Pi / 4 compact polarimetric SAR target decomposition method, program product and storage medium

Abstract

The invention relates to a pi / 4 compact polarimetric SAR target decomposition method, a program product and a storage medium. The method comprises the following steps: S1, obtaining complete polarimetric SAR data, and converting the complete polarimetric SAR data into a Stokes vector of a pi / 4 reduced polarimetric SAR; s2, selecting a volume scattering model according to the co-polarization ratio; s3, constructing a decomposition model according to the Stokes vector and the selected volume scattering model; s4, acquiring volume scattering energy, dihedral angle scattering energy and surface scattering energy according to the constructed decomposition model; wherein the scattering mechanism components of each pixel point of the image are obtained according to the volume scattering energy, the dihedral angle scattering energy and the surface scattering energy, and the ground object target scattering mechanism is interpreted according to different proportions of the scattering energy, so that different ground object type areas can be effectively distinguished, and the ground object scattering mechanism is obtained and accurately interpreted.

Description

Technical Field

[0001] The present invention relates to the field of radar remote sensing, and more specifically, to a π / 4 reduced polarimetric SAR (Synthetic Aperture Radar) target decomposition method, a program product and a storage medium. Background Art

[0002] Polarimetric Synthetic Aperture Radar (PolSAR) can observe the earth around the clock and in all weather conditions by transmitting and receiving electromagnetic waves, providing rich scattering information for the interpretation of ground objects. By effectively determining and understanding the scattering mechanism, the ability of polarimetric SAR images in tasks such as target detection and ground object classification can be greatly improved, making polarimetric SAR play a more important role in emergency rescue, urban analysis and planning, and other fields.

[0003] As an important branch of polarimetric SAR, compact polarimetric SAR can avoid the shortcomings of full polarimetric SAR and provide more information than single-polarization and dual-polarization modes.

[0004] The π / 4 mode is an important working mode of the compact polarimetric SAR, and the π / 4 compact polarimetric SAR target decomposition technology is an important technical means to interpret the scattering mechanism of various objects in the π / 4 compact polarimetric SAR images. In the application, the inventors found that the interpretation results of the scattering mechanism of some building areas with a large angle to the radar line of sight are similar to those of the forest area scattering mechanism, and it is difficult to distinguish different types of objects. The problem of overestimation of the volume scattering energy of inclined buildings is an important problem that restricts the accuracy of image scattering mechanism interpretation. Summary of the invention

[0005] In view of the above technical problems, the present invention provides a π / 4 reduced polarimetric SAR target decomposition method, a program product and a storage medium.

[0006] An embodiment of the present invention provides a π / 4 reduced polarization synthetic aperture radar SAR target decomposition method, the target decomposition method comprising the following steps:

[0007] S1. Obtain full polarization SAR data and convert it into Stokes vector of π / 4 reduced polarization SAR;

[0008] S2. Selecting a volume scattering model based on the co-polarization ratio;

[0009] S3. Construct a decomposition model based on the Stokes vector and the selected volume scattering model;

[0010] S4. Obtain the volume scattering energy, dihedral angle scattering energy, and surface scattering energy according to the constructed decomposition model;

[0011] Among them, obtain the scattering mechanism composition components of each pixel point of the image according to the volume scattering energy, dihedral angle scattering energy, and surface scattering energy, and interpret the scattering mechanism of the ground object target according to the different proportions of the scattering energy.

[0012] In some embodiments, in step S1, converting the fully polarized SAR data into the Stokes vector of π / 4 reduced polarization SAR includes:

[0013] Construct a fully polarized coherence matrix according to the fully polarized SAR data, and the fully polarized coherence matrix is expressed as follows:

[0014]

[0015] Among them, T represents the fully polarized coherence matrix, and T ij (i = 1, 2, 3; j = 1, 2, 3) represents the element in the i-th row and j-th column of T;

[0016] Obtain the Stokes vector of π / 4 reduced polarization SAR according to the relationship between the coherence matrix in the π / 4 reduced polarization mode and the fully polarized coherence matrix. Among them, the coherence matrix in the π / 4 reduced polarization mode is expressed as J, and its relationship with the fully polarized coherence matrix is as follows:

[0017]

[0018] Among them, the obtained Stokes vector is expressed as:

[0019]

[0020] Among them, G represents the Stokes vector, and g k represents the element in the k-th row of the Stokes vector, k = 0, 1, 2, 3, Re(·) represents the real part of the element, and Im(·) represents the imaginary part of the element.

