A joint earth-moon wide response on-orbit radiometric calibration method and system

Abstract

The application provides a kind of wide response on-orbit radiometric calibration method and system of combination of earth and moon, comprising: the method for eliminating the error introduced by bidirectional reflection characteristics based on multi-angle observation data;Based on the moon image and ROLO irradiance model, the method for constructing the matching pair of moon reference radiance and image quantization value;Based on the standard data of RadCalNet radiometric calibration field and its image, the method for constructing the matching pair of earth reference radiance and image quantization value;The method for obtaining wide response range on-orbit radiometric calibration coefficient by combining earth and moon reference radiance and image quantization value matching pair.The application expands the response range coverage of on-orbit radiometric calibration to load by combining the moon and the earth as low and high response interval reference sources respectively;Based on the deep space background, the dark current background noise of earth and moon image is corrected respectively, to ensure the consistency of earth and moon data, and improve the reliability and accuracy of on-orbit radiometric calibration.

Description

Technical Field

[0001] This invention relates to the field of remote sensing quantitative data processing technology, and in particular to a combined Earth-Moon wide-response on-orbit radiometric calibration method and system. Background Technology

[0002] In-orbit absolute radiometric calibration is an irreplaceable cornerstone for satellite remote sensing data to move from "raw observation" to "quantitative application." It converts the DN values ​​of satellite-acquired images into physically meaningful surface or top-atmosphere radiance / reflectance values. By eliminating the influence of non-target factors such as sensor response characteristics, changes in illumination conditions, and atmospheric transmission attenuation, it establishes comparability between data acquired at different times and from different sensors, providing a reliable, comparable, and quantifiable physical basis for subsequent quantitative information inversion and application. With the ever-expanding demand for quantitative applications of remote sensing data, improving the reliability of in-orbit absolute radiometric calibration has become an urgent requirement.

[0003] Current on-orbit radiometric calibration methods mainly include spaceborne calibration, site-alternate calibration, cross-calibration, and lunar calibration. A single calibration method is often insufficient to achieve radiometric calibration across a wide response range for satellite payloads. Spaceborne calibration, using artificial calibration sources / solar diffuse reflectors, is limited by its fixed output radiation intensity, allowing for radiometric calibration of satellite payloads only within a specific response range. Furthermore, due to limitations in size, cost, and power consumption, most satellites cannot install such devices. Site-alternate calibration and cross-calibration utilize homogeneous calibration targets such as deserts or Gobi deserts on the ground to establish a radiometric reference transfer link from the sun to the calibration target and then to the satellite payload. However, these methods have the following limitations: 1) Deserts or Gobi deserts have uniform spectral characteristics and high reflectivity, making it difficult to simultaneously calibrate radiometric data within the lower response range of the satellite payload; 2) Calibration accuracy is difficult to improve due to the influence of atmospheric radiation transmission. Lunar calibration uses the moon as a reference radiation source, but due to the overall low reflectivity of the lunar surface, it is difficult to achieve radiometric calibration within the higher response range of the satellite payload.

[0004] Therefore, in reality, there is a need for an on-orbit radiometric calibration method with a wide response range that can simultaneously cover both the low and high ranges of satellite payload response, so as to provide more reliable support for the quantitative application of remote sensing satellite data. Summary of the Invention

[0005] This invention provides a combined Earth-Moon wide-response on-orbit radiometric calibration method and system to address the shortcomings of existing technologies and improve the accuracy of on-orbit radiometric calibration.

[0006] In a first aspect, the present invention provides a combined Earth-Moon wide-response on-orbit radiometric calibration method, comprising:

[0007] The lunar observation plan is used to obtain a full lunar disk image, and the corresponding observation geometric data are calculated based on the imaging time of each lunar observation image.

[0008] The lunar disk region on the lunar observation image is extracted using a region detection algorithm. The quantization values ​​of all pixels in the lunar disk region are integrated to obtain the initial quantization value of the lunar disk integral.

[0009] The final quantized value of the lunar disk integral is obtained using the deep space background on the full lunar disk image;

[0010] The ROLO lunar disk irradiance model was used to predict the lunar disk integral radiance, and the lunar reference radiance for each spectral band was obtained.

