CN-122021056-A - Simulation method for real-time imaging of infrared polarization characteristics of aerial target

CN122021056ACN 122021056 ACN122021056 ACN 122021056ACN-122021056-A

Abstract

The invention relates to a simulation method for real-time imaging of infrared polarization characteristics of an aerial target, which comprises the steps of obtaining a three-dimensional geometric model, surface parameter information and aerosol mode parameters of the aerial target, constructing a lookup table about temperature and radiation brightness based on a blackbody radiation formula, constructing a lookup table about a reflection angle and a Fresnel reflection Mueller matrix based on the material characteristics of the surface of the target, constructing a lookup table about a scattering angle and a scattering Mueller matrix, constructing a lookup table about zenith angle, azimuth angle and sky background Stokes vector according to LibRadtran calculation results, rendering the aerial target based on a volume dissipation coefficient and each lookup table to obtain the total radiation quantity of the aerial target surface reaching each pixel, and carrying out quantitative analysis on the total radiation quantity, the polarization degree and the polarization angle of the aerial target surface reaching each pixel to obtain a visual gray map. The invention provides a full-link simulation method which is parameterized, reproducible, expandable, small in calculation amount and capable of performing real-time calculation.

Inventors

ZHANG CHAO
YANG HAO
WANG XIAORUI
Luo Mingxia
YUAN YING
HU YANHONG
LIU XIN
LI YUE
GUO JINKUN

Assignees

西安电子科技大学

Dates

Publication Date: 20260512
Application Date: 20260319

Claims (10)

