On-orbit autonomous geometric calibration method and system for wide-field optical remote sensing satellites

Abstract

This invention proposes an on-orbit autonomous geometric calibration method and system for wide-field-of-view optical remote sensing satellites. The method includes: camera imaging and transmitting the captured images to an on-board calibration type autonomous identification module; the on-board calibration type autonomous identification module, combined with satellite orbit and attitude data, determines whether the camera's field of view simultaneously images deep space and the ground; if both exist simultaneously, the Earth's edge is extracted as the boundary between stars and landmarks to delineate their distribution areas; if not, the calibration point type is explicitly determined to be either a landmark or a star; based on the calibration point type, the corresponding image is transmitted to an on-board stellar autonomous calibration module or an on-board landmark autonomous calibration module, and geometric calibration parameters are calculated; the calculated calibration parameters are transmitted to an on-board information processing unit for satellite imaging. This invention ensures the geometric calibration accuracy across the entire field of view of the camera; it avoids the process of transmitting satellite images down to the ground for calculation, thus improving the real-time performance of the calibration parameters.

Description

Technical Field

[0001] This invention belongs to the field of geometric calibration of optical remote sensing satellites, and specifically relates to an on-orbit autonomous geometric calibration method and system for wide field-of-view optical remote sensing satellites. Background Technology

[0002] On-orbit geometric calibration of optical remote sensing satellites is a crucial step in ensuring high-precision positioning. Due to factors such as vibrations during satellite launch and orbit insertion, on-orbit stress release, and complex external heat flow environments, parameters such as camera distortion and mounting matrix required for on-orbit imaging may deviate from the calibration values ​​in ground laboratories. Therefore, it is necessary to recalibrate the imaging parameters after the satellite is in orbit to ensure high positioning accuracy.

[0003] Current main geometric calibration methods include two types: landmark-based and star-based. These methods acquire control points through ground calibration points and stars, respectively, to achieve on-orbit geometric calibration. After geometric calibration of traditional small field-of-view satellites, the pointing error generated by calculating the edge field of view using calibration parameters from the camera's central field of view is relatively small. However, as the field of view of optical remote sensing satellites gradually expands, the pointing error calculated using the same set of calibration parameters for both the central and edge fields of view increases, leading to a decrease in target positioning accuracy. Although geometric calibration can be performed using stars within the camera's field of view by tilting the satellite to point at a specific sky region, the satellite cannot image the target area while tilted, failing to meet the requirements of long-duration imaging missions.

[0004] In addition, traditional geometric calibration methods require downloading the captured landmark or star images to a ground system for processing. The ground system then calculates the calibration parameters and uploads them to the satellite. However, due to the limitations of image data downloading rate, ground system calculation time, and parameter upload process, it is impossible to achieve real-time on-orbit geometric calibration parameter processing. Summary of the Invention

[0005] In view of this, the present invention provides an on-orbit autonomous geometric calibration method for wide-field-of-view optical remote sensing satellites, comprising:

[0006] Step S1: The camera captures an image and transmits the captured image to the on-board calibration type autonomous identification module;

[0007] In step S2, the on-board calibration type autonomous identification module combines satellite orbit and satellite attitude data to determine whether the camera's field of view simultaneously images deep space and the ground. If both exist simultaneously, the edge of the Earth is extracted as the boundary between stars and landmarks to divide the distribution areas of stars and landmarks. If they do not exist simultaneously, the calibration point type is clearly determined to be either a landmark or a star.

[0008] Step S3: Based on the type of calibration point, transmit the corresponding image to the on-board star autonomous calibration module or the on-board landmark autonomous calibration module, and calculate the geometric calibration parameters.

[0009] Step S4: The calculated calibration parameters are transmitted to the on-board information processing unit for satellite imaging.

[0010] Specifically, the autonomous calculation process of the on-board star autonomous calibration module in step 3 is as follows:

[0011] Step S301: For the i-th star in the image, the on-board autonomous calibration module extracts the centroid using Gaussian surface fitting;

[0012] Step S302: Calculate the centroid (x0, y0) of the star distribution in the entire image based on the positions of the centroids of all stars in the extracted image.

[0013] Step S303: Establish a coordinate system with the centroid (x0, y0) of the star distribution in the image as the center, and divide the entire field of view into N regions. The angle corresponding to each region is 360° / N. Number each region j in a clockwise direction, where the numbering value is j = 1, 2, ..., N.