[0021] In some embodiments, the co-polarization ratio is expressed as follows:

[0022]

[0023] Among them, S HH is the backscattering of horizontal transmission and horizontal reception, and S VV is the backscattering of vertical transmission and vertical reception.

[0024] In some embodiments, in step S2, selecting the volume scattering model according to the co-polarization ratio includes:

[0025] When 10lg(<SVV ><S HH ) < -2 dB, select the first volume scattering model whose probability density model follows a sine distribution. The expression of the first volume scattering model in the π / 4 compact polarization mode is:

[0026]

[0027] where G v1 represents the Stokes vector of the random volume scattering mechanism part in the first volume scattering model, θ d represents the angle between the ground target and the radar line of sight direction, m v represents the volume scattering component;

[0028] When 10lg(<S VV > / <S HH ) > 2 dB, select the second volume scattering model whose probability density model follows a cosine distribution. The expression of the second volume scattering model in the π / 4 compact polarization mode is:

[0029]

[0030] where G v2 represents the Stokes vector of the random volume scattering mechanism part in the second volume scattering model;

[0031] When -2 dB < 10lg(<S VV > / <S HH ) < 2 dB, select the third volume scattering model whose probability density model follows a uniform distribution. The expression of the third volume scattering model in the π / 4 compact polarization mode is:

[0032]

[0033] where G v3 represents the Stokes vector of the random volume scattering mechanism part in the third volume scattering model.

[0034] In some embodiments, in step S3:

[0035] The first decomposition model constructed according to the first volume scattering model is as follows:

[0036]

[0037] where G p represents the Stokes vector of the rank-1 scattering mechanism part, m v and m p respectively represent the coefficients of the volume scattering component and the rank-1 scattering component, and α and are scattering parameters;

[0038] Let c = ±cos2α, and obtain the first relational expression according to the corresponding relationship of each element in the matrix as follows:

[0039]

[0040] The second decomposition model constructed according to the second body scattering model is as follows:

[0041]

[0042] Let c = ±cos2α, and obtain the second relational expression according to the corresponding relationship of each element in the matrix as follows:

[0043]

[0044] The third decomposition model constructed according to the third body scattering model is as follows:

[0045]

[0046] Let c = ±cos2α, and obtain the third relational expression according to the corresponding relationship of each element in the matrix as follows:

[0047]

[0048] In some embodiments, in step S4, obtaining the body scattering energy, the dihedral angle scattering energy, and the surface scattering energy includes:

[0049] Obtain a, b, c, m according to the first relational expression p , m v The first expressions are as follows:

[0050]

[0051] The body scattering energy, the dihedral angle scattering energy, and the surface scattering energy can be obtained according to this first expression as follows:

[0052]

[0053] P v = 2m v

[0054] where P S represents the surface scattering energy, P d represents the dihedral angle scattering energy, and P v represents the body scattering energy;

[0055] Obtain a, b, c, m according to the second relational expressionp , m v The second expression of, as follows:

[0056]

[0057] According to this second expression, the volume scattering energy, the dihedral angle scattering energy, and the surface scattering energy can be obtained as follows:

[0058]

[0059] P v = 2m v ;

[0060] According to the third relational expression, a, b, c, m p , m v The third expression of, as follows:

[0061]

[0062] According to this third expression, the volume scattering energy, the dihedral angle scattering energy, and the surface scattering energy can be obtained as follows:

[0063]

[0064] P v = 2m v .

[0065] In some embodiments, the method for interpreting the scattering mechanism of a ground object according to the different proportions of scattering energy includes: using a false color map to display the interpretation result.

