Ground background radiation image generation method and device in clear sky state

Abstract

The invention discloses a ground background radiation image generation method and device in a clear sky state, and belongs to the field of image generation. The method comprises the following steps: calculating a temperature value of each surface element of the three-dimensional ground according to preset environment data under a clear sky condition and obtained ground material data; determining an atmosphere lookup table changing along with the height and the zenith angle according to preset environment data and the read radiation data under a clear sky condition; according to the temperature value and the environment data, calculating to obtain an emergent radiation brightness value of each surface element of the three-dimensional ground; calculating the apparent radiation brightness value of each surface element of the three-dimensional earth surface according to the emergent radiation brightness value of the three-dimensional earth surface and the atmosphere lookup table; and rasterizing and resampling in a shader according to the apparent radiation brightness value to obtain a ground background radiation image in a clear sky state. According to the invention, high-confidence radiance image data in front of a sensor mouth for ground optical detection can be generated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of image generation, in particular to a method and device for generating a ground background radiation image in a clear sky state. BACKGROUND

[0002] Optical scene simulation of the earth is a comprehensive method of generating high-precision virtual images by simulating the optical imaging process of the earth's surface and atmospheric environment through computer modeling and rendering technology. This technology is widely used in remote sensing system testing, military simulation, automatic driving training and disaster monitoring, and provides a low-cost, controllable virtual experiment environment for optical sensor performance verification, algorithm optimization and task planning.

[0003] In related technologies, the imaging process in a clear sky state often lacks a systematic physical calculation model due to the low resolution of satellite remote sensing, resulting in imaging results that cannot meet the real-time generation and application requirements of high-resolution ground scene radiation images at close range.

[0004] Therefore, there is an urgent need for a method and device for generating a ground background radiation image in a clear sky state to solve the above technical problems. SUMMARY

[0005] The present application provides a method and device for generating a ground background radiation image in a clear sky state, which can solve the problem of real-time generation of ground background radiation images under specified conditions in a clear sky state. The technical solution is as follows:

[0006] On the one hand, a method for generating a ground background radiation image in a clear sky state is provided, the method comprising:

[0007] According to the preset environmental data under the clear sky condition and the obtained ground material data, the temperature value of each surface element of the three-dimensional ground is calculated;

[0008] According to the preset environmental data under the clear sky condition and the read radiation data, an atmospheric lookup table varying with height and zenith angle is determined;

[0009] According to the temperature value and the environmental data, the exit radiation brightness value of each surface element of the three-dimensional ground is calculated;

[0010] According to the exit radiation brightness value of the three-dimensional ground and the atmospheric lookup table, the apparent radiation brightness value of each surface element of the three-dimensional ground surface is calculated;

[0011] According to the apparent radiation brightness value, rasterization resampling is performed in the shader to obtain a ground background radiation image in a clear sky state.

[0012] On the other hand, a device for generating a ground background radiation image in a clear sky state is provided, the device comprising:

[0013] The first calculation module is configured to calculate a temperature value of each surface unit of the three-dimensional ground according to preset environmental data under a clear sky condition and acquired ground material data;

[0014] The determining module is configured to determine an atmospheric lookup table varying with height and zenith angle according to the preset environmental data under the clear sky condition and the read radiation data;

[0015] The second calculation module is configured to calculate an outgoing radiation brightness value of each surface unit of the three-dimensional ground according to the temperature value and the environmental data;

[0016] The third calculation module is configured to calculate an apparent radiation brightness value of each surface unit of the three-dimensional ground according to the outgoing radiation brightness value of the three-dimensional ground and the atmospheric lookup table;

[0017] The processing module is configured to perform rasterization resampling in a shader according to the apparent radiation brightness value to obtain a ground background radiation image under a clear sky condition.

[0018] In another aspect, a computer device is provided, which includes a memory and a processor, the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory to realize the steps of the ground background radiation image generation method under a clear sky condition.

[0019] In another aspect, a computer readable storage medium is provided, which stores a computer program, and the computer program is executed by a processor to realize the steps of the ground background radiation image generation method under a clear sky condition.

