Star field geometric calibration method considering space-time decoupling and unsteady-state imaging

Abstract

The invention provides a fixed star field geometric calibration method considering space-time decoupling and unsteady-state imaging, and the method comprises the steps: cataloguing a fixed star field adaptive to a satellite according to a GAIA (Gauge Assisted Independent Architecture) satellite catalogue and the attitude performance of an optical remote sensing satellite, and constructing a fixed star point extraction operator with a fixed star motion compensation function, the method comprises the following steps: performing star point identification on star map features in a satellite image field generated based on a fixed star field to obtain fixed star control points, performing astronomical correction on motion, parallax and aberration in fixed star coordinates, and obtaining observable limit stars and fixed star imaging window values according to a point spread function (PSF) of an image optical system. Carrying out adaptive weighting on the reliability of a fixed star observation coordinate, constructing a camera interior orientation element adaptive distortion model, and constructing a fixed star field geometric calibration model according to fixed star control points on attitude stationary correction under a non-stationary imaging condition of a satellite; and solving the fixed star field geometric calibration model based on a random sampling consistency method and a partial least square method to obtain geometric calibration parameters.

Description

Technical Field

[0001] The present invention relates to the technical field of optical remote sensing satellite image geometric processing, and in particular to a stellar field geometric calibration method that takes into account time-space decoupling and non-steady-state imaging. Background Art

[0002] In recent years, Earth observation satellite systems have gradually demonstrated intelligent characteristics similar to those of the human brain, including perception, cognition, and decision-making capabilities, thereby building an efficient space-based information network. The system integrates multi-dimensional functions such as data acquisition, information extraction, and intelligent perception, among which high-resolution linear array push-broom cameras are one of the key information sources. However, during the on-orbit operation of the satellite, the geometric imaging parameters of the camera will be affected by multiple factors such as vibration, temperature stability, and focal length adjustment, which will lead to changes in imaging parameters and a serious decrease in imaging quality. In order to ensure that the Earth observation satellite system maintains a high level of geometric accuracy, the camera must be calibrated at a high frequency. Realizing the normalization of geometric calibration of high-resolution linear array cameras is of great significance to improving the performance of Earth observation satellite systems.

[0003] A satellite constellation refers to a group of satellites in orbit and operating normally, which work together in a specific configuration. Compared with the traditional single-satellite service model, constellation satellites have the characteristics of rich payload types, wide spans of high and low orbits, complex and diverse application scenarios, and more refined service models. In recent years, with the continuous development of commercial remote sensing companies at home and abroad, they have begun to gradually deploy satellite constellations, aiming to achieve rapid acquisition of remote sensing information on a global scale through constellation networking. However, at the current stage, traditional geometric calibration methods can no longer meet the needs of constellations in data processing and service provision. Therefore, in-depth research and innovation on the calibration methods of constellation satellites to adapt to their complex operating environment and diverse application scenarios is an important challenge facing the current remote sensing field.

[0004] Compared with traditional calibration methods and field-free calibration methods, the calibration method based on star fields has significantly overcome its limitations, especially in the high-frequency on-board calibration of high-resolution linear array cameras. However, there are inherent differences between the imaging modes of star observation and traditional observation. Due to the constraints of attitude stability, stars may appear blurred in the image, and robust extraction of the center is crucial. In addition, there are differences in the imaging time of each line of the linear array. Stable attitude correction under non-stationary imaging conditions of satellites is very critical for star field calibration. Summary of the invention

[0005] The present disclosure proposes a stellar field geometric calibration method, device, electronic device, storage medium and computer program product that take into account space-time decoupling and non-steady-state imaging, aiming to solve the technical problems in the related technology at least to a certain extent.

[0006] The first aspect of the present disclosure proposes a stellar field geometric calibration method that takes into account time-space decoupling and non-steady-state imaging, including: cataloging a stellar field adapted to a satellite based on the GAIA star catalog and the attitude performance of an optical remote sensing satellite; constructing a stellar star point extraction operator with a stellar motion compensation function to identify star points of star map features within the field of view of a satellite image generated based on the stellar field, and obtain stellar control points; performing astronomical corrections on proper motion, parallax, and aberration in stellar coordinates; obtaining observable limit stars and stellar imaging window values ​​based on a point spread function (PSF) of an imaging optical system, and adaptively weighting the reliability of stellar observation coordinates; constructing an adaptive distortion model for in-camera orientation elements, and constructing a stellar field geometric calibration model for a steady attitude correction under non-steady imaging conditions of the satellite based on stellar control points; and solving the stellar field geometric calibration model based on a random sampling consistency method and a partial least squares method to obtain geometric calibration parameters.

