specific value (i.e., the set polarization azimuth or polarization ellipticity angle). And then extracting a section under the condition of alpha=beta in the three-dimensional polarization correlation directional diagram, and calculating an average value of three-dimensional polarization correlation values under the section to obtain the section correlation degree. A schematic of the cross section is shown in fig. 3 (b).
The extraction process of the section related waviness comprises the following steps:
and calculating the standard deviation of the three-dimensional polarization correlation value under the section as the section correlation fluctuation degree.
Specifically, the cross-section-related wavinessFirst, a specific value of POA or PEA is given, where α represents POA or PEA and β represents the given specific value (i.e., the set polarization azimuth or polarization ellipticity angle). And then extracting a section under the condition of alpha=beta in the three-dimensional polarization correlation directional diagram, and calculating the standard deviation of the three-dimensional polarization correlation value under the section to obtain the section correlation fluctuation degree. A schematic of the cross section is shown in fig. 3 (b).
The extraction process of the correlation difference degree comprises the following steps:
And respectively extracting cross sections at two different set polarization azimuth angles or polarization ellipticity angles in the three-dimensional polarization correlation directional diagram, respectively calculating the maximum correlation values of the cross sections of the two cross sections, calculating the difference, and taking the absolute value of the obtained difference as the correlation difference degree.
Specifically, the degree of correlation differenceFirst, two specific values of POA or PEA are given, where POA or PEA is represented by α and α ', and the given specific values are represented by β and β' (i.e., the polarization azimuth or the polarization ellipticity angle is set). Then extracting the cross sections of the three-dimensional polarization correlation directional diagram under the given two angle constraints, and respectively calculating the maximum correlation value/>, of the cross sections under the two cross sectionsAnd/>The difference between the two features is the correlation difference/>A schematic of the cross section is shown in fig. 3 (b).
The extraction process of the normalized correlation difference degree comprises the following steps:
and calculating the difference value of the maximum correlation values of the two sections, and taking the absolute value of the ratio of the difference value to the sum of the maximum correlation values of the sections as the normalized correlation difference.
Specifically, normalized correlation variabilityFirst, two specific values of POA or PEA are given, where POA or PEA is represented by α and α ', and the given specific values are represented by β and β' (i.e., the polarization azimuth or the polarization ellipticity angle is set). Then extracting the cross sections of the three-dimensional polarization correlation directional diagram under the given two angle constraints, and respectively calculating the maximum correlation value/>, of the cross sections under the two cross sectionsAnd/>The ratio of the difference between the two features to the sum is the normalized correlation difference/>I.e./>A schematic of the cross section is shown in fig. 3 (b).
The extraction process of the section related contrast is as follows:
The sections of the three-dimensional polarization-related directional diagram at two set polarization azimuth angles or polarization ellipticity angles are respectively extracted, and the two sections set here can be the same or different. Calculating a cross section maximum correlation value of one cross section, calculating a cross section minimum correlation value of the other cross section, calculating a difference between the obtained cross section maximum correlation value and the cross section minimum correlation value, and taking the absolute value of the obtained difference as a cross section correlation contrast;
In particular, cross-section dependent contrast First, two specific values of POA or PEA are given, where α and α 'are represented by POA or PEA, and β' are represented by given specific values (i.e. setting the polarization azimuth or the polarization ellipticity angle), and it should be noted that the two given cross sections may be the same cross section or different cross sections. For one of the sections at α=β, the section maximum correlation value/>, is calculatedFor another section located at α '=β', the minimum correlation value/>, of its section is calculatedThe absolute value of the difference between the two features is/>I.e./>A schematic of the cross section is shown in fig. 3 (b).
The extraction process of the cross-section related inverse entropy comprises the following steps:
The sections of the three-dimensional polarization-related directional diagram at two set polarization azimuth angles or polarization ellipticity angles are respectively extracted, and the two sections set here can be the same or different. Calculating a cross section maximum correlation value of one cross section, and calculating a cross section minimum correlation value of the other cross section; respectively calculating a difference value and a sum value of the maximum correlation value and the minimum correlation value of the cross section, and taking the absolute value of the ratio of the difference value and the sum value as the cross section correlation inverse entropy;
Specifically, cross-section-related inverse entropy First, two specific values of POA or PEA are given, where α and α 'are represented by POA or PEA, and β' are represented by given specific values (i.e. setting the polarization azimuth or the polarization ellipticity angle), and it should be noted that the two given cross sections may be the same cross section or different cross sections. For one of the sections at α=β, the section maximum correlation value/>, is calculatedFor another section located at α '=β', the minimum correlation value/>, of its section is calculatedThe absolute value of the difference between the two features is/>I.e./>A schematic of the cross section is shown in fig. 3 (b). In one embodiment, in order to more intuitively and fully describe the polarization-dependent direction diagram interpretation method of the radar, an example of the effective application of the feature extracted in the method is described below, taking the feature of the maximum gaussian curvature value GC max as an example.
