A method for geometric calibration of star field considering space-time decoupling and non-steady imaging

Abstract

The present disclosure provides a star field geometric calibration method considering space-time decoupling and non-steady imaging, which comprises: constructing a star point extraction operator with star motion compensation function according to the GAIA star catalog, the optical remote sensing satellite attitude performance catalog and the satellite adapted star field, to identify star points based on the star field generated satellite image field star map features, to obtain star control points, to make astronomical correction on proper motion, parallax and aberration in star coordinates, to obtain observable limit stars and star imaging window values according to the point spread function PSF of the image optical system, to adaptively weight the reliability of star observation coordinates, to construct an adaptive distortion model of camera interior orientation elements, to correct the attitude stability under the non-steady imaging condition of the satellite according to the star control points, to construct a star field geometric calibration model, and to solve the star field geometric calibration model based on the random sampling consistency method and the partial least squares method to obtain the geometric calibration parameters.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of optical remote sensing satellite image geometric processing, and particularly relates to a star field geometric calibration method considering space-time decoupling and non-steady imaging. BACKGROUND

[0002] In recent years, the earth observation satellite system gradually exhibits intelligent characteristics similar to the human brain, including perception, cognition and decision-making ability, thereby constructing an efficient space-based spatial information network. The system integrates multi-dimensional functions such as data acquisition, information extraction and intelligent perception, among which the high-resolution linear array push-broom camera is one of the key information sources. However, during the on-orbit operation of the satellite, the geometric imaging parameters of the camera are affected by multiple factors such as vibration, temperature stability and focal length adjustment, thereby causing changes in imaging parameters and serious decline in imaging quality. In order to ensure that the earth observation satellite system maintains a high level of geometric accuracy, it is necessary to implement high-frequency geometric calibration of the camera. Realizing the normalization of geometric calibration of high-resolution linear array cameras is of great significance to improving the efficiency of the earth observation satellite system.

[0003] Satellite constellation refers to a set of on-orbit and normally operating satellites that work together in a specific configuration. Compared with the traditional single-satellite service mode, constellation satellites have the characteristics of rich load types, wide high-low orbit span, complex and diverse application scenarios, and more refined service mode. In recent years, with the continuous development of domestic and foreign commercial remote sensing companies, they have begun to gradually deploy satellite constellations, aiming to achieve rapid acquisition of remote sensing information in the global range through constellation networking. However, at the current stage, the traditional geometric calibration method cannot meet the needs of constellation in data processing and service provision. Therefore, it is an important challenge in the current remote sensing field to conduct in-depth research and innovation on the calibration method of constellation satellites to adapt to their complex operating environment and diverse application scenarios.

[0004] The calibration method based on star field significantly overcomes the limitations of traditional calibration methods and field-free calibration methods, especially in high-frequency calibration of high-resolution linear array cameras. However, there are inherent differences between star observation and traditional observation imaging modes. Due to the constraints of attitude stability, the stars may appear blurred in the image, and robust extraction of the star is crucial. In addition, there are differences in imaging time for each row of the linear array, and attitude stability correction is very important for star field calibration under non-steady satellite imaging conditions. SUMMARY

[0005] The present disclosure proposes a star field geometric calibration method considering space-time decoupling and non-steady imaging, device, electronic equipment, storage medium and computer program product, aiming to at least solve the technical problems in the related art to some extent.

[0006] The first aspect of the present disclosure provides a star field geometric calibration method considering space-time decoupling and non-steady imaging, comprising: constructing a star field adapted to a GAIA star catalog and an optical remote sensing satellite attitude performance catalog; constructing a star point extraction operator with a star motion compensation function to identify star points based on star field generated star map features in a satellite image field of view to obtain star control points; performing astronomical correction on proper motion, parallax and aberration in star coordinates; obtaining observable limit stars and star imaging window values according to a point spread function (PSF) of an image optical system, and adaptively weighting the reliability of star observation coordinates; constructing an adaptive distortion model of camera interior orientation elements, correcting satellite non-steady imaging conditions according to star control points, and constructing a star field geometric calibration model; and solving the star field geometric calibration model based on a random sample consensus method and a partial least squares method to obtain geometric calibration parameters.

