Composite target scattering center modeling method and system based on ray tracing

Abstract

This application provides a ray tracing-based composite target scattering center modeling method and system, including: constructing a nested geometric model of a dielectric-PEC composite target; defining the direction of the target surface's outer normal based on the number of closed surface layers in the nested geometric model, and obtaining a multi-region surface discrete grid model through surface discretization and component decomposition; obtaining a set of ray paths containing regional source information and scattering mechanism information, and classifying the two types of information based on whether they are identical to obtain ray path subsets; screening the ray path set of the main contributing region from the obtained ray path subsets; and forward deducing multiple model parameters based on the correspondence between the three-dimensional attribute scattering center model and the geometric structure to obtain a parameterized attribute scattering center model. This application provides a method for defining electromagnetic parameters of dielectric materials, enabling high-frequency electromagnetic modeling of dielectric-PEC composite targets with higher-order complex scattering mechanisms containing transmission.

Description

Technical Field

[0001] The present application relates to the technical field of high-frequency electromagnetic scattering modeling of radar targets, and in particular to a composite target scattering center modeling method and system based on ray tracing. Background Art

[0002] With the widespread use of dielectric materials in modern weaponry, many radar targets are composed of a combination of dielectric and PEC materials, such as stealth targets with absorbing dielectric coatings, various aircraft with hybrid dielectric and PEC (Perfect Electrical Conductor) wing designs, and various radomes. Given the crucial technical support provided by radar target characterization technology for target detection, tracking, and identification, research into electromagnetic scattering modeling methods and techniques, including target scattering center models, for targets composed of hybrid dielectric (i.e., isotropically uniform and lossless dielectric) and perfect electrical conductor materials has become a cutting-edge topic in this field. In the optical region of radar characteristics, the total target field can be viewed as the superposition of coherent scattering from numerous independent scattering centers on the target. The scattering center model provides a concise and complete description of the target's total scattering field, providing physical information such as the amplitude, position, polarization, and structure of the target's scattering response. Consequently, it has been widely used in fields such as scattering feature extraction and target identification.

[0003] Traditional inverse methods extract the electromagnetic parameters of scattering centers through an inversion process, starting with radar characteristic data obtained from actual measurements or electromagnetic simulations. In practical applications, the acquisition of multi-angle and multi-frequency radar echo data and the iterative optimization process are often very time-consuming. Because the electromagnetic wave propagation mechanism and process are not clearly defined in inverse methods, the extracted scattering center models lack physical meaning and cannot correspond to the target structure.

[0004] In contrast, forward methods utilize high-frequency computational methods with ray field characteristics to directly separate scattering centers from nested geometric models and forward-derive their electromagnetic parameters. This near-analytical separation and high-frequency quantitative description ensure that the electromagnetic scattering mechanisms of the scattering center models derived using forward methods are clear, closely linked to the local structure, and possess unique electromagnetic parameters. However, all these modeling methods are still limited to PEC targets. In reality, there are numerous complex targets containing dielectric materials, whose geometries and electromagnetic material distributions are more diverse, and whose electromagnetic wave scattering mechanisms are even more complex.

[0005] As research deepens, existing technologies also show many shortcomings: in the multi-layer nested structure containing dielectrics and PEC materials, there are multiple transmission-coupled scattering mechanisms of the "transmission / ... / reflection / ...transmission" type, and the calculation and separation of its scattering contribution is a huge challenge; the existing scattering center attribute parameter inference method cannot meet the calculation of the scattering center attribute parameters corresponding to the internal structure existing in the dielectric-PEC composite target. Summary of the Invention

[0006] The present application provides a composite target scattering center modeling method and system based on ray tracing, which can solve the problem in the prior art that in a multi-layer nested structure containing a medium and PEC material, there is a "transmission / ... / reflection / ...transmission" type of multiple transmission-coupled scattering mechanism, and the calculation and separation of its scattering contribution is a huge challenge; the existing scattering center attribute parameter inference method cannot meet the technical problem of calculating the scattering center attribute parameters corresponding to the internal structure in the medium-PEC composite target.

[0007] In a first aspect, the present application provides a composite target scattering center modeling method based on ray tracing, comprising the following steps:

[0008] Constructing a nested geometric model of the medium-PEC composite target based on known geometric information and material properties of the medium-PEC composite target;

[0009] Obtaining the number of closed surface layers of the nested geometric model, defining the outer normal direction of the target surface according to the number of closed surface layers of the nested geometric model, and obtaining a multi-region surface discrete grid model through surface discretization and component decomposition;

[0010] Given the attitude angle, frequency, polarization mode and number of rays, the ray tracing method is used to trace the reflection and transmission ray paths of each discrete element of the multi-region surface discrete grid model, and a set of ray paths containing regional source information and scattering mechanism information is obtained. According to the regional source and scattering mechanism, the ray path subsets representing different scattering centers are classified from the ray path set.

[0011] Filtering a set of ray paths whose scattering intensity is greater than an intensity threshold from the obtained ray path subset to obtain a set of ray paths in a main contribution area;

[0012] For the ray path set of the main contributing area, multiple model parameters are forward derived according to the correspondence between the three-dimensional attribute scattering center model parameters and the geometric structure. The multiple model parameters include amplitude parameters, frequency-dependent parameters, length parameters and three-dimensional position parameters. Based on the derived multiple model parameters, a parameterized attribute scattering center model of the medium-PEC composite target is constructed.

[0013] In conjunction with the first aspect, in one embodiment, the method uses a ray tracing method to trace the reflection and transmission ray paths of each discrete element of a multi-region surface discrete grid model under a given attitude angle, frequency, polarization mode, and number of ray actions, thereby obtaining a set of ray paths containing regional source information and scattering mechanism information, and classifying ray path subsets representing different scattering centers from the set of ray paths based on the regional source and scattering mechanism. The method specifically includes the following steps:

[0014] Under the given attitude angle, frequency, polarization mode and number of rays, the ray tracing method is used to track the reflection and transmission ray paths of each discrete surface element of the multi-region surface discrete grid model. According to the mechanism information of each point on the ray path and the material electromagnetic parameters of the corresponding space in the ray path collection, the propagation of the GO ray field is tracked, and the GO electric field information at each point on the ray path is obtained, thus obtaining the ray path collection with regional source and scattering mechanism information.