It should be noted that, the examples given in the present specification are only illustrative, and not the only limitation of the specific embodiments of the present invention, and those skilled in the art may implement three-dimensional polarization-dependent pattern interpretation by extracting different features by using the above-mentioned method for interpreting the polarization-dependent pattern of radar in the same way under the illustration of the embodiments provided by the present invention.
As shown in fig. 5, a typical scatterer is given: under the condition of Gaussian curvature values of the dihedral angle, the dipole and the spiral body in the (theta, tau) parameter space, under the horizontal and vertical polarization, the scattering matrix elements [ S HH SHV SVH SVV ] are [ 100 1], [1 0-1 ], [ 1000 ] and 1/2 [1 j j-1 ] respectively. According to the GC max feature defined in the present application, for the dihedral and left helix, GC max =0. For dihedral angles GC has distinct values at (θ=45°, τ=0°) and (θ= -45 °, τ=0°) respectively. For dipoles, GC has a distinct value at (θ=0°, τ=0°). Therefore, the GC max can distinguish between different scatter types from the location to which the value corresponds.
The measured polarization data of the C-band Radarsat-2 is selected for illustration. The data area is located in a near shore area, a large number of ship targets are distributed in a scene when shooting on a certain day. The nominal distance and azimuth resolution of the data were 12m and 8m respectively, and the Pauli plot is shown in FIG. 6.
Selecting a pixel located in sea area and a pixel located in ship part, three types of three-dimensional polarization related patterns are shown in figure 7, wherein letters a, b and c in the reference numerals of each column of subgraphs respectively represent different 3-D-PCPsAnd/>The reference numeral 1 in each row of subgraphs represents the ship pixel and the numeral 2 represents the sea pixel.
From fig. 7, it can be observed that the three-dimensional polarization-dependent pattern of the measured data is distorted from the 3D-PCP of the exemplary scatterer shown in fig. 4, because the scattering type of the measured data is often a mixture of scattering mechanisms. The three types of 3D-PCPs for the selected ship pixels are similar to the three types of 3D-PCPs for the second line dihedral angle in fig. 4, but the notches in fig. 4 (a 2) are still observed, marked with arrows in fig. 7 (c 1), although the deformation is more severe in fig. 7 (c 1). And for the selected sea pixel, the 3D-PCP is similar to the three types of 3D-PCP in the first line of the three-sided angle in fig. 4. Note that the scattering matrices for the plate and the dihedral angles are the same, and in combination with the actual scene analysis, the principle scattering mechanism for the selected pixels is odd scattering, the scattering type being similar to that of a plate scatterer.
Taking GC max as an example, distribution of Gaussian curvature values GC corresponding to three types of 3D-PCP of two selected pixel points in parameter spaces of a polarization azimuth angle theta and a polarization ellipticity angle tau is shown in figure 8, wherein letters a, b and c in the reference numerals of each column of subgraphs respectively represent different 3D-PCPsAnd/>The reference numeral 1 in each row of subgraphs represents the ship pixel and the numeral 2 represents the sea pixel. It can be observed from the profile that three types of 3D-PCP derivative GC max for ship pixels would be significantly larger than sea pixels, while three types of GC max for sea pixels approach 0. Therefore, the GC max feature can well distinguish between odd and even scattering types, which can be used in detection applications for ships.
It should be understood that, although the steps in the flowchart of fig. 2 are shown in sequence as indicated by the arrows, the steps are not necessarily performed in sequence as indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least a portion of the steps of fig. 2 may include multiple sub-steps or stages that are not necessarily performed at the same time, but may be performed at different times, nor does the order in which the sub-steps or stages are performed necessarily occur sequentially, but may be performed alternately or alternately with other steps or at least a portion of the sub-steps or stages of other steps.
