A method and device for modeling and simulating atmospheric background radiation of an air optical detection

Abstract

The application discloses a method and device for modeling and simulating atmospheric background radiation of space optical detection, and belongs to the field of optical simulation. The method comprises the following steps: determining whether a detection scene is a cloudy scene according to whether a cloud layer exists in the detection scene; if yes, generating a target three-dimensional cloud field by using a particle system; establishing a first lookup table of radiation brightness of a clear sky scene with respect to a detector height and a pixel line-of-sight zenith angle and a second lookup table of radiation brightness and transmittance of each segmented path of a cloudy scene with respect to the detector height and a detection line-of-sight zenith angle according to initial environment parameters; determining space data in all pixel data obtained by detection according to periodic height and view direction geometric information of the detector; and determining radiation brightness values for generating a front radiation brightness image according to the space data and the lookup table of the corresponding scene. The application can realize complex space optical visual simulation.

Description

Technical Field

[0001] This invention relates to the field of optical simulation technology, and in particular to a method and apparatus for modeling and simulating atmospheric background radiation for airborne optical detection. Background Technology

[0002] In both hardware-in-the-loop and fully digital optical scene simulations, images from aerial reconnaissance are primarily affected by optical signals generated by the atmosphere and clouds within it, requiring specialized models to characterize the atmospheric optical background and provide background image simulation data. Currently, optical scene simulation mainly utilizes computer graphics engines for visual simulation, primarily targeting full-color visible light scenes perceived by human vision, and also focusing on physical scenes of land and sea surfaces.

[0003] In related technologies, in simulation tasks for special optical scenarios such as the selection and design of detection payloads and the evaluation of their effectiveness, it is necessary to generate quantitative radiance images of any specified spectral band. At the same time, the order-of-magnitude changes in radiance with detection angle, detection height and spectral band during air detection are something that cannot be achieved by ordinary visual simulation at present.

[0004] Therefore, there is an urgent need for a method and device for modeling and simulating atmospheric background radiation using airborne optical detection to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention provides a method and apparatus for modeling and simulating atmospheric background radiation using aerial optical detection, which can solve the problem that related technologies struggle to simulate complex visual scenes. The technical solution is as follows:

[0006] On the one hand, a method for modeling and simulating atmospheric background radiation for airborne optical detection is provided, the method comprising:

[0007] The presence of clouds in the detection scene determines whether the detection scene is a cloud-covered scene; if so, a particle system is used to generate a three-dimensional cloud field for the target.

[0008] Based on the initial environmental parameters, a first lookup table is established for the radiance of the clear sky scene with respect to the detector height and the zenith angle of the pixel line of sight, and a second lookup table is established for the radiance and transmittance of each segment of the path in the cloud scene with respect to the detector height and the zenith angle of the detector line of sight.

[0009] Based on the periodic height and line-of-sight geometry information of the detector, determine the air data in all the detected pixel data;

[0010] Based on the empty data, a lookup table for the corresponding scene is searched to determine the radiance value used to generate the frontal radiance image.

[0011] On the other hand, an atmospheric background radiation modeling and simulation device for airborne optical detection is provided, the device comprising:

[0012] The first determining module is used to determine whether the detection scene is a cloud scene based on whether there are clouds in the detection scene; if so, a particle system is used to generate a target three-dimensional cloud field.

[0013] The modeling module is used to establish, based on the initial environmental parameters, a first lookup table of radiance in clear sky scene with respect to detector height and pixel line-of-sight zenith angle, and a second lookup table of radiance and transmittance of each segment of path in cloud scene with respect to detector height and detector line-of-sight zenith angle.

[0014] The second determining module is used to determine the air data in all the detected pixel data based on the periodic height and line-of-sight geometry information of the detector.

[0015] The third determining module is used to look up the corresponding scene in the lookup table based on the air data to determine the radiance value used to generate the frontal radiance image.

[0016] On the other hand, a computer device is provided, the computer device including a memory and a processor, the memory for storing computer programs, and the processor for executing the computer programs stored in the memory to implement the steps of the above-described atmospheric background radiation modeling and simulation method for airborne optical detection.