[0007] The second aspect of the present disclosure proposes a stellar field geometry calibration device that takes into account time-space decoupling and non-steady-state imaging, including: a first construction module, which is used to catalog the stellar field adapted to the satellite according to the GAIA star catalog and the attitude performance of the optical remote sensing satellite; a second construction module, which is used to construct a stellar star point extraction operator with a stellar motion compensation function, so as to identify the star points of the star map features in the field of view of the satellite image generated based on the stellar field, and obtain the stellar control points; a correction module, which is used to perform astronomical corrections on the proper motion, parallax and aberration in the stellar coordinates; an acquisition module, which is used to obtain the observable limit star and the stellar imaging window value according to the point spread function PSF of the imaging optical system, and adaptively weight the reliability of the stellar observation coordinates; a third construction module, which is used to construct an adaptive distortion model of the orientation elements in the camera, and to perform a stellar field geometry calibration model according to the stellar control points to perform a steady attitude correction under the non-steady imaging conditions of the satellite; a processing module, which is used to solve the stellar field geometry calibration model based on the random sampling consistency method and the partial least squares method to obtain the geometry calibration parameters.

[0008] The third aspect of the present disclosure proposes an electronic device, comprising: a processor; a memory for storing instructions executable by the processor; wherein the processor is configured to execute instructions to implement a stellar field geometric calibration method that takes into account time-space decoupling and non-steady-state imaging.

[0009] A fourth aspect of the present disclosure provides a computer-readable storage medium. When instructions in the computer-readable storage medium are executed by a processor of an electronic device, the electronic device can perform a stellar field geometry calibration method that takes into account time-space decoupling and non-steady-state imaging.

[0010] The fifth aspect embodiment of the present disclosure proposes a computer program product, including a computer program, characterized in that the computer program is executed by a processor to perform a stellar field geometric calibration method that takes into account time-space decoupling and non-steady-state imaging.

[0011] The star field geometric calibration method, device, electronic device, storage medium and computer program product proposed in this embodiment that take into account time-space decoupling and non-steady-state imaging have at least the following beneficial effects: based on the GAIA star catalog and the optical remote sensing satellite attitude performance catalog and the satellite-adapted star field, a star point extraction operator with a star motion compensation function is constructed to identify star points of star map features within the field of view of the satellite image generated based on the star field, obtain star control points, perform astronomical corrections on proper motion, parallax and aberration in star coordinates, and obtain observable polar coordinates according to the point spread function PSF of the imaging optical system. The star limit and star imaging window values ​​are set, and the reliability of the star observation coordinates is adaptively weighted. An adaptive distortion model of the camera's internal orientation elements is constructed. The satellite's attitude is smoothly corrected under non-stationary imaging conditions according to the star control points. A star field geometric calibration model is constructed. The star field geometric calibration model is solved based on the random sampling consistency method and the partial least squares method to obtain the geometric calibration parameters, thereby achieving high-precision extraction of star points under the decoupling of time and space factors, adaptive weighting of coordinates taking into account the star magnitude brightness, and stable attitude correction under non-stationary imaging conditions, which can significantly improve the geometric positioning accuracy of optical remote sensing satellites.

[0012] Additional aspects and advantages of the present disclosure will be given in part in the following description and in part will be obvious from the following description or learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above and / or additional aspects and advantages of the present disclosure will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0014] Figure 1 It is a flow chart of a stellar field geometric calibration method taking into account time-space decoupling and non-steady-state imaging according to the first embodiment of the present disclosure;

[0015] Figure 2 It is a block diagram of a stellar field geometric calibration device taking into account time-space decoupling and non-steady-state imaging according to the present disclosure;

[0016] Figure 3 A block diagram of an exemplary electronic device suitable for implementing embodiments of the present disclosure is shown. DETAILED DESCRIPTION

[0017] Embodiments of the present disclosure are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present disclosure, and are not to be construed as limitations of the present disclosure. On the contrary, the embodiments of the present disclosure include all changes, modifications, and equivalents that fall within the spirit and connotation of the appended claims.

[0018] Among them, it should be noted that the executor of the stellar field geometry calibration method taking into account the space-time decoupling and non-steady-state imaging in this embodiment can be a stellar field geometry calibration device taking into account the space-time decoupling and non-steady-state imaging. The device can be implemented by software and / or hardware. The device can be configured in an electronic device, and the electronic device can include but is not limited to a terminal, a server, etc.

[0019] It should be noted that the process of obtaining, storing, using, and processing information in the disclosed technical solution complies with the relevant provisions of national laws and regulations and does not violate public order and good morals.

[0020] Figure 1 is a flow chart of a stellar field geometric calibration method taking into account time-space decoupling and non-steady-state imaging according to the first embodiment of the present disclosure, such as Figure 1 As shown, the method includes:

[0021] S101: Catalog satellite-adapted star fields based on the GAIA star catalog and the attitude performance of optical remote sensing satellites.

[0022] Optionally, in some embodiments, the star calibration field adapted to the satellite according to the GAIA star catalog and the optical remote sensing satellite attitude performance catalog can be determined according to the optical satellite field of view (FOV) and resolution to determine the simulated star map image in the entire sky, the number of star distribution, uniformity index, coverage index and non-collinearity index in the simulated star map image, and the star field is determined according to the number of star distribution, uniformity index, coverage index and non-collinearity index.