Referring to fig. 9, in one embodiment, there is further provided a polarization dependent directional diagram translating apparatus 100 for a radar, including a data acquisition module 11, a unitary transformation module 13, a three-dimensional visualization module 15, and a feature extraction module 17. The data acquisition module 11 is used for acquiring a scattering matrix of radar data target pixels and obtaining a target matrix of the scattering matrix; the target matrix includes a polarization coherence matrix or a polarization covariance matrix. The unitary transformation module 13 is configured to perform unitary transformation on the target matrix, and obtain a three-dimensional polarization correlation value by using elements of the target matrix after unitary transformation. The three-dimensional visualization module 15 is used for performing polarization correlation directional diagram visualization processing in a three-dimensional coordinate system according to the three-dimensional polarization correlation value to generate a three-dimensional polarization correlation directional diagram of the radar; the three coordinate axes of the three-dimensional polarization correlation pattern are respectively a three-dimensional polarization correlation value, a three-dimensional polarization correlation value and a polarization ellipticity angle of the radar. The feature extraction module 17 is used for extracting features of the three-dimensional polarization related directional diagram to obtain interpretation features for quantitatively identifying scattering mechanisms corresponding to the three-dimensional polarization related directional diagram; the interpretation features include one or more of a maximum correlation value, a minimum correlation value, a maximum curve curvature value, a cross-section maximum correlation value, a cross-section minimum correlation value, a cross-section correlation degree, a cross-section correlation waviness, a correlation difference degree, a normalized correlation difference degree, a cross-section correlation contrast, a cross-section correlation inverse entropy, a maximum gaussian curvature value, a maximum average curvature value, and a maximum dominant curvature value.
According to the polarization dependent directional diagram translating device 100 of the radar, after the scattering matrix of radar data target pixels is obtained through cooperation of the modules, three-dimensional polarization dependent values are obtained through unitary transformation, then the three-dimensional polarization dependent values are displayed in a three-dimensional coordinate system, three-dimensional polarization dependent directional diagram construction and visualization of the radar are achieved, further feature extraction is carried out on the three-dimensional polarization dependent directional diagram, translating features of a scattering mechanism can be obtained, quantitative efficient translating of the polarization dependent directional diagram of the radar is achieved, the purpose of greatly improving target scattering mechanism translating performance is effectively achieved, and subsequent target detection and classification efficiency of the radar is improved.
For a specific definition of the polarization dependent direction diagram translating device 100 of the radar, reference may be made to the corresponding definition of the polarization dependent direction diagram translating method of the radar above, and no further description is given here. The respective modules in the above-described polarization dependent directional diagram interpretation apparatus 100 of the radar may be implemented in whole or in part by software, hardware, and a combination thereof. The above modules may be embedded in hardware or may be stored in a memory of the above device, which may be, but not limited to, various computer devices or radar management devices in the art, or may be stored in software in a device that is embedded in hardware or may be independent of a specific data processing function, so that the processor may call and execute operations corresponding to the above modules.
In yet another aspect, a radar information interpretation system is provided, including a memory and a processor, the memory storing a computer program, the processor executing the computer program to perform the steps of: acquiring a scattering matrix of radar data target pixels and obtaining a target matrix of the scattering matrix; the target matrix comprises a polarization coherence matrix or a polarization covariance matrix; performing unitary transformation on the target matrix, and obtaining a three-dimensional polarization correlation value by using elements of the target matrix after unitary transformation; performing polarization correlation directional diagram visualization processing in a three-dimensional coordinate system according to the three-dimensional polarization correlation value to generate a three-dimensional polarization correlation directional diagram of the radar; three coordinate axes of the three-dimensional polarization correlation pattern are respectively a three-dimensional polarization correlation value, a three-dimensional polarization correlation value and a polarization ellipticity angle of the radar; extracting features of the three-dimensional polarization related directional diagram to obtain interpretation features for quantitatively identifying scattering mechanisms corresponding to the three-dimensional polarization related directional diagram; the interpretation features include one or more of a maximum correlation value, a minimum correlation value, a maximum curve curvature value, a cross-section maximum correlation value, a cross-section minimum correlation value, a cross-section correlation degree, a cross-section correlation waviness, a correlation difference degree, a normalized correlation difference degree, a cross-section correlation contrast, a cross-section correlation inverse entropy, a maximum gaussian curvature value, a maximum average curvature value, and a maximum dominant curvature value.