[0015] And according to whether the regional sources and scattering mechanism information in the total set of ray paths are the same, the ray paths in the ray path set are identified and classified, and the ray paths with the same identities are grouped together to obtain a subset of multiple action ray paths representing different scattering sources.

[0016] In conjunction with the first aspect, in one embodiment, the identification and classification of ray paths in the ray path set based on whether the regional sources and scattering mechanism information in the total set of ray paths are the same, grouping ray paths with the same identities, and obtaining a subset of multiple action ray paths representing different scattering sources specifically includes the following steps:

[0017] Marking the identity of each ray path in the total set of one-time action ray paths, grouping ray paths with the same identity, and obtaining multiple one-time action ray path subsets;

[0018] Read the number of elements in the secondary action ray path set. If the number of elements in the secondary action ray path set is not 0, mark the identity of each ray path in the total set of secondary action ray paths, group ray paths with the same identity, and obtain subsets of secondary action ray paths with different scattering sources.

[0019] By analogy, continue to perform identity tagging on each ray path in the subsequent multiple action ray path total set, and collect ray paths with the same identity until the number of ray actions reaches the set threshold N m Or the number of elements in the n-th illuminated surface set is 0, and the subset of multiple action ray paths is obtained.

[0020] In combination with the first aspect, in one embodiment, screening a set of ray paths having scattering intensities greater than an intensity threshold from the obtained ray path subsets, and obtaining a set of ray paths that make the majority of contributions in each ray path subset, specifically includes the following steps:

[0021] The total scattered field for each subset of ray paths is calculated using the GO-PO algorithm;

[0022] The total scattering fields of all the obtained scattering subsets are sorted from large to small according to the scattering field intensity value, and a set of strong scattering paths whose scattering field values ​​of the ray path subset are greater than the intensity threshold is obtained;

[0023] The included angle between the outgoing direction and the receiving direction of each ray in the strong scattering path set is calculated, and the ray path set with a value less than ±3 degrees is regarded as the main contributing ray path set.

[0024] In combination with the first aspect, in one embodiment, the calculating of the total scattered field of each ray path subset using the GO-PO algorithm specifically includes the following steps:

[0025] For the single-action scattering path, the PO algorithm is used to calculate the far-field scattering intensity excited by each incident ray to obtain the scattering field of the single-action scattering path;

[0026] For multiple-action ray paths, the GO-PO algorithm is used to calculate the PO contribution of each reflection point of the GO ray to the observation point to obtain the scattered field of the multiple-action ray path, where the PO calculation is only applied to the last reflection or transmission of the surface;

[0027] The scattered fields of all ray paths in each ray path subset are then added together to obtain the total scattered field of each ray path subset.

[0028] In conjunction with the first aspect, in one embodiment, forward deducing a frequency-dependent parameter from a plurality of model parameters specifically includes the following steps:

[0029] According to the corresponding relationship between the frequency dependence factor and the geometric structure surface type, the frequency dependence factor expressed by multiplication is obtained by tracing the ray field propagation process and determining the geometric structure surface type.

[0030] In conjunction with the first aspect, in one embodiment, forward deducing the position parameter from the plurality of model parameters specifically includes the following steps:

[0031] Firstly, the action point and equivalent action point of each ray path in the ray path set of the main contribution area are determined;

[0032] For single scattering, the ray bounce point is the ray's action point;

[0033] For multiple action ray paths, combined with the principle of equivalent optical path difference, the equivalent action point position of each ray path is determined. Finally, the weighted average of all multiple action ray action points or equivalent action points in the ray path of the main contribution area is the position parameter of the scattering center.

[0034] In conjunction with the first aspect, in one embodiment, forward deducing a length parameter from a plurality of model parameters specifically includes the following steps:

[0035] The action points or equivalent action points of all ray paths in the ray path subset that meet the in-phase condition are projected in the azimuth direction, and the length parameters of the distributed scattering center are determined by the projection information data.

[0036] In a second aspect, the present application provides a composite target scattering center modeling system based on ray tracing, comprising:

[0037] A geometric model building module is used to build a nested geometric model of the medium-PEC composite target based on the known geometric information and material properties of the medium-PEC composite target;

[0038] a multi-region surface discrete grid model acquisition module, which is in communication with the geometric model construction module and is used to obtain the number of closed surface layers of the nested geometric model, define the outer normal direction of the target surface according to the number of closed surface layers of the nested geometric model, and obtain the multi-region surface discrete grid model through surface discretization and component decomposition;

[0039] a ray path subset acquisition module, communicatively connected to the multi-region surface discrete grid model acquisition module, configured to use a ray tracing method to trace the paths of reflection and transmission rays irradiated on discrete facets of the multi-region surface discrete grid model using a given attitude angle, frequency, polarization mode, and number of rays, to obtain a set of ray paths containing regional source information and scattering mechanism information, and to classify ray path subsets representing different scattering centers from the ray path set based on the regional source and scattering mechanism;

[0040] a main contribution ray set screening module, communicatively connected to the ray path subset acquisition module, for screening a set of ray paths having scattering intensities greater than an intensity threshold from the acquired ray path subset, and acquiring a ray path set of a main contribution area;

[0041] The composite target scattering center model construction module is communicatively connected to the main contribution ray set screening module and is used to forward derive multiple model parameters for the ray path set of the main contribution area based on the correspondence between the three-dimensional attribute scattering center model parameters and the geometric structure. The multiple model parameters include amplitude parameters, frequency-dependent parameters, length parameters and three-dimensional position parameters, and construct a parameterized attribute scattering center model of the medium-PEC composite target based on the derived multiple model parameters.