[0066] Another embodiment of the present invention provides a computer program product, which includes a computer program. When the computer program is executed by a processor, the processor is caused to perform the operations in the method according to any one of the embodiments of the present invention.

[0067] Another embodiment of the present invention provides a computer storage medium, which stores a computer program. When the instruction is executed by a processor, the processor is caused to perform the operations in the method according to any one of the embodiments of the present invention.

[0068] Implementing the present invention can obtain the following beneficial effects: The embodiments of the present invention select corresponding volume scattering models according to the co-polarization ratio. The volume scattering model fully considers the rotation angle of the building area, can effectively overcome the problem of overestimation of the volume scattering energy in the building area, effectively distinguish different ground object type areas, and obtain an accurate interpretation of the ground object scattering mechanism.

[0069] All aspects, features, advantages, etc. of the embodiments of the present invention will be specifically described below in conjunction with the accompanying drawings. Brief Description of the Drawings

[0070] Figure 1 is a flowchart of the π / 4 reduced polarization SAR target decomposition method according to an exemplary embodiment of the present invention.

[0071] Figure 2 is an optical image picture of a ground object target according to an exemplary embodiment of the present invention.

[0072] Figure 3 is according to Comparative Example 1 Figure 2 The false color map of the ground object target shown by Pauli decomposition.

[0073] Figure 4 is according to Comparative Example 2 Figure 2 The false color map of the ground object target based on the traditional m-χ decomposition algorithm shown.

[0074] Figure 5 is obtained according to an exemplary embodiment of the present invention Figure 2 The false color map of the decomposed ground object target shown.

[0075] Figure 6 is a block diagram showing an exemplary structure of a computer device that can be used to execute the π / 4 reduced polarization SAR target decomposition method according to an exemplary embodiment of the present invention. Detailed Embodiments

[0076] The exemplary embodiments of the present invention will be described in more detail below with reference to the drawings. It should be noted that the present invention can be implemented in various forms and is not limited to the exemplary embodiments described herein or shown in the drawings.

[0077] In this document, approximate terms such as "substantially", "about", "roughly", etc. are used as descriptive terms in this document, rather than as a limitation of the degree of precision. These terms are intended to cover a reasonable error range of measured or calculated values that can be recognized by those skilled in the art.

[0078] In this document, the terms "comprising", "including", and "having" are used in this document to indicate the presence of certain features, steps, operations, elements, and / or components, but do not exclude the presence or addition of other features, steps, operations, elements, components, or their combinations.

[0079] In this document, terms such as "first", "second", etc. do not represent any order of precedence or sequence, and are only used to distinguish different elements in the description, unless the context clearly indicates that they represent an order of precedence.

[0080] Figure 1 shows an example process of the π / 4 reduced polarization synthetic aperture radar (SAR) target decomposition method according to an exemplary embodiment of the present invention. Refer toFigure 1 , the target decomposition method includes the following steps:

[0081] S1. Obtain full-polarization SAR data and convert it into the Stokes vector of π / 4 compact-polarization SAR;

[0082] S2. Select a volume scattering model according to the co-polarization ratio;

[0083] S3. Construct a decomposition model based on the Stokes vector and the selected volume scattering model;

[0084] S4. According to the constructed decomposition model, obtain the volume scattering energy, dihedral angle scattering energy, and surface scattering energy;

[0085] Among them, according to the volume scattering energy, dihedral angle scattering energy, and surface scattering energy, the scattering mechanism composition components of each pixel point of the image are obtained, and according to the different proportions of the scattering energy, the scattering mechanisms of the ground object targets are interpreted.

[0086] According to the embodiments of the present invention, different volume scattering models can be selected according to the co-polarization ratio, so as to fully consider the rotation angle of the building area, effectively overcome the problem of overestimation of the volume scattering energy in the building area, effectively distinguish different ground object type areas, and obtain an accurate interpretation of the ground object scattering mechanism.