[0007] The second aspect of the present disclosure provides a star field geometric calibration device considering space-time decoupling and non-steady imaging, comprising: a first construction module configured to construct a star field adapted to a GAIA star catalog and an optical remote sensing satellite attitude performance catalog; a second construction module configured to construct a star point extraction operator with a star motion compensation function to identify star points based on star field generated star map features in a satellite image field of view to obtain star control points; a correction module configured to perform astronomical correction on proper motion, parallax and aberration in star coordinates; an acquisition module configured to obtain observable limit stars and star imaging window values according to a point spread function (PSF) of an image optical system, and adaptively weighting the reliability of star observation coordinates; a third construction module configured to construct an adaptive distortion model of camera interior orientation elements, correct satellite non-steady imaging conditions according to star control points, and construct a star field geometric calibration model; and a processing module configured to solve the star field geometric calibration model based on a random sample consensus method and a partial least squares method to obtain geometric calibration parameters.

[0008] The third aspect of the present disclosure provides an electronic device, comprising: a processor; a memory for storing processor-executable instructions; wherein the processor is configured to execute the instructions to implement a star field geometric calibration method considering space-time decoupling and non-steady imaging.

[0009] The fourth aspect of the present disclosure provides a computer-readable storage medium, when the instructions in the computer-readable storage medium are executed by the processor of the electronic device, the electronic device can execute the star field geometric calibration method considering space-time decoupling and non-steady imaging.

[0010] The fifth aspect of the present disclosure provides a computer program product comprising a computer program, wherein the computer program is configured to execute the star field geometric calibration method considering space-time decoupling and non-steady imaging by a processor.

[0011] The star field geometric calibration method, device, electronic device, storage medium and computer program product considering space-time decoupling and non-steady imaging have at least the following beneficial effects: a star point extraction operator with star motion compensation function is constructed according to the GAIA star catalog and the star field adapted to the attitude performance catalog of the optical remote sensing satellite, so as to identify star points based on the star field to generate star map features in the field of view of the satellite image, obtain star control points, perform astronomical correction 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 image optical system, and adaptively weight the reliability of the star observation coordinates, construct an adaptive distortion model of the camera interior orientation elements, correct the attitude stability under the non-steady imaging condition 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 consensus method and the partial least squares method to obtain geometric calibration parameters, so as to realize high-precision extraction of star points under space-time decoupling, adaptive coordinate weighting considering star brightness, attitude stability correction under non-steady imaging condition, and significantly improve the geometric positioning accuracy of the optical remote sensing satellite.

[0012] The additional aspects and advantages of the present disclosure will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

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

[0014] Figure 1 is a flowchart of a star field geometric calibration method considering space-time decoupling and non-steady imaging according to the first embodiment of the present disclosure;

[0015] Figure 2 is a block diagram of a star field geometric calibration device considering space-time decoupling and non-steady imaging according to the present disclosure;

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

[0017] Embodiments of the present disclosure are described below in detail, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only, for the purpose of explanation, and are not to be understood as limiting the present disclosure. On the contrary, the embodiments of the present disclosure include all changes, modifications and equivalents falling within the spirit and scope of the appended claims.

[0018] It should be noted that the execution subject of the star field geometric calibration method considering space-time decoupling and non-steady-state imaging in this embodiment can be a star field geometric calibration device considering space-time decoupling and non-steady-state imaging. The device can be realized by software and / or hardware. The device can be configured in an electronic device, which can include but is not limited to a terminal, a server end, and the like.

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

[0020] Figure 1 is a flowchart of the star field geometric calibration method considering space-time decoupling and non-steady-state imaging according to the first embodiment of the present disclosure, as shown in Figure 1 , the method comprises:

[0021] S101: According to the GAIA star catalog and the optical remote sensing satellite attitude performance catalog and the satellite adapted star field.

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

[0023] In the embodiments of the present disclosure, based on the simulation of stars in the whole sky field according to the GAIA star catalog, the FOV and the resolution of the optical satellite can be determined according to the FOV / 10 interval, Star Level is the observable magnitude, and the simulation star image in the whole sky area is obtained, and the number Num Star of stars, the uniformity, the coverage and the non-collinearity index of the star distribution in the field of view of a single satellite image are constructed, wherein the specific steps for determining the number Num Star of stars, the uniformity, the coverage and the non-collinearity index of the star distribution are as follows:

[0024] (1) Quantity index calculation: the number of stars in the field of view is counted to obtain Num Star index.

[0025] (2) Calculation of uniformity index: the range R and the standard deviation δ of the horizontal coordinates in the field of view are counted, which are used as the uniformity index of the star distribution in the field of view.