[0042] In conjunction with the second aspect, in one embodiment, the ray path subset acquisition module includes:

[0043] A ray path collection acquisition unit is used to use a ray tracing method to track the reflection and transmission ray paths of each discrete surface element of a multi-region surface discrete grid model under a given attitude angle, frequency, polarization mode and number of rays. Based on the mechanism information of each point on the ray path in the ray path collection and the material electromagnetic parameters of the corresponding space, the propagation of the GO ray field is tracked to obtain the GO electric field information at each point on the ray path, thereby obtaining a ray path collection with regional source and scattering mechanism information;

[0044] A ray path subset acquisition unit is communicatively connected to the ray path total set acquisition unit and is used to identify and classify the ray paths in the ray path set based on whether the regional sources and scattering mechanism information in the ray path total set are the same, group the ray paths with the same identity, and obtain a subset of multiple-action ray paths representing different scattering sources.

[0045] The beneficial effects of the technical solutions provided in the embodiments of the present application include at least:

[0046] This application proposes a ray tracing-based composite target scattering center modeling method. Compared with existing technologies, its advantage is that it provides a method for defining the electromagnetic parameters of dielectric materials and realizes high-frequency electromagnetic modeling of dielectric-PEC composite targets with higher-order complex scattering mechanisms including transmission.

[0047] Based on the high-frequency electromagnetic mechanism of complex targets and the principle of equivalent optical path difference, a method for calculating the equivalent point of internal coupling rays is proposed, which solves the problem of forward estimation of the three-dimensional position parameters of the scattering center of complex medium-PEC targets.

[0048] The entire modeling process is completely based on nested geometric models and material electromagnetic parameters. It has low computational complexity and the resulting parameterized model has a small amount of data, providing technical support for real-time and rapid identification of radar targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A schematic diagram of a process for modeling a composite target scattering center based on ray tracing provided in an embodiment of the present application;

[0050] Figure 2 A diagram of a nested geometric model of a modified SLICY target provided in an embodiment of the present application;

[0051] Figure 3 Schematic diagram of the target model entity components decomposition provided in the embodiment of the application;

[0052] Figure 4 Schematic diagram of target surface normal definition provided in the embodiment of the present application;

[0053] Figure 5 Flowchart of the frequency-dependent parameter forward estimation algorithm provided in the embodiment of the present application;

[0054] Figure 6 Flowchart of the method for calculating scattering center position parameters provided in the embodiment of the present application;

[0055] Figure 7 FEKO high-frequency algorithm simulation SAR image provided in the embodiment of the present application;

[0056] Figure 8 The scattering center model provided in the embodiment of the present application reconstructs the SAR image. DETAILED DESCRIPTION

[0057] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0058] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit the "first", "second" and "third" to different types.

[0059] In the description of the embodiments of this application, the words "exemplary," "for example," or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary," "for example," or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary," "for example," or "for example" is intended to present the relevant concepts in a concrete manner.

[0060] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; “and / or” in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, “multiple” refers to two or more than two.

[0061] In some processes described in the embodiments of the present application, multiple operations or steps are included that appear in a specific order. However, it should be understood that these operations or steps may not be performed in the order in which they appear in the embodiments of the present application or may be performed in parallel. The sequence numbers of the operations are only used to distinguish between different operations, and the sequence numbers themselves do not represent any order of execution. In addition, these processes may include more or fewer operations, and these operations or steps may be performed in sequence or in parallel, and these operations or steps may be combined.

[0062] First, some technical terms in this application are explained to facilitate those skilled in the art to understand this application.

[0063] The composite target is a radar detection target of a composite medium including two or more media, namely, an isotropic medium (referring to an isotropic lossless medium) and a perfect conductor.

[0064] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0065] First, please refer to Figure 1 The present invention provides a ray tracing-based composite target scattering center modeling method, comprising the following steps:

[0066] Step S1: constructing a nested geometric model of the medium-PEC composite target based on known geometric information and material properties of the medium-PEC composite target;

[0067] Step S2: obtaining the number of closed surface layers of the nested geometric model, defining the outer normal direction of the target surface according to the number of closed surface layers of the nested geometric model, and obtaining a multi-region surface discrete grid model through surface discretization and component decomposition;

[0068] Step S3: Under a given attitude angle, frequency, polarization mode, and number of rays, a ray tracing method is used to trace the paths of each reflected and transmitted ray irradiated on a discrete element of a multi-region surface discrete grid model, to obtain a set of ray paths containing regional source information and scattering mechanism information, and to classify ray path subsets representing different scattering centers from the ray path set according to the regional source and scattering mechanism;

[0069] Step S4: screening a set of ray paths whose scattering intensity is greater than an intensity threshold from the obtained ray path subset to obtain a ray path set of a main contribution area;

[0070] Step S5: For the ray path set of the main contribution area, based on the correspondence between the three-dimensional attribute scattering center model parameters and the geometric structure, multiple model parameters are forward derived, and the multiple model parameters include amplitude parameters, frequency-dependent parameters, length parameters, and three-dimensional position parameters. Based on the derived multiple model parameters, a parameterized attribute scattering center model of the medium-PEC composite target is constructed.

[0071] This application proposes a ray tracing-based composite target scattering center modeling method. Compared with existing technologies, its advantage is that it provides a method for defining the electromagnetic parameters of dielectric materials and realizes high-frequency electromagnetic modeling of dielectric-PEC composite targets with higher-order complex scattering mechanisms including transmission.

[0072] Based on the high-frequency electromagnetic mechanism of complex targets and the principle of equivalent optical path difference, a method for calculating the equivalent point of internal coupling rays is proposed, which solves the problem of forward estimation of the three-dimensional position parameters of the scattering center of complex medium-PEC targets.

[0073] The entire modeling process is completely based on nested geometric models and material electromagnetic parameters. It has low computational complexity and the resulting parameterized model has a small amount of data, providing technical support for real-time and rapid identification of radar targets.

[0074] In one embodiment, step S1, constructing a nested geometric model of the dielectric-PEC composite target based on known geometric information and material properties of the dielectric-PEC composite target, specifically includes the following steps:

[0075] According to the known geometric information and material properties of the dielectric-PEC composite radar target, the Workbench module in the commercial software ANSYS is used for geometric modeling to construct a nested geometric model of the dielectric-PEC composite target.

[0076] In a specific embodiment, if Figure 2 The figure shows the nested geometry model of the modified SLICY. Two cylinders and a trihedron are placed inside a rectangular cavity made of PEC, forming a nested geometry with dimensions of 3m × 3m × 2m. The outer shell, consisting of the rectangular cavity, two dihedrals, and a quarter-cylinder, is approximately 0.02m thick and made of an isotropic medium.