[0017] On the other hand, a computer-readable storage medium is provided, wherein a computer program is stored therein, and when the computer program is executed by a processor, it implements the steps of the above-described atmospheric background radiation modeling and simulation method for airborne optical detection.

[0018] On the other hand, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps of the above-described atmospheric background radiation modeling and simulation method for airborne optical detection.

[0019] The technical solution provided by this invention offers at least the following beneficial effects: It constructs computational models for the rapid generation of frontal radiation images of optical detectors for both clear-sky and cloudy atmospheres. For clear-sky atmospheres, a direct radiative transfer calculation method is used, while for cloudy atmospheres, a decoupling method for cloud and gas radiation is employed. Furthermore, based on a lookup table pre-calculation of the atmospheric radiation model, and utilizing an embedded atmospheric radiation reconstruction algorithm within an open-source graphics engine, rapid simulation of atmospheric background radiance images is achieved. This method can simulate and calculate in real-time the frontal radiance image of an optical detector during airborne detection and its changes with geometric parameters such as detection altitude, line-of-sight azimuth angle, and line-of-sight elevation angle, providing atmospheric background model support for fully digital and semi-physical simulations of airborne optical detection scenarios. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of an embodiment of the atmospheric background radiation modeling and simulation method for airborne optical detection provided by the present invention;

[0022] Figure 2 This is a schematic diagram of air detection under clear sky conditions provided by an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of air detection under cloud conditions provided by an embodiment of the present invention;

[0024] Figure 4 This is a structural diagram of an atmospheric background radiation modeling and simulation device for airborne optical detection provided in an embodiment of the present invention;

[0025] Figure 5 This is a hardware architecture diagram of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] As mentioned earlier, ordinary visual simulations cannot characterize the order-of-magnitude changes in radiance during air detection as a function of detection angle, detection altitude, and spectral band.

[0028] Based on this, the concept of the present invention is to construct calculation models for rapid generation of radiation images in front of the optical detector aperture for clear sky and cloudy atmosphere respectively, so as to simulate and calculate the radiation brightness image in front of the optical detector aperture and its changes with geometric parameters such as detection altitude, line of sight azimuth angle, and line of sight pitch angle in real time during air detection.

[0029] The specific implementation of the above concept is described below.

[0030] Please refer to Figure 1 This invention provides a method for modeling and simulating atmospheric background radiation for airborne optical detection, the method comprising:

[0031] Step 100: Determine whether the detection scene is a cloud scene based on whether there are clouds in the detection scene; if so, use a particle system to generate a three-dimensional cloud field for the target.

[0032] Step 102: Based on the initial environmental parameters, establish a first lookup table for the radiance of the clear sky scene with respect to the detector height and the zenith angle of the pixel line of sight, and establish a second lookup table for the radiance and transmittance of each segment of the path in the cloud scene with respect to the detector height and the zenith angle of the detector line of sight.

[0033] Step 104: Based on the periodic height and line-of-sight geometry information of the detector, determine the air data in all the detected pixel data;

[0034] Step 106: Based on the empty data, look up the corresponding scene lookup table to determine the radiance value used to generate the frontal radiance image.

[0035] In this embodiment of the invention, computational models for the rapid generation of frontal radiation images of optical detectors are constructed for clear-sky and cloudy atmospheres, respectively. The direct radiative transfer calculation method is used for clear-sky atmospheres, while the decoupling method of cloud and gas radiation is used for cloudy atmospheres. Furthermore, based on the lookup table pre-calculation of the atmospheric radiation model, an atmospheric radiation reconstruction algorithm embedded in an open-source graphics engine is used to achieve rapid simulation of atmospheric background radiance images. This method can simulate and calculate in real time the frontal radiance images of optical detectors during airborne detection and their changes with geometric parameters such as detection altitude, line-of-sight azimuth angle, and line-of-sight pitch angle, providing atmospheric background model support for fully digital and semi-physical simulations of airborne optical detection scenarios.

[0036] The following description Figure 1 The execution method of each step is shown.

