Method and device for real-time infrared rendering of aircraft tail flame based on voxelization method

Abstract

The present invention discloses a method and device for real-time infrared rendering of aircraft tail flames based on a voxelization method, which relates to the field of image processing and is used for real-time and high-precision rendering of infrared imaging of aircraft target tail flames. The present invention uses band spectrum data to calculate infrared physical quantities of tail flame flow field such as self-radiation and transmittance based on the temperature field, pressure field and component field distribution in the existing aircraft target thermal VTK three-dimensional flow field data; uses the voxelization method to voxelize the space area of ​​the tail flame flow field data according to the same scale and divide it into structural grids, each grid is a voxel; according to the thermal physical quantities (such as temperature field, pressure field, component field) in the original grid, calculate the corresponding infrared physical quantity of each voxel; regenerate the target tail flame voxelization file, calculate the infrared radiation brightness of the target tail flame, accurately describe the physical characteristics of the tail flame flow field, ensure the calculation accuracy, and meet the frame rate requirements of real-time rendering of infrared imaging.

Description

Technical Field

[0001] The invention relates to the technical field of 3D modeling in image processing, and in particular to a method and device for real-time infrared rendering of aircraft tail flame based on a voxelization method. Background Art

[0002] In the simulation of infrared scene calculations, the tail flame is a key indicator for aircraft target identification. Its own radiation effect will affect the infrared radiation effect of the aircraft target itself and related elements. In order to accurately simulate the infrared radiation effect of the tail flame of the aircraft target, the researchers proposed several simulation methods, including a tail flame modeling method based on a particle system, a tail flame flow field data simulation method based on an unstructured grid calculated by thermal solving software, and a tail flame flow field data simulation method based on a mathematical modeling method.

[0003] The first category is a particle system-based tail flame modeling method represented by a particle system-based liquid rocket tail flame real-time change simulation method proposed in a Chinese patent document with publication number CN116663376A. This type of method proposes a simplified tail flame flow field model suitable for real-time simulation, and then uses the OSG three-dimensional engine to establish a continuously changeable particle system, thereby realizing the real-time simulation of the tail flame changes during the flight of a liquid rocket. However, this method can only produce a fixed-form tail flame schematic effect, and cannot reflect the change law of the tail flame flow field with the flight parameters in real time.

[0004] The second category is represented by the paper "Modeling and Simulation of Missile Tail Flame Flow Field Characteristics" published by Qin Lanqi et al., which is a simulation method of tail flame flow field data based on unstructured grids calculated by thermal solution software. This method is based on the formation mechanism of missile tail flame flow field. According to combustion theory, fluid mechanics, and gas dynamics, the parameter model of tail flame flow field calculation is established considering the combustion chemical reaction in the combustion chamber, and the flow field parameters such as velocity, temperature, and pressure are calculated by combining Gambit and Fluent simulation software. Since the change process of the tail flame flow field has a complex theoretical mechanism, it needs to be accurately solved by computational fluid dynamics methods with the help of CFD software. The calculation scale and volume of the precise solution method are too large, and it is not suitable for high-real-time three-dimensional simulation scenarios.

[0005] Therefore, the first two methods do not meet the frame rate requirements of real-time infrared simulation.

[0006] The third category is represented by the paper "Theoretical Calculation and Simulation of Infrared Radiation of Jet Aircraft Tail Flame" published by Wang Zhongxian et al., which is a simulation method based on mathematical modeling methods to simulate the tail flame flow field data. This type of method regards the tail flame area as an axisymmetric non-uniform radiation source, which is generally divided into two parts: the initial section and the main section. In the initial section, the gas still maintains the characteristics it has when it is sprayed from the tail nozzle, that is, the component pressure and temperature parameters are basically constant and at the maximum value. The radiation intensity of the entire tail flame depends to a large extent on the theoretical calculation method of the infrared spectrum radiation intensity of the tail flame in this area. In the expanded area, the airflow becomes completely turbulent. In addition, this type of method only considers the infrared radiation of the tail flame during the calculation process, while the actual measurement data is affected by the infrared radiation of the nozzle, so the calculation accuracy is low. Summary of the invention

[0007] The object of the present invention is to provide a method and device for real-time infrared rendering of aircraft tail flames based on voxelization method to perform real-time and high-precision rendering of infrared imaging of aircraft target tail flames in order to address all or part of the above-mentioned problems.