[0023] In the embodiment of the present disclosure, based on the GAIA star catalog to simulate the stars in the whole sky, the stars can be simulated according to the field of view FOV and resolution of the optical satellite, and the whole sky area is spaced at FOV / 10. Level For the observable magnitude, we obtain the simulated star map image in the whole sky, and then construct the number Num of stars distributed in the field of view of a single satellite image for evaluation. Star , uniformity, coverage, non-collinearity indicators, among which the number of star distribution Num is determined Star , uniformity, coverage, and non-collinearity indicators. The specific steps are:

[0024] (1) Calculation of number indicators: Count the number of stars within the image field of view and obtain Num Star index;

[0025] (2) Calculation of uniformity index: The range R and standard deviation δ of the horizontal coordinates within the field of view are calculated to serve as an index for evaluating the uniformity of the star distribution within the field of view.

[0026] Among them, the range R is divided into the column direction range R sample , row direction range R line , the specific calculation formula is:

[0027]

[0028] Among them, sample max and sample min are the maximum and minimum values ​​of the coordinates of the star in the image at the field of view, line max and line min They are the maximum and minimum values ​​of the field angle stars located in the upper coordinates of the image;

[0029] Among them, the standard deviation δ is divided into the column direction standard deviation δ sample , row direction standard deviation δ line , the specific calculation formula is:

[0030]

[0031] Among them, sample i and line i Num Star The column and row coordinates of any star in the image, sample ave and line ave Num Star The mean column and row coordinates of the stars in the image;

[0032] (3) Calculation of non-collinearity index: randomly select star points at both ends of the field of view, fit a straight line, and then traverse the remaining star points in the field of view, and calculate the distance from the star to the fitting line. Set a threshold θ. Star points smaller than the threshold can be considered to be on the straight line and are eliminated. The number of star points not on the straight line is counted as the non-collinearity index.

[0033] In the disclosed embodiment, a suitable star field is screened by screening the whole sky field according to the reference points of more than 3 star points on the same straight line required for external calibration and the requirement of more than 6 star points in the field of view covered by each CCD for internal calibration, and preliminarily obtaining the area of ​​the whole sky field suitable for geometric calibration.

[0034] S102: construct a star point extraction operator with a star motion compensation function to identify star points based on the star map features in the field of view of the satellite image generated based on the star field, and obtain star control points.

[0035] Optionally, in some embodiments, a star point extraction operator with a star motion compensation function is constructed to generate star map features in the satellite image field of view based on the GAIA star catalog to perform star point identification and obtain star control points. A star point extraction operator with a star motion compensation function can be constructed based on the star motion direction and star linear features, and star map features in the satellite image field of view are extracted based on the star point extraction operator. The star map features are processed based on a spectrum matching algorithm to determine the star control points.

[0036] In the embodiment of the present disclosure, a star point extraction operator with a star motion compensation function is constructed by considering the star motion direction and linear characteristics, fitting the star mass center coordinates based on anisotropic Gaussian surfaces, and multiplying the star image by the rotation matrix R according to the star motion direction θ. θ :

[0037]

[0038] Further get the Gaussian surface fitting formula:

[0039]

[0040] Among them, A is a fixed coefficient, σ x and σ y denote the mean square error of Gaussian function in the x-direction and y-direction respectively, and exp(·) is the power function. When the anisotropic Gaussian surface is used to fit the star centroid, at least six star pixels are required. When the number of star pixels in the image is less than six, the interpolation method is required to interpolate the star target pixels first.

[0041] In the embodiment of the present disclosure, the star map features in the satellite image field are extracted based on the star point extraction operator, which can be generated by generating a total edge weight feature w for each star J above 92 in the GAIA star catalog. J (Minimum spanning tree MST) and adjacency matrix A J Features, where the total edge weight w J Features are used for coarse search, adjacency matrix A J The features are used for subsequent graph matching. The specific steps are:

[0042] (1) Neighborhood Graph G J The minimum spanning tree MST of is generated by selecting a primary star J and drawing its neighbor circles with radius r; generating a neighbor graph G of J by considering stars as vertices and the angular intervals between pairs of stars as weighted edges J , the neighbor graph G Jis a fully weighted graph, the edges of the weighted graph are connected by each star pair, and the weight of the edge is represented by the length; the neighbor graph G is generated by the Kruskal algorithm J The minimum spanning tree MST;

[0043] (2) Neighborhood Graph G J The adjacency matrix A J Generate: Adjacency matrix A J (i,j)=θ i,j , used to calculate the angular distance θ between star i and star j i,j The calculation formula is: in and is the unit vector of star i and star j in the inertial coordinate system.