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

[0027]

[0028] Wherein, sample max and sample min are the maximum and minimum values of the column coordinates of the stars in the field of view on the image, line max and line min are the maximum and minimum values of the row coordinates of the stars in the field of view on the image.

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

[0030]

[0031] Wherein, sample i and sample i are the average column coordinates and row coordinates of the Num Star stars on the image, sample ave and line ave are the average column coordinates and row coordinates of the Num Star stars on 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, then traverse the remaining star points in the field of view, calculate the distance from the star to the fitted straight line, set a threshold θ, and the star points less than the threshold can be considered to be on the straight line and be removed, and the number of star points not on the straight line is counted as the non-collinearity index.

[0033] In the embodiments of the present disclosure, suitable star fields can be selected according to the reference points on the same straight line required by external calibration, and the CCD covers more than 6 star points in the field of view required by internal calibration, the whole sky field is screened, and the region suitable for geometric calibration of the whole sky field is obtained.

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

[0035] Optionally, in some embodiments, a star point extraction operator with a star motion compensation function is constructed to identify star points of star map features in the satellite image field of view based on a GAIA star catalog to obtain star control points, which can be constructing a star point extraction operator with a star motion compensation function according to the star motion direction and the star linear feature, extracting star map features in the satellite image field of view based on the star point extraction operator, and processing the star map features based on a graph matching algorithm to determine the star control points.

[0036] In the embodiments of the present disclosure, the star point extraction operator with the star motion compensation function can be fitted based on an anisotropic Gaussian surface considering the star motion direction and the linear feature, and the star image is multiplied by a rotation matrix R θ :

[0037]

[0038] Further, the Gaussian surface fitting formula is obtained as follows:

[0039]

[0040] wherein A is a fixed coefficient, σ x and σ y represent Gaussian function mean square deviations in x and y directions respectively, and exp(·) is an exponential function. When at least six star pixels are needed to fit the star centroid based on the anisotropic Gaussian surface, if the number of star pixels in the image is less than six, the star target pixels need to be interpolated by an interpolation method.

[0041] In the embodiments of the present disclosure, the star map features in the satellite image field of view can be extracted based on the star point extraction operator, which can be generating total edge weight features w J (minimum spanning tree MST) and adjacency matrix A J of each of more than 92 stars J in the GAIA star catalog, wherein the total edge weight w J is used for coarse search, and the adjacency matrix A J is used for subsequent graph matching.

[0042] (1) Minimum spanning tree MST of neighbor graph G J : Select a main star J and draw a neighbor circle with a radius r; generate the neighbor graph G J of J by regarding the stars as vertices and regarding the angular interval between star pairs as weighted edges. Jis a complete 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 Kruskal algorithm J ;

[0043] (2) The neighbor graph G J ; J is generated: the adjacency matrix A J (i,j)=θ i,j , used for calculating the angular distance angle distance θ between star i and star j i,j The calculation formula is: Wherein and are unit vectors of stars i and j in the inertial coordinate system.

[0044] In the embodiments of the present disclosure, the specific steps for determining the star control points based on the graph matching algorithm processing the star map features are as follows:

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

[0046] (2) The spectral graph matching algorithm is used to match the neighbor graph G I and G J , and the corresponding star matching points are obtained, so as to complete the identification of the extracted star control points.

[0047] S103: Astronomical correction is performed on the proper motion, parallax and annual aberration in the star coordinates.

[0048] In the embodiments of the present disclosure, after the star point extraction operator with star motion compensation function is constructed to identify the star points based on the star field generated satellite image field-of-view star map features, and the star control points are obtained, the astronomical correction can be performed on the proper motion, parallax and annual aberration in the star coordinates.

[0049] Optionally, in some embodiments, the astronomical correction of the proper motion, parallax and annual aberration in the star coordinates can be adjusting the star coordinates in the star table to determine the position of the star in the celestial coordinate system at the shooting epoch, correcting the parallax according to the parameters in the star table to eliminate the parallax caused by the annual and daily motion of the earth, correcting the parallax of the parameters in the star table to eliminate the parallax caused by the annual and daily motion of the earth, correcting the atmospheric refraction of the star coordinates in the star table, and correcting the annual aberration of the object coordinates of the star according to the pointing direction of the optical axis at the camera imaging time, the satellite speed, and the included angle between them.

