A method for modeling the variable scale of ground target infrared radiation characteristics in a large scene

Abstract

The application provides a large scene ground target infrared radiation characteristic variable scale modeling method, comprising: constructing a target scene; dividing to obtain a grid division model; performing temperature field simulation on the grid division model to obtain temperature field bottom layer data; dividing the target scene into a key target area grid model and a non-key target area grid model; selecting and calling a grid model according to the distance between a position point and the ground target; obtaining target temperature field data by using an interpolation method; calculating the infrared radiation characteristic of the ground target according to the target temperature field data, generating an infrared image and outputting a calculation result. The large scene ground target infrared radiation characteristic variable scale modeling method models the ground target and the position background of the application scene and simulates and calculates the temperature field distribution to obtain temperature field bottom layer data, obtains target temperature field data by using an interpolation method, reduces the required calculation resources in the infrared radiation characteristic simulation calculation process and saves calculation time.

Description

Technical Field

[0001] This invention relates to a variable-scale modeling method for the infrared radiation characteristics of ground targets in large-scale scenarios. Background Technology

[0002] Infrared radiation characteristic simulation is a crucial method for acquiring infrared radiation characteristic data. During the actual operation of the seeker, as the detector approaches the target, the texture of the target's infrared characteristics gradually becomes clear. The infrared radiation characteristics of ground targets include not only the target itself but also the complex background terrain. The background terrain is often large and structurally complex, resulting in the need for enormous computational resources and significant time consumption for calculating detailed infrared radiation features. Among infrared radiation characteristic calculations, temperature field simulation is the most computationally intensive; high-precision temperature field simulation of ground targets in large-scale scenarios can require several days of computation. During the actual operation of the seeker, the mesh accuracy changes with the distance between the detector and the ground target. Performing temperature field simulations for different meshes to simulate the entire operation process leads to even greater computational load and longer processing time, making it difficult to meet practical requirements.

[0003] Currently, simulation methods for the infrared radiation characteristics of ground targets in complex large-scale scenes mainly rely on general infrared radiation characteristic simulation models. These models simulate infrared radiation characteristics under given infrared image resolution and scene conditions. However, they still face challenges such as the influence of changes in the distance between the detector and the target in actual situations on the detector's spatial resolution and scene size, as well as the problem of rapid simulation of large-scale scenes at the kilometer level. Summary of the Invention

[0004] The purpose of this invention is to provide a variable-scale modeling method for the infrared radiation characteristics of ground targets in large-scale scenarios, which has the advantages of solving computational resource limitations and fast computation speed.

[0005] To achieve the above objectives, this invention provides a method for modeling the infrared radiation characteristics of ground targets in large-scale scenarios at varying scales, comprising the following steps:

[0006] S10. Construct a target scenario that includes ground targets and position background based on the application scenario;

[0007] S20. Divide the ground target and the position background in the target scene into a grid to obtain a grid partitioning model;

[0008] S30. Based on the physical model of the temperature field of the ground target and the background of the position in a large scene, perform temperature field simulation on the mesh division model to obtain the underlying temperature field data of the ground target and the background of the position.

[0009] S40. Based on the field of view size of the infrared detector when it is in different positions, the target scene is divided into a key target area grid model and a non-key target area grid model. The grid accuracy of the key target area grid model is higher than that of the non-key target area grid model. The distance information between the infrared detector and the ground target is stored in the tag of the model file.

[0010] S50. Select position points at intervals on the movement trajectory of the infrared detector, and select the grid model to be called based on the distance between the position points and the ground target, combined with the distance information in the tag of the model file.

[0011] S60. Based on the underlying temperature field data and the called grid model, obtain the target temperature field data using interpolation.

[0012] S70. Based on the target temperature field data, the infrared radiation characteristics of the ground target are calculated using inverse Monte Carlo and ray tracing algorithms. An infrared image is generated based on the field of view of the infrared detector, and the calculation results are output.

[0013] Preferably, in step S10, the target scene is established in a geodetic coordinate system, the origin of which is set at the center of the field background, and the trajectory of the infrared detector is in a geocentric coordinate system. The transformation matrix for converting the trajectory of the infrared detector in the geocentric coordinate system to the geodetic coordinate system is:

[0014] M=|-sinB0cosL0-sinB0sinL0cosB0||Y-Y0|

[0015] In the formula, [X, Y, Z] are the coordinate positions of the infrared detector trajectory in the geocentric-ground coordinate system, [X0, Y0, Z0] are the coordinates of the background center of the field in the geocentric-ground coordinate system, and [L0, B0, A0] are the longitude, latitude and altitude of the background center of the field in the geocentric-ground coordinate system converted to the geodetic coordinate system.