[0037] First, for step 100, determine whether the detection scene is a cloud scene based on whether there are clouds in the detection scene; if so, use a particle system to generate a target three-dimensional cloud field.

[0038] The background radiation of the airborne optical detection scenario described in this embodiment of the invention mainly refers to the background generated by atmospheric gas radiation and cloud radiation. This is the main background object encountered by airborne optical detection. Therefore, it is necessary to construct calculation methods for airborne background radiation brightness according to clear sky and cloudy scenarios. Correspondingly, it is necessary to determine whether it is a clear sky scenario or a cloudy scenario before calculation. If it is a cloudy scenario, a particle system is used to generate a target three-dimensional cloud field of a specified height and type.

[0039] Then, for step 102, based on the initial environmental parameters, a first lookup table is established for the radiance of the clear sky scene with respect to the detector height and the zenith angle of the pixel line of sight, and a second lookup table is established for the radiance and transmittance of each segment of the path in the cloud scene with respect to the detector height and the zenith angle of the detector line of sight.

[0040] In this embodiment of the invention, when the detector is conducting aerial probing under clear sky conditions, the background radiation received by a single pixel mainly comes from the accumulation of atmospheric gas self-radiation and solar / lunar scattered radiation in front of the detector's aperture after transmission along the detection line of sight. Figure 2 As shown. Therefore, the formula for calculating the radiance of the atmospheric background in a clear sky scene is expressed as:

[0041]

[0042] Where L represents the radiance received in front of the detector aperture; ν1 and ν2 represent the starting and ending wavenumbers of the detector spectrum, respectively; H represents the detector height; θ represents the line-of-sight zenith angle at the detector, taking the local zenith direction as the positive direction, with the line of sight vertically upward (θ = 0) and the line of sight vertically downward (θ = 180). s represents the azimuth angle of the line of sight; s0 represents the starting point of the line of sight, i.e., the location of the detector; s t τ(s,s0) represents the endpoint of the line of sight, i.e., the intersection of the detector and the top of the atmosphere; J(s) represents the source function at point s on the line of sight; k(s) represents the extinction coefficient at point s; and τ(s,s0) represents the atmospheric optical thickness along the path from s to s0. The values ​​of these parameters at different altitudes are calculated using low- and mid-upper-level atmospheric radiative transfer software, and then integrated according to the formula to obtain the total radiance value.

[0043] Here, a one-dimensional spherical atmospheric model is constructed to calculate the line-of-sight geometry. The radiative transfer integral above is then transformed into the accumulation of parameters along the path. The formula for calculating the line-of-sight transmission length within each homogeneous layer can be expressed as:

[0044]

[0045] Among them, s i R is the line-of-sight transmission length in the i-th homogeneous atmosphere; R is the Earth's radius; H i H is the height of the upper boundary of the i-th homogeneous atmosphere. i-1 θ is the lower boundary height of the i-th homogeneous atmosphere; i To detect the line of sight at H i The zenith angle at a given height can be calculated using the following formula:

[0046]

[0047] Based on the above calculation formula, the radiance corresponding to the height of each detector and the zenith angle of the pixel line of sight in a clear sky scene can be calculated, and a first lookup table can be established based on these data.

[0048] Furthermore, models are established to illustrate the variations in radiance and transmittance of each segment of the path in cloud-covered scenarios with respect to detector height and the zenith angle of the line of sight, including:

[0049] Segmented path path radiance variation model:

[0050]

[0051] Among them, L n s1 represents the atmospheric path radiance of the nth segment; s2 represents the starting position of this path segment; J represents the ending position of this path segment. n (s) represents the source function at position s on the nth path segment; k n (s) represents the extinction coefficient at point s on the nth path segment;

[0052] Transmittance variation model:

[0053] T n =exp[-τ n (s1,s2)]

[0054] Among them, T n τ represents the atmospheric transmittance of the nth segment; n (s,s1) represents the atmospheric optical thickness between s and s1 on the nth path segment.