[0014] Step S304: For each region j, match the observed stars with the on-board navigation star catalog. After a successful match, obtain the right ascension and declination of the observed stars.

[0015] Step S305: Establish a geometric imaging model and substitute the right ascension and declination of the successfully matched stars into the imaging model to obtain the theoretical position of the stars on the detector calculated by the imaging model.

[0016] Specifically, the autonomous calculation process of the on-board landmark autonomous calibration module in step 3 is as follows:

[0017] Step S306: The calibration parameter autonomous calculation module extracts feature points of landmarks in the image;

[0018] Step S307: Calculate the centroid (x0, y0) of the landmark distribution in the entire image based on the centroid positions of all landmark points in the extracted image;

[0019] Step S308: Establish a coordinate system with the centroid (x0, y0) of the landmark distribution in the image as the center, and divide the entire field of view into N regions. The angle corresponding to each region is 360° / N. Number each region j in a clockwise direction, where the number j = 1, 2, ..., N.

[0020] Step S309: For each region j, match the observed landmarks with the landmark database. After a successful match, obtain the geographic coordinates of the landmark feature points in the WGS84 coordinate system.

[0021] Step S310: Establish a geometric imaging model and substitute the coordinates of the successfully matched landmark feature points into the imaging model to obtain the theoretical position of the landmark on the detector calculated by the imaging model.

[0022] Specifically, step S301 includes:

[0023] The stellar energy I(x,y) has an approximately Gaussian distribution and can be expressed as:

[0024]

[0025] Among them, A i Let σ be the energy intensity at the centroid position of the i-th calibration point. x and σ y Let A and σ be the standard deviations in the x and y directions, respectively. Based on the pixel response values ​​within a 3×3 region, solve for A and σ using the least squares method. x σ y and the position of the center of mass (x) i ,y i ).

[0026] Specifically, step S304 includes:

[0027] If the coordinates of the two centroids are (x1, y1) and (x2, y2) respectively, then the principal point of the camera is (x1, y1) and (x2, y2). c ,y c If the principal distance is f, then the measured angular distance is r. 12 It can be obtained from the following formula:

[0028]

[0029]

[0030] By finding two star pairs with the same angular distance in the star catalog, and then forming a triangle with a third star, the star corresponding to the barycenter can be determined by identifying each pair of the three sides.

[0031] Specifically, step S305 includes: substituting the right ascension and declination of the successfully matched star into the imaging model to obtain the theoretical position (x1, y1) of the star on the detector calculated by the imaging model. The imaging model is as follows:

[0032]

[0033] Where, (cosαcosδ,sinαcosδ,sinδ) T Let α be the observation vector of the star in the celestial coordinate system, and δ be the right ascension and declination of the star point in the celestial coordinate system. It is the transformation matrix from the J2000 coordinate system to the satellite body coordinate system. It is the transformation matrix from the satellite body coordinate system to the camera coordinate system. It is the transformation matrix from the camera coordinate system to the camera object space. λ is the transformation matrix from the camera object space to the detector, and λ is the correction matrix. and These are the angles between the image point's x and y directions and the center of the field of view, respectively, and their expressions are:

[0034]

[0035] Where a0, ..., a9, b0, ..., b9 are internal calibration parameters, and f is the camera focal length;

[0036] Under the strict geometric imaging model, a calibration adjustment model is established, and arbitrary external calibration parameters are substituted into the above formula:

[0037]

[0038] Construct adjustment calculation equations based on least squares:

[0039]

[0040] Specifically, step S310 includes: establishing a geometric imaging model, and substituting the coordinates of the successfully matched landmark feature points into the imaging model to obtain the theoretical position (x1, y1) of the landmark on the detector calculated by the imaging model. The imaging model is as follows:

[0041]

[0042] Among them, (X) WGS84 ,Y WGS84 Z WGS84 ) T The coordinates of the landmark in the WGS84 coordinate system It is the transformation matrix from the WGS84 coordinate system to the J2000 coordinate system. It is the transformation matrix from the J2000 coordinate system to the satellite body coordinate system. It is the transformation matrix from the satellite body coordinate system to the camera coordinate system. It is the transformation matrix from the camera coordinate system to the camera object space. λ is the transformation matrix from the camera object space to the detector, and λ is the correction matrix. and These are the angles between the image point's x and y directions and the center of the field of view, respectively, and their expressions are:

[0043]

[0044] Where a0, ..., a9, b0, ..., b9 are internal calibration parameters, and f is the camera focal length;

[0045] Under the strict geometric imaging model, a calibration adjustment model is established, and arbitrary external calibration parameters are substituted into the above formula:

[0046]

[0047] Construct adjustment calculation equations based on least squares:

[0048]

[0049] This invention also proposes an on-orbit autonomous geometric calibration system for wide-field-of-view optical remote sensing satellites, comprising:

[0050] The camera imaging transmission module is used to take pictures and transmit the captured images to the on-board calibration type autonomous identification module;

[0051] The on-board calibration type autonomous identification module is used to combine satellite orbit and satellite attitude data to determine whether the camera's field of view is simultaneously imaging deep space and the ground; if they are simultaneously present, the edge of the Earth is extracted as the boundary between stars and landmarks to divide the distribution areas of stars and landmarks; if they are not simultaneously present, the calibration point type is clearly determined to be either a landmark or a star.

[0052] The on-board star autonomous calibration module is used to match stars with the on-board star database and calculate geometric calibration parameters to achieve on-board autonomous calibration.

[0053] The on-board landmark autonomous calibration module is used to match landmarks with the landmark library and calculate geometric calibration parameters to achieve on-board autonomous calibration.

[0054] The calibration parameter transmission module is used to transmit the calculated calibration parameters to the on-board information processing unit for satellite imaging.

[0055] Specifically, the on-board stellar autonomous calibration module includes: a centroid extraction module, used to extract the centroid position of the star on the detector using a Gaussian surface fitting method; a star matching module, used to match the stars in the satellite image with the on-board navigation star catalog and extract the right ascension and declination of the stars in the satellite image; a stellar geometric imaging model module, used to establish a strict correspondence between the right ascension and declination of the star and the imaging position on the detector; and a stellar calibration parameter calculation module, used to calculate the geometric calibration parameters of the satellite's interior and exterior orientation elements.

[0056] Specifically, the on-board landmark autonomous calibration module includes: a landmark extraction module, used to extract landmark feature points based on the distribution of landmarks in images captured by the camera; a landmark matching module, used to match landmarks in satellite images with the on-board landmark database to obtain the geographical locations of landmark feature points; a landmark geometric imaging model module, used to establish a strict correspondence between the geographical locations of landmark feature points and the imaging positions on the detector; and a landmark calibration parameter calculation module, used to calculate the geometric calibration parameters of the satellite's interior and exterior orientation elements.

[0057] Beneficial effects:

[0058] 1. This invention utilizes the coverage of a wide field-of-view camera to simultaneously observe stars and landmarks, ensuring that there is a calibration point at any time within the camera's field of view.

[0059] 2. This invention observes both constant and landmark objects simultaneously, without requiring the camera's field of view to be turned to a specific sky area, thus not affecting the satellite's imaging mission.

[0060] 3. This invention performs geometric calibration by dividing the camera's field of view into sections, rationally allocating all calibration points to different field of view regions, thereby ensuring the geometric calibration accuracy of the camera's entire field of view;

[0061] 4. This invention achieves real-time on-board geometric calibration parameter calculation through an on-board autonomous geometric calibration module, avoiding the need to transmit satellite images to the ground for calculation, thus improving the real-time performance of calibration parameters; Attached Figure Description

[0062] Figure 1 This is a flowchart of the onboard autonomous geometric calibration process in this invention;

[0063] Figure 2 This is a structural diagram of the on-board autonomous calibration system in this invention. Detailed Implementation

[0064] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0065] This invention provides a method for on-orbit autonomous geometric calibration of wide-field-of-view optical remote sensing satellites, as follows: Figure 1 As shown below, taking a geostationary orbit satellite with a field of view of 10°×10° as an example, the structure diagram of the onboard autonomous calibration system is as follows. Figure 2 As shown in the accompanying drawings, specific embodiments of the present invention will be described below:

[0066] Step 1: The camera captures an image and transmits it to the on-board calibration type autonomous identification module;

[0067] Step 2: The on-board calibration type autonomous identification module combines satellite orbit and satellite attitude data to determine whether the camera's field of view simultaneously images deep space and the ground. If both exist simultaneously, the edge of the Earth is extracted as the boundary between stars and landmarks to divide the distribution areas of stars and landmarks. If they do not exist simultaneously, the calibration type is clearly defined as either a landmark or a star.