[0011] Based on the RadCalNet global radiometric calibration sites, a Ross-Li bidirectional reflectance model was constructed. Combined with the data released by the calibration sites, the directional reflectance and directional radiance of the calibration sites were calculated to obtain the reference radiance of the calibration sites for each spectral band.

[0012] The calibration field region is extracted from the full lunar disk image based on the calibration field range. The average quantization value of the calibration field region is calculated. The average quantization value of the calibration field region is corrected using the deep space background to obtain the final quantization value of the calibration field region.

[0013] A joint linear fit is performed on the final quantized value of the lunar disk integral, the lunar reference radiance, the calibration site reference radiance, and the quantized value of the calibration field area to obtain the wide-response range on-orbit absolute radiometric calibration coefficients of the remote sensing satellite payload. According to the joint Earth-Moon wide-response on-orbit radiometric calibration method provided by this invention, the corresponding observation geometric data are calculated based on the imaging time of each lunar observation image, including:

[0014] By incorporating the Coordinated Universal Time (UTC) of the satellite imaging time into the planetary and lunar ephemeris tables, the coordinates of the Sun J2000 coordinate system and the Moon J2000 coordinate system at the satellite imaging time are calculated.

[0015] Based on the coordinates of the Sun J2000 coordinate system and the Moon J2000 coordinate system, the three-dimensional spatial distance between the Sun and the Moon, as well as the latitude and longitude coordinates of the Sun's projection point on the Moon's surface, are calculated.

[0016] By incorporating the Coordinated Universal Time (UTC) of the satellite imaging time into the two rows of orbital elements of the satellite, the satellite's J2000 coordinates at the imaging time are calculated.

[0017] Based on the coordinates of the lunar J2000 coordinate system and the satellite J2000 coordinate system, the three-dimensional spatial distance between the satellite and the moon, as well as the latitude and longitude coordinates of the satellite's projection point on the lunar surface, are calculated.

[0018] Based on the coordinates of the Sun J2000 coordinate system, the Moon J2000 coordinate system, and the satellite J2000 coordinate system, the angle between the Sun-Moon vector and the Moon-Satellite vector is calculated.

[0019] According to the present invention, a wide-response on-orbit radiometric calibration method for joint Earth-Moon observations is provided, which uses a region detection algorithm to extract lunar disk regions from lunar observation images, including:

[0020] The Canny edge detection operator was used to extract all edges on the lunar observation image, resulting in several discontinuous edge regions.

[0021] The maximum connected component in several discontinuous edge regions was extracted using a connected component algorithm, which served as the continuous but incomplete edges of the lunar disk in the lunar observation image.

[0022] The incomplete edges were fitted using the least squares multi-point ellipse fitting method to obtain a circle, which was then used as the lunar disk region in the lunar observation image.

[0023] According to the present invention, a combined Earth-Moon wide-response on-orbit radiometric calibration method is provided, which uses the deep space background of the entire lunar disk image to obtain the final quantized value of the lunar disk integral, including:

[0024] Expand the lunar disk area by several pixels to obtain the lunar disk area complement, in order to eliminate the influence of stray light at the edge of the moon;

[0025] Using the lunar disk region complement as the deep space background, the average quantization value of all deep space background pixels is calculated as dark current background noise.

[0026] Subtract the dark current background noise from the initial quantization value of the lunar disk integral to obtain the final quantization value of the lunar disk integral.

[0027] According to the present invention, a combined Earth-Moon wide-response on-orbit radiometric calibration method is provided, which uses the ROLO lunar disk irradiance model to predict the lunar disk integral radiance and obtains the lunar reference radiance for each spectral band, including:

[0028] Substituting the observed geometric data into the ROLO lunar disk irradiance model, the lunar disk integral reflectance for multiple bands within a preset wavelength range is obtained. The lunar disk integral reflectance for any given band is... :

[0029]

[0030] in, , , , , , , , , , , , as well as These are all constant parameters of the model. , The coordinates of the sun's projection onto the moon's surface are latitude and longitude. , The coordinates of the satellite's projection point on the lunar surface are latitude and longitude. The angle between the Sun / Moon vector and the Moon / Satellite vector. , These are the summation indices for the corresponding summation expressions. For any band, It is a natural constant. Represents the lunar disk integral reflectance with respect to any wavelength, base 10. Take the logarithm;