[0050] In the embodiments of the present disclosure, the star right ascension and declination after self-motion and parallax correction is (α, δ), and the atmospheric refraction and aberration correction is represented as a rotation matrix R related to the imaging time t Abert

[0051]

[0052] wherein m is a proportional coefficient, is a rotation matrix of the camera coordinate system to the J2000 coordinate system at the imaging time t, (x, y) is the column and row coordinates of the image, (x0, y0) is the principal point coordinates of the image, and f is the principal distance of the image.

[0053] S104: Obtain observable limit stars and star imaging window values according to the point spread function PSF of the image optical system, and perform adaptive weighting on the reliability of the star observation coordinates.

[0054] In the embodiments of the present disclosure, the observable limit stars and star imaging window values can be obtained according to the point spread function PSF of the image optical system, and the reliability of the star observation coordinates can be adaptively weighted.

[0055] Optionally, in some embodiments, the observable limit stars and star imaging window values can be obtained according to the point spread function PSF of the image optical system, and the reliability of the star observation coordinates can be adaptively weighted, which can be to obtain the signal-to-noise ratio SNR of the target star of the image observation:

[0056]

[0057] wherein Star is the number of electrons of the star signal, Background is the number of background radiation electrons, Noise is the noise of the remote sensing sensor, and SNR is the signal-to-noise ratio. sensor The observable limit star is Star Level 1.5 times the SNR as the observable star threshold;

[0058] According to the point spread function PSF of the image optical system, the observation values of the pixels around the star imaging are calculated.

[0059] According to the observable limit star Star Level , the coordinate is the unit weight variance The weight of the observed star coordinates is calculated wherein i is the observed star i, is the variance of the observed star, and σ i The calculation formula is: wherein is the effective observation window value of the limit star.

[0060] ​The specific steps for calculating the pixel observations around the star image based on the point spread function (PSF) of the image optical system are as follows:

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

[0062]

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

[0064] (2) For position coordinates (x) p ,y p Integrating the energy at x, we obtain the energy E(x). p ,y p );

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

[0066] (4) The effective observation window for stars is the window range where the pixel value at the center of the star is reduced to 5%.

[0067] In this embodiment of the disclosure, the observable limiting magnitude Star can be used. Level The coordinates are unit weight variance Weights for calculating the coordinates of the observed stars Where i is the desired observation constant i. σ represents the variance of the observed stars. i The calculation formula is: in This represents the effective observation window size for limiting magnitudes.

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

[0069] In the embodiments of the present disclosure, after the observable limit star and the star imaging window value are obtained according to the point spread function (PSF) of the image optical system, and the reliability of the star observation coordinates is adaptively weighted, an adaptive distortion model of the camera interior orientation elements can be constructed, and the attitude stabilization correction under the non-stationary imaging condition of the satellite can be performed according to the star control points, and a star field geometric calibration model can be constructed.

[0070] Optionally, in some embodiments, the adaptive distortion model of the camera interior orientation elements can be constructed according to the interior distortion of the image, and an adaptive s-order model can be constructed for the interior orientation elements:

[0071]

[0072] wherein, δ sample and δ line respectively represent the interior orientation element distortion compensation terms in the column direction and the row direction, m i (i=0, 1, 2,..., s) represents the compensation model coefficients in the column direction, n i (i=0, 1, 2,..., s) represents the compensation model coefficients in the row direction, x and y respectively represent the column and row coordinates of the image, and s represents the adaptive order of the compensation model.

[0073] In the embodiments of the present disclosure, after the adaptive distortion model of the camera interior orientation elements is constructed, the attitude stabilization correction under the non-stationary imaging condition of the satellite can be performed according to the star control points, and a star field geometric calibration model can be constructed.

[0074] That is to say, in the embodiments of the present disclosure, the attitude can be compensated according to the modified star control point positions as the reference in the entire view angle range of the image, the original attitude data is inversely calculated to the image according to the modified star control point positions, and then the attitude compensation value adjustment equation is established according to the difference between the coordinates of the inversely calculated image side and the actual coordinates, so that the stabilized attitude data is obtained.

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

[0076]

[0077] wherein, (α0, δ0) respectively represent the right ascension and declination of the star point target in the celestial coordinate system identified through the star map; (a i ,b i ,c i )(i=1, 2, 3) represent nine elements of the attitude rotation matrix, which are the cosine functions of the attitude Euler angles (α, ω, κ).

