π / 4 Compact Polarimetric SAR Target Decomposition Method, Program Product, and Storage Medium

Abstract

The present invention relates to a π / 4 reduced polarimetric SAR target decomposition method, program product, and storage medium. The method comprises the following steps: S1. obtaining fully polarimetric SAR data and converting it into Stokes vectors for the π / 4 reduced polarimetric SAR; S2. selecting a volume scattering model based on a co-polarization ratio; S3. constructing a decomposition model based on the Stokes vectors and the selected volume scattering model; S4. obtaining volume scattering energy, dihedral scattering energy, and surface scattering energy based on the constructed decomposition model; wherein, based on the volume scattering energy, dihedral scattering energy, and surface scattering energy, the scattering mechanism components of each pixel point in the image are obtained, and based on the different scattering energy proportions, the scattering mechanism of the ground object target is interpreted, thereby effectively distinguishing different ground object types and obtaining an accurate interpretation of the ground object scattering mechanism.

Description

Technical Field

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

[0002] Polarimetric Synthetic Aperture Radar (PolSAR) transmits and receives electromagnetic waves, enabling all-day, all-weather Earth observation. This provides rich scattering information for interpreting ground objects. By effectively identifying and understanding scattering mechanisms, the capabilities of polarimetric SAR imagery in tasks such as target detection and object classification can be greatly enhanced, enabling polarimetric SAR to play a more significant role in emergency response, disaster relief, urban analysis, and planning.

[0003] As an important branch of polarimetric SAR, reduced 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 a key operating mode for compact polarimetric SAR (Compact Polarimetric SAR). π / 4 Compact Polarimetric SAR target decomposition is a crucial technique for interpreting the scattering mechanisms of various objects in π / 4 Compact Polarimetric SAR images. In applications, the inventors discovered that the interpretation of the scattering mechanisms of some buildings, which are located at a significant angle to the radar's line of sight, is similar to that of forests, making it difficult to distinguish between different object types. Furthermore, overestimation of the volume scattering energy of tilted buildings is a significant issue limiting 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 polarimetric synthetic aperture radar (SAR) target decomposition method, the target decomposition method comprising the following steps:

[0007] S1. Obtain fully polarimetric SAR data and convert it into Stokes vectors for a π / 4 reduced polarimetric SAR.

[0008] S2. Select 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. Obtaining volume scattering energy, dihedral scattering energy, and surface scattering energy based on the constructed decomposition model;

[0011] 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.

[0012] In some embodiments, in step S1, converting the full polarimetric SAR data into Stokes vectors of a π / 4 reduced polarimetric SAR includes:

[0013] A full polarization coherence matrix is constructed based on the full polarization SAR data. The full polarization coherence matrix is expressed as follows:

[0014]

[0015] Where T represents the full polarization coherence matrix, T ij represents the element in row i and column j of T, where i = 1, 2, 3; j = 1, 2, 3;

[0016] Based on 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. 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:

[0017]

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

[0019]

[0020] Where G represents the Stokes vector, g k Represents the element of 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 backscatter of horizontal transmission and horizontal reception, S VV It is the backscatter with vertical emission and vertical reception.

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

[0025] When 10lg( <SVV > / HH When >)<-2dB, the first-body scattering model with a probability density model obeying a sinusoidal distribution is selected, where the expression of the first-body scattering model in the π / 4 reduced polarization mode is:

[0026]

[0027] Among them, G v1 The Stokes vector, θ, represents the random bulk scattering mechanism in the first bulk scattering model. d Indicates the angle between the ground target and the radar line of sight. m v represents the volume scattering component;

[0028] When 10lg( VV > / HH When >)>2dB, the second-body scattering model with a probability density model obeying the cosine distribution is selected, where the expression of the second-body scattering model in the π / 4 reduced polarization mode is:

[0029]

[0030] Among them, G v2 Stokes vector representing the random bulk scattering mechanism part of the second bulk scattering model;

[0031] When -2dB<10lg( VV > / HH >)<2dB, the third-body scattering model with a uniform probability density model is selected. The expression of the third-body scattering model in the π / 4 reduced polarization mode is:

[0032]

[0033] Among them, G v3 The Stokes vector representing the random bulk scattering mechanism part of the third-body 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] Among them, G p The Stokes vector representing the rank-1 scattering mechanism, m v and m p Denote the coefficients of volume scattering component and rank 1 scattering component, α and is the scattering parameter;​​​​​

[0038] make c=±cos2α. According to the corresponding relationship between the elements in the matrix, the first relationship is obtained as follows:

[0039]

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

[0041]

[0042] make c=±cos2α. According to the corresponding relationship between the elements in the matrix, the second relationship is obtained as follows:

[0043]

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

[0045]

[0046] make c=±cos2α. According to the corresponding relationship between the elements in the matrix, the third relationship is obtained as follows:

[0047]

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

[0049] According to the first relationship, we can get a, b, c, and m. p , m V The first expression is as follows:

[0050]

[0051] According to the first expression, the volume scattering energy, dihedral scattering energy and surface scattering energy can be obtained as follows:

[0052]

[0053]

[0054] P v =2m v

[0055] Among them, P S represents the surface scattered energy, P d represents the dihedral scattering energy, P v represents the body scattered energy;

[0056] According to the second relationship, we can get a, b, c, and m. p , m v The second expression is as follows:

[0057]

[0058] According to the second expression, the volume scattering energy, dihedral scattering energy and surface scattering energy can be obtained as follows:

[0059]

[0060] P v =2m v ;

[0061] According to the third relational expression, a, b, c, and m are obtained. p , m v The third expression is as follows:

[0062]

[0063] According to the third expression, the volume scattering energy, dihedral scattering energy and surface scattering energy can be obtained as follows:

[0064]

[0065] P v =2m v .

[0066] In some embodiments, interpreting the scattering mechanism of the ground object according to different scattered energy proportions includes: displaying the interpretation result using a pseudo-color image.

[0067] 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 of the method described in any embodiment of the present invention.

[0068] Yet another embodiment of the present invention provides a computer storage medium storing a computer program. When the computer program is executed by a processor, the processor is caused to perform the operations of the method described in any embodiment of the present invention.

[0069] The implementation of the present invention can achieve the following beneficial effects: The embodiments of the present invention select a corresponding volume scattering model based on the co-polarization ratio. The volume scattering model fully considers the rotation angle of the building area, effectively overcomes the problem of overestimation of volume scattering energy in the building area, effectively distinguishes areas of different ground object types, and obtains an accurate interpretation of the ground object scattering mechanism.

[0070] Various aspects, features, advantages, etc. of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 4 is a flow chart of a π / 4 reduced polarimetric SAR target decomposition method according to an exemplary embodiment of the present invention.

[0072] Figure 2 1 is an optical image picture showing a ground object according to an exemplary embodiment of the present invention.

[0073] Figure 3 According to Comparative Example 1 Figure 2 The Pauli decomposition pseudo-color image of the ground object shown.

[0074] Figure 4 According to Comparative Example 2 Figure 2 The pseudo-color image of the ground object shown is based on the traditional m-χ decomposition algorithm.

[0075] Figure 5 According to an exemplary embodiment of the present invention Figure 2 The decomposed pseudo-color image of the ground object shown.

[0076] Figure 6 is a block diagram illustrating an exemplary structure of a computer device that may be used to execute the π / 4 reduced polarimetric SAR target decomposition method according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0077] The following will describe exemplary embodiments of the present invention in more detail with reference to the accompanying drawings. It should be noted that the present invention can be implemented in many forms and is not limited to the exemplary embodiments described herein or shown in the accompanying drawings.

[0078] In this article, the terms "substantially", "about", "approximately" and the like are used as descriptive terms rather than as limitations of precision. These terms are intended to encompass a reasonable error range of a measurement or calculation value that can be recognized by a person skilled in the art.

[0079] Herein, the terms “comprise,” “include,” and “have” are used to indicate the existence of certain features, steps, operations, elements, and / or components, but do not exclude the existence or addition of other features, steps, operations, elements, components, or combinations thereof.