[0031] Integral reflectance of the lunar disk Converted to lunar disk area partial irradiance :

[0032]

[0033] in, To observe the unit solid angle of the moon, This represents the equivalent solar irradiance for the spectral band. The unit is the astronomical unit. The distance between the Sun and the Moon in three-dimensional space. The three-dimensional spatial distance between the satellite and the moon;

[0034] irradiance of the lunar disk area Converted to lunar disk area fractional brightness ;

[0035] Lunar disk area radii Perform cubic spline interpolation to interpolate the spectral interval to a preset interval value to match the spectral response function of the satellite payload;

[0036] The lunar reference radiance for each spectral band is obtained by convolving the spectral response function of the satellite payload with the interpolated lunar disk area radiance L. :

[0037]

[0038] in, and These represent the start and end wavelengths of any spectral band of the satellite payload, respectively. For any wavelength, For any wavelength spectral response function, For any wavelength The lunar disk area fractional brightness function.

[0039] According to the present invention, a wide-response on-orbit radiometric calibration method for joint Earth-Moon communication is provided, which constructs a Ross-Li biaxial reflectivity model based on the RadCalNet radiometric calibration site, including:

[0040] The corresponding calibration field image was selected based on the atmospheric top reflectivity data released by the RadCalNet radiometric calibration site.

[0041] Constructing a Ross-Li biaxial reflectance model based on calibration field images:

[0042]

[0043] in, These are the satellite zenith angle, the solar zenith angle, and the relative azimuth angle, respectively. In order to be in Biaxial spectral reflectance under observation geometry and They are respectively in Volume scattering kernel and geometric optics kernel under observation geometry , as well as These are the weight coefficients of each kernel function that needs to be inverted.

[0044] According to the present invention, a combined Earth-Moon wide-response on-orbit radiometric calibration method calculates the directional radiance of the calibration site to obtain the reference radiance of the calibration site for each spectral band, including:

[0045] Calculate the directional radiance of the calibration site :

[0046]

[0047] in, The spectral solar constant for the satellite payload. The solar zenith angle at the moment of imaging. The Earth-Sun distance, The directional reflectivity of the calibration site;

[0048] The spectral response function of the satellite payload is compared with the directional radiance of the calibration site. Convolution is performed to obtain the calibration site reference radiance for each spectral band. :

[0049]

[0050] in, and These represent the start and end wavelengths of any spectral band of the satellite payload, respectively. For any wavelength, For any wavelength spectral response function, For any wavelength directional radiance function.

[0051] According to the present invention, a joint Earth-Moon wide-response on-orbit radiometric calibration method is provided, which uses the deep space background to correct the average quantization value of the calibration field region to obtain the final quantization value of the calibration field region, including:

[0052] The quantization value of the calibration field region is obtained by subtracting the average quantization value of all deep space background pixels from the average quantization value of the calibration field region.

[0053] According to the present invention, a wide-response on-orbit radiometric calibration method for the Earth and Moon is provided, which performs joint linear fitting on the final quantized value of the lunar disk integral, the lunar reference radiance, the calibration site reference radiance, and the quantized value of the calibration field region to obtain the wide-response range on-orbit absolute radiometric calibration coefficients of the remote sensing satellite payload, including:

[0054] parameter vector Analytical solution for:

[0055]

[0056] in, This represents the radiation calibration gain coefficient, i.e., the slope of the linear fitting result. This represents the radiation calibration bias coefficient, i.e., the intercept of the linear fitting result. This is the final quantified value of the monthly score. For lunar reference radiance, For the reference radiance of the calibration site, For the calibration field area quantization value, For the image quantization value matrix, For the reference radiance vector, superscript It is transpose. This represents the final quantified value of all monthly points. This represents the quantization values ​​for all calibration field regions. This indicates the number of pairs of lunar reference radiance values ​​that match the final quantized value of the lunar disk integral. This indicates the number of matching pairs between the reference radiance of all calibration sites and the quantization value of the calibration site area. Represents all lunar reference radiance. This indicates the reference radiance for all calibration sites.

[0057] In a second aspect, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the wide-response on-orbit radiometric calibration method for the joint Earth-Moon system as described above.