[0008] The technical solution adopted by the present invention is as follows:

[0009] A method for real-time infrared rendering of aircraft tail flame based on voxelization method, comprising:

[0010] According to the temperature field, pressure field and component field distribution in the aircraft target thermal VTK three-dimensional flow field data, the infrared physical quantities in each volume grid in the tail flame flow field data are calculated, including:

[0011] Calculate the self-radiation value of each volume grid in the tail plume flow field data :

[0012] ,in, is the volume mesh identifier, Volume Mesh The temperature, represents the wavelength, is Planck's constant, represents the speed of light, represents the Boltzmann constant, For infrared real-time simulation bands, follow the band step size The number of divided wave points, The value range is .

[0013] Calculate the transmittance of each volume grid in the tail plume flow field data :

[0014] , where Representation Volume Mesh Middle The transmittance of each component, , is the number of group fields, Volume Mesh The three-dimensional flow field data The molar content of each component, Volume Mesh The pressure, is the average half-width of the spectral band, is the average spacing between spectral band lines, The average absorption coefficient of the spectral band, is the volume mesh size;

[0015] voxelize the space area of ​​the aircraft tail flame flow field data;

[0016] According to the relationship between each voxel and the volume grid, the infrared physical quantity of each voxel is calculated;

[0017] According to the infrared physical quantity of each voxel, the infrared radiation brightness of the tail flame of the aircraft target is calculated;

[0018] Infrared imaging rendering is performed based on the infrared radiation brightness of the tail flame of the aircraft target.

[0019] Optionally, voxelizing the space region of the aircraft tail flame flow field data includes:

[0020] Traverse all volume grids in the tail flame flow field data and calculate the size of the spatial area of ​​the tail flame flow field data;

[0021] According to the size of the space area of ​​the tail flame flow field data, a rectangular solid of the same size is generated;

[0022] The cuboid entity is voxelized by using a voxelization method with the minimum size of the traversed volume grid as the scale, and divided into structural volume grids, each of which is a voxel.

[0023] Optionally, voxelizing the space region of the aircraft tail flame flow field data includes:

[0024] Traverse all volume grids in the tail flame flow field data and calculate the size of the spatial area of ​​the tail flame flow field data;

[0025] According to the size of the space area of ​​the tail flame flow field data, a rectangular solid of the same size is generated;

[0026] According to the length, width and height dimensions of the rectangular solid, the number of divisions in the three directions of length, width and height is set in the same proportion, and the number of divisions in the three directions of length, width and height is used as a scale. The rectangular solid is voxelized using a voxelization method and divided into structural grids, each structural grid being a voxel.

[0027] Optionally, the calculating the infrared physical quantity of each voxel according to the relationship between each voxel and the volume grid includes:

[0028] Calculate the number of volume grids corresponding to each voxel;

[0029] According to the volume of each body grid, normalize it and use it as the weight coefficient of each body grid;

[0030] For each voxel, the weight coefficients of the corresponding volume grids and the infrared physical quantity are weighted and summed to obtain the infrared physical quantity of the voxel.

[0031] Optionally, the calculating the infrared physical quantity of each voxel according to the relationship between each voxel and the volume grid includes:

[0032] Calculate the number of volume grids corresponding to each voxel;

[0033] For each voxel, the average value of the infrared physical quantities of each corresponding volume grid is calculated to obtain the infrared physical quantity of the voxel.

[0034] Optionally, calculating the infrared radiation brightness of the tail flame of the aircraft target according to the infrared physical quantity of each voxel includes:

[0035] Calculate the infrared radiation brightness of each pixel of the tail flame of the aircraft target in the light path based on ray tracing :

[0036] , ;in, is the voxel identifier of the detector-to-target ray rubber, From 0 to , is the number of voxels intersected by the detector-to-target ray, Representing voxels The self-radiation in Representing voxels The initial condition is the transmittance of the tail flame voxel when the light first intersects with the tail flame voxel. and the integrated infrared radiation brightness , when the light intersects the tail flame voxel for the last time, the transmittance of the tail flame voxel is and the integrated infrared radiation brightness ;go through The infrared radiation brightness of the tail flame in the light path is obtained by the iteration .