[0078] S106: The star field geometric calibration model is solved based on the random sample consensus method and the partial least squares method to obtain the geometric calibration parameters.

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

[0080] (1) Further, partial least squares (PLS) is used to solve the geometric calibration model of the stellar field: if the coordinates (x, y) of its star image point are taken as the observed values, 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 term is expanded according to Taylor series to obtain the error observation equation of the star target image point coordinates. The unknowns are then solved according to the partial least squares (PLS) method.

[0081] (2) The random sampling consensus algorithm is used to select the stellar control point with the highest number of inner points as the input for solving the model parameters. Ten stellar control points are selected in the image. The inner and outer element calibration coefficients of the image are calculated using 51). The obtained calibration coefficients are then compensated into the image. With a threshold of 0.5 pixels, the number of the remaining inner points is counted. Then, a set of 10 stellar control points with the highest number of inner points is searched in a loop as the input for the final solution of the geometric calibration model.

[0082] In this embodiment, a star point extraction operator with stellar motion compensation function is constructed by cataloging the GAIA star catalog and the attitude performance of optical remote sensing satellites and adapting the stellar field to the satellite. This operator identifies star points in the star map features of the satellite image field generated based on the stellar field, obtains stellar control points, performs astronomical corrections on proper motion, parallax, and axial aberration in the stellar coordinates, obtains the observable limit star and stellar imaging window value based on the point spread function (PSF) of the image optical system, adaptively weights the reliability of the stellar observation coordinates, constructs an adaptive distortion model of the camera's in-camera orientation elements, performs attitude stability correction under non-stationary imaging conditions based on the stellar control points, constructs a stellar field geometric calibration model, and solves the stellar field geometric calibration model based on the random sampling consistency method and partial least squares method to obtain geometric calibration parameters. This enables high-precision extraction of star points under spatiotemporal decoupling, adaptive weighting of coordinates considering star magnitude brightness, and attitude stability correction under non-stationary imaging conditions, significantly improving the geometric positioning accuracy of optical remote sensing satellites.

[0083] Figure 2 This is a block diagram of a stellar field geometry calibration device for spatiotemporal decoupling and unsteady-state imaging, as shown in this disclosure. Figure 2 As shown, the stellar field geometry calibration device 20, which considers spatiotemporal decoupling and unsteady-state imaging, includes:

[0084] The first construction module 201 is configured to construct a star field according to the GAIA star catalog and an optical remote sensing satellite attitude performance catalog and a star field adapted to a satellite;

[0085] The second construction module 202 is configured to construct a star point extraction operator with a star motion compensation function to identify star points based on a star field to generate a star map feature in a satellite image field of view, and obtain star control points.

[0086] The correction module 203 is configured to perform astronomical correction on proper motion, parallax and aberration of the star coordinates.

[0087] The acquisition module 204 is configured to acquire observable limit stars and star imaging window values according to a point spread function PSF of an image optical system, and perform adaptive weighting on the reliability of star observation coordinates.

[0088] The third construction module 205 is configured to construct an adaptive distortion model of camera interior orientation elements, correct satellite non-stationary imaging conditions according to the star control points, and construct a star field geometric calibration model.

[0089] The processing module 206 is configured to solve the star field geometric calibration model based on a random sample consensus method and a partial least squares method to obtain geometric calibration parameters.

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

[0091] determine a simulated star map image in the entire sky region according to a field of view FOV and a resolution of the optical satellite;

[0092] determine a star distribution quantity, a uniformity index, a coverage index and a non-collinearity index in the simulated star map image;

[0093] determine the star field according to the star distribution quantity, the uniformity index, the coverage index and the non-collinearity index.

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

[0095] construct a star point extraction operator with a star motion compensation function according to a star motion direction and a star linear feature;

[0096] extract a star map feature in the satellite image field of view based on the star point extraction operator;

[0097] process the star map feature based on a graph matching algorithm to determine the star control points.

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

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

[0100] Correct the parallax according to the parameters in the star catalog to eliminate the parallax caused by the annual and daily motion of the earth;

[0101] Correct the parallax according to the parameters in the star catalog to eliminate the parallax caused by the annual and daily motion of the earth;

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

[0103] According to the pointing direction of the optical axis of the camera at the imaging time, the satellite speed, and the included angle between the two, correct the aberration of the star on the object side.