[0077] In one embodiment, step S2, obtaining the number of closed surface layers of the nested geometric model, defining the outer normal direction of the target surface according to the number of closed surface layers of the nested geometric model, and obtaining a multi-region surface discrete mesh model through surface discretization and component decomposition, specifically includes the following steps:

[0078] Step S21, obtaining the number of closed surface layers of the nested geometric model;

[0079] Step S22: Find one or more closed surfaces S1, S2, ..., S in the nested geometric model according to the number of closed surface layers of the nested geometric model. p , p represents the total number of closed surfaces in the nested geometric model, and the outer normal directions of these closed surfaces are defined. The specific definition rules are as follows:

[0080] 1. The normal vectors of the outermost closed surface all point outward to free space;

[0081] 2. The normal vectors of the remaining closed surfaces are reversed in the order of the number of levels enclosed from the outside to the inside;

[0082] 3. The top closed surface visible in the same enclosing circle has equal enclosed levels and its normal directions do not affect each other;

[0083] The network model is obtained by fitting the target surface using triangular facets;

[0084] Step S23: decompose the target surface in the network model into multiple electrically large-sized regions, number the divided multiple electrically large-sized regions in sequence, and obtain a multi-region network model;

[0085] by Figure 2 As an example of the nested geometric model, the multi-region network model with unified surface normals at all levels and region numbers implemented in steps S22 and S23 is shown in FIG. Figure 4 As shown;

[0086] Step S24: Decompose the target surface of the multi-region network model into a combination of electrically large-sized solid components according to the requirements of high-frequency theory on the subdivision size, and obtain a multi-region surface discrete grid model;

[0087] Specifically, Figure 2Taking the nested geometric model of the medium-PEC composite target as an example, steps S23 and S24 are implemented as follows: the surface of the nested geometric model GM of the medium-PEC composite target is divided into 16 electrically large size areas, and the decomposition results of the target CAD model entity parts are as follows: Figure 3 As shown, all electrically large areas are numbered in sequence. According to the high-frequency electromagnetic scattering theory, the target surface is decomposed into a combination of electrically large solid components. The entire model is discretized into 89,360 triangular face elements.

[0088] Step S25, describe the material parameters of the materials on both sides of the interface of the nested geometric model; specifically, Figure 2 Taking the nested geometric model as an example, the parameters of the material of the composite target are defined. The material statistics on both sides of each interface of the target are as follows:

[0089] The outer side of the shell interface composed of a cuboid, two dihedral angles and a quarter cylinder is free space, and the inner side of the interface is an isotropic dielectric body. The electromagnetic parameter ε r =4+j0,μ r =1+j0,ε r 、μ r are the relative permittivity and relative permeability of the medium respectively;

[0090] The internal components of the nested geometric model include large and small cylinders;

[0091] There is free space outside the trihedral interface and ideal conductors inside the interface.

[0092] Based on step S21-step S22, the external normal directions of all closed surfaces of the nested geometric model are obtained; based on step S23, the network model of the nested geometric model after being decomposed into components is obtained; based on step S24, the network model after being decomposed into components obtained in step S23 is further surface discretized to obtain the network model of the nested geometric model after being surface discretized and decomposed into components; based on step S25, the material parameter description information of the nested geometric model is obtained for subsequent ray path subset acquisition and forward derivation of model parameters.

[0093] In one embodiment, step S3, under a given attitude angle, frequency, polarization mode, and number of rays, uses a ray tracing method to trace the paths of each reflected and transmitted ray irradiated on a discrete element of a multi-region surface discrete grid model, obtains a set of ray paths containing regional source information and scattering mechanism information, and classifies ray path subsets representing different scattering centers from the ray path set according to the regional source and scattering mechanism, specifically comprising the following steps:

[0094] Step S31: Under the given attitude angle, frequency, polarization mode and number of rays, the ray tracing method is used to trace the reflection and transmission ray paths of each discrete surface element of the multi-region surface discrete grid model until the ray escapes the target surface or the number of ray bounces reaches a preset value. According to the mechanism information of each point on the ray path and the material electromagnetic parameters of the corresponding space in the ray path collection, the propagation of the GO ray field is traced, the GO electric field information at each point on the ray path is obtained, and the ray path collection with regional source and scattering mechanism information is obtained. The number of incident rays is the number of all visible surface elements in the current radar viewing angle.

[0095] Step S32: Based on whether the regional sources and scattering mechanism information in the total set of ray paths are the same, the ray paths in the ray path set are identified and classified, ray paths with the same identity are grouped together, and a subset of multiple action ray paths representing different scattering sources is obtained.

[0096] In a specific embodiment, the frequency of the radar incident plane wave is set to 10 GHz, and the plane wave is directed parallel to the nested geometric model at a pitch angle of 90° and an azimuth angle of 0°. Each illuminated small triangular surface element on the nested geometric model corresponds to an incident ray, and the illuminated point is the midpoint of the surface element. Then, based on the ray splitting and tracing method, rays that meet the conditions on the surface and interior of the complex medium target are obtained to form a total set of ray paths. Step S31 is specifically implemented as follows:

[0097] Set the maximum number of action rays to 9, use the Z-Buffer method in OpenGL technology to obtain the initial illuminated surface set, and obtain the first action illuminated surface set;

[0098] Sequentially read the nth ray in the set of ray paths that initially illuminate the surface, use the laws of reflection and refraction in geometric optics to determine the direction of the reflected wave and the direction of the refracted wave on the medium interface at the surface initially illuminated by the nth ray, and determine the surface element illuminated by the reflected and refracted waves based on the presence or absence of a dielectric body. Sequentially track and record each ray to obtain the total set of secondary action ray paths;

[0099] The i-th ray r i Each ejection point Q on the propagation path on the surface and inside the model n The number of the area I n , put it into the index sequence of the ray action point area: [I1,I2,...,I n ,...I N ], I n is the region number of the nth ray, N is the maximum number of active rays. The scattering mechanism J of the ray at the active point n Put it into the scattering mechanism sequence: [J1,J2,...,J n,...J N ], J n The scattering mechanism of the nth ray at the point of action, including reflected or refracted rays, is represented by R or T.