[0016] Preferably, in step S20, in the grid partitioning model, the ground target uses 1 / 10 of the minimum structural size of the target heat source as the minimum grid size; the field background uses 1 / 2 of the size of typical ground features as the grid size.

[0017] Preferably, in step S30, a temperature field simulation is performed using a mesh generation model. The simulation process employs the transient temperature field calculation governing equations as follows: In the formula, T is temperature, t is time, ρ is the density of the material, and c p q is the specific heat capacity of the material, k is the thermal conductivity of the material, and q is the thermal conductivity of the material. VFor internal heat sources, the thermal boundary includes solar radiation, sky background radiation, ground background radiation, convective heat transfer between ground targets and the environment, radiative heat transfer of other components to the surface, and radiative heat transfer between the target and the environment. High-precision temperature field data is obtained through simulation as the underlying temperature field data.

[0018] Preferably, the target scene is established in a geodetic coordinate system, with the origin of the geodetic coordinate system set at the center of the field background. In step S40, the key target area is divided according to the position and field of view of the infrared detector, and the size of the key target area is: In the formula, θ 1、 θ2 is the field of view angle of the infrared detector in the horizontal and vertical directions, z is the vertical height of the infrared detector in the geodetic coordinate system, φ is the detection elevation angle, defined as the angle between the detection direction and the xy plane, and azimuth angle is defined as... The angle between the projection of the detection direction onto the xy-plane and the positive x-axis is given by: Horizontal length a = 2tan(θ1 / 2)·(z / sinφ), Vertical length... The coordinates of the field of view center of the infrared detector are [z / tanφ·cosφ, z / tanφ·sinφ, 0], and the horizontal dimension of a single pixel is a. e = a / M, the vertical dimension of a single cell is b e =b / N, where M and N are the number of pixels in the horizontal and vertical directions, respectively, determined according to the required number of pixels in the modeling; when dividing the key target area into grids, the grid size cannot be larger than the pixel size; when dividing the non-key target area, the grid size is larger than the size of a single pixel; a series of points [x] are selected on the trajectory of the infrared detector. i y i , z i A multi-level network is generated, and the center distance R from the infrared detector to the key target area is indicated in the data label of each level of the network. i , a series of R i This forms a column vector R0.

[0019] Preferably, in step S50, the slant distance from any position [x, y, z] of the infrared detector to the key target area or the non-key target area along the field of view of the infrared detector is R. Based on the minimum distance method, the mesh model is invoked, and the minimum distance is ΔR. min =min(|RR) i |), by finding the minimum distance, find the column vector R0 that is closest to the slant distance R. i The corresponding level of the mesh model is invoked by matching the distance information in the tags of the mesh model file.

[0020] Preferably, in step S60, the interpolation method includes a three-dimensional linear interpolation method, which uses the centroid coordinates and temperature coordinates of the triangular mesh as data for the mesh cell. In the underlying temperature field data, the centroid P′ of the triangular mesh... i The coordinates are In the formula, P1(x′1, y′1, z′1), P2(x′2, y′2, z′2), and P3(x′3, y′3, z′3) are the coordinates of the three vertices of the mesh, and the temperature of the triangular mesh is T′. i Calculate the centroid coordinates of all triangular meshes and obtain the corresponding mesh temperature. Then, calculate the centroid coordinates p of any triangular mesh in the called mesh model. i for In the formula, P1(x1, y1, z1), P2(x2, y2, z2), and P3(x3, y3, z3) are the coordinates of the three vertices of the called mesh triangular facet. Using the barycentric coordinates and temperature in the mesh model, the barycentric coordinates of the called mesh are retrieved, and the temperature T of each triangular facet of the called mesh is obtained through linear interpolation. i .

[0021] Preferably, in step S70, during the calculation of infrared radiation characteristics using the inverse Monte Carlo and ray tracing methods, the position x, y, z of the infrared detector, the detection elevation angle φ, and the azimuth angle are specified. The selection of the field of view angles θ1 and θ2 in the horizontal and vertical directions of the infrared detector is the same as in step S40.