[0037] Optionally, the infrared imaging rendering based on the infrared radiation brightness of the tail flame of the target aircraft is to convert the infrared radiation brightness of each pixel of the tail flame of the target aircraft into Convert to Color , and then rendered in fusion with the original pixels of the tail flame of the aircraft target.

[0038] Optionally, the infrared radiation brightness of each pixel of the aircraft target tail flame Convert to Color The methods include:

[0039] The color of each pixel is calculated according to the following formula :

[0040] , where , Representing pixels p transparency, Representing pixels p The original color, Represents the color of the target object, is the maximum infrared radiation brightness of the current window, It is the minimum infrared radiation brightness of the current window.

[0041] The present invention also provides an aircraft tail flame infrared real-time rendering device based on voxelization method, comprising a processor and a storage medium, wherein the processor runs a computer program stored in the storage medium to execute the above-mentioned aircraft tail flame infrared real-time rendering method based on voxelization method.

[0042] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0043] The present invention calculates infrared physical quantities of the tail flame flow field such as self-radiation and transmittance based on the temperature field, pressure field and component field distribution in the existing aircraft target thermal VTK three-dimensional flow field data, and uses band spectrum data; uses a voxelization method to voxelize the space area of ​​the tail flame flow field data according to the same scale and divide it into structural grids, each grid being a voxel; calculates the corresponding infrared physical quantity of each voxel according to the thermal physical quantities (such as temperature field, pressure field and component field) in the original grid; regenerates the target tail flame voxelization file, calculates the infrared radiation brightness of the target tail flame, accurately describes the physical characteristics of the tail flame flow field, ensures the calculation accuracy, and meets the frame rate requirement of real-time rendering of infrared imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0045] Figure 1 The flowchart of one embodiment of a method for real-time infrared rendering of aircraft tail flame based on voxelization method. DETAILED DESCRIPTION

[0046] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0047] Any feature disclosed in this specification (including any additional claims and abstract), unless otherwise stated, may be replaced by other alternative features that are equivalent or have similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0048] The embodiment of the present application provides a method for real-time infrared rendering of aircraft tail flames based on voxelization method, such as Figure 1 As shown, it includes the following processes:

[0049] (1) According to the temperature field, pressure field and component field distribution in the VTK three-dimensional flow field data of the aircraft target, the infrared physical quantities in each volume grid in the tail flame flow field data are calculated.

[0050] In some embodiments, the infrared physical quantities of the volume grid in the tail flame flow field data include self-radiation value and transmittance. Then step (1) includes the following sub-steps:

[0051] 1.1) According to the temperature field distribution in the aircraft target thermal VTK three-dimensional flow field data, calculate the self-radiation value in each volume grid in the tail flame flow field data :

[0052] ,in, is the volume mesh identifier, Volume Mesh The temperature, represents the wavelength, is Planck's constant, represents the speed of light, represents the Boltzmann constant, For infrared real-time simulation band (such as the medium-wave infrared band is 3 -5 ) According to the band step The number of divided wave points, The value range is .

[0053] 1.2) According to the pressure field and component field (including CO2, HO2, etc.) distribution in the aircraft target thermal VTK three-dimensional flow field data, calculate the transmittance of each volume grid in the tail flame flow field data :

[0054] , where Representation Volume Mesh Middle The transmittance of each component, , is the number of group fields, Volume Mesh The three-dimensional flow field data The molar content of each component, Volume Mesh The pressure, is the average half-width of the spectral band, is the average spacing between spectral band lines, The average absorption coefficient of the spectral band, is the volume mesh size.

[0055] (2) Voxelize the space area of ​​the aircraft tail flame flow field data.

[0056] In some embodiments, the process of voxelizing a spatial region includes the following sub-steps:

[0057] 2.1) Traverse all volume grids in the tail flame flow field data and calculate the size of the space area of ​​the tail flame flow field data. Assume that the minimum size of the traversed volume grid is .

[0058] 2.2) Generate a rectangular entity of the same size according to the size of the space area of ​​the tail flame flow field data.