[0080] Herein, the terms "first", "second" and the like do not indicate any priority or order, but are only used to distinguish different elements in the description, unless the context clearly indicates a priority.

[0081] Figure 1FIG2 shows an example process of a π / 4 reduced polarization synthetic aperture radar SAR target decomposition method according to an exemplary embodiment of the present invention. Figure 1 , the target decomposition method comprises the following steps:

[0082] S1. Obtain fully polarimetric SAR data and convert it into Stokes vectors for π / 4 reduced polarimetric SAR.

[0083] S2. Select a volume scattering model based on the co-polarization ratio;

[0084] S3. Construct a decomposition model based on the Stokes vector and the selected volume scattering model;

[0085] S4. Obtaining volume scattering energy, dihedral scattering energy, and surface scattering energy based on the constructed decomposition model;

[0086] 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.

[0087] According to the embodiments of the present invention, different volume scattering models can be selected based on the co-polarization ratio, thereby fully considering the rotation angle of the building area. This can effectively overcome the problem of overestimation of volume scattering energy in the building area, effectively distinguish between areas with different ground object types, and obtain an accurate interpretation of the ground object scattering mechanism.

[0088] In some embodiments, in step S1, converting the fully polarimetric SAR data into the Stokes vector of the π / 4 reduced polarimetric SAR includes: constructing a fully polarimetric coherence matrix based on the fully polarimetric SAR data; and obtaining the Stokes vector of the π / 4 reduced polarimetric SAR based on the relationship between the coherence matrix in the π / 4 reduced polarimetric mode and the fully polarimetric coherence matrix.

[0089] In some embodiments, a full polarization coherence matrix is constructed based on the full polarization SAR data. The full polarization coherence matrix is expressed as follows:

[0090]

[0091] Where 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 i-th row and j-th column element of the full polarization coherence matrix T; the superscript “H” indicates transposition.

[0092] in,

[0093] S HH is the backscatter of horizontal transmission and horizontal reception, S HVis the backscatter with vertical emission and horizontal reception, S VV It is the backscatter with vertical emission and vertical reception.

[0094] In some embodiments, 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:

[0095]

[0096] Among them, the coherence matrix J in the π / 4 reduced polarization mode can be expressed as:

[0097]

[0098] According to equations (3) and (4), the Stokes vector can be obtained, which is expressed as:

[0099]

[0100] Where G represents the Stokes vector, g k Represents the element of 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.

[0101] In some embodiments, in step S2, a volume scattering model is selected according to a co-polarization ratio, where the co-polarization ratio is expressed as follows:

[0102]

[0103] 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.

[0104] In some embodiments, in step S2, selecting a volume scattering model according to the co-polarization ratio includes: when 101g( VV > HH >)<-2dB, the volume scattering model with a probability density model obeying a sinusoidal distribution is selected.

[0105] The volume scattering model in full polarization SAR is expressed as:

[0106]

[0107] The volume scattering model expression in the π / 4 reduced polarization mode is:

[0108]

[0109] Among them, G v1 ​​Stokes vector representing the random volume scattering mechanism in the volume scattering model where the probability density model follows a sinusoidal distribution; It represents the angle between the ground object and the radar line of sight; m v Represents the volume scattering component.

[0110] In some embodiments, in step S2, selecting a volume scattering model according to the co-polarization ratio includes: when 101g( VV > / HH When >)>2dB, the volume scattering model with a probability density model obeying the cosine distribution is selected.

[0111] The full polarimetric SAR expression of this volume scattering model is:

[0112]

[0113] The volume scattering model expression in the π / 4 reduced polarization mode is:

[0114]

[0115] Among them, G v2 The Stokes vector representing the random volume scattering mechanism in a volume scattering model where the probability density model follows a cosine distribution.

[0116] In some embodiments, in step S2, selecting a volume scattering model according to the co-polarization ratio includes: when -2dB<101g( VV > / HH >)<2dB, the volume scattering model with a probability density model obeying a uniform distribution is selected.