[0044] In the embodiment of the present disclosure, the specific steps of processing star map features based on the spectrum matching algorithm to determine the star control points are:

[0045] (1) The minimum spanning tree (MST) generated by the star image and the database main star set is used as the input of the k-nearest vector retrieval, and the candidate matching star set S is output. I ;

[0046] (2) Use the spectral graph matching algorithm to match the neighbor graph G I With G J Matching is performed to obtain corresponding star matching points, thereby completing the identification of the extracted star control points.

[0047] S103: Perform astronomical corrections for proper motion, parallax and aberration in stellar coordinates.

[0048] In the disclosed embodiment, a stellar star point extraction operator with a stellar motion compensation function is constructed to identify star points of star map features within the field of view of a satellite image generated based on a stellar field. After obtaining stellar control points, astronomical corrections can be made to proper motion, parallax and aberration in stellar coordinates.

[0049] Optionally, in some embodiments, astronomical corrections are made to proper motion, parallax and aberration in star coordinates by adjusting the star coordinates in the star catalog to determine the position of the star in the celestial coordinate system at the shooting epoch, performing parallax correction based on the parameters in the star catalog to eliminate the parallax caused by the annual and diurnal motion of the earth, performing parallax correction on the parameters in the star catalog to eliminate the parallax caused by the annual and diurnal motion of the earth, performing atmospheric refraction correction on the star coordinates in the star catalog, and performing aberration correction on the object coordinates of the star based on the direction of the optical axis at the time of camera imaging, the satellite speed, and the angle between the two.

[0050] In the embodiment of the present disclosure, the right ascension and declination of the star after proper motion and parallax correction are (α, δ), and the atmospheric refraction and aberration correction are expressed as the rotation matrix R associated with the imaging time t Abert (t), then the star imaging model after taking into account astronomical corrections such as aberration, proper motion, and parallax is:

[0051]

[0052] Where m is the proportionality coefficient, is the rotation matrix from the camera coordinate system to the J2000 coordinate system at imaging time t, (x, y) is the column and row coordinates of the image, (x 0 ,y 0 ) is the coordinate of the principal point of the image, and f is the principal distance of the image.

[0053] S104: Obtain the observable limit star and the stellar imaging window value according to the point spread function PSF of the imaging optical system, and adaptively weight the reliability of the stellar observation coordinates.

[0054] In the disclosed embodiment, the observable limit star and the stellar imaging window value may be obtained according to the point spread function PSF of the imaging optical system, and the reliability of the stellar observation coordinates may be adaptively weighted.

[0055] Optionally, in some embodiments, the observable limit star and the star imaging window value are obtained according to the point spread function PSF of the imaging optical system, and the reliability of the star observation coordinates is adaptively weighted, so as to obtain the signal-to-noise ratio SNR of the target star observed by the image:

[0056]

[0057] Among them, Star is the number of electrons in the star signal, Background is the number of electrons in the background radiation, and Noise is sensor is the remote sensing sensor noise, and the observable limit magnitude Star Level 1.5 times the SNR is used as the threshold for observable stars;

[0058] Calculate the pixel observation values ​​around the star imaging location based on the point spread function PSF of the imaging optical system;

[0059] According to the observable limit star Star Level The coordinates of the unit weight variance Calculate the weights of the observed star coordinates Among them, i is the required observation constant i, is the variance of the observed stars, σ i The calculation formula is: in is the effective observation window value of the limiting star.

[0060] Among them, the specific steps of calculating the pixel observation values ​​around the star imaging location according to the point spread function PSF of the imaging optical system are:

[0061] (1) First, calculate the energy distribution model of the star p(x,y):

[0062]

[0063] Where (x star ,y star ) and σ PSF are the center coordinates and Gaussian radius of the star point respectively, (x, y) is the pixel coordinates of the energy to be calculated;

[0064] (2) For the position coordinates (x p ,y p ) is integrated to obtain the energy E(x p ,y p );

[0065] (3) The linear model is used to further calculate the position coordinates (x p ,y p ) is the pixel value Itensity(x p ,y p )=bias*E(x p ,y p )+gain, where bias is the grayscale amplitude at the center of the constant, and gain is a constant;

[0066] (4) Based on the pixel value of the center coordinate of the star point, the window range in which the pixel value decays to 5% is regarded as the effective observation window for the star.

[0067] In the disclosed embodiment, the observable limiting magnitude Star Level The coordinates of the unit weight variance Calculate the weights of the observed star coordinates Where i is the desired observation constant i, is the variance of the observed star, σ i The calculation formula is: in is the effective observation window size of the limiting magnitude.

[0068] S105: Construct an adaptive distortion model of the camera's internal orientation elements, perform a steady correction on the satellite's attitude under non-steady imaging conditions based on the star control points, and construct a star field geometric calibration model.

[0069] In the disclosed embodiment, after obtaining the observable limit star and the stellar imaging window value according to the point spread function PSF of the imaging optical system and adaptively weighting the reliability of the stellar observation coordinates, an adaptive distortion model of the camera's internal orientation elements can be constructed, and the satellite's attitude can be smoothly corrected under non-stationary imaging conditions according to the stellar control points to construct a stellar field geometry calibration model.