[0068] Step 3: Based on the calibration point type in Step 2, transmit the corresponding image to the on-board star autonomous calibration module or the on-board landmark autonomous calibration module, and calculate the geometric calibration parameters.

[0069] Furthermore, the autonomous calculation process of the on-board star autonomous calibration module in step 3 is as follows:

[0070] Step 301: For the i-th star or landmark in the image, the on-board autonomous calibration module extracts the centroid using Gaussian surface fitting. The energy I(x,y) of the star or landmark approximates a Gaussian distribution, which can be expressed as:

[0071]

[0072] Among them, A i Let σ be the energy intensity at the centroid position of the i-th calibration point. x and σ y Let be the standard deviations in the x and y directions, respectively. Taking the logarithm of both sides of the formula, we get:

[0073]

[0074] make

[0075] The above equation then becomes:

[0076] ln(I(x,y))=a+bx+cy+dx 2 +fy 2

[0077] Its equivalent matrix form is:

[0078]

[0079] The solution can be found using the least squares method.

[0080] Step 302: Based on the extracted centroid positions of all stars or landmarks in the image, calculate the centroid (x0, y0) of the distribution of stars and landmarks in the entire image. The specific calculation method is as follows:

[0081]

[0082] Step 303: Establish a coordinate system with the centroid (x0, y0) of the distribution of stars and landmarks in the image as the center, and divide the entire field of view into 4 regions. Each region corresponds to an angle of 90 degrees, and number each region j in a clockwise direction, where the numbering value is j = 1, 2, 3, 4.

[0083] Step 304: For each region j, match the observed stars with the on-board navigation star catalog. Upon successful matching, obtain the right ascension and declination of the observed stars. If the coordinates of the two centroids are (x1, y1) and (x2, y2), the principal point of the camera is (x1, y1) and (x2, y2). c ,y c If the principal distance is f, then the measured angular distance r12 can be obtained by the following formula:

[0084]

[0085]

[0086] By finding two star pairs with the same angular distance in the star catalog, and then forming a triangle with a third star, the star index corresponding to the barycenter can be determined by performing pairwise "side-side-side" identification.

[0087] Step 305: Establish a geometric imaging model and substitute the right ascension and declination of the successfully matched stars into the imaging model to obtain the theoretical position (x1, y1) of the star on the detector calculated by the imaging model. The imaging model is as follows:

[0088]

[0089] Where, (cosαcosδ,sinαcosδ,sinδ) T Let α be the observation vector of the star in the celestial coordinate system, and δ be the right ascension and declination of the star point in the celestial coordinate system. It is the transformation matrix from the J2000 coordinate system to the satellite body coordinate system. It is the transformation matrix from the satellite body coordinate system to the camera coordinate system, and its expression is:

[0090]

[0091] in, ω and κ are the camera mounting angles. It is the transformation matrix from the camera coordinate system to the camera object space. λ is the transformation matrix from the camera object space to the detector, and λ is the correction matrix. and These are the angles between the image point's x and y directions and the center of the field of view, respectively, and their expressions are:

[0092]

[0093] Where a0, ..., a9, b0, ..., b9 are internal calibration parameters, and f is the camera focal length.

[0094] Under the above rigorous geometric imaging model, a calibration adjustment model is established, and arbitrary external calibration parameters are substituted into the above formula:

[0095]

[0096] Construct adjustment calculation equations based on least squares:

[0097]

[0098] First, taking the internal calibration parameters as known quantities, we solve for the external calibration parameters to obtain the error equation:

[0099] V = AX - L

[0100] in,

[0101] We get X = (A) T A) -1 (A T L) can be used to calculate the external calibration parameters.

[0102] Then, taking the external calibration parameters as known quantities, we solve for the internal calibration parameters to obtain the error equation:

[0103] V = BX - L

[0104] in,

[0105]

[0106] We get X = (B) T B) -1 (B T L) can be used to calculate the internal calibration parameters.