[0020] In another aspect, a computer program product is provided, which includes a computer program, and the computer program is executed by a processor to realize the steps of the ground background radiation image generation method under a clear sky condition.

[0021] The technical scheme provided by the application can bring at least the following beneficial effects: based on a three-dimensional ground geometric model containing three-dimensional elevation and ground material data, through ground heat calculation under a clear sky condition, ground outgoing radiation calculation, detector port front apparent radiation calculation, and in a manner of pre-calculation of radiation characteristic quantities and embedded ground radiation calculation model in a computer graphics engine, real-time simulation of a ground background radiation image under a specified time, a specified location, a specified meteorological condition and a specified detection geometry condition is realized. The method can realize real-time simulation calculation of a real detection scene radiation brightness image under any specified optical spectrum, a specified ground object and a detection geometry condition, and meanwhile, the method supports performance identification, algorithm effectiveness evaluation and matching identification template preparation of an optical detection sensor on a semi-physical and full-digital simulation test. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor under the premise of the drawings.

[0023] Figure 1 is a flow chart of generating a ground background radiation image in a clear sky state provided by an embodiment of the present application;

[0024] Figure 2 is a schematic diagram of decomposing a ground object radiation process in a clear sky state provided by an embodiment of the present application;

[0025] Figure 3 is a structural diagram of a ground background radiation image generating device in a clear sky state provided by an embodiment of the present application;

[0026] Figure 4 is a hardware architecture diagram of a computer device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0027] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0028] As described above, the current simulation of the ground optical scene is limited by the resolution of satellite remote sensing on one hand, and on the other hand, there is no systematic physical calculation model for rendering calculation, which leads to the fact that the simulation result cannot meet the generation and application requirements of the high-resolution ground scene radiation image in a close distance.

[0029] Based on this, the idea of the present application is that the ground three-dimensional model and the ground material data are basic inputs, under the specified environmental conditions, the ground temperature, the ground exit radiation and the apparent radiation brightness are calculated, and the radiation algorithm is embedded in the computer graphics engine operation, so as to realize the real-time generation of the ground background radiation brightness image.

[0030] The specific implementation of the above idea will be described below.

[0031] Please refer to Figure 1 The embodiment of the present application provides a method for generating a ground background radiation image in a clear sky state, which comprises the following steps:

[0032] Step 100, according to the preset environmental data under clear sky conditions and the obtained ground material data, the temperature value of each surface element of the three-dimensional ground is calculated;

[0033] Step 102, according to the preset environmental data under clear sky conditions and the read radiation data, the atmospheric lookup table changing with height and zenith angle is determined;

[0034] Step 104, according to the temperature value and the environmental data, the outgoing radiation brightness value of each surface element of the three-dimensional ground is calculated;

[0035] Step 106, according to the outgoing radiation brightness value of the three-dimensional ground and the atmospheric lookup table, the apparent radiation brightness value of each surface element of the three-dimensional ground is calculated;

[0036] Step 108, according to the apparent radiation brightness value, rasterization resampling is carried out in the shader to obtain the ground background radiation image under clear sky conditions.

[0037] In the embodiment of the application, based on the three-dimensional geometric model of the ground containing three-dimensional elevation and ground material data, through ground heat calculation under clear sky conditions, ground outgoing radiation calculation, detector port front apparent radiation calculation, the radiation characteristic quantity pre-calculation and the computer graphics engine embedded ground radiation calculation model are realized. The ground background radiation image real-time simulation under the specified time, specified location, specified weather conditions and specified detection geometric conditions is realized. The method can realize real-time simulation calculation of the real detection scene radiation brightness image under the condition of any specified optical spectrum, specified ground object and detection geometry, and can support performance identification, algorithm effectiveness evaluation and matching identification template preparation in semi-physical and full-digital simulation test of the optical detection sensor.

[0038] The execution mode of each step is described below. Figure 1

[0039] First, for steps 100 and 102, according to the preset environmental data under clear sky conditions and the obtained ground material data, the temperature value of each surface element of the three-dimensional ground is calculated; according to the preset environmental data under clear sky conditions and the read radiation data, the atmospheric lookup table changing with height and zenith angle is determined.