[0022] In summary, compared with existing technologies, the variable-scale modeling method for infrared radiation characteristics of ground targets in large-scale scenarios provided by this invention has the following beneficial effects:

[0023] The present invention provides a variable-scale modeling method for the infrared radiation characteristics of ground targets in large-scale scenarios. This method obtains the underlying temperature field data by pre-modeling the ground targets and the background of the application scenario and simulating the temperature field distribution. It then adjusts the key target area and non-key target area according to the distance between the infrared detector and the ground target. Finally, it uses interpolation to obtain the target temperature field data, which reduces the computational resources required in the infrared radiation characteristic simulation calculation process and saves computation time. Attached Figure Description

[0024] Figure 1 Flowchart of a method for modeling the infrared radiation of ground targets at varying scales in large-scale scenarios.

[0025] Figure 2 This is a schematic diagram illustrating the use of grid temperature interpolation based on the underlying temperature field data. Detailed Implementation

[0026] The following will be combined with the appendix in the embodiments of the present invention. Figure 1 ~Attached Figure 2 The technical solutions, structural features, objectives and effects achieved in the embodiments of the present invention will be described in detail.

[0027] It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions. They are only used to facilitate and clarify the purpose of illustrating the embodiments of the present invention, and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationship, or adjustments to the size should still fall within the scope of the technical content disclosed in the present invention, provided that they do not affect the effects and objectives that the present invention can produce.

[0028] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only the expressly listed elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0029] like Figure 1 As shown, this invention provides a variable-scale modeling method for the infrared radiation characteristics of ground targets in large-scale scenes. The modeling method includes the following steps:

[0030] S10. Construct a target scene based on the application scenario, including the ground target and the background of the position. The target scene is established in a geodetic coordinate system, with the origin of the geodetic coordinate system set at the center of the background. Generally, the trajectory of the infrared detector is in a geocentric coordinate system. Therefore, it is first necessary to transform the geocentric coordinate system of the infrared detector to the geodetic coordinate system of the target scene. The transformation matrix for transforming the trajectory of the infrared detector in the geocentric coordinate system to the geodetic coordinate system is:

[0031]

[0032] In the formula, [X, Y, Z] are the coordinate positions of the infrared detector trajectory in the geocentric-ground coordinate system, [X0, Y0, Z0] are the coordinates of the background center of the field in the geocentric-ground coordinate system, and [L0, B0, A0] are the longitude, latitude and altitude of the background center of the field in the geocentric-ground coordinate system converted to the geodetic coordinate system.

[0033] S20. The ground targets and the background of the target site in the target scene are meshed to obtain a mesh model. In the mesh model of step S20, the minimum mesh size for ground targets is 1 / 10 of the minimum structural size of the target heat source; the mesh size for the background of the target site is 1 / 2 of the size of typical ground feature characteristics. In infrared characteristic simulation, the importance of ground targets is higher than that of the background of the target site. Therefore, the mesh size for ground targets is more refined, while the mesh size for the background of the target site is larger than that for ground targets, thus saving computational resources required for simulating the background of the target site.

[0034] S30. Based on the physical model of the temperature field of ground targets and the background of the position in a large scene, temperature field simulation is performed on the meshed model to obtain the underlying temperature field data of the ground targets and the background of the position. In step S30, temperature field simulation is performed using the meshed model. The transient temperature field calculation control equation is as follows: In the formula, T is temperature, t is time, ρ is the density of the material, and c p q is the specific heat capacity of the material, k is the thermal conductivity of the material, and q is the thermal conductivity of the material. V For internal heat sources, the thermal boundary includes solar radiation, sky background radiation, ground background radiation, convective heat transfer between ground targets and the environment, radiative heat transfer of other components to the surface, and radiative heat transfer between the target and the environment. High-precision temperature field data is obtained through simulation as the underlying temperature field data.