[0055] Based on the segmented path radiance variation model, the path radiance corresponding to the height of each detector and the zenith angle of the pixel line of sight in a cloudy scene is calculated. Based on the transmittance variation model, the transmittance corresponding to the height of each detector and the zenith angle of the pixel line of sight in a cloudy scene is calculated. A second lookup table containing the path radiance and the transmittance is then established.

[0056] It is worth noting that the calculation of the above-mentioned clear sky background radiation, path radiation, and transmittance takes several minutes. In order to achieve the ability to generate atmospheric background radiation brightness images in real time, the embodiments of the present invention adopt preprocessing calculation for the above calculation process, that is, calculate the data corresponding to the height of each detector and the zenith angle of the pixel line of sight according to the above model, and establish a corresponding dataset lookup table, thereby providing a data basis for subsequent radiation image generation.

[0057] For step 104, the air data in all the detected pixel data is determined based on the periodic height and line-of-sight geometry information of the detector.

[0058] In this embodiment of the invention, the aerial data is determined as follows: In the graphics engine, based on the periodic altitude and line-of-sight geometry information of the detector, it is determined pixel by pixel whether its line of sight is for aerial detection. The criterion is: when the zenith angle of the line of sight θ ≤ θ t At that time, the pixel data was determined to be air detection data; where θ t The critical zenith angle, where the line of sight is tangent to the Earth's surface, is calculated using the following formula:

[0059]

[0060] In the formula, R is the Earth's radius; H is the probe's altitude;

[0061] When the zenith angle of the line of sight θ>θ t At that time, the pixel data is determined to be ground detection data, and a null value is assigned to the data.

[0062] For step 106, based on the acquired detection data, the lookup table for the corresponding scene is searched according to the air data to obtain the radiance value used to generate the frontal radiance image.

[0063] The lookup table constructed through step 102 above can speed up the efficiency of image generation. For clear sky scenes, since there is no cloud interference, the first lookup table can be directly consulted based on the actual detector height and the actual pixel line-of-sight zenith angle to obtain the corresponding radiance value.

[0064] Furthermore, for cloud scenes, since the cloud layer does not cover the entire day, there are still situations similar to clear sky scenes in cloud scenes. In some cases, the line of sight of a single pixel does not intersect with the cloud field, and the background it perceives is still the background radiation of clear sky. Therefore, before searching, it is necessary to determine whether the pixel data is clear sky pixel data (i.e., the pixel data is not obscured by cloud layer) based on the spatial distribution of the three-dimensional cloud field. If so, the radiance value corresponding to the clear sky pixel data is determined according to the first lookup table.

[0065] The other part is the intersection of the line of sight of a single pixel with the cloud field, which is regarded as cloud-covered pixel data (that is, the pixel data is blocked by clouds). Then, the influence of the positional relationship between the detector and the cloud layer on the radiance needs to be considered. In other words, a cloud change model needs to be established to calculate the radiance in front of the pixel.

[0066] Specifically, the process first finds the radiance and transmittance corresponding to the cloud pixel data by looking up the second lookup table.

[0067] Then follow as follows Figure 3 The detector shown establishes corresponding cloud change models for both below-cloud and above-cloud scenarios:

[0068] The radiance received by the detector under the cloud can be expressed as follows:

[0069]

[0070] in, The pixel of the detector at altitude H below the cloud points towards the line of sight. The received background radiation brightness at that time; It represents the atmospheric path radiation portion along the line of sight from the top of the atmosphere to the top of the clouds; T represents the portion of the cloud path radiating from the top of the cloud to the bottom of the cloud in the line of sight. cd Cloud transmittance representing this portion; T represents the atmospheric radiation range from the cloud base to the probe's aperture along the line of sight. ad χ represents the atmospheric transmittance of this part. 1d , χ cd These are the spectral weighting factors after multiplying the two-way radiation and transmittance spectra into integral multiplication; H t H b These are the cloud top height and cloud base height, respectively.