[0117] The full polarimetric SAR expression of this volume scattering model is:

[0118]

[0119] The volume scattering model expression in the π / 4 reduced polarization mode is:

[0120]

[0121] Among them, G v3 The Stokes vector representing the random volume scattering mechanism in a volume scattering model where the probability density model follows a uniform distribution.

[0122] In some embodiments, in step S3, a decomposition model is constructed based on the relationship between the Stocks vector (SV) portion of the random volume scattering mechanism in the Stokes vector and surface scattering and dihedral scattering.

[0123] ​​​​For example, a random volume over ground (RVoG) two-layer coherent scattering model can be used as follows:

[0124] G=G vi +G p (13)

[0125] In the above formula (13), G vi The Stokes vector representing the random volume scattering mechanism, 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-mentioned equations (8), (10), and (12), G p Stokes vector representing the rank-1 portion of the scattering mechanism, including surface scattering and dihedral scattering in the π / 4 polarization mode.

[0126] In some embodiments, based on a volume scattering model that obeys a sinusoidal distribution (101 g ( VV > / HH >)<-2dB), the decomposition model constructed in the π / 4 reduced polarization mode is as follows:

[0127]

[0128] Among them, m v and m p Represent the coefficients of volume scattering component and rank 1 scattering component respectively. α and is the scattering parameter, which can be estimated by SV elements:

[0129]

[0130] make c=±cos2α. According to the corresponding relationship between the elements in the matrix, the first relationship is obtained as follows:

[0131]

[0132] In some embodiments, a decomposition model in the π / 4 reduced polarization mode constructed based on a volume scattering model obeying a cosine distribution (101gSVVSHH>2dB) is as follows:

[0133]

[0134] make c=±cos2α. According to the corresponding relationship between the elements in the matrix, the second relationship is obtained as follows:

[0135]

[0136] ​​In some embodiments, based on a volume scattering model that obeys a uniform distribution (-2dB<101g ( VV > / HH The decomposition model of the π / 4 reduced polarization mode constructed by >)<2dB) is as follows:

[0137]

[0138] make c=±cos2α. According to the corresponding relationship between the elements in the matrix, the third relationship is obtained as follows:

[0139]

[0140] In some embodiments, in step S4, when a volume scattering model (101g ( VV > / HH >)<-2dB), a, b, c, m are obtained according to the first relationship (Formula (16)) p , m v The first expression is as follows:

[0141]

[0142] From the above formula, we can see that the five unknown quantities (a, b, c, m p , m v ) corresponds to five equations, and the unique solutions of the five unknown quantities can be obtained. Thus, the volume scattering energy, dihedral scattering energy and surface scattering energy can be obtained:

[0143]

[0144] P v =2m v

[0145] Among them, P S represents the surface scattered energy, P d represents the dihedral scattering energy, P v represents the volume scattered energy.

[0146] The scattering mechanism components of each pixel in the image can be obtained by using volume scattering energy, dihedral scattering energy and surface scattering energy. According to the different proportions of scattering energy, the scattering mechanism of the ground object can be reasonably interpreted. The interpretation results of the scattering mechanism can be used as the basis for classifying different ground object types.

[0147] In some embodiments, in step S4, a volume scattering model (101g( VV > / HH ​​​​​​>)>2dB), according to the second relationship (formula (18)), a, b, c, m are obtained p , m v The second expression is as follows:

[0148]

[0149] According to the second expression, the volume scattering energy, dihedral scattering energy and surface scattering energy can be obtained as follows:

[0150]

[0151] P v =2m v .

[0152] Similarly, the scattering mechanism components of each pixel in the image can be obtained by using volume scattering energy, dihedral scattering energy, and surface scattering energy. According to the different proportions of scattering energy, the scattering mechanism of the ground object can be reasonably interpreted. The interpretation results of the scattering mechanism can be used as the basis for classifying different ground object types.