[0087] In some embodiments, in step S1, converting the full-polarization SAR data into the Stokes vector of π / 4 compact-polarization SAR includes: constructing a full-polarization coherence matrix according to the full-polarization SAR data; obtaining the Stokes vector of π / 4 compact-polarization SAR according to the relationship between the coherence matrix in the π / 4 compact-polarization mode and the full-polarization coherence matrix.

[0088] In some embodiments, constructing a full-polarization coherence matrix according to the full-polarization SAR data, the full-polarization coherence matrix is expressed as follows:

[0089]

[0090] Among them, T represents the full-polarization coherence matrix; k3 represents the Pauli basis of the full-polarization image; T ij (i = 1, 2, 3; j = 1, 2, 3) represents the element in the i-th row and j-th column of the full-polarization coherence matrix T; the superscript "H" represents transpose.

[0091] Among them,

[0092] S HH is the backscattering of horizontal transmission and horizontal reception, S HV is the backscattering of vertical transmission and horizontal reception, S VV is the backscattering of vertical transmission and vertical reception.

[0093] In some embodiments, in the π / 4 reduced polarization mode, the coherence matrix is denoted as J, and its relationship with the full polarization coherence matrix is as follows:

[0094]

[0095] Among them, the coherence matrix J in the π / 4 reduced polarization mode can be expressed as:

[0096]

[0097] According to equations (3) and (4), the Stokes vector can be obtained and expressed as:

[0098]

[0099] Among them, G represents the Stokes vector, and g k represents the element in the k-th row of the Stokes vector, where k = 0, 1, 2, 3, Re(·) represents the real part of the element, and Im(·) represents the imaginary part of the element.

[0100] In some embodiments, in step S2, a volume scattering model is selected according to the co-polarization ratio, where the co-polarization ratio is expressed as follows:

[0101]

[0102] Among them, S HH is the backscattering of horizontal transmission and horizontal reception, and S VV is the backscattering of vertical transmission and vertical reception.

[0103] In some embodiments, in step S2, the selecting the volume scattering model according to the co-polarization ratio includes: when 10lg(<S VV > / <S HH >) < -2 dB, select a volume scattering model whose probability density model follows a sine distribution.

[0104] The expression of this volume scattering model in full polarization SAR is:

[0105]

[0106] Among them, the expression of the volume scattering model in the π / 4 reduced polarization mode is:

[0107]

[0108] Among them, G v1 represents the Stokes vector of the random volume scattering mechanism part in the volume scattering model whose probability density model follows a sine distribution; It represents the angle between the ground object target and the radar line of sight direction; m v Represents the volume scattering component.

[0109] In some embodiments, in step S2, the selecting the volume scattering model according to the co-polarization ratio includes: when 10lg(<S VV > / <S HH >) > 2 dB, select the volume scattering model whose probability density model follows a cosine distribution.

[0110] The full-polarization SAR expression of this volume scattering model is:

[0111]

[0112] Among them, the expression of the volume scattering model in the π / 4 compact polarization mode is:

[0113]

[0114] Among them, G v2 Represents the Stokes vector of the random volume scattering mechanism part in the volume scattering model whose probability density model follows a cosine distribution.

[0115] In some embodiments, in step S2, the selecting the volume scattering model according to the co-polarization ratio includes: when -2 dB < 10lg(<S VV > / <S HH >) < 2 dB, select the volume scattering model whose probability density model follows a uniform distribution.

[0116] The full-polarization SAR expression of this volume scattering model is:

[0117]

[0118] Among them, the expression of the volume scattering model in the π / 4 compact polarization mode is:

[0119]

[0120] Among them, G v3 Represents the Stokes vector of the random volume scattering mechanism part in the volume scattering model whose probability density model follows a uniform distribution.

[0121] In some embodiments, in step S3, according to the relationship between the Stocks vector (SV) part of the random volume scattering mechanism in the Stokes vector and surface scattering and dihedral angle scattering, a decomposition model is constructed.