[0071] The radiance received by the detector in the cloud can be expressed similarly as follows:

[0072]

[0073] in, The pixel of the detector at altitude H above the cloud points towards the line of sight. The received background radiation brightness at that time; It represents the atmospheric path radiation portion along the line of sight, from the top of the atmosphere to the cloud base. T represents the portion of the cloud path radiating from the cloud base to the cloud top along the line of sight. cu Cloud transmittance representing this portion; T represents the atmospheric radiation range from the cloud top to the probe's port in the line-of-sight direction. au χ represents the atmospheric transmittance of this part. 1u , χ cu These are the spectral weighting factors after multiplying the two-segment radiation and transmittance spectra into an integral multiplication.

[0074] The above modeling, based on segmented representations of homogeneous atmosphere and cloud radiation, aims to efficiently generate radiation from heterogeneously distributed cloud fields and extend the calculation of background radiance for multi-layered clouds. In practice, to save preprocessing time during scene generation, the segmented expressions are simplified and merged in actual calculations. For the under-cloud scenario, the simplified expression is:

[0075]

[0076] in, T represents the path radiation portion along the line of sight from the cloud top to the front of the detector port. ac,d χ represents the path transmittance of this part; d It is the spectral weighting factor obtained by multiplying the combined path path radiation and path transmittance spectra into an integral multiplication.

[0077] For cloud-based scenarios, the simplified expression is:

[0078]

[0079] in, T represents the path radiation portion along the line of sight from the cloud base to the front of the detector port. ac,u χ represents the path transmittance of this part; u It is the spectral weighting factor obtained by multiplying the combined path path radiation and path transmittance spectra into an integral multiplication.

[0080] It is worth noting that this step involves calculations performed in the graphics engine, and all of them are simple algebraic calculations in parallel on the GPU. Therefore, it is possible to render and generate an aperture front radiation brightness image in real time according to the detector's periodic information.

[0081] Please refer to Figure 4 This invention provides an atmospheric background radiation modeling and simulation device for airborne optical detection, the device comprising:

[0082] The first determining module 400 is used to determine whether the detection scene is a cloud scene based on whether there are clouds in the detection scene; if so, a particle system is used to generate a target three-dimensional cloud field.

[0083] Modeling module 402 is used to establish, based on the initial environmental parameters, a first lookup table of radiance in clear sky scene with respect to detector height and pixel line-of-sight zenith angle, and a second lookup table of radiance and transmittance of each segment of path in cloud scene with respect to detector height and detector line-of-sight zenith angle.

[0084] The second determining module 404 is used to determine the air data in all the detected pixel data based on the periodic height and line-of-sight geometry information of the detector.

[0085] The third determining module 406 is used to look up the corresponding scene's lookup table based on the air data to determine the radiance value used to generate the frontal radiance image.

[0086] In this embodiment of the invention, when the modeling module 402 executes the first lookup table for establishing the radiance of a clear-sky scene with respect to the detector height and the zenith angle of the detector line of sight, it is specifically used to perform the following operations:

[0087] Based on the cumulative values ​​of atmospheric gas self-radiation and solar / lunar scattered radiation transmitted along the detection line of sight to the detector aperture, a model is established to show the variation of radiance with detector altitude and zenith angle of the detection line of sight in clear-sky scenarios:

[0088]

[0089] In the formula, L is the radiance received in front of the detector aperture; ν1 and ν2 are the starting and ending wavenumbers of the detector spectrum, respectively; H is the detector height; and θ is the line-of-sight zenith angle at the detector. s is the azimuth angle of the line of sight; s0 is the starting position of the line of sight; s t τ is the endpoint of the line of sight; J(s) is the source function at s on the line of sight; k(s) is the extinction coefficient at s; τ(s,s0) is the atmospheric optical thickness along the path between s and s0.

[0090] Based on the clear sky variation model, the radiance corresponding to the height of each detector and the zenith angle of the pixel line of sight under clear sky conditions is calculated, and the first lookup table is established.

