CN117478197A - Determination method for active push-broom imaging integration time of optical agile satellite - Google Patents

Determination method for active push-broom imaging integration time of optical agile satellite Download PDF

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CN117478197A
CN117478197A CN202311211363.5A CN202311211363A CN117478197A CN 117478197 A CN117478197 A CN 117478197A CN 202311211363 A CN202311211363 A CN 202311211363A CN 117478197 A CN117478197 A CN 117478197A
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coordinate system
satellite
camera
optical
photographing point
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余婧
王跃
杨文涛
范立佳
姜洋
汪精华
于龙江
李雨廷
刘亚利
李何羿
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China Academy of Space Technology CAST
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    • H04—ELECTRIC COMMUNICATION TECHNIQUE
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
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    • H04B7/15—Active relay systems
    • H04B7/185—Space-based or airborne stations; Stations for satellite systems
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Abstract

A method for determining the integral time of active push-broom imaging of an optical agile satellite comprises the following steps: (1) Acquiring the calculation time, orbit parameters and attitude data of an optical agile satellite and the position of a camera in a satellite body coordinate system; (2) Determining a theoretical photographing point of a camera visual axis on the ground, and combining the theoretical photographing point geographic elevation data to obtain a real photographing point and a distance between a satellite and the real photographing point; (3) Calculating the ground speed vector of a real photographing point in a camera body coordinate system; (4) And calculating the integration time of the camera according to the distance between the satellite and the real photographing point and the ground speed vector of the real photographing point in the camera body coordinate system. The method fully considers the influence of the satellite attitude angle and the satellite attitude angular speed in the imaging process, and is applicable to both an active push-broom imaging mode and a traditional passive push-broom imaging mode.