1. The simulation method for real-time imaging of the infrared polarization characteristics of the aerial target is characterized by comprising the following steps of: acquiring a three-dimensional geometric model of an aerial target, surface parameter information of the aerial target and parameters of an aerosol mode; Calculating the radiation brightness of the aerial target in a preset medium wave infrared band at different temperatures based on a blackbody radiation formula to construct a first lookup table about the temperature and the radiation brightness, calculating a Fresnel reflection Mueller matrix of the aerial target at different reflection angles by using a polarized bidirectional reflection distribution function according to the material characteristics of the surface of the aerial target to construct a second lookup table about the reflection angles and the Fresnel reflection Mueller matrix, calculating a volume extinction coefficient and a scattering Mueller matrix of an aerosol mode in the medium wave infrared band, constructing a third lookup table about the scattering angle and the scattering Mueller matrix, and calculating a sky background Stokes vector of the aerosol mode at different zenith angles and azimuth angles at present to construct a fourth lookup table about the zenith angles, the azimuth angles and the sky background Stokes vector, wherein the polarized bidirectional reflection distribution function is used for describing the polarization transformation relation between the Stokes vector of incident light and the Stokes vector of emergent light; Rendering the aerial target based on the three-dimensional geometric model, the volume extinction coefficient, the first lookup table, the second lookup table, the third lookup table and the fourth lookup table of the aerial target to obtain the total radiation amount reaching each pixel from the surface of the aerial target; And carrying out quantitative analysis on the total radiation quantity, the polarization degree and the polarization angle of the aerial target surface reaching each pixel to obtain a visual gray level diagram.
2. The simulation method according to claim 1, wherein the surface parameter information of the airborne target includes mesh information, surface texture distribution, surface temperature distribution, surface normal texture, and roughness texture of the airborne target; Parameters of the aerosol pattern include composition, content, and electromagnetic properties of the atmospheric aerosol.
3. The simulation method according to claim 1, wherein calculating the radiance of the airborne target at different temperatures within a predetermined mid-wave infrared band based on a blackbody radiation formula to construct a first lookup table regarding temperature and radiance comprises: calculating the radiation brightness of the aerial target in the intermediate wave infrared band at different temperatures through a blackbody radiation formula, wherein the radiation brightness calculation formula is expressed as follows: Wherein, the In order for the radiation to be of a brightness, For the surface temperature of the airborne target, In order to be a band of wavelengths, The upper and lower limits of the observation band are respectively, For the first radiation constant to be chosen, Is a second radiation constant; Based on the radiance calculated by the radiance calculation formula at different temperatures, a first lookup table is constructed for the temperature and the radiance.
4. The simulation method of claim 1, wherein calculating fresnel reflection Mueller matrices for the airborne target at different reflection angles using a polarization bi-directional reflection distribution function based on material properties of the surface of the airborne target to construct a second lookup table for the reflection angle and the fresnel reflection Mueller matrices comprises: replacing a fresnel reflection coefficient F in a scalar bi-directional reflection distribution function with a fresnel reflection Mueller matrix characterizing reflection polarization characteristics to construct the polarization bi-directional reflection distribution function, the fresnel reflection Mueller matrix expressed as: Wherein, the For a fresnel reflection Mueller matrix, For reflectivity for s-direction polarized light, For reflectivity for p-direction polarized light, Is complex conjugated; Based on different reflection angles, calculating a corresponding Fresnel reflection Mueller matrix by using the polarization bidirectional reflection distribution function, and constructing a reflection angle and a Fresnel reflection Mueller matrix 、、、 Is included in the first table.
5. A simulation method according to claim 1, wherein calculating the bulk extinction coefficient and scattering Mueller matrix of the aerosol pattern in the mid-wave infrared band and constructing a third lookup table for the scattering angle and scattering Mueller matrix comprises: modeling the atmospheric environment according to the Mie scattering theory and the polydispersion system theory to calculate the volume extinction coefficient of the aerosol mode in the mid-wave infrared band; Based on the spherical particle mie scattering theory, a scattering Mueller matrix with symmetry is constructed, and the scattering Mueller matrix is expressed as: Wherein, the In order to scatter the Mueller matrix, In order to be a scattering angle, , , , , 、 Are all amplitude functions of Mie scattering, re is the real part of complex number, Is the imaginary part of the complex number, Is complex conjugated; And obtaining a corresponding scattering Mueller matrix based on different scattering angles to construct a third lookup table of the scattering angles and the scattering Mueller matrix.
6. The simulation method of claim 1, wherein calculating sky background stokes vectors for the current aerosol pattern at different zenith angles, azimuth angles to construct a fourth lookup table for the zenith angles, azimuth angles and the sky background stokes vectors comprises: Calculating sky background Stokes vectors of the current aerosol mode under different zenith angles and azimuth angles by libRadtran; a fourth lookup table is constructed for the zenith angle, the azimuth angle, and the sky background stokes vector.
7. The simulation method of claim 1, wherein rendering the aerial target based on the three-dimensional geometric model, the volumetric extinction coefficient, the first lookup table, the second lookup table, the third lookup table, and the fourth lookup table of the aerial target to obtain a total amount of radiation reaching each pixel from a surface of the aerial target comprises: Importing the three-dimensional geometric model of the aerial target, the volumetric extinction coefficient, the first lookup table, the second lookup table, the third lookup table and the fourth lookup table into a graphics rendering engine, executing a rendering pipeline by a graphics processor, and performing the following calculation for each pixel of the aerial target: a) Calculating a zero line-of-sight Stokes vector of the current pixel; b) Calculating the large air path radiation of the current pixel from the camera to the surface of the aerial target; c) And obtaining the total radiation quantity of the air target surface reaching the current pixel according to the zero line-of-sight radiation and the large air path radiation.
8. The simulation method of claim 7, wherein the zero line-of-sight Stokes vector is represented as: Wherein, the Is the zero line-of-sight Stokes vector for the current pixel, For the target spontaneous emission Stokes vector, For the Mueller reflection matrix of the target surface, Is the Stokes vector of the incident light.
9. The simulation method of claim 8, wherein the large gas path radiation is expressed as: Wherein, the For large gas path radiation of the current pixel from the camera to the aerial target surface, For the transmission of the scattering point to the camera, In order to be a volume scattering coefficient, In order to scatter the Mueller matrix, For the path from the camera to the target surface, Is the scattering angle.
10. Simulation method according to claim 9, characterized in that the total amount of radiation is expressed as: Wherein, the For the total amount of radiation that the aerial target surface reaches the current pixel, Is the transmittance of the current pixel to the camera.