[0107] Furthermore, the autonomous calculation process of the on-board landmark autonomous calibration module in step 3 is as follows:

[0108] Step 306: The calibration parameter autonomous calculation module extracts feature points of landmarks in the image;

[0109] Step 307: Based on the extracted centroid positions of all stars or landmarks in the image, calculate the centroid (x0, y0) of the distribution of stars and landmarks in the entire image. The specific calculation method is as follows:

[0110]

[0111] Step 308: Establish a coordinate system with the centroid (x0, y0) of the distribution of stars and landmarks in the image as the center, and divide the entire field of view into 4 regions. Each region corresponds to an angle of 90 degrees, and number each region j in a clockwise direction, where the numbering value is j = 1, 2, 3, 4.

[0112] Step 309: For each region j, match the observed landmarks with the landmark database. If the match is successful, obtain the geographic coordinates of the landmark feature points in the WGS84 coordinate system.

[0113] Step 310: Establish a geometric imaging model and substitute the coordinates of the successfully matched landmark feature points into the imaging model to obtain the theoretical position (x1, y1) of the landmark on the detector calculated by the imaging model. The imaging model is as follows:

[0114]

[0115] Construct adjustment calculation equations based on least squares:

[0116]

[0117] First, taking the internal calibration parameters as known quantities, we solve for the external calibration parameters to obtain the error equation:

[0118] V = PX - L1

[0119] in,

[0120] We get X = (P) T P) -1 (P T L1) can be used to solve the external calibration parameters.

[0121] Then, taking the external calibration parameters as known quantities, we solve for the internal calibration parameters to obtain the error equation:

[0122] V = QX - L1

[0123] in,

[0124]

[0125] We get X = (Q) T Q) -1 (Q T L1) can be used to calculate the internal calibration parameters.

[0126] Step 4: The onboard geometric parameter autonomous calculation module transmits the calibration parameters to the onboard information processing unit for satellite imaging;

[0127] The present invention also provides an on-orbit autonomous geometric calibration system for a wide field-of-view optical remote sensing satellite, comprising: a camera imaging transmission module for taking pictures and transmitting the captured images to an on-board calibration type autonomous identification module;

[0128] The on-board calibration type autonomous identification module is used to combine satellite orbit and satellite attitude data to determine whether the camera's field of view is simultaneously imaging deep space and the ground; if they are simultaneously present, the edge of the Earth is extracted as the boundary between stars and landmarks to divide the distribution areas of stars and landmarks; if they are not simultaneously present, the calibration point type is clearly determined to be either a landmark or a star.

[0129] The on-board star autonomous calibration module is used to match stars with the on-board star database and calculate geometric calibration parameters to achieve on-board autonomous calibration.

[0130] The on-board landmark autonomous calibration module is used to match landmarks with the landmark library and calculate geometric calibration parameters to achieve on-board autonomous calibration.

[0131] The calibration parameter transmission module is used to transmit the calculated calibration parameters to the on-board information processing unit for satellite imaging.

[0132] The onboard stellar autonomous calibration module includes: a centroid extraction module, used to extract the centroid position of a star on the detector using a Gaussian surface fitting method; a star matching module, used to match stars in satellite images with the onboard navigation star catalog and extract the right ascension and declination of stars in satellite images; a stellar geometric imaging model module, used to establish a strict correspondence between the right ascension and declination of stars and their imaging positions on the detector; and a stellar calibration parameter calculation module, used to calculate the geometric calibration parameters of the satellite's interior and exterior orientation elements.

[0133] The on-board landmark autonomous calibration module includes: a landmark extraction module for extracting landmark feature points based on the landmark distribution in camera-captured images; a landmark matching module for matching landmarks in satellite images with an on-board landmark database to obtain the geographical locations of the landmark feature points; a landmark geometric imaging model module for establishing a strict correspondence between the geographical locations of landmark feature points and their imaging positions on the detector; and a landmark calibration parameter calculation module for calculating the geometric calibration parameters of the satellite's interior and exterior orientation elements. The specific implementation method of this embodiment is similar to that in the method embodiment, and therefore will not be described in detail here.