[0091] In this embodiment of the invention, when the modeling module 402 executes the following operations to establish a second lookup table of radiance and transmittance of each segment of the cloud scene with respect to detector height and zenith angle of the detector line of sight:

[0092] Establish a segmented path path radiance variation model:

[0093]

[0094] Among them, L n s1 represents the atmospheric path radiance of the nth segment; s2 represents the starting position of this path segment; J represents the ending position of this path segment. n (s) represents the source function at position s on the nth path segment; k n (s) represents the extinction coefficient at point s on the nth path segment;

[0095] Establish a transmittance variation model:

[0096] T n =exp[-τ n (s1,s2)]

[0097] Among them, T n τ represents the atmospheric transmittance of the nth segment; n (s,s1) represents the atmospheric optical thickness between s and s1 on the nth path segment.

[0098] Based on the segmented path radiance variation model, the path radiance corresponding to the height of each detector and the zenith angle of the pixel line of sight in a cloudy scene is calculated. Based on the transmittance variation model, the transmittance corresponding to the height of each detector and the zenith angle of the pixel line of sight in a cloudy scene is calculated. A second lookup table containing the path radiance and the transmittance is then established.

[0099] In this embodiment of the invention, the second determining module 404 determines the air-to-ground data in all detected pixel data based on the periodic height and line-of-sight geometric information of the detector, including:

[0100] When the zenith angle of the line of sight θ≤θ t At that time, the pixel data is determined to be air detection data; wherein, θ t The critical zenith angle, where the line of sight is tangent to the Earth's surface, is calculated using the following formula:

[0101]

[0102] In the formula, R is the Earth's radius; H is the probe's altitude;

[0103] When the zenith angle of the line of sight θ>θ t At that time, the pixel data is determined to be ground detection data, and a null value is assigned to the data.

[0104] In this embodiment of the invention, when the third determining module 406 executes the lookup table for the corresponding scene based on the air data to obtain the radiance value for generating the frontal radiance image, it specifically performs the following operations: when the scene is a clear sky scene, it searches the first lookup table based on the actual detector height and the actual pixel line-of-sight zenith angle to obtain the corresponding radiance value; when the scene is a cloudy scene, it determines whether the pixel data is clear sky pixel data based on the spatial distribution of the three-dimensional cloud field. If so, it determines the radiance value corresponding to the clear sky pixel data based on the first lookup table; otherwise, it determines the corresponding path radiance and transmittance based on the actual detector height and the actual pixel line-of-sight zenith angle of the cloudy pixel data, and inputs the determination result into a preset cloud change model to calculate the radiance value corresponding to the cloudy pixel data.

[0105] In this embodiment of the invention, the cloud change model is established in the following manner:

[0106] Based on the positional relationship between the detector and the cloud layer, a cloud change model is established; wherein, when the detector is located below the cloud layer, the cloud change model is as follows:

[0107]

[0108] In the formula, To show the detector's pixels pointing towards the line of sight at altitude H below the clouds. The received background radiation brightness at that time; The atmospheric path radiation portion along the line of sight from the top of the atmosphere to the top of the cloud; T represents the path radiation portion from the cloud top to the probe's in front of the probe's in the line-of-sight direction. ac,d χ represents the path transmittance of the path radiation portion along the line of sight from the cloud top to the probe's aperture; d The spectral weighting factor is the result of multiplying the combined path path radiation and path transmittance spectra into an integral multiplication.

[0109] When the detector is located above the cloud layer, the cloud change model is as follows:

[0110]

[0111] In the formula, To ensure the detector's pixels point towards the line of sight at altitude H above the cloud. The received background radiation brightness at that time; The atmospheric path radiation portion along the line of sight, from the top of the atmosphere to the cloud base. T represents the path radiation portion from the cloud base to the probe's aperture in the line-of-sight direction. ac,u χ represents the path transmittance of the path radiation portion from the cloud base to the probe aperture in the line-of-sight direction; u The spectral weighting factor is the result of multiplying the combined path path radiation and path transmittance spectra into an integral multiplication.

[0112] It should be noted that the atmospheric background radiation modeling and simulation device for airborne optical detection provided in the above embodiments is only an example of the division of the above functional modules. In practical applications, the above 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 atmospheric background radiation modeling and simulation device for airborne optical detection provided in the above embodiments and the atmospheric background radiation modeling and simulation method embodiments for airborne optical detection belong to the same concept. The specific implementation process is detailed in the method embodiments and will not be repeated here.