[0153] In some embodiments, in step S4, a volume scattering model that obeys a uniform distribution (-2dB<101g) is selected. VV > / HH >)<2dB), a, b, c, m are obtained according to the third relational expression (Equation (20)) p , m v The third expression is as follows:

[0154]

[0155] Similarly, the volume scattering energy, dihedral scattering energy, and surface scattering energy can be obtained according to the third expression as shown below:

[0156]

[0157] P v =2m v .

[0158] Similarly, the scattering mechanism components of each pixel in the image can be obtained by using volume scattering energy, dihedral scattering energy, and surface scattering energy. According to the different proportions of scattering energy, the scattering mechanism of the ground object can be reasonably interpreted. The interpretation results of the scattering mechanism can be used as the basis for classifying different ground object types.

[0159] In some embodiments, interpreting the scattering mechanism of the ground object according to different scattered energy proportions includes: displaying the interpretation result using a pseudo-color image.

[0160] Refer to the following Figures 2 to 5 ​​The advantages of the embodiments of the present invention will be described below. Figure 2 An optical image of the target area is shown, and L-band polarimetric SAR data collected by the E-SAR system in the target area is used as an example of application verification of the algorithm effectiveness. Figure 3 The Pauli decomposition pseudo-color image corresponding to the target area (Comparative Example 1) is shown. Figure 4 Shows the traditional m- χ The pseudo-color image of the decomposition algorithm (Comparative Example 2) shows a pseudo-color image obtained using the method proposed in an embodiment of the present invention. A comparison shows that for building areas (such as the yellow rectangle in the figure), especially those with tilted buildings at a large angle to the radar line of sight, the pseudo-color image of the decomposition result obtained by the embodiment of the present invention appears pink, indicating that the scattered energy is primarily surface scattering and dihedral scattering, which can be well distinguished from the scattering mechanism of forest areas. This helps to better distinguish different ground object types and effectively solves the problem of overestimation of volume scattered energy in building areas.

[0161] The above describes in detail the π / 4 reduced polarimetric synthetic aperture radar (SAR) target decomposition method according to an embodiment of the present invention. It should be understood that some or all of the operations of the method can be programmed as a program product, the program of which can be stored on a storage medium and executed by a computer or similar device. Figure 6 An exemplary structure of a computer device capable of executing the method according to the embodiment of the present invention is shown.

[0162] Reference Figure 6 The computer device 100 includes at least a processor 101 and a memory 102, wherein the memory 102 may be an example of a storage medium on which a computer program (or computer-readable instructions) is stored, and the processor 101 executes the computer program to perform part or all of the operations in the method described in any embodiment of the present invention.

[0163] 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. The processor 101, memory 102, and data storage device 103 communicate with each other via a bus and interact with peripheral devices, such as the display 104 and the communication module 106, via the bus and an I / O module 107. Specifically, the data storage device 103 may store applications and their various configuration files, as well as data, including but not limited to SAR data. The memory 102 stores computer programs. The processor 101 executes the computer program to perform various operations or steps of the π / 4 reduced polarimetric synthetic aperture radar (SAR) target decomposition method, including, but not limited to, invoking the communication module 106 to obtain fully polarimetric SAR data and converting it into Stokes vectors for π / 4 reduced polarimetric SAR; selecting a volume scattering model based on the co-polarization ratio; constructing a decomposition model based on the Stokes vectors and the selected volume scattering model; obtaining volume scattering energy, dihedral scattering energy, and surface scattering energy based on the constructed decomposition model; obtaining the scattering mechanism components of each pixel in the image based on the volume scattering energy, dihedral scattering energy, and surface scattering energy; interpreting the scattering mechanism of the ground object based on the different scattering energy proportions; and displaying the image on the display 104 or transmitting it to another system, device, or apparatus via a communication connection for display. In optional embodiments, the communication module 106 may be omitted if communication with the other system, device, or apparatus is not required. In some embodiments, the computer device 100 may further include a speaker 105 for voice output.