[0040] In the embodiment of the application, the temperature value is calculated by the following steps: inputting the ground material data and the environmental data into the preset ground temperature model, outputting the temperature lookup table of the illumination temperature and the shadow temperature of each ground material changing with the surface normal direction angle and the azimuth angle; using the computer graphics engine GPU to perform real-time calculation on the temperature lookup table to obtain the temperature value of each surface element of the three-dimensional ground.

[0041] ​Specifically, the temperature value of a specified ground object material is calculated by using a one-dimensional heat conduction equation. For each material, three types of boundary conditions are read in the equation:

[0042] ① The light and thermal physical parameters of the material are read from a material physical property library;

[0043] ② The near-surface atmospheric temperature, humidity, wind speed and wind direction are read from a meteorological assumption or a meteorological database;

[0044] ③ The atmospheric radiation heat flux, including the direct solar radiation heat flux, the sky scattered radiation heat flux and the atmospheric emission radiation heat flux, is read from an environmental heat flow calculation module.

[0045] For the environmental heat flow calculation module, the general atmospheric radiation transfer software is used to read the meteorological parameters to calculate the direct solar radiation heat flux reaching the ground, and a method based on radiation brightness is designed to quickly calculate the atmospheric wide-band radiation heat flux, and the mathematical expression is as follows:

[0046] E boa =2πμ1·L boa (μ1)

[0047] Wherein, E boa is the atmospheric radiation flux reaching the ground in a specified spectrum, that is, the atmospheric radiation heat flux received by the ground in the spectrum, which is called the sky scattered radiation heat flux in the 0.2-2.5 μm spectrum and the atmospheric emission radiation heat flux in the 2.5-40 μm spectrum; L boa is the atmospheric radiation brightness reaching the ground at a specific zenith angle under the two-flow approximation; μ1=cos(θ1), θ1=55°, is the zenith angle of the upper hemisphere space under the two-flow condition.

[0048] Then, in the initialization stage, the illumination temperature and the shadow temperature lookup table of each ground material varying with the normal direction angle 0-90 degrees and the azimuth angle 0-360 degrees are calculated. Based on these pre-computed results, the three-dimensional ground model is loaded again, and in the real-time calculation stage using the computer graphics engine, the temperature value of each ground facet is calculated based on the lookup table GPU acceleration.

[0049] Further, according to the preset environmental parameters, the general atmospheric radiation transfer software is used to calculate the atmospheric radiation and the atmospheric transmittance lookup table varying with the probe height 0-20 km and the observation zenith angle 90-180 degrees (downward observation zenith angle).

[0050] Then, for step 104, the outgoing radiation brightness value of each facet of the three-dimensional ground is calculated according to the temperature value and the environmental data.

[0051] In the embodiment of the application, first, the outgoing radiation parameters reaching the ground are calculated according to the preset environmental data, and the radiation modeling process is shown in the schematic diagramFigure 2 The exit radiation parameters include direct solar radiation irradiance, atmospheric diffuse radiation flux, blackbody radiation luminance, tilt factor and spectral integration correction factor.

[0052] The tilt factor is calculated by the following formula:

[0053]

[0054] Wherein, E a represents the normal direction of the ground tilt facet receives the atmospheric diffuse radiation flux.

[0055] The spectral integration correction factor includes the spectral integration correction factor caused by the difference between the solar spectrum and the ground material reflectivity spectrum distribution, the spectral integration correction factor caused by the difference between the atmospheric diffuse spectrum and the ground material reflectivity spectrum distribution, and the spectral integration correction factor caused by the difference between the blackbody radiation spectrum and the ground material emissivity spectrum distribution, which is calculated by the following formula:

[0056]

[0057] Wherein, for χ sun , χ sky , χ sb , F corresponds to E sun , E sky , L sb respectively, and W corresponds to R, R and ε respectively.