[0100] Trace each ray in turn to obtain each ray path of the current number of rays, and obtain the total set of ray paths under the action of m rays: U m =[r1,r2,...,r n ,...,r m ],r n Represents the nth ray path.

[0101] In one embodiment, step S32, based on whether the regional sources and scattering mechanism information in the total set of ray paths are the same, identifies and classifies the ray paths in the ray path set, groups ray paths with the same identity, and obtains a subset of multiple-action ray paths representing different scattering sources, specifically comprising the following steps:

[0102] Step S321: tag each ray in the set of primary action ray paths, group ray paths with the same identity, and obtain a subset of primary action ray paths with different scattering sources;

[0103] Step S322: Read the number of elements in the secondary action ray path set. If the number of elements in the secondary action ray path set is not zero, mark each ray path in the secondary action ray path set with an identity, group ray paths with the same identity, and obtain a subset of secondary action ray paths with different scattering sources.

[0104] By analogy, step S322 is repeated to continue to mark the identity of each ray path in the subsequent multiple action ray path set, and to group the ray paths with the same identity until the number of ray actions reaches the set threshold N. m Or the number of elements in the n-th illuminated surface set is 0, and a subset of multiple action ray paths representing different scattering sources is obtained.

[0105] In a specific embodiment, steps S321 and S322 and subsequent steps are performed to mark the identity of each ray in the total set of ray paths for each interaction, group ray paths with the same identity, and obtain a subset of ray paths that interact with the scattering source a corresponding number of times. Specifically, the steps are implemented as follows:

[0106] For example, we can label each ray in the total set of ray paths of a single action, group ray paths with the same identity, and obtain subsets of ray paths of a single action with different scattering sources:

[0107] The identity information P1 = {I1, J1} of the first ray R1 in the total set of ray paths U1 is marked as 0;

[0108] Read the second ray. If the two sequences I2 representing the identity are the same as I1, and Q2 or the reverse sequence of Q2 is the same as Q1, then mark its identity information P2 as 0, otherwise mark it as 1;

[0109] Read the third ray and compare its two identity sequences with the first two rays using the same rules as above. Mark the identity information P3 with the same number as the rays that meet the conditions. If they are different, add 1 to the total number of existing identities. Repeat this process until the identity information of each ray in the total set of ray paths is fully marked.

[0110] According to the identity information marked on the ray path, rays with the same identity mark are grouped into the same subset, and the primary action ray path subsets of different scattering sources are classified;

[0111] If the number of elements in the secondary action ray path set is not 0, read each ray in the secondary action ray path set in turn;

[0112] According to the above method, a subset of secondary action ray paths representing different scattering sources is determined;

[0113] By analogy, the classification of different scattering sources in the total concentration of multiple action ray paths is completed.

[0114] In one embodiment, step S4, screening a set of ray paths having scattering intensities greater than an intensity threshold from the acquired ray path subset to obtain a set of ray paths in a major contribution area, mainly includes the following steps:

[0115] Step S41, using the GO-PO algorithm to calculate the total scattered field of each ray path subset;

[0116] Step S42: sorting the total scattering fields of all the acquired scattering subsets from large to small according to the scattering field intensity values, and acquiring a set of strong scattering paths whose ray path subset scattering field values ​​are greater than an intensity threshold;

[0117] Step S43: Calculate the angle between the emitting direction and the receiving direction of each ray in the strong scattering path set, and take the ray path set with an angle smaller than a preset angle value as the main contributing ray path set; specifically, the preset angle value is ±3 degrees.

[0118] In one embodiment, the step S41 of calculating the total scattered field of each ray path subset using the GO-PO algorithm specifically includes the following steps:

[0119] Based on the scattering mechanism of the last bounce point on each ray path, the GO-PO algorithm is used to calculate the reflected or transmitted field of each ray path. Specifically, according to the theory of geometric optics, the amplitude and phase of the scattered field caused by multiple coupling interactions are tracked one by one. The angle between the incident ray and the normal of the surface element at the last bounce point on each path is obtained.

[0120] If the angle is greater than 90°, the physical optics algorithm is used to calculate the reflection field formed by the path on the surface;

[0121] If the angle is less than 90°, the transmission field formed by the path on the surface is calculated using the physical optics algorithm;

[0122] Then, according to the Huygens principle, the scattered fields of each ray path in the ray path subset are added according to the acquired reflected field or transmitted field to obtain the total scattered field of each ray path subset.

[0123] In one embodiment, step S5, for the ray path set of the main contributing region, multiple model parameters are forward derived based on the correspondence between the three-dimensional attribute scattering center model and the geometric structure. The multiple model parameters include amplitude parameters, frequency-dependent parameters, length parameters, and three-dimensional position parameters, to obtain the three-dimensional attribute scattering center model in the parameterized attribute scattering center model of the medium-PEC composite target:

[0124]

[0125] The parameters that need to be solved in this three-dimensional attribute scattering center model include the amplitude parameter A i , frequency dependence factor α i , length parameter L i , three-dimensional position parameters. f represents the center frequency of the radar bandwidth, f c represents the sampling frequency, is the central azimuth, Characterizes the imaging azimuth of the distributed scattering center. Contains the length parameter L i The sinc function reflects the spread width of the distributed scattering center and characterizes the dependence of the scattering center on the azimuth angle, and γ i = 0. The dependence of the point scattering center on the azimuth angle is expressed by the decaying exponential function, L i =0,γ i Take something like 10 -10 A very small value, i is the amplitude parameter of the i-th scattering center, α i Describe the frequency dependence, (x i ,y i ,z i ) is the three-dimensional position of the scattering center.

[0126] In one embodiment, the step S5 of forward deriving the frequency-dependent parameters among the multiple model parameters specifically includes the following steps:

[0127] According to the corresponding relationship between the frequency dependence factor and the geometric structure surface type, the frequency dependence factor expressed by multiplication is obtained by tracing the ray field propagation process and determining the geometric structure surface type.