[0070] Optionally, in some embodiments, constructing the camera internal orientation element adaptive distortion model may be to construct an adaptive s-order model for the internal orientation element according to the internal distortion of the image:

[0071]

[0072] Among them, δ sample and δ line They represent the distortion compensation items of the inner elements in the column direction and the row direction, respectively, and m i (i=0,1,2,...,s) represents the compensation model coefficient in the column direction, n i (i=0,1,2,...,s) represents the compensation model coefficient in the row direction, x and y represent the column and row coordinates of the image respectively, and s represents the adaptive order of the compensation model.

[0073] In the disclosed embodiment, after the adaptive distortion model of the camera's internal orientation elements is built, the satellite's attitude can be smoothly corrected under non-stationary imaging conditions according to the star control points to build a star field geometry calibration model.

[0074] That is to say, in the embodiments of the present disclosure, the attitude can be compensated for based on the corrected star control point positions in the entire viewing angle range of the image. The original attitude data is used to back-calculate to the image based on the corrected star control point positions. Then, the attitude compensation value adjustment equation is established based on the difference between the back-calculated image coordinates and the actual coordinates to obtain stable attitude data.

[0075] In the embodiment of the present disclosure, the star field geometric calibration model can be expressed as:

[0076]

[0077] Among them, (α 0 ,δ 0 ) respectively represent the right ascension and declination of the star point target obtained by star map recognition in the celestial coordinate system; (a i ,b i ,c i )(i=1,2,3) are represented as the nine elements of the attitude rotation matrix, which are the sine and cosine functions of the attitude Euler angles (α,ω,κ).

[0078] S106: Solve the stellar field geometric calibration model based on the random sampling consistency method and the partial least squares method to obtain the geometric calibration parameters.

[0079] In the embodiment of the present disclosure, the parameter solution of the stellar field geometric calibration model using random sampling consistency and partial least squares includes the following steps:

[0080] (1) Partial Least Squares (PLS) is further used to solve the stellar field geometric calibration model: if the coordinates (x, y) of the star image point are taken as the observed value, the internal parameter m i (i=0,1,2,...,s),n i (i=0,1,2,...,s) and attitude Euler angles (α,ω,κ) are unknown parameters. Based on the formula, the unknown parameters are differentiated respectively, and then the first-order terms are expanded according to the Taylor series to obtain the error observation equation of the image point coordinates of the star point target. The unknowns are further solved according to the partial least squares PLS method;

[0081] (2) A random sampling consensus algorithm is used to select the star control point with the highest number of inliers as the input for solving the model parameters. Ten star control points in the image are selected and 51) is applied to solve the calibration coefficients of the internal and external elements of the image. The obtained calibration coefficients are then compensated to the image. The threshold is 0.5 pixels, and the remaining inliers are counted. Then, a set of 10 star control points with the highest number of inliers are cyclically searched as the input for the final solution of the geometric calibration model.

[0082] In the disclosed embodiment, a star field adapted to the satellite is cataloged according to the GAIA star catalog and the attitude performance of the optical remote sensing satellite, and a star point extraction operator with a star motion compensation function is constructed to identify star points of star map features within the field of view of the satellite image generated based on the star field, obtain star control points, perform astronomical corrections on proper motion, parallax and aberration in the star coordinates, obtain observable limit stars and star imaging window values ​​according to the point spread function PSF of the imaging optical system, and adaptively weight the reliability of the star observation coordinates, construct an adaptive distortion model of the camera's internal orientation elements, perform a steady attitude correction under non-stationary imaging conditions of the satellite according to the star control points, construct a star field geometric calibration model, and solve the star field geometric calibration model based on the random sampling consistency method and the partial least squares method to obtain geometric calibration parameters, so as to achieve high-precision extraction of star points under decoupling of time and space factors, adaptive weighting of coordinates taking into account the brightness of the star magnitude, and steady attitude correction under non-stationary imaging conditions, thereby significantly improving the geometric positioning accuracy of the optical remote sensing satellite.

[0083] Figure 2 is a block diagram of a stellar field geometric calibration device that takes into account time-space decoupling and non-steady-state imaging according to the present disclosure, such as Figure 2As shown, the stellar field geometric calibration device 20 taking into account time-space decoupling and non-steady-state imaging comprises:

[0084] The first building module 201 is used to catalogue the star field adapted to the satellite according to the GAIA star catalog and the attitude performance of the optical remote sensing satellite;

[0085] The second construction module 202 is used to construct a star point extraction operator with a star motion compensation function to identify star points based on the star map features in the field of view of the satellite image generated based on the star field, and obtain star control points;

[0086] Correction module 203, used for performing astronomical correction on proper motion, parallax and aberration in star coordinates;

[0087] An acquisition module 204 is used to acquire the observable limit star and the star imaging window value according to the point spread function PSF of the imaging optical system, and to adaptively weight the reliability of the star observation coordinates;

[0088] The third construction module 205 is used to construct an adaptive distortion model of the camera's internal orientation elements, to perform a steady attitude correction on the satellite under non-steady imaging conditions according to the star control points, and to construct a star field geometric calibration model;

[0089] The processing module 206 is used to solve the stellar field geometric calibration model based on the random sampling consistency method and the partial least squares method to obtain the geometric calibration parameters.