[0122] For example, the random volume over ground (RVoG) model can be adopted, as follows:

[0123] G = G vi +G p (13)

[0124] In the above formula (13), G vi represents the Stokes vector of the random volume scattering mechanism part. For i = 1, 2, 3, different values of i represent different selected volume scattering models, and the expressions of the scattering models correspond to the above formulas (8), (10), and (12). G p represents the Stokes vector of the rank-1 scattering mechanism part, including surface scattering and dihedral angle scattering in the π / 4 polarization mode.

[0125] In some embodiments, based on the volume scattering model that follows a sine distribution (10lg(<S VV > / <S HH >) < -2dB), the decomposition model in the π / 4 reduced polarization mode is constructed as follows:

[0126]

[0127] where m v and m p represent the coefficients of the volume scattering component and the rank-1 scattering component, respectively. α and are scattering parameters and can be estimated through the SV elements:

[0128]

[0129] Let c = ±cos2α, and the first relational expression is obtained according to the corresponding relationship of each element in the matrix as follows:

[0130]

[0131] In some embodiments, based on the volume scattering model that follows a cosine distribution (10lgSVVSHH > 2dB), the decomposition model in the π / 4 reduced polarization mode is constructed as follows:

[0132]

[0133] Let c = ±cos2α, and the second relational expression is obtained according to the corresponding relationship of each element in the matrix as follows:

[0134]

[0135] In some embodiments, based on the volume scattering model that follows a uniform distribution (-2dB < 10lg(<S VV > / <S HH) The decomposition model in the π / 4 reduced polarization mode constructed with <2 dB) is as follows:

[0136]

[0137] Let c = ±cos2α, and the third relation is obtained according to the corresponding relationship of each element in the matrix as follows:

[0138]

[0139] In some embodiments, in step S4, when selecting the volume scattering model that follows a sine distribution (10lg(<S VV > / <S HH ) < -2 dB), a, b, c, m p , m v The first expressions are as follows:

[0140]

[0141] As can be seen from the above formula, the five unknowns (a, b, c, m p , m v ) correspond to five equations, and the unique solutions of the five unknowns can be obtained. Thus, the volume scattering energy, dihedral angle scattering energy, and surface scattering energy can be obtained:

[0142]

[0143] P v = 2m v

[0144] Among them, P S represents the surface scattering energy, P d represents the dihedral angle scattering energy, and P v represents the volume scattering energy.

[0145] Using the volume scattering energy, dihedral angle scattering energy, and surface scattering energy, the scattering mechanism composition components of each pixel point of the image can be obtained. According to the different proportions of the scattering energy, the scattering mechanism of the ground object can be reasonably interpreted, and the scattering mechanism interpretation result can be used as the basis for dividing different ground object types.

[0146] In some embodiments, in step S4, when selecting the volume scattering model that follows a cosine distribution (10lg(<S VV > / <S HH ) > 2 dB), a, b, c, m p , m v The second expressions are as follows:

[0147]

[0148] According to the second expression, the volume scattering energy, the dihedral angle scattering energy, and the surface scattering energy can be obtained as follows:

[0149]

[0150] P v = 2m v .

[0151] Similarly, the scattering mechanism composition components of each pixel in the image can be obtained by using the volume scattering energy, the dihedral angle scattering energy, and the surface scattering energy. According to the different proportions of the scattering energy, the scattering mechanism of the ground object target can be reasonably interpreted, and the interpretation result of the scattering mechanism can be used as the basis for classifying different ground object types.

[0152] In some embodiments, in step S4, when selecting a volume scattering model that follows a uniform distribution (-2dB < 10lg(<S VV > / <S HH ) < 2dB), a, b, c, and m p , m v of the third expression are obtained according to the third relational expression (Equation (20)) as follows:

[0153]

[0154] Similarly, according to this third expression, the volume scattering energy, the dihedral angle scattering energy, and the surface scattering energy can be obtained as follows:

[0155]

[0156] P v = 2m v .