[0058] The present invention provides a combined Earth-Moon wide-response on-orbit radiometric calibration method and system. By leveraging the complementarity of Earth-Moon radiometric characteristics, the Moon is used as a low-reflectivity reference source, while Earth is used as a high-reflectivity reference source. The obtained radiometric calibration coefficients can simultaneously accommodate the high / low response range of the payload, thus meeting diverse quantitative remote sensing application needs. Furthermore, by utilizing deep space data obtained during lunar observations as a reference for dark current background noise, it can be used not only for dark current correction of lunar images but also extended to the correction of Earth images, ensuring consistency between Earth-Moon observation data. Additionally, by constructing a biaxial reflectivity model using multi-angle observation images from the calibration field and correcting the reference data published at the calibration field based on this model, errors introduced by biaxial reflectivity characteristics are eliminated, thereby further improving the accuracy of on-orbit radiometric calibration. Attached Figure Description

[0059] To more clearly illustrate the technical solutions in this 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 this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0060] Figure 1 This is a flowchart illustrating the wide-response on-orbit radiometric calibration method for the Earth-Moon system provided by this invention.

[0061] Figure 2 This is a schematic diagram of the RadCalNet radiometric calibration field and the spectral reflectance curve of the moon provided by this invention;

[0062] Figure 3 This is a schematic diagram of linear fitting of the joint Earth-Moon reference radiance and image quantization value matching pair provided by the present invention;

[0063] Figure 4 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0065] Figure 1 This is a flowchart illustrating the wide-response on-orbit radiometric calibration method for the Earth-Moon system provided in an embodiment of the present invention, as shown below. Figure 1 As shown, it includes:

[0066] S1. First, based on the satellite's orbit and the moon's position, plan lunar observations to obtain full lunar disk images, and obtain lunar images at least ten times under different lunar phase angles;

[0067] S101. Based on the completeness of the moon in the images, filter out images with incomplete lunar disk surfaces;

[0068] S2. Based on the imaging time of each lunar observation image, and combining ephemeris data and satellite orbit data, calculate the corresponding observation geometry, specifically including:

[0069] S201. Substitute the Coordinated Universal Time (UTC) of the satellite imaging time into the planetary and lunar ephemeris DE441 to calculate the coordinates of the Sun in the J2000 coordinate system at the imaging time. , , );

[0070] S202. Substitute the Coordinated Universal Time (UTC) of the satellite imaging time into the planetary and lunar ephemeris DE441 to calculate the coordinates of the Moon in the J2000 coordinate system at the imaging time. , , );

[0071] S203. Calculate the three-dimensional spatial distance between the Sun and the Moon based on steps S201 and S202. The specific formula is as follows:

[0072]

[0073] S204. Calculate the latitude and longitude coordinates of the point where the sun projects onto the lunar surface based on steps S201 and S202. , );

[0074] S205. Substitute the Coordinated Universal Time (UTC) of the satellite imaging time into the two orbital elements of the satellite to calculate the satellite's coordinates in the J2000 coordinate system at the imaging time. , , );

[0075] S206. Calculate the three-dimensional spatial distance between the satellite and the moon based on steps S202 and S205. The specific formula is as follows:

[0076]

[0077] S207. Calculate the latitude and longitude coordinates of the satellite's projection point on the lunar surface according to steps S202 and S205. , );

[0078] S208. Calculate the Sun-Moon vector based on the position coordinates of the Sun, Moon, and satellite obtained in steps S201, S202, and S205. With lunar-satellite vectors The angle between The specific formula is as follows:

[0079]

[0080]

[0081] S3. Extract the lunar disk region from the lunar observation image;

[0082] S301. Use the Canny edge detection operator to extract all edges on the image, thereby extracting several discontinuous edge regions;

[0083] S302. Use the connected component algorithm to extract the largest connected component, and regard it as a continuous but incomplete edge of the lunar disk on the image;

[0084] S303. Based on the incomplete edges obtained in S302, a circle is fitted using the least squares multi-point ellipse fitting method, and it is used as the lunar disk region on the image.

[0085] Taking lunar observation by satellite payload as an example, when the satellite maneuvers in orbit to cover the moon with its field of view, it can complete the imaging of the moon and thus obtain a reference source in the low response range of the sensor.