[0090] In some embodiments of the present disclosure, the first building module 201 is further used to:

[0091] Determine the simulated star map image in the whole sky area according to the optical satellite field of view FOV and resolution;

[0092] Determine the number of stars distributed in the simulated star map image, uniformity index, coverage index and non-collinearity index;

[0093] The stellar field is determined based on the number of stellar distribution, uniformity index, coverage index and non-collinearity index.

[0094] In some embodiments of the present disclosure, the second building module 202 is further configured to:

[0095] According to the star motion direction and star linear characteristics, a star point extraction operator with star motion compensation function is constructed;

[0096] Extract star map features in the satellite image field of view based on star point extraction operator;

[0097] Star map features are processed based on a pattern matching algorithm to determine star control points.

[0098] In some embodiments of the present disclosure, the correction module 203 is further configured to:

[0099] Adjust the star coordinates in the star catalog to determine the position of the star in the celestial coordinate system at the time of the shooting epoch;

[0100] Parallax correction is performed according to the parameters in the star catalog to eliminate the parallax caused by the annual and diurnal motions of the Earth;

[0101] Parallax correction is performed on the parameters in the star catalog to eliminate the parallax caused by the annual and diurnal motions of the Earth;

[0102] Correct the coordinates of stars in the star catalog for atmospheric refraction;

[0103] According to the direction of the optical axis at the time of camera imaging, the satellite speed, and the angle between the two, the object coordinates of the star are corrected for aberration.

[0104] In some embodiments of the present disclosure, the acquisition module 204 is further configured to:

[0105] Get the signal-to-noise ratio (SNR) of the target star observed by image:

[0106]

[0107] Among them, Star is the number of electrons in the star signal, Background is the number of electrons in the background radiation, and Noise is sensor is the remote sensing sensor noise, and the observable limit magnitude Star Level 1.5 times the SNR is used as the threshold for observable stars;

[0108] Calculate the pixel observation values ​​around the star imaging location based on the point spread function PSF of the imaging optical system;

[0109] According to the observable limit star Star Level The coordinates of the unit weight variance Calculate the weights of the observed star coordinates Among them, i is the required observation constant i, is the variance of the observed stars, σ i The calculation formula is: in is the effective observation window value of the limiting star.

[0110] In some embodiments of the present disclosure, the third building block 205 is further configured to:

[0111] According to the internal distortion of the image, an adaptive s-order model is constructed for the internal orientation elements:

[0112]

[0113] Among them, δ sample and δ line They represent the distortion compensation items of the inner elements in the column direction and the row direction, respectively, and m i (i=0,1,2,...,s) represents the compensation model coefficient in the column direction, n i (i=0,1,2,...,s) represents the compensation model coefficient in the row direction, x and y represent the column and row coordinates of the image respectively, and s represents the adaptive order of the compensation model.

[0114] In some embodiments of the present disclosure, the geometric calibration model is expressed as:

[0115]

[0116] Among them, (α 0 ,δ 0 ) respectively represent the right ascension and declination of the star point target in the celestial coordinate system obtained by star map recognition; (a i ,b i ,c i )(i=1,2,3) are represented as the nine elements of the attitude rotation matrix, which are the sine and cosine functions of the attitude Euler angles (α,ω,κ).

[0117] In this embodiment, a star point extraction operator with a star motion compensation function is constructed by cataloging a star field adapted to a satellite based on the GAIA star catalog and the attitude performance of an optical remote sensing satellite, so as to identify star points for star map features within the field of view of a satellite image generated based on the star field, obtain star control points, perform astronomical corrections on proper motion, parallax and aberration in star coordinates, obtain observable limit stars and star imaging window values ​​based on the point spread function PSF of the imaging optical system, and adaptively weight the reliability of star observation coordinates, construct an adaptive distortion model of the camera's internal orientation elements, perform a steady attitude correction under non-stationary imaging conditions of the satellite based on the star control points, construct a star field geometric calibration model, and solve the star field geometric calibration model based on a random sampling consistency method and a partial least squares method to obtain geometric calibration parameters, thereby achieving high-precision extraction of star points under decoupling of spatiotemporal factors, adaptive weighting of coordinates taking into account star magnitude brightness, and steady attitude correction under non-stationary imaging conditions, thereby significantly improving the geometric positioning accuracy of optical remote sensing satellites.

[0118] In order to implement the above-mentioned embodiments, the present application also proposes an electronic device, comprising: a processor, and a memory communicatively connected to the processor; the memory stores computer-executable instructions; the processor executes the computer-executable instructions stored in the memory to implement the stellar field geometry calibration method that takes into account time-space decoupling and non-steady-state imaging provided by the above-mentioned embodiments.