[0157] Similarly, the scattering mechanism composition components of each pixel in the image can be obtained by using the volume scattering energy, the dihedral angle scattering energy, and the surface scattering energy. According to the different proportions of the scattering energy, the scattering mechanism of the ground object target can be reasonably interpreted, and the interpretation result of the scattering mechanism can be used as the basis for classifying different ground object types.

[0158] In some embodiments, the interpretation of the scattering mechanism of the ground object target according to the different proportions of the scattering energy includes: using a false color map to display the interpretation result.

[0159] The following will refer to Figures 2 to 5 to illustrate the advantages of the embodiments of the present invention. Figure 2 shows the optical image of the target area. The L-band polarimetric SAR data collected in the target area by the E-SAR system is used as an example for validating the effectiveness of the algorithm.Figure 3 shows the Pauli decomposition false color map corresponding to the target area (Comparative Example 1). Figure 4 shows the false color map based on the traditional m- χ decomposition algorithm (Comparative Example 2), and the figure shows the false color map obtained by the method according to the embodiment of the present invention. By comparison, for the building area (such as the yellow rectangle in the figure), especially for the inclined building area with a large angle with respect to the radar line of sight, the false color map of the decomposition result obtained by the embodiment of the present invention presents pink, that is, the scattering energy is mainly surface scattering and dihedral angle scattering, which can be well distinguished from the scattering mechanism of the forest area, is beneficial to better distinguish different ground object types, and effectively solves the problem of overestimation of the volume scattering energy in the building area.

[0160] The π / 4 reduced polarization synthetic aperture radar (SAR) target decomposition method according to the embodiment of the present invention has been elaborated in detail above. It should be understood that part or all of the operations of the method can be programmed into a program product, and the program of the program product can be stored on a storage medium and can be executed by a computer or similar device. Figure 6 shows an exemplary structure of a computer device capable of executing the method according to the embodiment of the present invention.

[0161] Referring to Figure 6 , the computer device 100 includes at least a processor 101 and a memory 102. The memory 102 can be an example of a storage medium, on which a computer program (or computer-readable instructions) is stored. The processor 101 executes the computer program to perform part or all of the operations in the method according to any one of the embodiments of the present invention.

[0162] In some embodiments, the computer device 100 may further include a data storage device 103, a display 104, a speaker 105, and a communication module 106. Among them, the processor 101, the memory 102, and the data storage device 103 communicate with each other through a bus, and interact with peripheral devices, such as the display 104 and the communication module 106, through the bus and the I / O module 107. Specifically, the data storage device 103 can store application programs and their various configuration files and data, including but not limited to SAR data. A computer program is stored on the memory 102. The processor 101 executes the computer program to perform various operations or steps of the π / 4 reduced polarization synthetic aperture radar (SAR) target decomposition method. For example, including but not limited to, calling the communication module 106 to obtain full polarization SAR data and converting it into the Stokes vector of π / 4 reduced polarization SAR; selecting a volume scattering model according to the co-polarization ratio; constructing a decomposition model based on the Stokes vector and the selected volume scattering model; obtaining the volume scattering energy, the dihedral angle scattering energy, and the surface scattering energy according to the constructed decomposition model; obtaining the scattering mechanism composition components of each pixel point of the image according to the volume scattering energy, the dihedral angle scattering energy, and the surface scattering energy, and interpreting the scattering mechanism of the ground object target according to the different proportions of the scattering energy, and displaying the image on the display 104 or sending it to other systems, devices, or equipment for display through a communication connection. In an alternative embodiment, the communication module 106 may be omitted when there is no need to communicate with the other systems, devices, or equipment. In some embodiments, the computer device 100 may further include a speaker 105 for voice output.

[0163] In some embodiments, the processor 101 may include any suitable semiconductor-based electronic processing unit, chip, microchip, or integrated circuit (IC). The memory 102 is a programmable memory, which may include any suitable electronic storage device configured to store instructions and be reprogrammable. For example, the programmable memory may include an erasable programmable read-only memory (EPROM) device. The data storage device 103 may be a persistent storage device, which may include any suitable electronic memory configured to retain the stored information when the power is cycled. For example, the data storage device 103 may include a hard disk drive, a solid-state drive (SSD), a flash drive, a hybrid drive, etc., or any combination of these.