[0059] 2.3) The minimum size of the traversed volume mesh The cuboid entity is voxelized by a voxelization method and divided into structure grids, each of which is a voxel.

[0060] Alternatively, in some other embodiments, the process of voxelizing a spatial region includes the following sub-steps:

[0061] 2.1) Traverse all volume grids in the tail flame flow field data and calculate the size of the space area of ​​the tail flame flow field data. Assume that the minimum size of the traversed volume grid is .

[0062] 2.2) Generate a rectangular entity of the same size according to the size of the space area of ​​the tail flame flow field data.

[0063] 2.3) According to the length, width and height dimensions of the rectangular solid, the number of divisions in the three directions of length, width and height is set in the same proportion, and the number of divisions set in the three directions of length, width and height is used as a scale. The rectangular solid is voxelized by a voxelization method and divided into structural grids, each structural grid being a voxel.

[0064] According to the idea of ​​this embodiment, in some feasible implementations, step 2.3) includes the following process:

[0065] 2.3a) According to the dimensions x_size, y_size, and z_size of the cuboid entity in the three directions, calculate the proportional coefficients x_rate, y_rate, and z_rate in these three directions respectively:

[0066] x_rate=x_size / (x_size+y_size+z_size);

[0067] y_rate=y_size / (x_size+y_size+z_size);

[0068] z_rate=z_size / (x_size+y_size+z_size).

[0069] 2.3b) According to the proportional coefficients x_rate, y_rate, and z_rate in the three directions, set the number of subdivisions Nx, Ny, and Nz in the x, y, and z directions in the same proportion:

[0070] Nx=R×x_rate;

[0071] Ny=R×y_rate;

[0072] Nz=R×z_rate.

[0073] 2.3c) According to the number of divisions Nx, Ny, and Nz in the three directions, the cuboid entity is voxelized at that scale and divided into structural grids.

[0074] (3) Based on the relationship between each voxel and the volume grid, calculate the infrared physical quantity of each voxel.

[0075] In some embodiments, the method for calculating the infrared physical quantity of a voxel includes the following sub-steps:

[0076] 3.1) Calculate the number of volume meshes corresponding to each voxel . It can be calculated by sampling.

[0077] 3.2) Based on the volume of each body mesh, normalize it and use it as the weight coefficient of each body mesh.

[0078] In some feasible implementations, this sub-step can calculate the weight coefficient of each body mesh according to the following method:

[0079] According to the number of primitive grids corresponding to each voxel , calculate the volume of each mesh separately , which is normalized as the weight coefficient of each volume mesh , the calculation formula is as follows:

[0080] , here The value range is , is the identifier of the volume mesh in the voxel.

[0081] 3.3) For each voxel, the weight coefficients of the corresponding volume grids and the infrared physical quantity are weighted and summed to obtain the infrared physical quantity of the voxel.

[0082] In some feasible implementations, the infrared physical quantity of each voxel calculated in this sub-step includes the transmittance and self-radiation value , and the calculation methods of the two are as follows:

[0083] , ; represent the transmittance and self-radiation value of volume mesh j respectively.

[0084] In some other embodiments, the method for calculating the infrared physical quantity of a voxel includes the following sub-steps:

[0085] 3.1) Calculate the number of volume meshes corresponding to each voxel .

[0086] 3.2) For each voxel, calculate the average value of the infrared physical quantities of each corresponding volume grid to obtain the infrared physical quantity of the voxel.

[0087] In some embodiments, the sub-step includes:

[0088] 3.2a) According to the number of primitive grids corresponding to each voxel , calculate the sum of the infrared physical quantities of all volume meshes corresponding to each voxel and ,in represents the sum of transmittance, Represents the sum of self-radiation values.

[0089] 3.2b) Calculate the average value of infrared physical quantity in voxel and , which is the transmittance of the infrared physical quantity contained in each voxel and self-radiation , as follows:

[0090] , ; In the formula, represents the average transmittance, Represents the average value of the self-radiation value.

[0091] (4) Based on the infrared physical quantity of each voxel, calculate the infrared radiation brightness of the tail flame of the aircraft target.