[0134] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0135] It will be apparent to those skilled in the art that the embodiments of the present invention are not limited to the details of the exemplary embodiments described above, and that the embodiments of the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the embodiments of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the embodiments of the present invention is defined by the appended claims rather than the foregoing description. Therefore, all variations falling within the meaning and scope of equivalents of the claims are intended to be encompassed within the embodiments of the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims. Furthermore, it is clear that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units, modules, or devices recited in the system, apparatus, or terminal claims may also be implemented by the same unit, module, or device through software or hardware. The terms "first," "second," etc., are used to indicate names and do not indicate any particular order.

[0136] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention and are not intended to limit them. Although the embodiments of the present invention have been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the embodiments of the present invention should not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for on-orbit autonomous geometric calibration of a wide-field-of-view optical remote sensing satellite, characterized in that, include: Step S1: The camera captures an image and transmits the captured image to the on-board calibration type autonomous identification module; In step S2, the on-board calibration type autonomous identification module combines satellite orbit and satellite attitude data to determine whether the camera's field of view simultaneously images deep space and the ground. If both exist simultaneously, the edge of the Earth is extracted as the boundary between stars and landmarks to divide the distribution areas of stars and landmarks. If they do not exist simultaneously, the type of the calibration point is clearly defined as a landmark or a star. Step S3: Based on the calibration point type, the corresponding image is transmitted to the on-board star autonomous calibration module or the on-board landmark autonomous calibration module, and the geometric calibration parameters are calculated. The autonomous calculation process of the on-board star autonomous calibration module in step S3 is as follows: Step S301: For the i-th star in the image, the on-board autonomous calibration module extracts the centroid using Gaussian surface fitting; Step S302: Calculate the centroid (x0, y0) of the star distribution in the entire image based on the centroid positions of all stars in the extracted image. Step S303: Establish a coordinate system with the centroid (x0, y0) of the star distribution in the image as the center, and divide the entire field of view into N regions. The angle corresponding to each region is 360° / N. Number each region j in a clockwise direction, where the value of the number is j=1,2,…,N; Step S304: For each region j, match the observed stars with the on-board navigation star catalog. After a successful match, obtain the right ascension and declination of the observed stars. Step S305: Establish a geometric imaging model and substitute the right ascension and declination of the successfully matched stars into the imaging model to obtain the theoretical position of the stars on the detector calculated by the imaging model. The autonomous calculation process of the on-board landmark autonomous calibration module in step 3 is as follows: Step S306: The calibration parameter autonomous calculation module extracts feature points of landmarks in the image; Step S307: Calculate the centroid (x0, y0) of the landmark distribution in the entire image based on the centroid positions of all landmark points in the extracted image. Step S308: Establish a coordinate system with the centroid (x0, y0) of the landmark distribution in the image as the center, and divide the entire field of view into N regions. The angle corresponding to each region is 360° / N. Number each region j in a clockwise direction, where the value of the number is j=1,2,…,N; Step S309: For each region j, match the observed landmarks with the landmark database. After a successful match, obtain the geographic coordinates of the landmark feature points in the WGS84 coordinate system. Step S310: Establish a geometric imaging model and substitute the coordinates of the successfully matched landmark feature points into the imaging model to obtain the theoretical position of the landmark on the detector calculated by the imaging model. Step S4: The calculated geometric calibration parameters are transmitted to the on-board information processing unit for satellite imaging.

2. The on-orbit autonomous geometric calibration method for wide-field-of-view optical remote sensing satellites as described in claim 1, characterized in that, Step S301 specifically includes: Stellar energy I (x,y) is approximately Gaussian distributed, and can be expressed as: Among them, A i Let be the energy intensity at the centroid position of the i-th calibration point. σ x and σ y Let A and B be the standard deviations in the x and y directions, respectively. Based on the pixel response values ​​within a 3×3 region, solve for A using the least squares method. σ x , σ y and the position of the center of mass (x) i ,y i ).

3. The on-orbit autonomous geometric calibration method for wide-field-of-view optical remote sensing satellites as described in claim 1 or 2, characterized in that, Step S304 specifically includes: If the coordinates of the two centroids are respectively and The main point of the camera is If the principal distance is f, then the measured angular distance is r. 12 It can be obtained from the following formula: By finding two star pairs with the same angular distance in the star catalog, and then forming a triangle with a third star, the star corresponding to the barycenter can be determined by identifying each pair of the three sides.