[0086] S4. Based on step S3, integrate the quantized values ​​of all pixels within the lunar disk area to obtain the initial quantized values ​​of the lunar disk integration. ;

[0087] S5. Based on the lunar disk region extracted in step S3, the sensor dark current background noise is corrected using the deep space background in the image.

[0088] S501. Expand the lunar disk area extracted in S3 by 3-5 pixels to eliminate the influence of stray light at the edge of the moon.

[0089] S502. Take the complement of the region obtained in step S501 as the deep space background and calculate the average quantization value of all deep space background pixels. This serves as dark current background noise.

[0090] S503, the step S4 Subtract the step S502 Obtain the integrated quantization value of the lunar disk after dark current background noise correction. :

[0091]

[0092] S6. Predict the integral radiance of the lunar disk using the ROLO lunar disk irradiance model;

[0093] S601. Substituting the observed geometry calculated in step S2 into the ROLO model, the lunar disk integral reflectance in 32 bands within the range of 350-2400 nm can be obtained, where the... Moon disk integral reflectance in each band As shown in the following formula:

[0094]

[0095] in , , , , , , , , , , , as well as These are all constant parameters of the model; , These are the summation indices for the corresponding summation expressions. For any band, It is a natural constant. Represents the lunar disk integral reflectance with respect to any wavelength, base 10. Take the logarithm.

[0096] S602, the result obtained in S601 Converted to lunar disk area partial irradiance The specific formula is as follows:

[0097]

[0098] in To observe the unit solid angle of the moon, AU represents the equivalent solar irradiance for the spectral band, where AU is an astronomical unit; further, It can be converted into lunar disk area fractional brightness. ;

[0099] S603, the result obtained in step S602 Cubic spline interpolation was performed to interpolate the spectral interval to 1 nm to match the spectral response function (SRF) of the satellite payload;

[0100] S604. Convolve the spectral response function SRF of the satellite payload with the interpolated lunar disk area fractional radiance L to obtain the reference radiance for each spectral band. The specific formula is as follows:

[0101]

[0102] in, and These are the start and end wavelengths of a certain spectral band on the satellite payload. For any wavelength, For any wavelength spectral response function, For any wavelength The lunar disk area fractional brightness function;

[0103] S7. Based on the location distribution of RadCalNet radiometric calibration sites and the satellite orbit, conduct multi-angle observations of each site, and acquire at least ten cloud-free observation data of different satellite zenith angles and solar zenith angles for each calibration site.

[0104] It should be noted that RadCalNet consists of four normalized radiometric calibration fields: the RVUS field, the GONA field, the LCFR field, and the BSCN field. The RVUS field is a rectangular field centered at 38.49°N, 115.69°W, with sides of 1000 meters; the GONA field is a circular field centered at 23.60°S, 15.12°E, with a radius of 30 meters; the LCFR field is a circular field centered at 43.56°N, 4.86°E, with a radius of 30 meters; and the BSCN field is a rectangular field centered at 40.86°N, 109.62°E, with sides of 300 meters. The satellite can obtain reference sources for the sensor's high-response range by observing these four calibration fields in orbit.

[0105] Figure 2 This is a schematic diagram of the RadCalNet radiative calibration field and the spectral reflectance curves of the Moon. Figure 2 It can be seen that the reflectivity of each radiation calibration field of RadCalNet is relatively large, while the reflectivity of the moon is significantly smaller, thus covering the high / low response range of the sensor respectively.

[0106] S8. Select the corresponding calibration field image based on the atmospheric top reflectivity data released by the RadCalNet radiometric calibration site, and use it to construct the Ross-Li biaxial reflectivity model. The specific expression is as follows:

[0107]

[0108] in, These are the satellite zenith angle, the solar zenith angle, and the relative azimuth angle, respectively. In order to be in Biaxial spectral reflectance under observation geometry; and Then respectively in Volume scattering kernel and geometric optics kernel under observation geometry; and , as well as These represent the weight coefficients of each kernel function that needs to be inverted;

[0109] S9. Based on the bidirectional reflectivity model constructed in step S8 and the corresponding solar and satellite zenith angles during satellite imaging, calculate the directional reflectivity of the calibration field. ;

[0110] S10. Calculate the directional radiance of the calibration field. The specific formula is as follows:

[0111]

[0112] in The spectral solar constant for the satellite payload. The solar zenith angle at the moment of imaging. The Earth-Sun distance;

[0113] S11. The spectral response function (SRF) of the satellite payload is compared with the directional radiance of the calibration field. Convolution is performed to obtain the reference radiance for each spectral band. The specific formula is as follows:

[0114]

[0115] in, and These represent the start and end wavelengths of any spectral band of the satellite payload, respectively. For any wavelength, For any wavelength spectral response function, For any wavelength directional radiance function.