[0058] Then the exit radiation luminance value of each facet is calculated by the following formula:

[0059]

[0060] Wherein, L s represents the exit radiation luminance of the ground facet with coordinates (x, y, z) in the specified spectral range; other parameters in this expression are the values in the same spectral range. E sun represents the direct solar radiation irradiance reaching the ground; μ sun = cos(θ sun ), θ sun is the direction angle of the direct sunlight beam relative to the normal of the facet; R represents the material reflectivity of the ground facet; χ sun represents the spectral integration correction factor caused by the difference between the solar spectrum and the ground material reflectivity spectrum distribution; δ sun represents the shadow factor of the solar shadow caused by the mutual shielding of the three-dimensional structure of the ground, δ sun is 0, indicating that the facet is in the shadow, δ sun is 1, indicating that the facet is in the light, and δsun Always 0.E sky Represent the hemispheric atmospheric diffuse radiation flux reaching the ground;f sky Represent the proportion factor of the partial receiving atmospheric diffuse radiation flux caused by the surface element tilt, also known as the tilt factor;χ sky Represent the spectral integral correction factor generated by the difference between the atmospheric diffuse spectrum and the ground material reflectivity spectrum distribution.L sb Represent the blackbody radiation value corresponding to the surface element temperature;ε represents the material emissivity of the ground surface element;χ sb Represent the spectral integral correction factor generated by the difference between the blackbody radiation spectrum and the ground material emissivity spectrum distribution.ο represents the radiation high-order term generated by the multiple scattering effect between the ground surface elements, which is usually given as a high-order constant based on Monte Carlo simulation.

[0061] The calculation process reconstructs the radiation value of each ground surface element according to the ground exit radiation luminance formula in the computer graphics engine calculation shader; since this part is GPU accelerated calculation, it can achieve real-time generation efficiency of about 50HZ.

[0062] According to the exit radiation luminance value of the three-dimensional ground and the atmospheric lookup table, the apparent radiation luminance value of each surface element of the three-dimensional ground is calculated.

[0063] In the embodiment of the application, the apparent radiation luminance calculation expression of each surface element of the three-dimensional ground in front of the detector port under clear sky conditions is:

[0064] L(x,y,z)=L s (x,y,z)·T a ·χ a +L ap +L am (x,y)

[0065] Wherein, L represents the apparent radiation luminance of the ground surface element with coordinates (x, y, z) in front of the detector port in the specified spectral range;T a represents the atmospheric transmittance in the specified spectral range on the radiation transmission path from the ground to the detector;χ a represents the spectral integral correction factor generated by the difference between the ground exit radiation spectrum and the atmospheric transmittance spectrum distribution.L ap represents the path radiation luminance of the atmosphere on the radiation transmission path from the ground to the detector.L am Represent the radiation luminance generated by the adjacent effect, that is, the contribution amount of the radiation transmission path of the ground surface element with coordinates (x, y, z) to the surface element after the atmospheric scattering of the non-homogeneous ground surface, since it is affected by the ground elevation and can be ignored, therefore, its expression also only retains the horizontal coordinates, and the calculation expression of the parameter is:

[0066]

[0067] where L s (ξ,η) is the exit radiance of the surrounding feature cell around (x,y); M(x,y;ξ,η) is the atmospheric optical transfer function, and the method constructs a parameterization scheme to calculate the function value, and the expression is:

[0068]

[0069] where r represents the horizontal distance from the surrounding cell to (x,y), f m represents a normalization factor, and the expression of r is:

[0070]

[0071] In actual proximity effect calculation, generally, (x,y) coordinates are taken as the center, the contribution of the ground surface cell radiation in a 100m horizontal sliding window after the atmospheric optical transfer is calculated, and for the edge of the region, the length of the sliding window on one side is automatically reduced. In view of the fact that the proximity effect contributes less to the total radiance, this approximation is reasonable.

[0072] For step 108, the apparent radiance value is rasterized and resampled in a shader to obtain the ground background radiation image in a clear sky state.

[0073] In the embodiment of the application, the ground background radiation image is obtained by the following method: generating a camera mouth surface two-dimensional pixel arrangement according to preset parameters of a detection camera; performing rasterization and resampling calculation on the distribution of the apparent radiance value of each surface cell of a three-dimensional ground surface according to the camera mouth surface two-dimensional pixel arrangement; and sequentially mapping the calculation result to each camera pixel to render a ground background radiation image in a clear sky state. Since this process is also implemented in a computer graphics engine calculation shader, the efficiency of image generation remains real-time.