4. The on-orbit autonomous geometric calibration method for wide-field-of-view optical remote sensing satellites as described in claim 1 or 2, characterized in that, Step S305 specifically includes: substituting the right ascension and declination of the successfully matched star into the imaging model to obtain the theoretical position (x1, y1) of the star on the detector calculated by the imaging model. The imaging model is as follows: in, This represents the observation vector of stellar observations in the celestial coordinate system. α and δ The right ascension and declination of a point in the celestial coordinate system. It is the transformation matrix from the J2000 coordinate system to the satellite body coordinate system. It is the transformation matrix from the satellite body coordinate system to the camera coordinate system. It is the transformation matrix from the camera coordinate system to the camera object space. It is the transformation matrix from the camera object space to the detector. It is a correction matrix. and These are the angles between the image point's x and y directions and the center of the field of view, respectively, and their expressions are: Where a0, ..., a9, b0, ..., b9 are internal calibration parameters, and f is the camera focal length; Under the strict geometric imaging model, a calibration adjustment model is established, and arbitrary external calibration parameters are substituted into the above formula: Construct adjustment calculation equations based on least squares: 。 5. The on-orbit autonomous geometric calibration method for wide-field-of-view optical remote sensing satellites as described in claim 1, characterized in that, Step S310 includes: establishing a geometric imaging model, and substituting the coordinates of the successfully matched landmark feature points into the imaging model to obtain the theoretical position (x1, y1) of the landmark on the detector calculated by the imaging model. The imaging model is as follows: in, The coordinates of the landmark in the WGS84 coordinate system It is the transformation matrix from the WGS84 coordinate system to the J2000 coordinate system. It is the transformation matrix from the J2000 coordinate system to the satellite body coordinate system. It is the transformation matrix from the satellite body coordinate system to the camera coordinate system. It is the transformation matrix from the camera coordinate system to the camera object space. It is the transformation matrix from the camera object space to the detector. It is a correction matrix. and These are the angles between the image point's x and y directions and the center of the field of view, respectively, and their expressions are: Where a0, ..., a9, b0, ..., b9 are internal calibration parameters, and f is the camera focal length; Under the strict geometric imaging model, a calibration adjustment model is established, and arbitrary external calibration parameters are substituted into the above formula: Construct adjustment calculation equations based on least squares: 。 6. A wide-field-of-view optical remote sensing satellite on-orbit autonomous geometric calibration system, characterized in that, include: The camera imaging transmission module is used to take pictures and transmit the captured images to the on-board calibration type autonomous identification module; The on-board calibration type autonomous identification module is used to combine satellite orbit and satellite attitude data to determine whether the camera's field of view is simultaneously imaging deep space and the ground; if they are simultaneously present, the edge of the Earth is extracted as the boundary between stars and landmarks to divide the distribution areas of stars and landmarks; if they are not simultaneously present, the calibration type is clearly defined as landmark or star. The on-board star autonomous calibration module is used to match stars with the on-board star database and calculate geometric calibration parameters to achieve on-board autonomous calibration. The onboard stellar autonomous calibration module includes: a centroid extraction module, used to extract the centroid position of a star on the detector using a Gaussian surface fitting method; a star matching module, used to match stars in satellite images with the onboard navigation star catalog and extract the right ascension and declination of stars in satellite images; a stellar geometric imaging model module, used to establish a strict correspondence between the right ascension and declination of stars and their imaging positions on the detector; and a stellar calibration parameter calculation module, used to calculate the geometric calibration parameters of the satellite's interior and exterior orientation elements. The on-board landmark autonomous calibration module is used to match landmarks with a landmark database and calculate geometric calibration parameters to achieve on-board autonomous calibration. This module includes: a landmark extraction module, used to extract landmark feature points based on the distribution of landmarks in images captured by the camera; a landmark matching module, used to match landmarks in satellite images with the on-board landmark database to obtain the geographical locations of the landmark feature points; a landmark geometric imaging model module, used to establish a strict correspondence between the geographical locations of landmark feature points and their imaging positions on the detector; and a landmark calibration parameter calculation module, used to calculate the geometric calibration parameters of the satellite's interior and exterior orientation elements. The calibration point type determination module is used to transmit the corresponding image to the on-board star autonomous calibration module or the on-board landmark autonomous calibration module, and to solve the geometric calibration parameters; The calibration parameter transmission module is used to transmit the calibration parameters to the on-board information processing unit for satellite imaging.

Images