[0116] S12. Extract the calibration field region on the image based on the calibration field range, and calculate its average quantization value. ;

[0117] S13, the step S12 Subtract from step S5 Quantization values ​​of the calibration field region after dark current background noise correction were obtained. :

[0118]

[0119] S14. The results obtained in steps S5, S6, S11, and S13 , , as well as Linear fitting is performed to obtain the on-orbit absolute radiometric calibration coefficients for the satellite payload over a wide response range. The slope of the linear fitting result is the radiometric calibration gain coefficient *a*, and its intercept is the radiometric calibration bias coefficient *b*, as shown in the following equation:

[0120]

[0121] in For the image quantization value matrix, The reference radiance vector. From this, the parameter vector can be obtained. Analytical solution for:

[0122] .

[0123] in, This represents the radiation calibration gain coefficient, i.e., the slope of the linear fitting result. This represents the radiation calibration bias coefficient, i.e., the intercept of the linear fitting result. This is the final quantified value of the monthly score. For lunar reference radiance, For the reference radiance of the calibration site, For the calibration field area quantization value, For the image quantization value matrix, For the reference radiance vector, superscript It is transpose.

[0124] This represents the final quantified value of all monthly points. This represents the quantization values ​​for all calibration field regions. This indicates the number of pairs of lunar reference radiance values ​​that match the final quantized value of the lunar disk integral. This indicates the number of matching pairs between the reference radiance of all calibration sites and the quantization value of the calibration site area. Represents all lunar reference radiance. This indicates the reference radiance for all calibration sites.

[0125] Figure 3 The diagram shows a linear fit between the combined Earth-Moon reference radiance and the image quantization value matching pairs. It can be seen that the matching pairs from the Moon are located in the low response range of the sensor (the region with smaller quantization values), while the matching pairs from the RadCalNet radiometric calibration field are located in the high response range of the sensor (the region with larger quantization values).

[0126] Figure 4 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 4As shown, the electronic device may include: a processor 410, a communication interface 420, a memory 430, and a communication bus 440. The processor 410, communication interface 420, and memory 430 communicate with each other via the communication bus 440. The processor 410 can call logical instructions in the memory 430 to execute a joint Earth-Moon wide-response on-orbit radiometric calibration method. This method includes: planning lunar observations to obtain a full lunar disk image; calculating the corresponding observation geometry data based on the imaging time of each lunar observation image; extracting the lunar disk region on the lunar observation image using a region detection algorithm; integrating the quantization values ​​of pixels within all lunar disk regions to obtain the initial quantization value of the lunar disk integral; obtaining the final quantization value of the lunar disk integral using the deep space background on the full lunar disk image; predicting the lunar disk integral radiance using the ROLO lunar disk irradiance model to obtain the lunar reference radiance for each spectral band; and using the global radiometric calibration network... A Ross-Li bidirectional reflectance model was constructed at the RadCalNet radiometric calibration site. Combined with data released from the calibration site, the directional reflectance and directional radiance of the calibration site were calculated to obtain the reference radiance of the calibration site for each spectral band. The calibration field region was extracted from the full lunar disk image based on the calibration site range. The average quantization value of the calibration field region was calculated, and the average quantization value of the calibration field region was corrected using the deep space background to obtain the final quantization value of the calibration field region. A joint linear fit was performed on the final quantization value of the lunar disk integral, the lunar reference radiance, the calibration site reference radiance, and the quantization value of the calibration field region to obtain the wide-response-range on-orbit absolute radiometric calibration coefficients of the remote sensing satellite payload.

[0127] Furthermore, the logical instructions in the aforementioned memory 430 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0128] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0129] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, 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 computer-readable 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 the various embodiments or some parts of the embodiments.