[0035] S40. Based on the field of view of the infrared detector at different positions, the target scene is divided into a key target area mesh model and a non-key target area mesh model. The mesh accuracy of the key target area mesh model is higher than that of the non-key target area mesh model, and the distance information between the infrared detector and the ground target is stored in the tag of the model file. The target scene is established in a geodetic coordinate system, with the origin of the geodetic coordinate system set at the center of the field background. In step S40, the key target area is divided according to the position and field of view of the infrared detector. The size of the key target area is: In the formula, θ1 and θ2 are the field of view angles of the infrared detector in the horizontal and vertical directions, z is the position of the infrared detector in the geodetic coordinate system, φ is the detection elevation angle, defined as the angle between the detection direction and the xy plane, and φ is the azimuth angle. The angle between the projection of the detection direction onto the xy-plane and the positive x-axis is given by: Horizontal length a = 2tan(θ1 / 2)·(z / sinφ), Vertical length... The coordinates of the field of view center of the infrared detector are [z / tanφ·cosφ, z / tanφ·sinφ, 0], and the horizontal dimension of a single pixel is a. e = a / M, the vertical dimension of a single cell is b e=b / N, where M and N are the number of pixels in the horizontal and vertical directions, respectively, determined according to the pixel count requirements for modeling; when meshing key target areas, the mesh size cannot be larger than the pixel size; when meshing non-key target areas, the mesh size is larger than the size of a single pixel; select a series of points [x] on the motion trajectory of the infrared detector. i y i , z i Generate a multi-level network, and indicate the center distance R from the infrared detector to the key target area in the data label of each level network. i , a series of R i This forms a column vector R0.

[0036] S50. Select position points at intervals along the movement trajectory of the infrared detector. Based on the distance between the position points and the ground target, and combined with the distance information in the model file's tags, select the mesh model to be called. In step S50, for any position [x, y, z] of the infrared detector, the slant distance from the infrared detector's field of view to the key target area or non-key target area is R. According to the minimum distance method, call the mesh model; the minimum distance is ΔR. min =min(|RR) i |), by finding the minimum distance, find the column vector R0 that is closest to the slant distance R. i It calls the corresponding level of the mesh model by matching the distance information in the labels of the mesh model file.

[0037] S60. Based on the underlying temperature field data and the invoked mesh model, obtain the target temperature field data using interpolation. For example... Figure 2 As shown, in step S60, the interpolation method includes a three-dimensional linear interpolation method. This method uses the centroid coordinates and temperature coordinates of the triangular mesh as data for the mesh unit. In the underlying temperature field data, the centroid P′ of the triangular mesh... i The coordinates are In the formula, P1(x′1, y′1, z′1), P2(x′2, y′2, z′2), and P3(x′3, y′3, z′3) are the coordinates of the three vertices of the mesh, and the temperature of the triangular mesh is T′. i Calculate the centroid coordinates of all triangular meshes and obtain the corresponding mesh temperature. Then, calculate the centroid coordinates p of any triangular mesh in the called mesh model. i for In the formula, P1(x1, y1, z1), P2(x2, y2, z2), and P3(x3, y3, z3) are the coordinates of the three vertices of the called mesh triangular facet. Using the barycentric coordinates and temperature in the mesh model, the barycentric coordinates of the called mesh are retrieved, and the temperature T of each triangular facet of the called mesh is obtained through linear interpolation. i .

[0038] S70. Based on the target temperature field data, the infrared radiation characteristics of the ground target are calculated using inverse Monte Carlo and ray tracing algorithms. An infrared image is generated based on the field of view of the infrared detector, and the calculation results are output. In step S70, during the calculation of infrared radiation characteristics using the inverse Monte Carlo and ray tracing methods, the position of the infrared detector (x, y, z), the detection elevation angle (φ), and the azimuth angle are... The horizontal and vertical field of view θ of the infrared detector 1、 The selection of θ2 is the same as in step S40.

[0039] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for variable-scale modeling of the infrared radiation characteristics of ground targets in large-scale scenes, characterized in that, The modeling method includes the following steps: S10, constructing a target scene including ground targets and a position background based on the application scenario; S20, dividing the ground targets and the position background in the target scene into meshes to obtain a mesh division model; S30, performing temperature field simulation on the mesh division model based on the temperature field physical model of the ground targets and the position background in a large scene to obtain the underlying temperature field data of the ground targets and the position background; S40, dividing the target scene into a key target area mesh model and a non-key target area mesh model according to the field of view size of the infrared detector when the infrared detector is in different positions, wherein the mesh accuracy of the key target area mesh model is higher than that of the non-key target area mesh model. The mesh accuracy of the non-key target area mesh model is determined, and the distance information between the infrared detector and the ground target is stored in the tag of the model file; S50, position points are selected at intervals on the movement trajectory of the infrared detector, and the mesh model to be called is selected based on the distance between the position points and the ground target, combined with the distance information in the tag of the model file; S60, target temperature field data is obtained by interpolation based on the underlying temperature field data and the called mesh model; S70, infrared radiation characteristics of the ground target are calculated using inverse Monte Carlo and ray tracing algorithms based on the target temperature field data, and an infrared image is generated based on the field of view of the infrared detector and the calculation results are output; In step S40, the key target area is divided according to the position and field of view of the infrared detector. The size of the key target area is: In the formula, These represent the horizontal and vertical field of view angles of the infrared detector. z The vertical height of the infrared detector in the geodetic coordinate system. To detect the pitch angle, it is defined as the direction of detection and... xy The angle between two planes is defined as the azimuth angle. For the direction of detection xy Plane projection and x Positive angle of axis, horizontal length Vertical length The coordinates of the center of the infrared detector's field of view are The horizontal dimension of a single pixel is The vertical dimension of a single pixel is , M , N The number of pixels in the horizontal and vertical directions are determined according to the required number of pixels for modeling; when dividing the key target area into a grid, the grid size cannot be larger than the pixel size; when dividing the non-key target area, the grid size is larger than the size of a single pixel; a series of points are selected on the trajectory of the infrared detector. A multi-level network is generated, and the center distance from the infrared detector to the key target area is indicated in the data label of each level of the network. A series Form a column vector .