[0164] Therefore, the processor 101 can control the output of information on the I / O module 107 by storing information in the memory and / or executing the programs / instructions stored in the memory. For example, several aspects of the methods described herein may be performed by the processor 101 according to the programs / instructions stored in the memory (e.g., the memory 102 and / or the data storage device 103).

[0165] Moreover, the processor 101 may be in electronic communication with the I / O module 107 and / or the communication module 106 to receive or transmit relevant instructions and information. The I / O module 107 may include any suitable mechanical or virtual user interface configured to enable a user to interact with the computer device 100 or to allow the user to perform one or more functions of the computer device 100 itself. For example, a graphical user interface (GUI) on a screen or other display. In some instances, the user interface may include a voice interface capable of voice recognition through which an operator may provide voice commands to the processor.

[0166] The communication module 106 may include any suitable devices and / or structures configured to facilitate information interaction between the computer device 100 and external electronic devices. The communication module 106 may include devices configured to send and / or receive wireless or wired information to / from other devices. For example, the communication module 106 may include an antenna, a transceiver, a connector for wired reception and / or transmission of data, a data exchange device, etc., or any combination thereof. The communication module 106 may also include supporting components, such as, a filter circuit, an encryption / decryption circuit, and / or an integrated circuit (IC) chip for processing signals (e.g., a chip). In some embodiments, the communication module 106 may include a WiFi device configured to connect to a local wireless network.

[0167] In some embodiments, the computer device 100 may include a smart phone, a wearable computer, a portable / movable electronic device, a tablet computer, a smart watch, a personal digital assistant (PDA), a personal computer (PC), a desktop computer, a laptop computer, a server, etc. The computer device 100 may include or install one or more application programs (APPs), and one of the APPs is configured to execute the π / 4 reduced polarization synthetic aperture radar (SAR) target decomposition method described herein.

[0168] Although not shown, it should be understood that the computer device 100 further includes a power supply component, which may include any suitable device and / or structure configured to provide an electrical interface between the computer device 100 and a power supply. The power supply may include any suitable source of electrical energy, such as a battery, a socket, a capacitor, a fuel cell, etc., or any combination thereof. Additionally or alternatively, the power supply may be included in the power supply component. For example, a battery or a battery pack may be included within the computer device 100. In some embodiments, the battery may be rechargeable, for example, by charging through a cable or an interface provided by the power supply component. In some embodiments, the power supply component may share features with or duplicate features of the communication module 106. For example, a USB or a micro-USB cable connector may be included in the computer device 100, such that power supply or data communication is performed by the same component.

[0169] Those skilled in the art should understand that the above-disclosed content is only an illustration of the embodiments of the present invention, and the scope of the rights claimed in this application is not limited thereto. Without departing from the spirit or principle of the present invention, various modifications, changes, substitutions, and other variations can be made to the embodiments disclosed herein, and these variations are within the scope covered by the claims of this application.

Claims

1. A π / 4 reduced polarization synthetic aperture radar SAR target decomposition method, comprising the following steps: S1. Obtain full polarimetric SAR data and convert it into Stokes vector of π / 4 reduced polarimetric SAR; S2. Selecting a volume scattering model based on the co-polarization ratio; S3. Construct a decomposition model based on the Stokes vector and the selected volume scattering model; S4. Obtaining volume scattering energy, dihedral scattering energy and surface scattering energy according to the constructed decomposition model; The components of the scattering mechanism of each pixel point in the image are obtained according to the volume scattering energy, dihedral scattering energy and surface scattering energy, and the scattering mechanism of the ground object target is interpreted according to the different proportions of the scattering energy.