[0119] In order to implement the above embodiments, the present application also proposes a computer-readable storage medium, in which computer execution instructions are stored. When the computer execution instructions are executed by a processor, they are used to implement the stellar field geometry calibration method that takes into account time-space decoupling and non-steady-state imaging provided by the above embodiments.

[0120] Figure 3 A block diagram of an exemplary electronic device suitable for implementing embodiments of the present disclosure is shown.

[0121] Figure 3 The electronic device 7 shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present disclosure.

[0122] like Figure 3 As shown, the electronic device 7 is in the form of a general purpose computing device. The components of the electronic device 7 may include, but are not limited to: one or more processors or processing units 16, a memory 28, and a bus 18 connecting different system components (including the memory 28 and the processing unit 16).

[0123] The bus 18 represents one or more of several types of bus structures, including a memory bus or memory controller, a peripheral bus, a graphics acceleration port, a processor or a local bus using any of a variety of bus structures. For example, these architectures include but are not limited to Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MAC) bus, Enhanced ISA bus, Video Electronics Standards Association (VESA) local bus and Peripheral Component Interconnection (PCI) bus.

[0124] The electronic device 7 typically includes a variety of computer system readable media. These media can be any available media that can be accessed by the electronic device 7, including volatile and non-volatile media, removable and non-removable media.

[0125] The memory 28 may include computer system readable media in the form of volatile memory, such as random access memory (RAM) 30 and / or cache memory 32. The electronic device 7 may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, the storage system 34 may be used to read and write non-removable, non-volatile magnetic media ( Figure 3 Not shown, often called a "hard drive").

[0126] although Figure 3 Not shown in the figure, a disk drive for reading and writing a removable non-volatile disk (e.g., a "floppy disk"), and an optical disk drive for reading and writing a removable non-volatile optical disk (e.g., a compact disc read only memory (hereinafter referred to as: CD-ROM), a digital versatile disc read only memory (hereinafter referred to as: DVD-ROM) or other optical media) may be provided. In these cases, each drive may be connected to the bus 18 via one or more data medium interfaces. The memory 28 may include at least one program product having a set (e.g., at least one) of program modules that are configured to perform the functions of the various embodiments of the present disclosure.

[0127] A program / utility 40 having a set (at least one) of program modules 42 may be stored, for example, in the memory 28, such program modules 42 including but not limited to an operating system, one or more application programs, other program modules, and program data, each of which or some combination may include an implementation of a network environment. The program modules 42 generally perform the functions and / or methods of the embodiments described in the present disclosure.

[0128] The electronic device 7 may also communicate with one or more external devices 14 (e.g., keyboard, pointing device, display 24, etc.), may also communicate with one or more devices that enable the human body to interact with the electronic device 7, and / or communicate with any device that enables the electronic device 7 to communicate with one or more other computing devices (e.g., network card, modem, etc.). Such communication may be performed through an input / output (I / O) interface 22. Furthermore, the electronic device 7 may also communicate with one or more networks (e.g., a local area network (LAN), a wide area network (WAN), and / or a public network, such as the Internet) through a network adapter 20. As shown, the network adapter 20 communicates with other modules of the electronic device 7 through a bus 18. It should be understood that, although not shown in the figure, other hardware and / or software modules may be used in conjunction with the electronic device 7, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems.

[0129] The processing unit 16 executes various functional applications and parameter information determination by running the program stored in the memory 28, such as implementing the stellar field geometry calibration method that takes into account the time-space decoupling and non-steady-state imaging mentioned in the above-mentioned embodiments, or implementing the business data acquisition method mentioned in the above-mentioned embodiments.

[0130] It should be noted that, in the description of the present disclosure, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present disclosure, unless otherwise specified, the meaning of "plurality" is two or more.

[0131] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present disclosure includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present disclosure belong.

[0132] It should be understood that the various parts of the present disclosure can be implemented in hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0133] A person of ordinary skill in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0134] In addition, each functional unit in each embodiment of the present disclosure may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0135] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0136] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0137] Although the embodiments of the present disclosure have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present disclosure. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present disclosure.

Claims

1. A stellar field geometric calibration method taking into account time-space decoupling and non-steady-state imaging, characterized in that: The method comprises: Catalog the star fields adapted to the satellite based on the GAIA star catalog and the attitude performance of the optical remote sensing satellite; Constructing a star point extraction operator with a star motion compensation function to identify star points of star map features within the field of view of the satellite image generated by the star field to obtain star control points; Astronomical corrections for proper motion, parallax, and aberration in stellar coordinates; Obtain the observable limit stars and stellar imaging window values ​​according to the point spread function (PSF) of the imaging optical system, and adaptively weight the reliability of the stellar observation coordinates; An adaptive distortion model of the camera's internal orientation elements is constructed, and a stellar field geometric calibration model is constructed by performing a steady attitude correction on the satellite under non-steady imaging conditions according to the stellar control points; The stellar field geometric calibration model is solved based on the random sampling consistency method and the partial least squares method to obtain the geometric calibration parameters.