[0128] In one embodiment, the step S5 of forward deducing the position parameter from the plurality of model parameters specifically includes the following steps:

[0129] First, determine the action point and equivalent action point of each ray path in the main contribution area;

[0130] For a single scattered ray, the ray bounce point is the point of action of the ray, and the three-dimensional coordinates of the ray bounce point are used as the position parameters of the scattering center;

[0131] For multiple action ray paths, combined with the principle of equivalent optical path difference, the equivalent action point position of each ray is determined, and finally the weighted average of all equivalent action points in the set is the position parameter of the scattering center.

[0132] In one embodiment, the step S5 of forward deducing the length parameter from the plurality of model parameters specifically includes the following steps:

[0133] All equivalent point positions corresponding to the position parameters of the scattering center are projected in the azimuth direction, and the length parameters of the distributed scattering center are determined by the projection information data.

[0134] In one embodiment, step S5 is specifically implemented as follows:

[0135] According to the different number of ray coupling, scattering centers can be divided into single-action scattering centers and coupled-action scattering centers. Coupled-action scattering centers can be further divided into surface multiple-action scattering centers and internal multiple-action scattering centers.

[0136] A. Amplitude parameter A i The ray path set S of the main contribution area obtained in step S4 is calculated k The scattered field intensity is expressed as .

[0137] B. Figure 5 As shown, the frequency dependence factor α i , which describes the effect of frequency on scattering, is calculated as follows:

[0138] The frequency dependence factor α parameters of some typical structures have been obtained through theoretical derivation.

[0139] For a primary scattering center, the frequency dependence factor of the main contributing area is used as the frequency dependence factor of the entire component;

[0140] For the external coupling scattering center, the frequency dependence parameter of the coupling scattering center is obtained by multiplying the frequency dependence factors of the main contribution area of ​​each component;

[0141] For the internal coupling scattering center, the frequency dependence factor of the area where the scattering mechanism in the ray path is reflection is taken as the frequency dependence parameter of the scattering center.

[0142] It is important to note that the frequency-dependent parameters of the scattering center of a single-curved surface-single-curved surface coupling do not satisfy the above product relationship.

[0143] Weighted average of the ray's action point or equivalent action point:

[0144]

[0145] Where, represent Ray Weight J s (Q n ) represents the surface current on the last action element, Indicates the optical emission direction of the last surface element on the corresponding ray path.

[0146] C. Figure 6 As shown, the position parameters of the scattering center are:

[0147] (1) Read each ray path in the ray path subset

[0148] (2) Determine ray r n Is it a single action ray or a coupled action ray?

[0149] (31) For the scattering center of a primary action ray, the center of each triangular facet in the ray path subset is directly used as the reflection action point.

[0150] (32) For the scattering center of the coupled action ray inside the medium and the scattering center of the coupled action ray on the surface, the action point is selected as the equivalent action point of the coupled scattering center, and the equivalent reflection point of each ray is calculated using the principle of equivalent optical path difference. Specifically, first consider the ray from the medium surface Q a Refracted into the interior, through the Q on the other surface of the medium b Reflection, finally point Q from the surface c The equivalent position calculation of the three-way coupling action ray refracted from the surface of the medium. In the case of a single station, the equivalent position can be obtained by the principle of equivalent optical path difference.

[0151]

[0152] Where, b,c represent the a to Q b , Q b to Q c The optical path between.

[0153] The equivalent position of the internal coupling action ray with a higher order action ray can be obtained by modifying the optical path length and the optical path length inside the medium in the above formula.

[0154] (4) Equivalent reflection points for all rays in the ray path subset The equivalent three-dimensional geometric position parameters of the scattering center S are calculated by weighted average

[0155] (5) According to the equivalent three-dimensional geometric position parameters Get the position parameters of the scattering center

[0156] D.L i is the spread length parameter of the scattering source on the imaging surface, and its calculation method is as follows:

[0157] Project the action points or equivalent action points of all ray paths in the corresponding ray path subset obtained during the position parameter calculation onto the imaging plane, and find the two equivalent endpoints (x m ,y m ),(x n ,y n ).

[0158] Use the formula Find the distance Δv between the two equivalent endpoints;

[0159] Determine whether the distance difference Δv is greater than one resolution unit. If the distance difference is greater than one resolution unit, the scattering center is a distributed scattering center, and the length parameter L = Δv;

[0160] Otherwise, the scattering center is a local scattering center, and the length parameter L=0.

[0161] The parameterized attribute scattering center model finally obtained by this application is shown in the following table. The verification results are as follows: Figure 7 and Figure 8 As shown, Figure 7 This is a simulated SAR (Synthetic Aperture Radar) image obtained by the FEKO high-frequency algorithm. Figure 8The SAR image is reconstructed based on the parameterized attribute scattering center model, and the similarity between the two images is 91.3%.

[0162] Table 1 Parameterized attribute scattering center model obtained in this application

[0163]

[0164] In a second aspect, the present application provides a composite target scattering center modeling system based on ray tracing, comprising:

[0165] A geometric model building module is used to build a nested geometric model of the medium-PEC composite target based on the known geometric information and material properties of the medium-PEC composite target;

[0166] a multi-region surface discrete grid model acquisition module, which is in communication with the geometric model construction module and is used to obtain the number of closed surface layers of the nested geometric model, define the outer normal direction of the target surface according to the number of closed surface layers of the nested geometric model, and obtain the multi-region surface discrete grid model through surface discretization and component decomposition;

[0167] a ray path subset acquisition module, communicatively connected to the multi-region surface discrete grid model acquisition module, configured to use a ray tracing method to trace the paths of reflection and transmission rays irradiated on discrete facets of the multi-region surface discrete grid model using a given attitude angle, frequency, polarization mode, and number of rays, to obtain a set of ray paths containing regional source information and scattering mechanism information, and to classify ray path subsets representing different scattering centers from the ray path set based on the regional source and scattering mechanism;

[0168] a main contribution ray set screening module, communicatively connected to the ray path subset acquisition module, for screening a set of ray paths having scattering intensities greater than an intensity threshold from the acquired ray path subset, and acquiring a ray path set of a main contribution area;

[0169] The composite target scattering center model construction module is communicatively connected to the main contribution ray set screening module and is used to forward derive multiple model parameters for the ray path set of the main contribution area based on the correspondence between the three-dimensional attribute scattering center model parameters and the geometric structure. The multiple model parameters include amplitude parameters, frequency-dependent parameters, length parameters and three-dimensional position parameters, and construct a parameterized attribute scattering center model of the medium-PEC composite target based on the derived multiple model parameters.