[0113] Embodiments of this application also provide a computer device, please refer to... Figure 5 The computer device includes a processor and a memory, the memory storing at least one instruction, at least one program, code set or instruction set, the at least one instruction, at least one program, code set or instruction set being loaded and executed by the processor to implement the atmospheric background radiation modeling and simulation method for airborne optical detection provided in the above-described method embodiments.

[0114] Embodiments of this application also provide a computer-readable storage medium storing at least one instruction, at least one program, code set, or instruction set, wherein the at least one instruction, at least one program, code set, or instruction set is loaded and executed by a processor to implement the atmospheric background radiation modeling and simulation method for airborne optical detection provided in the above-described method embodiments.

[0115] Embodiments of this application also provide a computer program product, which includes a computer program. A processor of a computer device reads the computer program from a computer-readable storage medium and executes the computer program, causing the computer device to perform the atmospheric background radiation modeling and simulation method for airborne optical detection as described in any of the above embodiments.

[0116] For ease of description, the above systems or devices are described separately as various modules or units based on their functions. Of course, in implementing this application, the functions of each unit can be implemented in one or more software and / or hardware components.

[0117] As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of this application.

[0118] Finally, it should be noted that in this document, relational terms such as first, second, third, and fourth are used only 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 those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0119] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A method for modeling and simulating atmospheric background radiation using airborne optical detection, characterized in that, The method includes: The presence of clouds in the detection scene determines whether the detection scene is a cloud-covered scene; if so, a particle system is used to generate a three-dimensional cloud field for the target. Based on the initial environmental parameters, a first lookup table is established for the radiance of the clear sky scene with respect to the detector height and the zenith angle of the pixel line of sight, and a second lookup table is established for the radiance and transmittance of each segment of the path in the cloud scene with respect to the detector height and the zenith angle of the detector line of sight. The second lookup table is established through the following procedure: Establish a segmented path path radiance variation model: Among them, L n s1 represents the atmospheric path radiance of the nth segment; s2 represents the starting position of this path segment; J represents the ending position of this path segment. n (s) represents the source function at position s on the nth path segment; k n (s) represents the extinction coefficient at point s on the nth path segment; Establish a transmittance variation model: Among them, T n τ represents the atmospheric transmittance of the nth segment; n (s,s1) represents the atmospheric optical thickness between s and s1 on the nth path segment. Based on the segmented path radiance variation model, the path radiance corresponding to the height of each detector and the zenith angle of the pixel line of sight in the cloud scene is calculated. Based on the transmittance variation model, the transmittance corresponding to the height of each detector and the zenith angle of the pixel line of sight in the cloud scene is calculated. A second lookup table containing the path radiance and the transmittance is established. Based on the periodic height and line-of-sight geometry information of the detector, determine the air-to-ground data in all detected pixel data, including: When the zenith angle of the line of sight θ≤θ t At that time, the pixel data is determined to be air detection data; wherein, θ t The critical zenith angle, where the line of sight is tangent to the Earth's surface, is calculated using the following formula: In the formula, R is the Earth's radius; H is the probe's altitude; When the zenith angle of the line of sight θ>θ t At that time, the pixel data is determined to be ground detection data, and a null value is assigned to the data; Based on the empty data, a lookup table for the corresponding scene is searched to determine the radiance value used to generate the frontal radiance image.

2. The method as described in claim 1, characterized in that, The establishment of the first lookup table for the radiance of a clear-sky scene with respect to the detector altitude and the zenith angle of the detector line of sight includes: Based on the cumulative values ​​of atmospheric gas self-radiation and solar / lunar scattered radiation transmitted along the detection line of sight to the detector aperture, a model is established to show the variation of radiance with detector altitude and zenith angle of the detection line of sight in clear-sky scenarios: In the formula, L is the radiance received in front of the detector aperture; ν1 and ν2 are the starting and ending wavenumbers of the detector's spectral band, respectively; H is the detector altitude; θ is the line-of-sight zenith angle at the detector; φ is the line-of-sight azimuth angle; s0 is the starting position of the line-of-sight; s t τ is the endpoint of the line of sight; J(s) is the source function at s on the line of sight; k(s) is the extinction coefficient at s; τ(s,s0) is the atmospheric optical thickness along the path between s and s0. Based on the clear sky variation model, the radiance corresponding to the height of each detector and the zenith angle of the pixel line of sight under clear sky conditions is calculated, and the first lookup table is established.