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

[0105] Obtain the signal-to-noise ratio (SNR) of the target star in the image observation:

[0106]

[0107] Where Star is the number of electrons of the star signal, Background is the number of background radiation electrons, Noise is the noise of the remote sensing sensor, and Star is the observable limit star. sensor Star is the observable limit star. Level 1.5 times the SNR is taken as the observable star threshold;

[0108] Calculate the observed value of the pixels around the star imaging according to the point spread function (PSF) of the image optical system;

[0109] According to the coordinates of the observable limit star Star Level , the unit weight variance is calculated. The weight of the observed star coordinates is calculated. Where i is the observed star i, is the variance of the observed star, and σ i The calculation formula is: Where is the effective observation window value of the limit star.

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

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

[0112]

[0113] Where δ sample and δ linedenote the internal orientation element distortion compensation terms in the column and row directions, respectively, m i denote the compensation model coefficients in the column direction, n i denote the compensation model coefficients in the row direction, x and y denote the column and row coordinates of the image, respectively, and s denotes the adaptive order of the compensation model.

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

[0115]

[0116] where (a0, d0) denote the right ascension and declination of the star point target identified by the star map in the celestial coordinate system, respectively; (a i ,b i ,c i )(i = 1, 2, 3) denote the nine elements of the attitude rotation matrix, which are the cosine functions of the attitude Euler angles (a, w, k).

[0117] In the present embodiment, a star point extraction operator with star motion compensation function is constructed by adapting the star field to the GAIA star catalog and the attitude performance catalog of the optical remote sensing satellite, to perform star point identification on the star map features in the field of view of the satellite image generated based on the star field, to obtain star control points, to perform astronomical correction on the proper motion, parallax and aberration in the star coordinates, to obtain the observable limit stars and star imaging window values according to the point spread function PSF of the image optical system, to perform adaptive weighting on the reliability of the star observation coordinates, to construct an adaptive distortion model of the camera internal orientation elements, to perform attitude smoothing correction under non-stable imaging conditions of the satellite according to the star control points, to construct a star field geometric calibration model, to solve the star field geometric calibration model based on the random sampling consistency method and the partial least squares method, to obtain the geometric calibration parameters, so as to realize high-precision extraction of star points under the decoupling of time and space factors, adaptive coordinate weighting considering star brightness, attitude smoothing correction under non-stable imaging conditions, and significantly improve the geometric positioning accuracy of the optical remote sensing satellite.

[0118] To realize the above-mentioned embodiments, the present application further provides an electronic device, comprising a processor and a memory in communication connection with the processor; the memory stores computer execution instructions; and the processor executes the computer execution instructions stored in the memory to realize the star field geometric calibration method considering time and space decoupling and non-stable imaging provided by the foregoing embodiments.

[0119] To achieve the above-mentioned embodiments, the application further provides a computer readable storage medium, wherein the computer readable storage medium stores computer execution instructions, and the computer execution instructions are executed by a processor to implement the star field geometric calibration method considering space-time decoupling and non-steady imaging provided by the foregoing embodiments.

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

[0121] Figure 3 The electronic device 7 shown is merely an example and should not limit the function and scope of use of the embodiments of the disclosure in any way.

[0122] As shown in Figure 3 The electronic device 7 is in the form of a general computing device. The components of the electronic device 7 can include, but are not limited to, one or more processors or processing units 16, memory 28, and a bus 18 that connects 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 bus, a processor or local bus using any of a variety of bus architectures. 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 Interconnect (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 and includes both volatile and nonvolatile media, removable and non-removable media.

[0125] Memory 28 can include computer system readable media in the form of volatile memory, such as random access memory (RAM) 30 and / or cache memory 32. Electronic device 7 can further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, storage system 34 can be provided for reading from and writing to a non-removable, non-volatile magnetic media (not shown and typically called a "hard drive"). Figure 3

[0126] Although Figure 3 not shown in FIG. 1, a disk drive, an optical disk drive and / or a tape drive, a flash memory or other similar medium can also be used. In these instances, each can also be connected to bus 18 by one or more data media interfaces. The drives and their associated computer-readable media provide nonvolatile storage of data, data structures, computer-executable instructions and so on for electronic device 7. For example, a hard disk can used for non-volatile memory according to some embodiments. Although

[0127] The programs / utility 40, having a set (at least one) of program modules 42, can be stored in memory 28 by way of example, and not limitation, as well as an operating system, one or more application programs, other program modules, and program data, each or some combination thereof, can include implementation of the network environment. The programs 42 generally carry out the functions and / or methodologies of embodiments of the disclosure as described herein.