[0170] In one embodiment, the ray path subset acquisition module includes:

[0171] A ray path collection acquisition unit is used to use a ray tracing method to track the reflection and transmission ray paths of each discrete surface element of a multi-region surface discrete grid model under a given attitude angle, frequency, polarization mode and number of rays. Based on the mechanism information of each point on the ray path in the ray path collection and the material electromagnetic parameters of the corresponding space, the propagation of the GO ray field is tracked to obtain the GO electric field information at each point on the ray path, thereby obtaining a ray path collection with regional source and scattering mechanism information;

[0172] A ray path subset acquisition unit is communicatively connected to the ray path total set acquisition unit and is used to identify and classify the ray paths in the ray path set based on whether the regional sources and scattering mechanism information in the ray path total set are the same, group the ray paths with the same identity, and obtain a subset of multiple-action ray paths representing different scattering sources.

[0173] Among them, the functional implementation of each module in the above-mentioned composite target scattering center modeling system based on ray tracing corresponds to the various steps in the above-mentioned composite target scattering center modeling method embodiment based on ray tracing, and their functions and implementation processes will not be repeated here one by one.

[0174] In a third aspect, an embodiment of the present application provides a composite target scattering center modeling device based on ray tracing. The composite target scattering center modeling device based on ray tracing can be a personal computer (PC), a laptop computer, a server, or other device with data processing capabilities.

[0175] In an embodiment of the present application, a composite target scattering center modeling device based on ray tracing may include a processor, a memory, a communication interface, and a communication bus.

[0176] The communication bus may be of any type and is used to interconnect the processor, memory, and communication interface.

[0177] Communication interfaces include input / output (I / O) interfaces, physical interfaces, and logical interfaces, which are used to interconnect components within the ray tracing-based composite target scattering center modeling device, as well as interfaces used to interconnect the ray tracing-based composite target scattering center modeling device with other devices (such as other computing devices or user devices). Physical interfaces can be Ethernet, fiber, or ATM interfaces; user devices can be displays, keyboards, and other devices.

[0178] The memory can be various types of storage media, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), flash memory, optical storage, hard disk, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), etc.

[0179] The processor may be a general-purpose processor that can invoke a ray tracing-based composite target scattering center modeling program stored in a memory and execute the ray tracing-based composite target scattering center modeling method provided in the embodiments of the present application. For example, the general-purpose processor may be a central processing unit (CPU). The method executed when the ray tracing-based composite target scattering center modeling program is invoked can be referenced to the various embodiments of the ray tracing-based composite target scattering center modeling method of the present application and will not be further described here.

[0180] In a fourth aspect, an embodiment of the present application also provides a readable storage medium.

[0181] The readable storage medium of the present application stores a composite target scattering center modeling program based on ray tracing, wherein when the composite target scattering center modeling program based on ray tracing is executed by a processor, the steps of the composite target scattering center modeling method based on ray tracing as described above are implemented.

[0182] Among them, the method implemented when the composite target scattering center modeling program based on ray tracing is executed can refer to the various embodiments of the composite target scattering center modeling method based on ray tracing in this application, and will not be repeated here.

[0183] It should be noted that the serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0184] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, of course, it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes a number of instructions for enabling a terminal device to execute the methods described in each embodiment of the present application.

[0185] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A composite target scattering center modeling method based on ray tracing, characterized in that: The following steps are involved: Constructing a nested geometric model of the medium-PEC composite target based on known geometric information and material properties of the medium-PEC composite target; Obtaining the number of closed surface layers of the nested geometric model, defining the outer normal direction of the target surface according to the number of closed surface layers of the nested geometric model, and obtaining a multi-region surface discrete grid model through surface discretization and component decomposition; Given the attitude angle, frequency, polarization mode and number of rays, the ray tracing method is used to trace the reflection and transmission ray paths of each discrete element of the multi-region surface discrete grid model, and a set of ray paths containing regional source information and scattering mechanism information is obtained. According to the regional source and scattering mechanism, the ray path subsets representing different scattering centers are classified from the ray path set. Filtering a set of ray paths whose scattering intensity is greater than an intensity threshold from the obtained ray path subset to obtain a set of ray paths in a main contribution area; For the ray path set of the main contributing area, multiple model parameters are forward derived according to the correspondence between the three-dimensional attribute scattering center model parameters and the geometric structure. The multiple model parameters include amplitude parameters, frequency-dependent parameters, length parameters and three-dimensional position parameters. Based on the derived multiple model parameters, a parameterized attribute scattering center model of the medium-PEC composite target is constructed.

2. The composite target scattering center modeling method based on ray tracing according to claim 1, characterized in that: The method uses a ray tracing method to trace the paths of each reflected and transmitted ray irradiated on a discrete element of a multi-region surface discrete grid model under a given attitude angle, frequency, polarization mode, and number of rays, to obtain a set of ray paths containing regional source information and scattering mechanism information, and classifies ray path subsets representing different scattering centers from the ray path set according to the regional source and scattering mechanism, specifically comprising the following steps: Under the given attitude angle, frequency, polarization mode and number of rays, the ray tracing method is used to track the reflection and transmission ray paths of each discrete surface element of the multi-region surface discrete grid model. According to the mechanism information of each point on the ray path and the material electromagnetic parameters of the corresponding space in the ray path collection, the propagation of the GO ray field is tracked, and the GO electric field information at each point on the ray path is obtained, thus obtaining the ray path collection with regional source and scattering mechanism information. According to whether the regional sources and scattering mechanism information in the total set of ray paths are the same, the ray paths in the ray path set are identified and classified, and the ray paths with the same identities are grouped together to obtain a subset of multiple action ray paths representing different scattering sources.