It should be noted that the radar information interpretation system may be, but not limited to, a management device, a computer or other output data analysis system of a polarized radar in the art, and as long as a device capable of acquiring the polarized information may be included, it may include other necessary components besides the above-mentioned memory and processor, which are not listed in detail in this specification, depending on the specific device type of the radar information interpretation system. The polarization feature amount visualized in the three-dimensional polarization correlation pattern is not limited to the element values extracted from the unitary transformed polarization coherence matrix or polarization covariance matrix, and may include a mathematical operation between these element values, and a polarization feature extracted from another type of polarization matrix by unitary transformation (which may be also referred to as polarization basis transformation).
In one embodiment, the processor may also implement the steps or sub-steps added to the embodiments of the polarization dependent direction diagram interpretation method of the radar described above when executing the computer program.
In yet another aspect, there is also provided a computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of: acquiring a scattering matrix of radar data target pixels and obtaining a target matrix of the scattering matrix; the target matrix comprises a polarization coherence matrix or a polarization covariance matrix; performing unitary transformation on the target matrix, and obtaining a three-dimensional polarization correlation value by using elements of the target matrix after unitary transformation; performing polarization correlation directional diagram visualization processing in a three-dimensional coordinate system according to the three-dimensional polarization correlation value to generate a three-dimensional polarization correlation directional diagram of the radar; three coordinate axes of the three-dimensional polarization correlation pattern are respectively a three-dimensional polarization correlation value, a three-dimensional polarization correlation value and a polarization ellipticity angle of the radar; extracting features of the three-dimensional polarization related directional diagram to obtain interpretation features for quantitatively identifying scattering mechanisms corresponding to the three-dimensional polarization related directional diagram; the interpretation features include one or more of a maximum correlation value, a minimum correlation value, a maximum curve curvature value, a cross-section maximum correlation value, a cross-section minimum correlation value, a cross-section correlation degree, a cross-section correlation waviness, a correlation difference degree, a normalized correlation difference degree, a cross-section correlation contrast, a cross-section correlation inverse entropy, a maximum gaussian curvature value, a maximum average curvature value, and a maximum dominant curvature value.
In one embodiment, the computer program may also implement the steps or sub-steps added to the embodiments of the method for interpreting polarization dependent direction maps of radars described above when executed by a processor.
Those skilled in the art will appreciate that implementing all or part of the above-described methods may be accomplished by way of a computer program, which may be stored on a non-transitory computer readable storage medium, that when executed may comprise the steps of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in embodiments provided herein may include non-volatile and/or volatile memory. The nonvolatile memory can include Read Only Memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (SYNCHLINK) DRAM (SLDRAM), memory bus dynamic random access memory (Rambus DRAM, RDRAM for short), and interface dynamic random access memory (DRDRAM), among others.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description. It should be noted that in the above-mentioned corresponding embodiments of the present application, taking the vertical and horizontal polarization bases as examples, a series of feature values are derived from the obtained three-dimensional correlation pattern, and for the three-dimensional correlation pattern obtained under any polarization base, a series of feature values of the pattern can be derived according to the same definition as above, and these feature values and their corresponding applications are also within the scope of the present application.
The foregoing examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it is possible for those skilled in the art to make several variations and modifications without departing from the spirit of the present application, which fall within the protection scope of the present application. The scope of the application is therefore intended to be covered by the appended claims.
Claims (10)
1. A method for interpreting a polarization dependent directional diagram of a radar, comprising the steps of:
Acquiring a scattering matrix of radar data target pixels and obtaining a target matrix of the scattering matrix; the target matrix comprises a polarization coherence matrix or a polarization covariance matrix;
performing unitary transformation on the target matrix, and obtaining a three-dimensional polarization correlation value by using elements of the target matrix after unitary transformation;
Performing polarization correlation directional diagram visualization processing in a three-dimensional coordinate system according to the three-dimensional polarization correlation value to generate a three-dimensional polarization correlation directional diagram of the radar; three coordinate axes of the three-dimensional polarization correlation directional diagram are the three-dimensional polarization correlation value, the three-dimensional polarization correlation value and the polarization ellipticity angle of the radar respectively;
Extracting features of the three-dimensional polarization related directional diagram to obtain interpretation features for quantitatively identifying scattering mechanisms corresponding to the three-dimensional polarization related directional diagram; the interpretation features include one or more of a maximum correlation value, a minimum correlation value, a maximum curve curvature value, a cross-section maximum correlation value, a cross-section minimum correlation value, a cross-section correlation degree, a cross-section correlation fluctuation degree, a correlation difference degree, a normalized correlation difference degree, a cross-section correlation contrast, a cross-section correlation inverse entropy, a maximum gaussian curvature value, a maximum average curvature value, and a maximum dominant curvature value.