2. The method according to claim 1, characterized in that The star calibration field adapted to the satellite according to the catalog of GAIA star catalog and the attitude performance of optical remote sensing satellites includes: Determine the simulated star map image in the whole sky area according to the optical satellite field of view and resolution; Determine the number of star distributions, uniformity index, coverage index and non-collinearity index in the simulated star map image; The star field is determined according to the star distribution quantity, the uniformity index, the coverage index and the non-collinearity index.

3. The method according to claim 1, characterized in that The star point extraction operator with star motion compensation function is constructed to identify star points based on the star map features in the field of view of the satellite image generated by the GAIA star catalog to obtain star control points, including: According to the star motion direction and the star linear characteristics, the star point extraction operator with the star motion compensation function is constructed; Extracting star map features in the satellite image field of view based on the star point extraction operator; The star map features are processed based on a spectrum matching algorithm to determine the star control points.

4. The method according to claim 1, characterized in that The astronomical correction of proper motion, parallax and aberration in stellar coordinates includes: Adjust the star coordinates in the star catalog to determine the position of the star in the celestial coordinate system at the time of the shooting epoch; Perform parallax correction according to the parameters in the star catalog to eliminate the parallax caused by the annual and diurnal motions of the Earth; Performing parallax correction on the parameters in the star catalog to eliminate the parallax caused by the annual and diurnal motions of the Earth; Performing atmospheric refraction correction on the coordinates of stars in the star catalog; According to the direction of the optical axis at the moment of camera imaging, the satellite speed and the angle between the two, the object coordinates of the star are corrected for aberration.

5. The method according to claim 1, characterized in that The method of obtaining the observable limiting magnitude and the range of the stellar imaging window according to the point spread function PSF of the imaging optical system and adaptively weighting the reliability of the stellar observation coordinates includes: Get the signal-to-noise ratio (SNR) of the target star observed by image: Among them, Star is the number of electrons in the star signal, Background is the number of electrons in the background radiation, and Noise is sensor is the remote sensing sensor noise, and the observable limit magnitude Star Level 1.5 times the SNR is used as the threshold for observable stars; Calculate the pixel observation values ​​around the star imaging location based on the point spread function PSF of the imaging optical system; According to the observable limit star Star Level The coordinates of the unit weight variance Calculate the weights of the observed star coordinates Among them, i is the required observation constant i, is the variance of the observed stars, σ i The calculation formula is: in is the effective observation window value of the limiting star.

6. The method according to claim 5, characterized in that The step of constructing the camera internal orientation element adaptive distortion model comprises: According to the internal distortion of the image, an adaptive s-order model is constructed for the internal orientation elements: Among them, δ sample and δ line They represent the internal element distortion compensation items in the column direction and the row direction, respectively, and m i (i=0,1,2,...,s) represents the compensation model coefficient in the column direction, n i (i=0,1,2,...,s) represents the compensation model coefficient in the row direction, x and y represent the column and row coordinates of the image respectively, and s represents the adaptive order of the compensation model.

7. The method according to claim 6, characterized in that The geometric calibration model is expressed as: Among them, (α0, δ0) represent the right ascension and declination of the star point target in the celestial coordinate system obtained by star map recognition; (a i ,b i ,c i )(i=1,2,3) are represented as the nine elements of the attitude rotation matrix, which are the sine and cosine functions of the attitude Euler angles (α,ω,κ).

8. A stellar field geometric calibration device taking into account time-space decoupling and non-steady-state imaging, characterized in that: include: The first building block is used to catalogue the star field adapted to the satellite based on the GAIA star catalog and the attitude performance of the optical remote sensing satellite; The second construction module is used to construct a star point extraction operator with a star motion compensation function to perform star point recognition on star map features within the field of view of the satellite image generated by the star field to obtain star control points; Correction module, used for astronomical corrections of proper motion, parallax and aberration in stellar coordinates; The acquisition module is used to obtain the observable limit star and the star imaging window value according to the point spread function PSF of the imaging optical system, and to adaptively weight the reliability of the star observation coordinates; The third construction module is used to construct an adaptive distortion model of the camera's internal orientation elements, to perform a steady attitude correction on the satellite under non-steady imaging conditions according to the star control points, and to construct a star field geometric calibration model; The processing module is used to solve the stellar field geometric calibration model based on the random sampling consistency method and the partial least squares method to obtain the geometric calibration parameters.

9. An electronic device, characterized in that: include: processor; a memory for storing instructions executable by the processor; The processor is configured to execute the instructions to implement the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, when instructions in the computer-readable storage medium are executed by a processor of an electronic device, the electronic device is enabled to execute the method according to any one of claims 1 to 7.

Images