3. The composite target scattering center modeling method based on ray tracing according to claim 2, characterized in that: The method further comprises the following steps: identifying and classifying the ray paths in the ray path set based on whether the regional sources and scattering mechanism information in the ray path set are the same, grouping the ray paths with the same identity, and obtaining a subset of the ray paths that have acted multiple times. Mark each ray path in the set of ray paths of a single action, group ray paths with the same identity, and obtain a ray path subset of the ray of a single action; Read the number of elements in the secondary action ray path set. If the number of elements in the secondary action ray path set is not 0, mark each ray path in the secondary action ray path set with an identity, group ray paths with the same identity, and obtain a subset of secondary action ray paths representing different scattering sources. By analogy, continue to perform identity tagging on each ray path in the total set of subsequent ray action times, and collect ray paths with the same identity until the number of ray actions reaches the set threshold N. m Or the number of elements in the n-th illuminated surface set is 0, and a subset of multiple action ray paths of different scattering sources is obtained.

4. The composite target scattering center modeling method based on ray tracing according to claim 1, characterized in that: The method of screening the ray path sets whose scattering intensities are greater than an intensity threshold from the obtained ray path subsets and obtaining the ray path sets that make the main contribution in each ray path subset specifically includes the following steps: The total scattered field for each subset of ray paths is calculated using the GO-PO algorithm; The total scattering fields of all the obtained scattering subsets are sorted from large to small according to the scattering field intensity value, and a set of strong scattering paths whose scattering field values ​​of the ray path subset are greater than the intensity threshold is obtained; The angle between the outgoing direction and the receiving direction of each ray in the strong scattering path set is calculated, and the ray path set with a value less than the preset angle is regarded as the main contributing ray path set.

5. The composite target scattering center modeling method based on ray tracing according to claim 4, characterized in that: The method of calculating the total scattered field of each ray path subset using the GO-PO algorithm specifically includes the following steps: For the single-action scattering path, the PO algorithm is used to calculate the far-field scattering intensity excited by each incident ray to obtain the scattering field of the single-action scattering path; For multiple-action ray paths, the GO-PO algorithm is used to calculate the PO contribution of each reflection point of the GO ray to the observation point to obtain the scattered field of the multiple-action ray path, where the PO calculation is only applied to the last reflection or transmission of the surface; The scattered fields of all ray paths in each ray path subset are then added together to obtain the total scattered field of each ray path subset.

6. The composite target scattering center modeling method based on ray tracing according to claim 1, characterized in that: The forward derivation of the frequency-dependent parameters among the multiple model parameters specifically includes the following steps: According to the corresponding relationship between the frequency dependence factor and the geometric structure surface type, the frequency dependence factor expressed by multiplication is obtained by tracing the ray field propagation process and determining the geometric structure surface type.

7. The composite target scattering center modeling method based on ray tracing according to claim 1, characterized in that: The forward derivation of the position parameter from the plurality of model parameters specifically comprises the following steps: Firstly, the action point and equivalent action point of each ray path in the ray path set of the main contribution area are determined; For single scattering, the ray bounce point is the ray's action point; For multiple action ray paths, combined with the principle of equivalent optical path difference, the equivalent action point position of each ray path is determined. Finally, the weighted average of all multiple action ray action points or equivalent action points in the ray path of the main contribution area is the position parameter of the scattering center.

8. The composite target scattering center modeling method based on ray tracing according to claim 7, characterized in that: The forward derivation of the length parameter from the plurality of model parameters specifically comprises the following steps: The action points or equivalent action points of all ray paths in the ray path subset that meet the in-phase condition are projected in the azimuth direction, and the length parameters of the distributed scattering center are determined by the projection information data.

9. A composite target scattering center modeling system based on ray tracing, characterized in that: include: A geometric model building module is used to build a nested geometric model of the medium-PEC composite target based on the known geometric information and material properties of the medium-PEC composite target; a multi-region surface discrete grid model acquisition module, which is in communication with the geometric model construction module and is used to obtain the number of closed surface layers of the nested geometric model, define the outer normal direction of the target surface according to the number of closed surface layers of the nested geometric model, and obtain the multi-region surface discrete grid model through surface discretization and component decomposition; a ray path subset acquisition module, communicatively connected to the multi-region surface discrete grid model acquisition module, configured to use a ray tracing method to trace the paths of reflection and transmission rays irradiated on discrete facets of the multi-region surface discrete grid model using a given attitude angle, frequency, polarization mode, and number of rays, to obtain a set of ray paths containing regional source information and scattering mechanism information, and to classify ray path subsets representing different scattering centers from the ray path set based on the regional source and scattering mechanism; a main contribution ray set screening module, communicatively connected to the ray path subset acquisition module, for screening a set of ray paths having scattering intensities greater than an intensity threshold from the acquired ray path subset, and acquiring a ray path set of a main contribution area; The composite target scattering center model construction module is communicatively connected to the main contribution ray set screening module and is used to forward derive multiple model parameters for the ray path set of the main contribution area based on the correspondence between the three-dimensional attribute scattering center model parameters and the geometric structure. The multiple model parameters include amplitude parameters, frequency-dependent parameters, length parameters and three-dimensional position parameters, and construct a parameterized attribute scattering center model of the medium-PEC composite target based on the derived multiple model parameters.

10. The composite target scattering center modeling system based on ray tracing according to claim 9, characterized in that: The ray path subset acquisition module includes: A ray path collection acquisition unit is used to use a ray tracing method to track the reflection and transmission ray paths of each discrete surface element of a multi-region surface discrete grid model under a given attitude angle, frequency, polarization mode and number of rays. Based on the mechanism information of each point on the ray path in the ray path collection and the material electromagnetic parameters of the corresponding space, the propagation of the GO ray field is tracked to obtain the GO electric field information at each point on the ray path, thereby obtaining a ray path collection with regional source and scattering mechanism information; A ray path subset acquisition unit is communicatively connected to the ray path total set acquisition unit and is used to identify and classify the ray paths in the ray path set based on whether the regional sources and scattering mechanism information in the ray path total set are the same, group the ray paths with the same identity, and obtain a subset of multiple-action ray paths representing different scattering sources.

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