[0128] ​The electronic device 7 can also communicate with one or more external devices 14 such as a keyboard, a pointing device, a display 24, etc.; other human interface devices; and / or one or more devices that enable functionality of the electronic device 7 such as a card reader, a modem, a network adapter, etc. This communication can be via the input / output (I / O) interface 22. Still yet, the electronic device 7 can communicate with one or more networks, such as a local area network (LAN), a wide area network (WAN), and / or the Internet, through a network adapter 20. As an example, the network adapter 20 can include a modem you can use to connect to the Internet or other external devices. The network adapter 20 can be any of a number of devices you can use to connect to a network including, but not limited to, a modem, a network adapter, a token ring adapter, etc. Further, the electronic device 7 can include one or more input / output (I / O) devices 22 such as a keyboard, a mouse, etc. The input / output (I / O) devices 22 can include one or more devices that enable a human user to interact with the electronic device 7 and / or one or more devices that enable the electronic device 7 to interact with one or more other devices. As an example, the input / output (I / O) devices 22 can include a display, a keyboard, a mouse, a printer, etc.

[0129] The processing unit 16 performs various function applications and parameter information determinations by running programs stored in the memory 28, such as implementing the star field geometric calibration method for business with spatio-temporal decoupling and non-steady-state imaging mentioned in the foregoing embodiments, or implementing the business data acquisition method mentioned in the foregoing embodiments.

[0130] It should be noted that in the description of the present disclosure, the terms "first", "second", etc. are only for the purpose of description 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 "a plurality of" is two or more.

[0131] Any process or method descriptions or any other descriptions in flow charts or otherwise herein described can be understood as representing code modules, segments, or portions of code that include one or more executable instructions for implementing specific logic functions or other steps in the processes. The various embodiments of the present disclosure can include additional or fewer steps or processes, and the order of the steps or processes can be changed, including according to the function involved, without departing from the scope of the embodiments of the present disclosure, which should be understood by those skilled in the art.

[0132] It should be understood that various parts of the present disclosure can be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, and as in another embodiment, it can be implemented by any one or a combination of the following technologies known in the art: discrete logic circuit with logic gates for implementing logical functions of data signals, application specific integrated circuit (ASIC) with appropriate combination logic gates, programmable gate array (PGA), field programmable gate array (FPGA), etc.

[0133] Those skilled in the art of the present technology can understand that all or part of the steps carried out by the above-mentioned embodiment method can be completed by a program instructing the relevant hardware, and the program can be stored in a computer readable storage medium. When the program is executed, it 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 can be integrated into one processing module, or each unit can exist physically separately, or two or more units can be integrated into one module. The above-mentioned integrated module can be realized in the form of hardware or in the form of a software function module. When the integrated module is realized in the form of a software function module and sold or used as an independent product, it can 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 the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. In the present specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can 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 should be understood that the above-described embodiments are exemplary and cannot be understood as limiting the present disclosure, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present disclosure.

Claims

1. A method for geometric calibration of star field considering spatio-temporal decoupling and non-stationary imaging, characterized in that, The method comprises: a star field adapted to the GAIA star table and the attitude performance catalog of an optical remote sensing satellite; constructing a star point extraction operator with star motion compensation function to identify star points of star map features in the star field to generate a satellite image field to obtain star control points; astronomically correcting proper motion, parallax and aberration in star coordinates; obtaining observable limit stars and star imaging window values according to a point spread function (PSF) of an image optical system and adaptively weighting reliability of star observation coordinates; constructing an adaptive distortion model of camera interior orientation elements, correcting attitude stability under non-stable imaging conditions of the satellite according to the star control points, and constructing a star field geometric calibration model; solving the star field geometric calibration model based on a random sample consensus (RANSAC) method and a partial least squares (PLS) method to obtain geometric calibration parameters; wherein the obtaining observable limit stars and star imaging window values according to the PSF of the image optical system and adaptively weighting reliability of star observation coordinates comprises: Signal-to-noise ratio of target star for acquisition imagery observation : ， wherein, Background is the background radiation electrons, is the remote sensing sensor noise, and 1.5 times the SNR is taken as the observable star threshold, and when the SNR reaches 1.5 times, the corresponding star magnitude is the observable limit star magnitude ; calculating pixel observation values around star imaging according to the PSF of the image optical system; The The corresponding star is taken as the observable limit star, and the weight variance of the coordinate of the observable limit star is taken as the unit weight variance The weight of the observed star coordinate is calculated , wherein The observed star , The variance of the observed star is The calculation formula is: , wherein The effective observation window value of the limit star.