[0092] In some embodiments, this step includes the following sub-steps:

[0093] 4.1) Generate a file in a format that meets the infrared simulation requirements based on the infrared physical quantity of each voxel.

[0094] 4.2) Calculate the infrared radiation brightness of each pixel of the tail flame of the aircraft target in the ray path based on ray tracing :

[0095] , ;in, is the voxel identifier of the detector-to-target ray rubber, From 0 to , is the number of voxels intersected by the detector-to-target ray, Representing voxels The self-radiation in Representing voxels The initial condition is the transmittance of the tail flame voxel when the light first intersects with the tail flame voxel. and the integrated infrared radiation brightness , when the ray (leaving the tail flame model) intersects the tail flame voxel for the last time, the transmittance of the tail flame voxel is and the integrated infrared radiation brightness ;go through The infrared radiation brightness of the tail flame in the light path is obtained by the iteration .

[0096] (5) Infrared imaging rendering based on the infrared radiation brightness of the aircraft target tail flame.

[0097] In some embodiments, this step converts the infrared radiation brightness of each pixel of the aircraft target tail flame into Convert to Color , and then rendered in fusion with the original pixels of the tail flame of the aircraft target.

[0098] In some feasible implementations, the fusion rendering includes the following sub-steps:

[0099] 5.1) Calculate the color value of the current pixel.

[0100] When the light passes through the voxel cube, the light is sampled at equal distances, and the sampled data obtained each time is repeatedly accumulated. The formula is as follows:

[0101] The color of each pixel is calculated according to the following formula :

[0102] ,in, Representing pixels p transparency, Representing pixels p The original color, Represents the color of the target object, the converted color That is the color obtained by observing the target through the object.

[0103] Since the object in the present embodiment is a tail flame, The calculation method is as follows:

[0104] ,in, is the maximum infrared radiation brightness of the current window, is the minimum infrared radiation brightness of the current window, It is the infrared radiation brightness of the current pixel.

[0105] 5.2) Calculate the infrared radiation brightness of each pixel of the target tail flame in the path based on ray tracing , and convert it into the corresponding color by the method in sub-step 5.1) , and then render it in fusion with the original pixels.

[0106] The embodiment of the present application also proposes a device for real-time infrared rendering of aircraft tail flames based on a voxelization method, the device includes a processor and a storage medium, the storage medium stores a computer program, the processor is connected to the storage medium, and runs the computer program stored in the storage medium to execute the real-time infrared rendering method of aircraft tail flames based on a voxelization method in the above embodiment. That is, the real-time infrared rendering method of aircraft tail flames based on a voxelization method in the above embodiment can be executed by running the computer program stored in the storage medium.

[0107] The solution of the embodiment of the present application converts the unstructured grid tail flame flow field data into tail flame voxel infrared physical quantities using the voxelization method, which can not only preserve the physical properties of the aircraft tail flame flow field distribution (such as temperature distribution, pressure distribution and component distribution, etc.), but also meet the frame rate requirements of real-time infrared simulation. In addition, this solution can also be applied to high-fidelity infrared simulation to speed up the calculation efficiency of high-fidelity simulation, and can also be applied to infrared real-time simulation of ship plume targets.

[0108] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A method for real-time infrared rendering of aircraft tail flames based on voxelization method, characterized in that: include: According to the temperature field, pressure field and component field distribution in the aircraft target thermal VTK three-dimensional flow field data, the infrared physical quantities in each volume grid in the tail flame flow field data are calculated, including: Calculate the self-radiation value of each volume grid in the tail plume flow field data : ， in, is the volume mesh identifier, Volume Mesh The temperature, represents the wavelength, is Planck's constant, represents the speed of light, represents the Boltzmann constant, For infrared real-time simulation bands, follow the band step size The number of divided wave points, The value range is ; Calculate the transmittance of each volume grid in the tail plume flow field data : ， In the formula, Representation Volume Mesh Middle The transmittance of each component, , is the number of group fields, Volume Mesh The three-dimensional flow field data The molar content of each component, Volume Mesh The pressure, is the average half-width of the spectral band, is the average spacing between spectral band lines, is the average absorption coefficient of the spectral band, is the volume mesh size; voxelize the space area of ​​the aircraft tail flame flow field data; According to the relationship between each voxel and the volume grid, the infrared physical quantity of each voxel is calculated; The infrared radiation brightness of the tail flame of the aircraft target is calculated according to the infrared physical quantity of each voxel, including: calculating the infrared radiation brightness of each pixel of the tail flame of the aircraft target in the light path according to ray tracing : ， ； in, is the voxel identifier of the detector-to-target ray rubber, From 0 to , is the number of voxels intersected by the detector-to-target ray, Representing voxels The self-radiation in Representing voxels The initial condition is the transmittance of the tail flame voxel when the light first intersects with the tail flame voxel. and the integrated infrared radiation brightness , when the light intersects the tail flame voxel for the last time, the transmittance of the tail flame voxel is and the integrated infrared radiation brightness ;go through The infrared radiation brightness of the tail flame in the light path is obtained by the iteration ; Infrared imaging rendering is performed based on the infrared radiation brightness of the tail flame of the aircraft target.