2. The method of claim 1, wherein: In step S1, converting the full polarization SAR data into the Stokes vector of the π / 4 reduced polarization SAR includes: A full polarization coherence matrix is ​​constructed according to the full polarization SAR data. The full polarization coherence matrix is ​​expressed as follows: Where T represents the full polarization coherence matrix, T ij (i=1,2,3; j=1,2,3) represents the i-th row and j-th column element in T; According to the relationship between the coherence matrix in the π / 4 reduced polarization mode and the full polarization coherence matrix, the Stokes vector of the π / 4 reduced polarization SAR is obtained, where the coherence matrix in the π / 4 reduced polarization mode is represented by J, and its relationship with the full polarization coherence matrix is ​​as follows: Among them, the obtained Stokes vector is expressed as: Where G represents the Stokes vector, g k represents the element of the kth row of the Stokes vector, k = 0, 1, 2, 3, Re(·) represents the real part of the element, and Im(·) represents the imaginary part of the element.

3. The method of claim 2, wherein: The co-polarization ratio is expressed as follows: Among them, S HH is the backscatter of horizontal transmission and horizontal reception, S VV It is the backscatter with vertical emission and vertical reception.

4. The method of claim 3, wherein: In step S2, selecting a volume scattering model according to the co-polarization ratio includes: When 10lg( VV > HH >)<-2dB, the first-body scattering model whose probability density model obeys the sinusoidal distribution is selected, where the expression of the first-body scattering model in the π / 4 reduced polarization mode is:​​ Among them, G v1 The Stokes vector, θ, represents the random volume scattering mechanism part of the first volume scattering model. d Indicates the angle between the ground object and the radar line of sight. m v represents the volume scattering component; When 10lg( VV > / HH >)>2dB, the second body scattering model whose probability density model obeys the cosine distribution is selected, where the expression of the second body scattering model in the π / 4 reduced polarization mode is:​​ Among them, G v2 Stokes vector representing the random volume scattering mechanism part of the second volume scattering model; When -2dB<10lg( VV > / HH >)<2dB, the third body scattering model with a probability density model obeying a uniform distribution is selected, where the expression of the third body scattering model in the π / 4 reduced polarization mode is:​​ Among them, G v3 Stokes vector representing the random volume scattering mechanism part of the third volume scattering model.

5. The method of claim 4, wherein: In step S3: The first decomposition model constructed according to the first volume scattering model is as follows: Among them, G p The Stokes vector representing the rank-1 scattering mechanism, m v and m p Represent the coefficients of volume scattering component and rank 1 scattering component, α and is the scattering parameter; make c=±cos2α, and the first relationship is obtained according to the corresponding relationship between the elements in the matrix, as follows: The second decomposition model constructed according to the second volume scattering model is as follows: make c=±cos2α, and the second relationship is obtained according to the corresponding relationship between the elements in the matrix, as follows: The third decomposition model constructed according to the third volume scattering model is as follows: make c=±cos2α, and the third relationship is obtained according to the corresponding relationship between the elements in the matrix, as follows:

6. The method of claim 5, wherein: In step S4, obtaining volume scattering energy, dihedral scattering energy and surface scattering energy includes: According to the first relationship, we can get a, b, c, m p , m v The first expression is as follows: According to the first expression, the volume scattering energy, dihedral scattering energy and surface scattering energy can be obtained as shown below: P v =2m v Among them, P S represents the surface scattered energy, P d represents the dihedral scattering energy, P v represents the volume scattered energy; According to the second relationship, we can get a, b, c, m p , m v The second expression is as follows: According to the second expression, the volume scattering energy, dihedral scattering energy and surface scattering energy can be obtained as shown below: P v =2m v ; According to the third relational expression, a, b, c, m are obtained. p , m v The third expression is as follows: According to the third expression, the volume scattering energy, the dihedral scattering energy and the surface scattering energy can be obtained as shown below: P v =2m v 。 7. The method of claim 1, wherein: The interpreting the scattering mechanism of the ground object target according to different scattering energy proportions includes: using a pseudo-color image to display the interpretation result.

8. A computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the processor is caused to perform the operations of the method according to any one of claims 1 to 7.

9. A computer storage medium storing a computer program, wherein when the instructions are executed by a processor, the processor is caused to perform the operations of the method according to any one of claims 1 to 7.

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