Description

Simulation method for real-time imaging of infrared polarization characteristics of aerial target Technical Field The invention relates to the technical field of infrared imaging, in particular to a simulation method for real-time imaging of infrared polarization characteristics of an aerial target. Background Conventional infrared imaging typically uses only radiation intensity (brightness/gray scale) to achieve detection, identification, and tracking. However, in a scene with low contrast, aerosol scattering, etc., the intensity information of the target and the background may be highly close, resulting in insufficient contrast. The polarization information provides independent observation dimensions except intensity, namely reflection, roughness, geometric relation, material electromagnetic property and atmospheric scattering of the surface of the target can change the polarization property of the light field, so that the target and the background show stronger distinguishability in polarization properties such as polarization degree, polarization angle and the like. Therefore, the infrared polarization imaging is used for camouflage identification, material distinction, object distinction under complex meteorological conditions and the like. The main physical mechanism of the infrared band polarization generation is that surface reflection induced polarization, sky radiation and solar radiation are reflected by the surface of a target to generate polarization characteristics, atmospheric and aerosol scattering induced polarization, a scattering phase function is calculated according to a Mie scattering theory, the polarization of spontaneous radiation is ideal blackbody radiation without polarization, but the directional emissivity of a real target has polarization effects due to different factors such as microscopic surface structure geometry. At present, the method for acquiring the infrared polarization image is generally divided into two types of computer simulation and experimental measurement, equipment required by experimental study comprises an infrared polarization camera, an aircraft, real-time outfield experimental environment conditions, computer auxiliary equipment and the like, so that the measurement of the radiation intensity and polarization characteristics of the aircraft in motion is realized, but the experiment is long in time consumption, long in early preparation time, high in equipment cost and accurate in data measurement, and the problem of poor stability exists in the experiment. The existing simulation calculation only carries out atmospheric transmission or target polarization characteristic simulation, the calculated amount required by the calculation simulation method is too large, the real-time calculation requirement cannot be met, and the dynamic scene update cannot be met. Therefore, providing a full-link simulation method that is parameterizable, reproducible, scalable, small in calculation amount, and capable of performing real-time calculation is a problem to be solved. Disclosure of Invention In order to solve the problems in the prior art, the invention provides a simulation method for real-time imaging of infrared polarization characteristics of an aerial target. The technical problems to be solved by the invention are realized by the following technical scheme: The invention provides a simulation method for real-time imaging of infrared polarization characteristics of an aerial target, which comprises the following steps: acquiring a three-dimensional geometric model of an aerial target, surface parameter information of the aerial target and parameters of an aerosol mode; Calculating the radiation brightness of the aerial target in a preset medium wave infrared band at different temperatures based on a blackbody radiation formula to construct a first lookup table about the temperature and the radiation brightness, calculating a Fresnel reflection Mueller matrix of the aerial target at different reflection angles by using a polarized bidirectional reflection distribution function according to the material characteristics of the surface of the aerial target to construct a second lookup table about the reflection angles and the Fresnel reflection Mueller matrix, calculating a volume extinction coefficient and a scattering Mueller matrix of an aerosol mode in the medium wave infrared band, constructing a third lookup table about the scattering angle and the scattering Mueller matrix, and calculating a sky background Stokes vector of the aerosol mode at different zenith angles and azimuth angles at present to construct a fourth lookup table about the zenith angles, the azimuth angles and the sky background Stokes vector, wherein the polarized bidirectional reflection distribution function is used for describing the polarization transformation relation between the Stokes vector of incident light and the Stokes vector of emergent light; Rendering the aerial target based