2. The method for variable-scale modeling of infrared radiation characteristics of ground targets in large-scale scenes as described in claim 1, characterized in that, In step S10, the target scene is established in a geodetic coordinate system, with the origin of the geodetic coordinate system set at the center of the field background. The trajectory of the infrared detector is in a geocentric coordinate system. The transformation matrix for converting the trajectory of the infrared detector in the geocentric coordinate system to the geodetic coordinate system is: In the formula, Let be the coordinates of the infrared detector trajectory in the geocentric-fixed coordinate system. The coordinates of the background center of the position in the geocentric-ground coordinate system. To convert the center coordinates of the background of the position in the geocentric coordinate system to the longitude, latitude and altitude in the geodetic coordinate system.

3. The method for variable-scale modeling of infrared radiation characteristics of ground targets in large-scale scenes as described in claim 1, characterized in that, In step S20, in the grid partitioning model, the ground target uses 1 / 10 of the minimum structural size of the target heat source as the minimum grid size; the field background uses 1 / 2 of the size of typical ground features as the grid size.

4. The method for variable-scale modeling of infrared radiation characteristics of ground targets in large-scale scenes as described in claim 1, characterized in that, In step S30, temperature field simulation is performed using a mesh generation model. The transient temperature field calculation governing equations are as follows: In the formula, T is the temperature. t For time, For the density of the material, Let k be the specific heat capacity of the material, and k be the thermal conductivity of the material. For internal heat sources, the thermal boundary includes solar radiation, sky background radiation, ground background radiation, convective heat transfer between ground targets and the environment, radiative heat transfer of other components to the surface, and radiative heat transfer between the target and the environment. High-precision temperature field data is obtained through simulation as the underlying temperature field data.

5. The method for variable-scale modeling of infrared radiation characteristics of ground targets in large-scale scenes as described in claim 1, characterized in that, In step S50, at any position of the infrared detector The slant distance from the infrared detector's field of view to the key target area or the non-key target area is... R Based on the minimum distance method, the mesh model is invoked, and the minimum distance is... By finding the minimum distance from the column vector Find the slope distance in R closest The corresponding level of the mesh model is invoked by matching the distance information in the tags of the mesh model file.

6. The method for variable-scale modeling of infrared radiation characteristics of ground targets in large-scale scenes as described in claim 1, characterized in that, In step S60, the interpolation method includes a three-dimensional linear interpolation method. This method uses the centroid coordinates and temperature coordinates of the triangular mesh as data for each mesh cell. In the underlying temperature field data, the centroid of the triangular mesh... The coordinates are In the formula, These are the coordinates of the three vertices of the mesh, and the temperature of this triangular mesh is... Calculate the centroid coordinates of all triangular meshes and obtain the corresponding mesh temperature. Also, calculate the centroid coordinates of any triangular mesh in the called mesh model. for In the formula To obtain the coordinates of the three vertices of the called mesh triangular facet, the barycenter coordinates and temperature in the mesh generation model are used. The barycenter coordinates of the called mesh are then retrieved, and the temperature of each triangular facet of the called mesh is obtained through linear interpolation. .

7. The method for variable-scale modeling of infrared radiation characteristics of ground targets in large-scale scenes as described in claim 1, characterized in that, In step S70, during the calculation of infrared radiation characteristics using the inverse Monte Carlo and ray tracing methods, the position of the infrared detector is... x, y, z Detecting pitch angle Azimuth The horizontal and vertical field of view of the infrared detector The selection is the same as in step S40.

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