[0130] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A combined Earth-Moon wide-response on-orbit radiometric calibration method, characterized in that, include: The lunar observation plan is used to obtain a full lunar disk image, and the corresponding observation geometric data are calculated based on the imaging time of each lunar observation image. The lunar disk region on the lunar observation image is extracted using a region detection algorithm. The quantization values ​​of all pixels in the lunar disk region are integrated to obtain the initial quantization value of the lunar disk integral. The final quantized value of the lunar disk integral is obtained using the deep space background on the full lunar disk image; The ROLO lunar disk irradiance model was used to predict the lunar disk integral radiance, and the lunar reference radiance for each spectral band was obtained. Based on the RadCalNet global radiometric calibration sites, a Ross-Li bidirectional reflectance model was constructed. Combined with the data released by the calibration sites, the directional reflectance and directional radiance of the calibration sites were calculated to obtain the reference radiance of the calibration sites for each spectral band. The calibration field region is extracted from the full lunar disk image based on the calibration field range. The average quantization value of the calibration field region is calculated. The average quantization value of the calibration field region is corrected using the deep space background to obtain the final quantization value of the calibration field region. By performing a joint linear fit on the final quantized value of the lunar disk integral, the lunar reference radiance, the calibration site reference radiance, and the calibration field area quantized value, the wide-response range on-orbit absolute radiometric calibration coefficient of the remote sensing satellite payload is obtained.

2. The combined Earth-Moon wide-response on-orbit radiometric calibration method according to claim 1, characterized in that, The corresponding observational geometric data are calculated based on the imaging time of each lunar observation image, including: By incorporating the Coordinated Universal Time (UTC) of the satellite imaging time into the planetary and lunar ephemeris tables, the coordinates in the solar J2000 coordinate system and the lunar J2000 coordinate system at the satellite imaging time are calculated. Based on the coordinates of the Sun J2000 coordinate system and the Moon J2000 coordinate system, the three-dimensional spatial distance between the Sun and the Moon, as well as the latitude and longitude coordinates of the Sun's projection point on the Moon's surface, are calculated. By incorporating the Coordinated Universal Time (UTC) of the satellite imaging time into the two rows of orbital elements of the satellite, the satellite's J2000 coordinates at the imaging time are calculated. Based on the coordinates of the lunar J2000 coordinate system and the satellite J2000 coordinate system, the three-dimensional spatial distance between the satellite and the moon, as well as the latitude and longitude coordinates of the satellite's projection point on the lunar surface, are calculated. Based on the coordinates of the Sun J2000 coordinate system, the Moon J2000 coordinate system, and the satellite J2000 coordinate system, the angle between the Sun-Moon vector and the Moon-Satellite vector is calculated.

3. The combined Earth-Moon wide-response on-orbit radiometric calibration method according to claim 1, characterized in that, The lunar disk region on lunar observation images was extracted using a region detection algorithm, including: The Canny edge detection operator was used to extract all edges on the lunar observation image, resulting in several discontinuous edge regions. The maximum connected component in several discontinuous edge regions was extracted using a connected component algorithm, which served as the continuous but incomplete edges of the lunar disk in the lunar observation image. The incomplete edges were fitted using the least squares multi-point ellipse fitting method to obtain a circle, which was then used as the lunar disk region in the lunar observation image.

4. The combined Earth-Moon wide-response on-orbit radiometric calibration method according to claim 1, characterized in that, The final quantized value of the lunar disk integral is obtained using the deep space background on the full lunar disk image, including: Expand the lunar disk area by several pixels to obtain the lunar disk area complement, in order to eliminate the influence of stray light at the edge of the moon; Using the lunar disk region complement as the deep space background, the average quantization value of all deep space background pixels is calculated as dark current background noise. Subtract the dark current background noise from the initial quantization value of the lunar disk integral to obtain the final quantization value of the lunar disk integral.