[0074] Please refer to Figure 3 The embodiment of the application provides a ground background radiation image generation device in a clear sky state, and the device comprises:

[0075] The first calculation module 300 is configured to calculate the temperature value of each surface cell of a three-dimensional ground surface according to preset environmental data in a clear sky condition and obtained ground material data;

[0076] The determination module 302 is configured to determine an atmospheric lookup table varying with height and zenith angle according to preset environmental data in a clear sky condition and read radiation data.

[0077] The second calculation module 304 is configured to calculate an outgoing radiation luminance value of each surface unit of the three-dimensional ground according to the temperature value and the environment data.

[0078] The third calculation module 306 is configured to calculate an apparent radiation luminance value of each surface unit of the three-dimensional ground according to the outgoing radiation luminance value of the three-dimensional ground and the atmospheric lookup table.

[0079] The processing module 308 is configured to perform rasterization resampling in a shader according to the apparent radiation luminance value to obtain a ground background radiation image in a clear sky state.

[0080] In the embodiment of the present application, the environment data includes atmospheric temperature, humidity, wind speed, wind direction and atmospheric radiation heat flow near the ground.

[0081] In the embodiment of the present application, when the first calculation module 300 performs calculation on the temperature value of each surface unit of the three-dimensional ground according to the preset environment data and the obtained ground material data in the clear sky condition, the first calculation module 300 is specifically configured to perform the following operation: inputting the ground material data and the environment data into a preset ground temperature model to output a temperature lookup table of illumination temperature and shadow temperature of each ground material varying with a normal direction angle and an azimuth angle of the surface unit; and performing real-time calculation on the temperature lookup table by using a computer graphics engine (GPU) to obtain the temperature value of each surface unit of the three-dimensional ground.

[0082] In the embodiment of the present application, when the second calculation module 304 performs calculation on the outgoing radiation luminance value of each surface unit of the three-dimensional ground according to the temperature value and the environment data, the second calculation module 304 is specifically configured to perform the following operation:

[0083] calculating an outgoing radiation parameter reaching the ground according to the preset environment data; wherein the outgoing radiation parameter includes a direct solar radiation illuminance, an atmospheric diffuse radiation flux, a blackbody radiation luminance, a tilt factor and a spectral integral correction factor;

[0084] calculating the outgoing radiation luminance value of each surface unit according to the outgoing radiation parameter and the temperature lookup table:

[0085]

[0086] In the formula, L s is the outgoing radiation luminance of the ground surface unit with a coordinate (x, y, z) in a specified spectral range; E sun is the direct solar radiation illuminance reaching the ground; μ sun = cos (θ sun ), θ sun is the direction angle of the direct solar light beam relative to the normal of the surface unit; R is the material reflectivity of the ground surface unit; χ sunis a spectral integral correction factor due to the difference between the solar spectrum and the reflectivity spectrum distribution of the ground material; δ sun is a shadow factor of the solar shadow due to the mutual occlusion of the three-dimensional structure of the ground; E sky is the hemispherical atmospheric diffuse radiation flux reaching the ground; f sky is a tilt factor due to the tilt of the surface element causing partial reception of the atmospheric diffuse radiation flux; χ sky is a spectral integral correction factor due to the difference between the atmospheric diffuse spectrum and the reflectivity spectrum distribution of the ground material; L sb is the blackbody radiation value corresponding to the temperature of the surface element; ε is the material emissivity of the ground surface element; χ sb is a spectral integral correction factor due to the difference between the blackbody radiation spectrum and the emissivity spectrum of the ground material.

[0087] In the embodiment of the present application, the apparent radiation brightness value is calculated by the following formula:

[0088] L(x,y,z)=L s (x,y,z)·T a ·χ a +L ap +L am (x,y)

[0089] Where L is the apparent radiation brightness of the ground surface element at coordinate (x, y, z) in the specified spectral range in front of the detector port; T a is the transmittance of the atmosphere in the specified spectral range on the radiation transmission path from the ground to the detector; χ a is a spectral integral correction factor due to the difference between the ground exit radiation spectrum and the atmospheric transmittance spectrum. L ap is the path radiation brightness of the atmosphere on the radiation transmission path from the ground to the detector; L am is the radiation brightness generated by the proximity effect.