2. The method of claim 1, wherein, the star calibration field adapted to the GAIA star table and the attitude performance catalog of the optical remote sensing satellite comprises: determining a simulated star map image in the whole sky according to a field angle and resolution of the optical satellite; determining a star distribution quantity, uniformity index, coverage index and non-collinearity index in the simulated star map image; determining the star calibration field according to the star distribution quantity, the uniformity index, the coverage index and the non-collinearity index.

3. The method of claim 1, wherein, The constructing a star point extraction operator with star motion compensation function to identify star points of star map features in the star field to generate a satellite image field to obtain star control points comprises: constructing the star point extraction operator with star motion compensation function according to a star motion direction and a star linear feature; extracting star map features in the satellite image field based on the star point extraction operator; processing the star map features based on a graph matching algorithm to determine the star control points.

4. The method of claim 1, wherein, The astronomically correcting proper motion, parallax and aberration in star coordinates comprises: adjusting star coordinates in a star table to determine a position of a star in a celestial coordinate system at a shooting epoch; performing parallax correction according to parameters in the star table to eliminate parallax caused by annual and daily motions of the earth; performing atmospheric refraction correction on the star coordinates in the star table; correcting an object side coordinate of the star according to a pointing direction of an optical axis at a camera imaging time, a satellite speed and an included angle between the optical axis and the satellite speed.

5. The method of claim 1, wherein, The constructing an adaptive distortion model of camera interior orientation elements comprises: According to the internal distortion condition of the image, an adaptive order model is constructed for the internal orientation elements: ， wherein, and respectively represent the column direction and the row direction internal orientation element distortion compensation terms, represents the compensation model coefficient in the column direction, represents the compensation model coefficient in the row direction, and respectively represent the column and row coordinates of the image, represents the adaptive order of the compensation model.

6. The method of claim 5, wherein, the geometric calibration model is expressed as: ； Wherein, a0 is the right ascension of the star point target identified by the star map in the celestial coordinate system; The nine elements of the attitude rotation matrix are the cosine and sine functions of the attitude Euler angles .

7. A device for geometric calibration of a star field, taking into account spatio-temporal decoupling and non-stationary imaging, characterized in that, comprises: a first constructing module for a star field adapted to the GAIA star table and the attitude performance catalog of an optical remote sensing satellite; a second constructing module for constructing a star point extraction operator with star motion compensation function to identify star points of star map features in the star field to generate a satellite image field to obtain star control points; A correction module is configured to correct the proper motion, parallax and aberration in the star coordinates; An acquisition module is configured to acquire observable limit stars and star imaging window values according to a point spread function (PSF) of an image optical system, and to perform adaptive weighting on the reliability of star observation coordinates; A third construction module is configured to construct an adaptive distortion model of camera interior orientation elements, to correct a non-stable attitude of a satellite under a star control point, and to construct a star field geometric calibration model; A processing module is configured to solve the star field geometric calibration model based on a random sample consensus method and a partial least squares method to obtain geometric calibration parameters; The acquisition of observable limit stars and star imaging window values according to the PSF of the image optical system and the adaptive weighting on the reliability of star observation coordinates include: Signal-to-noise ratio of target star for acquisition imagery observation : ， wherein, Background is the background radiation electrons, is the remote sensing sensor noise, and 1.5 times the SNR is taken as the observable star threshold, and when the SNR reaches 1.5 times, the corresponding star magnitude is the observable limit magnitude ; calculating the observation values of pixels around the star imaging according to the PSF of the image optical system; The The corresponding star is taken as the observable limit star, and the weight variance of the coordinate of the observable limit star is taken as the unit weight variance , the weight of the observed star coordinate is calculated , wherein is the observed star , is the variance of the observed star The calculation formula is: , wherein is the effective observation window value of the limit star.

8. An electronic device, comprising: The system includes: a processor; a memory for storing instructions executable by the processor; wherein the processor is configured to execute the instructions to implement the method of any one of claims 1-6. 9.A computer-readable storage medium, when instructions in the computer-readable storage medium are executed by a processor of an electronic device, enabling the electronic device to perform the method of any one of claims 1-6.

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