5. The combined Earth-Moon wide-response on-orbit radiometric calibration method according to claim 1, characterized in that, The ROLO lunar disk irradiance model was used to predict the lunar disk integral radiance, resulting in lunar reference radiance for each spectral band, including: Substituting the observed geometric data into the ROLO lunar disk irradiance model, the lunar disk integral reflectance for multiple bands within a preset wavelength range is obtained. The lunar disk integral reflectance for any given band is... : in, , , , , , , , , , , , as well as These are all constant parameters of the model. , The coordinates of the sun's projection onto the moon's surface are latitude and longitude. , The coordinates of the satellite's projection point on the lunar surface are latitude and longitude. The angle between the Sun / Moon vector and the Moon / Satellite vector. , These are the summation indices for the corresponding summation expressions. For any band, It is a natural constant. Represents the lunar disk integral reflectance with respect to any wavelength, base 10. Take the logarithm; Integral reflectance of the lunar disk Converted to lunar disk area partial irradiance : in, To observe the unit solid angle of the moon, This represents the equivalent solar irradiance for the spectral band. The unit is the astronomical unit. The distance between the Sun and the Moon in three-dimensional space. The three-dimensional spatial distance between the satellite and the moon; irradiance of the lunar disk area Converted to lunar disk area fractional brightness ; Lunar disk area radii Perform cubic spline interpolation to interpolate the spectral interval to a preset interval value to match the spectral response function of the satellite payload; The lunar reference radiance for each spectral band is obtained by convolving the spectral response function of the satellite payload with the interpolated lunar disk area radiance L. : in, and These are the start and end wavelengths for any spectral band of the satellite payload, respectively. For any wavelength, For any wavelength spectral response function, For any wavelength The lunar disk area fractional brightness function.

6. The combined Earth-Moon wide-response on-orbit radiometric calibration method according to claim 1, characterized in that, A Ross-Li biaxial reflectivity model was constructed based on the RadCalNet global radiometric calibration sites, including: The corresponding calibration field image was selected based on the atmospheric top reflectivity data released by the RadCalNet radiometric calibration site. Constructing a Ross-Li biaxial reflectivity model based on calibration field images: in, These are the satellite zenith angle, the solar zenith angle, and the relative azimuth angle, respectively. In order to be in Biaxial spectral reflectance under observation geometry and They are respectively in Volume scattering kernel and geometric optics kernel under observation geometry , as well as These are the weight coefficients of each kernel function that needs to be inverted.

7. The combined Earth-Moon wide-response on-orbit radiometric calibration method according to claim 1, characterized in that, Calculate the directional radiance of the calibration site to obtain the reference radiance of the calibration site for each spectral band, including: Calculate the directional radiance of the calibration site : in, The spectral solar constant for the satellite payload. The solar zenith angle at the moment of imaging. The Earth-Sun distance, The directional reflectivity of the calibration site; The spectral response function of the satellite payload is compared with the directional radiance of the calibration site. Convolution is performed to obtain the calibration site reference radiance for each spectral band. : in, and These are the start and end wavelengths for any spectral band of the satellite payload, respectively. For any wavelength, For any wavelength spectral response function, For any wavelength directional radiance function.

8. The combined Earth-Moon wide-response on-orbit radiometric calibration method according to claim 1, characterized in that, The average quantization value of the calibration field region is corrected using the deep space background to obtain the final quantization value of the calibration field region, including: The quantization value of the calibration field region is obtained by subtracting the average quantization value of all deep space background pixels from the average quantization value of the calibration field region.

9. The combined Earth-Moon wide-response on-orbit radiometric calibration method according to claim 1, characterized in that, A joint linear fit was performed on the final quantized value of the lunar disk integral, the lunar reference radiance, the calibration site reference radiance, and the quantized value of the calibration field area to obtain the wide-response-range on-orbit absolute radiometric calibration coefficients of the remote sensing satellite payload, including: parameter vector Analytical solution for: in, This represents the radiation calibration gain coefficient, i.e., the slope of the linear fitting result. This represents the radiation calibration bias coefficient, i.e., the intercept of the linear fitting result. This is the final quantified value of the monthly score. For lunar reference radiance, For the reference radiance of the calibration site, For the calibration field area quantization value, For the image quantization value matrix, For the reference radiance vector, superscript It is transpose. This represents the final quantified value of all monthly points. This represents the quantization values ​​for all calibration field regions. This indicates the number of pairs of lunar reference radiance values ​​that match the final quantized value of the lunar disk integral. This indicates the number of matching pairs between the reference radiance of all calibration sites and the quantization value of the calibration site area. Represents all lunar reference radiance, This indicates the reference radiance for all calibration sites.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the wide-response on-orbit radiometric calibration method for the joint Earth-Moon system as described in any one of claims 1 to 9.

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