3. The method as described in claim 2, characterized in that, The step of searching the lookup table for the corresponding scene based on the empty data to obtain the radiance value used to generate the frontal radiance image includes: When the scene is a clear sky scene, the corresponding radiance value is obtained by looking up the first lookup table based on the actual detector height and the actual pixel line-of-sight zenith angle. When the scene is a cloud scene, the pixel data is determined to be clear sky pixel data based on the spatial distribution of the three-dimensional cloud field. If it is, the radiance value corresponding to the clear sky pixel data is determined according to the first lookup table. Otherwise, the corresponding radiance and transmittance are determined according to the actual detector height and the actual pixel line-of-sight zenith angle of the cloud pixel data. The determination result is input into the preset cloud change model to calculate the radiance value corresponding to the cloud pixel data.

4. The method as described in claim 3, characterized in that, The cloud change model is established in the following way: Based on the positional relationship between the detector and the cloud layer, a cloud change model is established; wherein, when the detector is located below the cloud layer, the cloud change model is as follows: In the formula, L d (H,θ,φ) represents the background radiance received by the detector at a height H below the cloud when the pixel points towards the line of sight (θ,φ); L 1d (H t (θ, φ) represents the atmospheric path radiation component from the top of the atmosphere to the cloud top along the line of sight; L 2c,d (H t (H,θ,φ) represents the path path radiation from the cloud top to the probe's in front of the line of sight, and T... ac,d χ represents the path transmittance of the path radiation portion along the line of sight from the cloud top to the probe's aperture; d The spectral weighting factor is the result of multiplying the combined path path radiation and path transmittance spectra into an integral multiplication. When the detector is located above the cloud layer, the cloud change model is as follows: In the formula, L u (H,θ,φ) represents the background radiance received by the detector at a height H above the cloud when the pixel points towards the line of sight (θ,φ); L 1u (H b (θ, φ) represents the atmospheric path radiation component along the line of sight from the top of the atmosphere to the cloud base; L 2c,u (H b (H,θ,φ) represents the path path radiation from the cloud base to the probe's aperture along the line of sight, and T... ac,u χ represents the path transmittance of the path radiation portion from the cloud base to the probe aperture in the line-of-sight direction; u The spectral weighting factor is the result of multiplying the combined path path radiation and path transmittance spectra into an integral multiplication.

5. A modeling and simulation device for atmospheric background radiation in airborne optical detection, characterized in that, The apparatus, used in the method as described in any one of claims 1-4, comprises: The first determining module is used to determine whether the detection scene is a cloud scene based on whether there are clouds in the detection scene; if so, a particle system is used to generate a target three-dimensional cloud field. The modeling module is used to establish, based on the initial environmental parameters, a first lookup table of radiance in clear sky scene with respect to detector height and pixel line-of-sight zenith angle, and a second lookup table of radiance and transmittance of each segment of path in cloud scene with respect to detector height and detector line-of-sight zenith angle. The second determining module is used to determine the air data in all the detected pixel data based on the periodic height and line-of-sight geometry information of the detector. The third determining module is used to look up the corresponding scene in the lookup table based on the air data to determine the radiance value used to generate the frontal radiance image.

6. A computer device, characterized in that, The computer device includes a memory and a processor. The memory is used to store computer programs, and the processor is used to execute the computer programs stored in the memory to implement the steps of the method according to any one of claims 1-4.

7. 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 described in any one of claims 1-4.

8. A computer program product, characterized in that, Includes a computer program, which, when executed by a processor, implements the steps of the method according to any one of claims 1-4.

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