[0090] In the embodiment of the present application, the processing module 308 performs rasterization resampling in the shader according to the apparent radiation brightness value to obtain the ground background radiation image in clear sky state, and is specifically configured to perform the following operations: generating a camera port two-dimensional pixel arrangement according to the preset parameters of the detection camera; performing rasterization resampling calculation on the distribution of the apparent radiation brightness value of each surface element of the three-dimensional ground according to the camera port two-dimensional pixel arrangement; and sequentially mapping the calculation results to each camera pixel to render and generate the ground background radiation image in clear sky state.

[0091] It should be noted that the above-mentioned embodiment provides a device for generating a ground background radiation image under clear-sky conditions, and only illustrates the division of the above-mentioned functional modules. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the above-mentioned embodiment provides a device for generating a ground background radiation image under clear-sky conditions and the embodiment of the method for generating a ground background radiation image under clear-sky conditions, which are based on the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0092] The embodiment of the present application also provides a computer device, please refer to Figure 4 The computer device includes a processor and a memory, in which at least one instruction, at least one program, code set or instruction set is stored. The at least one instruction, at least one program, code set or instruction set is loaded and executed by the processor to implement the method for generating a ground background radiation image under clear sky conditions provided by the above-mentioned method embodiments.

[0093] An embodiment of the present application also provides a computer-readable storage medium, which stores at least one instruction, at least one program, code set or instruction set, and the at least one instruction, at least one program, code set or instruction set is loaded and executed by a processor to implement the method for generating ground background radiation image under clear sky conditions provided by the above-mentioned method embodiments.

[0094] An embodiment of the present application also provides a computer program product, which includes a computer program. The processor of a computer device reads the computer program from a computer-readable storage medium, and the processor executes the computer program, so that the computer device executes the method for generating a ground background radiation image under clear sky conditions described in any of the above embodiments.

[0095] For the convenience of description, the above systems or devices are described as being divided into various modules or units according to their functions. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0096] Through the description of the above embodiments, it can be seen that those skilled in the art can clearly understand that the present application can be implemented by means of software plus a necessary general hardware platform. 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 can be stored in a storage medium such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in various embodiments of the present application or certain parts of the embodiments.

[0097] Finally, it is to be understood that the phraseology or terminology such as "first," "second," "third," "fourth," and the like in the specification is for the purpose of differentiating one element from another element only and is not necessarily intended to imply any actual relationship or order between such elements. Also, the use of the terms "including," "containing," or any other similar forms is intended to cover a non-exclusive inclusion such that process, method, article, or apparatus that includes elements not expressly listed after such a term should not be excluded or discounted. An element proceeded by "comprises a..." does not, without more constraints, exclude the existence of additional elements of a like kind in the process, method, article, or apparatus that comprises the element.

[0098] The above description is merely that of the preferred embodiments of the application and modifications and alterations are possible without departing from the principles of the application as set forth in the claims.

Claims

1. A method for generating a ground background radiation image under clear sky conditions, characterized in that: The method comprises: Based on the preset environmental data under clear sky conditions and the acquired ground material data, the temperature value of each surface element of the three-dimensional ground is calculated; Based on the preset environmental data and the read radiation data under clear sky conditions, determine the atmospheric lookup table that varies with altitude and zenith angle; Calculating the outgoing radiation brightness value of each surface element of the three-dimensional ground according to the temperature value and the environmental data; Calculating the apparent radiance value of each bin of the three-dimensional ground surface based on the outgoing radiance value of the three-dimensional ground surface and the atmospheric lookup table; Rasterization resampling is performed in the shader according to the apparent radiation brightness value to obtain a ground background radiation image under a clear sky state.

2. The method according to claim 1, wherein The environmental data include atmospheric temperature, humidity, wind speed, wind direction and atmospheric radiation heat flux near the ground.

3. The method according to claim 1, wherein The temperature value of each surface element of the three-dimensional ground is calculated based on the preset environmental data under clear sky conditions and the acquired ground material data, including: Inputting the ground material data and the environmental data into a preset ground temperature model, and outputting a temperature lookup table of illumination temperature and shadow temperature of each ground material as a function of the facet normal direction angle and azimuth; The temperature lookup table is calculated in real time using a computer graphics engine (GPU) to obtain the temperature value of each facet of the three-dimensional ground.