2. The method for real-time infrared rendering of aircraft tail flame based on voxelization method as claimed in claim 1, characterized in that: The voxelization of the space region of the aircraft tail flame flow field data includes: Traverse all volume grids in the tail flame flow field data and calculate the size of the spatial area of ​​the tail flame flow field data; According to the size of the space area of ​​the tail flame flow field data, a rectangular solid of the same size is generated; The cuboid entity is voxelized by using a voxelization method with the minimum size of the traversed volume grid as the scale, and divided into structural volume grids, each of which is a voxel.

3. The method for real-time infrared rendering of aircraft tail flame based on voxelization method as claimed in claim 1, characterized in that: The voxelization of the space region of the aircraft tail flame flow field data includes: Traverse all volume grids in the tail flame flow field data and calculate the size of the spatial area of ​​the tail flame flow field data; According to the size of the space area of ​​the tail flame flow field data, a rectangular solid of the same size is generated; According to the length, width and height dimensions of the rectangular solid, the number of divisions in the three directions of length, width and height is set in the same proportion, and the number of divisions in the three directions of length, width and height is used as a scale. The rectangular solid is voxelized using a voxelization method and divided into structural grids, each structural grid being a voxel.

4. The method for real-time infrared rendering of aircraft tail flame based on voxelization method as claimed in claim 1, characterized in that: The step of calculating the infrared physical quantity of each voxel based on the relationship between each voxel and the volume grid includes: Calculate the number of volume grids corresponding to each voxel; According to the volume of each body grid, normalize it and use it as the weight coefficient of each body grid; For each voxel, the weight coefficients of the corresponding volume grids and the infrared physical quantity are weighted and summed to obtain the infrared physical quantity of the voxel.

5. The method for real-time infrared rendering of aircraft tail flame based on voxelization method as claimed in claim 1, characterized in that: The step of calculating the infrared physical quantity of each voxel based on the relationship between each voxel and the volume grid includes: Calculate the number of volume grids corresponding to each voxel; For each voxel, the average value of the infrared physical quantities of each corresponding volume grid is calculated to obtain the infrared physical quantity of the voxel.

6. The method for real-time infrared rendering of aircraft tail flame based on voxelization method as claimed in claim 1, characterized in that: The infrared imaging rendering based on the infrared radiation brightness of the tail flame of the aircraft target is to convert the infrared radiation brightness of each pixel of the tail flame of the aircraft target into Convert to Color , and then rendered in fusion with the original pixels of the tail flame of the aircraft target.

7. The method for real-time infrared rendering of aircraft tail flame based on voxelization method as claimed in claim 6, characterized in that: The infrared radiation brightness of each pixel of the tail flame of the aircraft target Convert to Color The methods include: The color of each pixel is calculated according to the following formula : ， In the formula, , in, Representing pixels p transparency, Representing pixels p The original color, Represents the color of the target object, is the maximum infrared radiation brightness of the current window, It is the minimum infrared radiation brightness of the current window.

8. A device for real-time infrared rendering of aircraft tail flames based on voxelization method, comprising a processor and a storage medium, characterized in that: The processor runs the computer program stored in the storage medium to execute the real-time infrared rendering method for aircraft tail flame based on voxelization method as described in any one of claims 1-7.

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