[0164] In some embodiments, processor 101 may include any suitable semiconductor-based electronic processing unit, chip, microchip, or integrated circuit (IC). Memory 102 is a programmable memory that 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. Data storage device 103 may be a persistent storage device that may include any suitable electronic memory configured to retain stored information when power is cycled. For example, 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 thereof.

[0165] Thus, the processor 101 can control the output of information on the I / O module 107 by storing information in the memory and / or executing programs / instructions stored in the memory. For example, several aspects of the methods described herein can be performed by the processor 101 according to programs / instructions stored in the memory (e.g., the memory 102 and / or the data storage device 103).

[0166] Furthermore, the processor 101 may electronically communicate with the I / O module 107 and / or the communication module 106 to receive or send 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 enable a user to perform one or more functions of the computer device 100 itself, such as a graphical user interface (GUI) on a screen or other display. In some examples, the user interface may include a voice interface capable of voice recognition, through which an operator may provide voice commands to the processor.

[0167] The communication module 106 may include any suitable device and / or structure configured to facilitate information exchange between the computer device 100 and an external electronic device. The communication module 106 may include a device configured to send and / or receive wireless or wired information with 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 filtering circuits, encryption / decryption circuits, and / or integrated circuit (IC) chips for processing signals (e.g., In some embodiments, the communication module 106 may include a WiFi device configured to connect to a local wireless network.

[0168] In some embodiments, the computer device 100 may include a smartphone, a wearable computer, a portable / mobile electronic device, a tablet computer, a smartwatch, a personal digital assistant (PDA), a personal computer (PC), a desktop computer, a notebook computer, a server, etc. The computer device 100 may include or have installed thereon one or more application programs (APPs), wherein one APP is configured to execute the π / 4 reduced polarimetric synthetic aperture radar (SAR) target decomposition method described herein.

[0169] Although not shown, it should be understood that the computer device 100 also includes a power supply assembly, which may include any suitable device and / or structure configured to provide an electrical interface between the computer device 100 and a power source. The power source may include any suitable source of electrical energy, such as a battery, an outlet, a capacitor, a fuel cell, etc., or any combination thereof. In addition or alternatively, the power source may be included in the power supply assembly. For example, a battery or battery pack may be included in the computer device 100. In some embodiments, the battery may be rechargeable, such as by charging via a cable or an interface provided by the power supply assembly. In some embodiments, the power supply assembly may share features with or duplicate features of the communication module 106. For example, a USB or micro-USB cable connector may be included in the computer device 100 so that power supply and data communication are performed by the same component.

[0170] Those skilled in the art should understand that the above disclosure is merely an illustration of the embodiments of the present invention, and the scope of the rights for which the patent protection is requested in this application is not limited thereto. Various modifications, alterations, substitutions, and other variations may be made to the embodiments disclosed herein without departing from the spirit or principles of the present invention, and such variations are within the scope of the claims of this application.

Claims

1. A π / 4 reduced polarimetric synthetic aperture radar (SAR) target decomposition method, comprising the following steps: S1. Obtain fully polarimetric SAR data and convert it into Stokes vectors for π / 4 reduced polarimetric SAR. S2. Select 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 based on 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 according to claim 1, wherein In step S1, converting the full polarimetric SAR data into the Stokes vector of the π / 4 reduced polarimetric SAR includes: A full polarization coherence matrix is constructed based on the full polarization SAR data. The full polarization coherence matrix is expressed as follows: Where T represents the full polarization coherence matrix, T ij represents the element in row i and column j of T, where i = 1, 2, 3; j = 1, 2, 3; Based on 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. 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 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.

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

5. The method according to 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 Denote the coefficients of volume scattering component and rank 1 scattering component, α and is the scattering parameter; make c=±cos2α. According to the corresponding relationship between the elements in the matrix, the first relationship is obtained as follows: The second decomposition model constructed according to the second body scattering model is as follows: make c=±cos2α. According to the corresponding relationship between the elements in the matrix, the second relationship is obtained as follows: The third decomposition model constructed according to the third volume scattering model is as follows: make c=±cos2α. According to the corresponding relationship between the elements in the matrix, the third relationship is obtained as follows:

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

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 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.

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