4. The method according to claim 1, wherein The step of calculating the outgoing radiation brightness value of each surface element of the three-dimensional ground according to the temperature value and the environmental data includes: Calculating the outgoing radiation parameters reaching the surface based on the preset environmental data; wherein the outgoing radiation parameters include direct solar radiation illuminance, atmospheric diffuse radiation flux, blackbody radiation brightness, tilt factor and spectral integral correction factor; Calculate the outgoing radiation brightness value of each surface element according to the outgoing radiation parameter and the temperature value: Where, L s is the outgoing radiation brightness of the ground surface element with coordinates (x, y, z) in the specified spectrum; E sun is the direct solar radiation reaching the ground; μ sun =cos(θ sun ),θ sun is the angle of the direct sunlight beam relative to the surface element normal; R is the material reflectivity of the ground surface element; χ sun is the spectral integral correction factor caused by the difference in spectral distribution between the solar spectrum and the reflectance of the ground material; δ sun is the shadow factor of the sun shadow; E sky is the hemispherical atmospheric diffuse radiation flux reaching the ground; f sky is the tilt factor of the partially received atmospheric diffuse radiation flux due to the tilt of the surface element; sky L is the spectral integral correction factor caused by the difference in spectral distribution between the atmospheric diffuse spectrum and the ground material reflectance; sb is the blackbody radiation value corresponding to the surface element temperature; ε is the material emissivity of the ground surface element; χ sb It is the spectral integral correction factor caused by the difference in spectral distribution between the blackbody radiation spectrum and the emissivity of the ground material.

5. The method according to claim 4, wherein The apparent radiance value is calculated by the following formula: L(x,y,z)=L s (x,y,z)·T a ·χ a +L ap +L am (x,y) Where L is the apparent radiance of the ground element with coordinates (x, y, z) in the specified spectral band in front of the detector aperture; T a is the transmittance of the atmosphere in the specified spectral band on the radiation transmission path from the ground to the detector; a L is the spectral integral correction factor caused by the difference in the distribution of the ground outgoing radiation spectrum and the atmospheric transmittance spectrum; ap is the atmospheric radiation brightness along the radiation transmission path from the ground to the detector; L am is the radiant brightness due to the proximity effect.

6. The method according to claim 1, wherein The rasterization resampling is performed in the shader according to the apparent radiance value to obtain a ground background radiation image under a clear sky state, including: Generate a two-dimensional pixel arrangement of the camera aperture according to the preset parameters of the detection camera; Performing rasterization resampling calculation on the distribution of the apparent radiance value of each facet of the three-dimensional ground according to the two-dimensional pixel arrangement of the camera aperture; The calculation results are mapped to each camera pixel in turn, and the ground background radiation image under clear sky conditions is rendered.

7. A device for generating a ground background radiation image under clear sky conditions, characterized in that: The device comprises: The first calculation module is used to calculate the temperature value of each surface element of the three-dimensional ground based on the preset environmental data under clear sky conditions and the acquired ground material data; A determination module, configured to determine an atmospheric lookup table that varies with altitude and zenith angle based on preset environmental data and read radiation data under clear sky conditions; A second calculation module is used to calculate the outgoing radiation brightness value of each surface element of the three-dimensional ground according to the temperature value and the environmental data; A third calculation module is used to calculate the apparent radiance value of each bin of the three-dimensional surface based on the outgoing radiance value of the three-dimensional ground and the atmospheric lookup table; The processing module is used to perform rasterization resampling in the shader according to the apparent radiation brightness value to obtain a ground background radiation image under a clear sky state.

8. A computer device, characterized in that: The computer device includes a memory and a processor, the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory to implement the steps of any one of the methods described in claims 1-6.

9. A computer-readable storage medium, characterized in that The storage medium stores a computer program, which, when executed by a processor, implements the steps of the method according to any one of claims 1 to 6.

10. A computer program product, characterized in that The method comprises a computer program, wherein when the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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