2. The method of claim 1, wherein when the target matrix is a polarization coherent matrix, the unitary transformation processing is performed on the polarization coherent matrix by the following conversion method:
T(θ，τ)＝U3p(θ,τ)TU3p(θ,τ)H
Wherein, unitary transformation formula is:
U3p(θ,τ)＝U3p(τ)U3p(θ)
Wherein T (θ, τ) represents the polarization coherence matrix after unitary transformation, U 3p (θ, τ) represents the polarization coherence matrix before unitary transformation, θ represents a polarization azimuth angle, τ represents the polarization ellipticity angle, the upper right corner mark H represents conjugate transpose, U 3p (τ) represents a unitary matrix containing a polarization ellipticity angle, and U 3p (θ) represents a unitary matrix containing a polarization azimuth angle.
3. The method of claim 1, wherein when the target matrix is a polarization covariance matrix, the unitary transformation is performed on the polarization covariance matrix by the following transformation method:
C(θ，τ)＝UT-CT(θ,τ)U-1 T-C
Wherein,
Wherein C (θ, τ) represents the polarization covariance matrix after unitary transformation, U T-C represents a special unitary matrix, T (θ, τ) represents the polarization coherence matrix after unitary transformation, θ represents a polarization azimuth angle, and τ represents the polarization ellipticity angle.
4. A method of polarization dependent directional diagram interpretation of a radar as claimed in claim 2 or 3, in which the three-dimensional polarization dependent directional diagram isAnd/>Wherein s 1 and s 2 are Pauli vectorsAnd Lexicographic vector/>Any one of the elements;
The three-dimensional polarization dependent pattern comprises a first three-dimensional polarization dependent pattern, a second three-dimensional polarization dependent pattern and a third three-dimensional polarization dependent pattern;
the first three-dimensional polarization-dependent pattern is
The second three-dimensional polarization-dependent pattern is
The third three-dimensional polarization-dependent pattern is
Where θ represents the polarization azimuth angle, τ represents the polarization ellipticity angle, s HH (θ, τ) represents the scattering matrix elements of the horizontally transmitted and horizontally received polarization channels,Conjugation of scattering matrix element s HV (θ, τ) representing the polarization channels of vertical transmission and horizontal reception,/>The conjugate of the scattering matrix element s VV (θ, τ) representing the vertically-transmitted and vertically-received polarized channels, s HH+VV (θ, τ) representing the sum of the scattering matrix elements of the horizontally-transmitted and horizontally-received polarized channels and the vertically-transmitted and vertically-received polarized channels, s HH-VV (θ, τ) representing the difference of the scattering matrix elements of the horizontally-transmitted and horizontally-received polarized channels and the vertically-transmitted and vertically-received polarized channels,/>Representing the conjugate of s HH-VV (θ, τ).
5. The method for interpreting a polarization dependent direction diagram of a radar according to claim 1, wherein said maximum gaussian curvature value is extracted by:
Calculating Gaussian curvature values of the three-dimensional polarization related values under a parameter space of a polarization azimuth angle and a polarization ellipticity angle;
Extracting the maximum value of absolute values of Gaussian curvature values as the maximum Gaussian curvature value;
the extraction process of the maximum average curvature value comprises the following steps:
calculating an average curvature value of the three-dimensional polarization related value under a parameter space of a polarization azimuth angle and a polarization ellipticity angle;
Extracting the maximum value in the absolute value of the average curvature value as the maximum average curvature value;
The extraction process of the maximum principal curvature value comprises the following steps:
calculating two principal curvature values of the three-dimensional polarization related value under a parameter space about a polarization azimuth angle and a polarization ellipticity angle;
taking the maximum value of the absolute values of the two main curvature values as the maximum main curvature value;
The maximum gaussian curvature value, the maximum average curvature value and the maximum dominant curvature value are used for identifying the surface curvature degree of the three-dimensional polarization-related directional diagram and the three-dimensional polarization-related value, and follow the change degrees of the polarization azimuth angle and the polarization ellipticity angle.
6. The polarization dependent directional diagram interpretation method of claim 1, wherein the maximum correlation value is a maximum value of the three-dimensional polarization dependent values in the three-dimensional polarization dependent directional diagram, and the minimum correlation value is a minimum value of the three-dimensional polarization dependent values in the three-dimensional polarization dependent directional diagram.
7. The method for interpreting a polarization dependent direction diagram of a radar according to claim 1, wherein said maximum curve curvature value is extracted by:
Extracting a cross section of the three-dimensional polarization related directional diagram at a set polarization azimuth angle or a set polarization ellipticity angle, calculating curve curvature values of all the curves in the cross section, and taking the maximum value in each curve curvature value as the maximum curve curvature value;
the extraction process of the maximum correlation value of the section is as follows:
calculating the maximum value of the three-dimensional polarization correlation values under the section as the maximum correlation value of the section;
the extraction process of the section minimum correlation value comprises the following steps:
calculating the minimum value in the three-dimensional polarization correlation values under the section as the section minimum correlation value;
The extraction process of the cross section correlation degree comprises the following steps:
calculating an average value of the three-dimensional polarization correlation values under the section as the section correlation degree;
the extraction process of the section related waviness comprises the following steps:
Calculating the standard deviation of the three-dimensional polarization correlation value under the section as the section correlation fluctuation degree;
The extraction process of the correlation difference degree comprises the following steps:
Respectively extracting cross sections at two different set polarization azimuth angles or polarization ellipticity angles in the three-dimensional polarization correlation directional diagram, respectively calculating the maximum correlation values of the two cross sections, calculating the difference, and taking the absolute value of the obtained difference as the correlation difference;
the extraction process of the normalized correlation difference degree comprises the following steps:
Calculating the difference value of the maximum correlation values of the two sections, and taking the absolute value of the ratio of the difference value to the sum of the maximum correlation values of the two sections as the normalized correlation difference;
the extraction process of the section related contrast is as follows:
Respectively extracting sections of the three-dimensional polarization correlation directional diagram at two set polarization azimuth angles or polarization ellipticity angles, calculating a section maximum correlation value of one section, calculating a section minimum correlation value of the other section, and taking the absolute value of the difference value between the obtained section maximum correlation value and the section minimum correlation value as the section correlation contrast;
The extraction process of the cross-section related inverse entropy comprises the following steps:
respectively extracting sections of the three-dimensional polarization correlation directional diagram at two set polarization azimuth angles or polarization ellipticity angles, calculating a section maximum correlation value of one section, and calculating a section minimum correlation value of the other section;
and respectively calculating a difference value and a sum value of the maximum correlation value and the minimum correlation value of the cross section, and taking the absolute value of the ratio of the difference value and the sum value as the cross section correlation inverse entropy.
8. A polarization dependent directional diagram interpretation apparatus of a radar, comprising:
The data acquisition module is used for acquiring a scattering matrix of radar data target pixels and obtaining a target matrix of the scattering matrix; the target matrix comprises a polarization coherence matrix or a polarization covariance matrix;
The unitary transformation module is used for carrying out unitary transformation processing on the target matrix and obtaining a three-dimensional polarization correlation value by utilizing elements of the target matrix after unitary transformation;
The three-dimensional visual module is used for carrying out polarization correlation directional diagram visual processing in a three-dimensional coordinate system according to the three-dimensional polarization correlation value to generate a three-dimensional polarization correlation directional diagram of the radar; three coordinate axes of the three-dimensional polarization correlation directional diagram are the three-dimensional polarization correlation value, the three-dimensional polarization correlation value and the polarization ellipticity angle of the radar respectively;
the feature extraction module is used for extracting features of the three-dimensional polarization related directional diagram to obtain interpretation features for quantitatively identifying scattering mechanisms corresponding to the three-dimensional polarization related directional diagram; the interpretation features include one or more of a maximum correlation value, a minimum correlation value, a maximum curve curvature value, a cross-section maximum correlation value, a cross-section minimum correlation value, a cross-section correlation degree, a cross-section correlation fluctuation degree, a correlation difference degree, a normalized correlation difference degree, a cross-section correlation contrast, a cross-section correlation inverse entropy, a maximum gaussian curvature value, a maximum average curvature value, and a maximum dominant curvature value.
9. A radar information interpretation system comprising a memory and a processor, the memory storing a computer program, characterized in that the processor, when executing the computer program, carries out the steps of the polarization dependent direction diagram interpretation method of a radar as claimed in any one of claims 1 to 7.
10. A computer-readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, carries out the steps of the polarization dependent direction diagram interpretation method of a radar as claimed in any one of claims 1 to 7.
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