Description

Determination method for active push-broom imaging integration time of optical agile satellite
Technical Field
The invention belongs to the technical field of overall design of optical remote sensing satellites, and relates to an integral time calculation method of an optical remote sensing satellite in an active push-broom imaging mode.
Background
Currently, the main high-resolution commercial remote sensing satellites in the world are agile satellites, such as Ikonos series, worldview series, french Pleiades series and the like in the United states, domestic high-resolution multimode satellites, high-view series satellites, beijing No. 3 satellites and the like.
The agile satellite can realize large-angle rapid maneuvering in a short time, compared with the traditional satellite, the attitude of the agile satellite can maneuver along 3 axial directions of rolling, pitching and yawing, when the satellite is positioned in front of, above and behind a target, the target can be observed, any time period can be freely selected in a longer time window to observe the target, and the imaging while maneuvering, namely 'imaging in motion', or 'active push-broom imaging', is realized, and the imaging mode is different from the traditional imaging mode of carrying out passive push-broom depending on the orbit speed, so that the flexibility of satellite observation can be greatly improved.
In the active push-broom imaging process of the optical remote sensing satellite, the observation slope distance and the image plane scanning speed are continuously changed, and the calculation method of the integration time is different from the traditional passive push-broom imaging process, so that the influence of the attitude angle and the attitude angular speed of the satellite on the integration time is required to be considered. There is no disclosure or data related to a detailed calculation method of integration time in an active push-broom imaging mode.
Disclosure of Invention
The invention solves the technical problems that: the method for determining the integral time of the optical agile satellite in the mode is suitable for passive push-broom imaging and active push-broom imaging processes.
The technical scheme of the invention is as follows: a method for determining the integral time of active push-broom imaging of an optical agile satellite comprises the following steps:
(1) Acquiring the calculation time, orbit parameters and attitude data of an optical agile satellite and the position of a camera in a satellite body coordinate system;
(2) Determining a theoretical photographing point of a camera visual axis on the ground, and combining the theoretical photographing point geographical elevation data to obtain a real photographing point and a distance between an optical agile satellite and the real photographing point;
(3) Calculating the ground speed vector of a real photographing point in a camera body coordinate system;
(4) And calculating the integration time of the camera according to the distance between the optical agile satellite and the real photographing point and the ground speed vector of the real photographing point in the camera body coordinate system.
Further, the orbit parameters include the position of the optical agile satellite in the WGS84 coordinate system, and the attitude data include the roll angle, pitch angle and yaw angle of the optical agile satellite.
Further, the determining the theoretical photographing point of the visual axis of the camera on the ground specifically includes:
(31) Acquiring a vector of a camera visual axis in a satellite body coordinate system, and obtaining a vector representation of the camera visual axis in a ground fixed coordinate system through coordinate system conversion;
(32) According to the position of the optical agile satellite in the ground fixed coordinate system and the position of the camera visual axis vector in the ground fixed coordinate system, a space linear equation of the camera visual axis vector in the ground fixed coordinate system is obtained, and an intersection point between the camera visual axis vector and an earth ellipsoid is obtained by combining the space linear equation and the earth ellipsoid equation, namely a theoretical photographing point;
(33) And obtaining the corrected real photographing point according to the theoretical photographing point position and the geographic elevation data of the theoretical photographing point, thereby obtaining the distance between the optical agile satellite and the real photographing point.
Further, the method obtains the vector of the camera visual axis in the satellite body coordinate system, and obtains the vector representation of the camera visual axis in the ground fixed coordinate system through coordinate system conversion, specifically comprises the following steps:
C F ＝L ECF,ECI ·L ECI,o ·L ob ·C C
wherein C is C ＝[X C Y C Z]′ C C is the vector representation of the camera visual axis in the satellite body coordinate system F ＝[X F Y F Z F ]'is a vector representation of the camera's visual axis in a geodetic fixed coordinate system, where L ECF,ECI L is a transformation matrix from a J2000 inertial coordinate system to a ground-fixed coordinate system ECI,o L is a transformation matrix from a satellite orbit coordinate system to a J2000 inertial coordinate system ob Is a transformation matrix from the satellite body coordinate system to the orbital coordinate system.
Further, the transformation matrix L from the J2000 inertial coordinate system to the ground-fixed coordinate system ECF,ECI The method comprises the following steps:
three equatorial moment parameters ζ transformed between standard epoch and equatorial coordinate system of calculated epoch A ,z A ,θ A The method comprises the following steps:
when Greenning flat fixed starIs that
t is the julian day time interval from J2000.0,JD (t) is the julian day corresponding to the calculation time, JD (J2000.0) = 2451545.0 is the julian day corresponding to epoch J2000.0; />The result units of (2) are time units, which are converted into angular units in use, the correspondence being 1 hour corresponding to 15 °.
Further, the transformation matrix L from the satellite orbit coordinate system to the J2000 inertial coordinate system ECI,o The method comprises the following steps: l (L) ECI,o ＝L z (-Ω)L x (π/2-i)L y (pi/2+u), wherein Ω is the ascent point of satellite orbit, i is the orbital tilt,for latitudinal argument, ω is the paraxial argument, +.>For true near point angle, L x ，L y ，L z The following forms respectively:
further, the true near point angleThe average and close point angle M and the eccentricity e in six satellite orbits are obtained through iterationThe method comprises the steps of carrying out a first treatment on the surface of the Firstly, solving a close point angle E, E-E sin E=M according to a close point angle M and an eccentricity E; then adopt simple iteration method E (k+1) ＝esin E (k) Solving an equation by +M, setting the error precision as sum of the maximum iteration times, stopping iteration when the precision reaches the requirement or the maximum iteration times, and calculating to obtain the true near point angle +.>
Further, the distance between the optical agile satellite and the real photographing point is as follows:
wherein the method comprises the steps ofPhi is the included angle between the star-earth connection and the camera visual axis, R is the satellite earth center distance, R is the theoretical photographing point earth center distance, and OP' is the local radius of the earth of the real photographing point.
Further, the ground speed vector of the real photographing point in the camera body coordinate system is:
v c ＝L cb ·L bo ·L oi ·v
wherein L is cb L is a transformation matrix from a satellite body coordinate system to a camera body coordinate system bo L is a transformation matrix from an orbit coordinate system to a satellite body coordinate system oi The transformation matrix from the J2000 inertial coordinate system to the satellite orbit coordinate system is shown as v, the relative velocity vector of the real photographing point relative to the on-board camera in the J2000 inertial coordinate system,
v＝ω e ×R-ω n ×R-ω s ×H-v r
wherein omega e Is the earth angular velocity vector, R is the vector from the earth's center to the real photographing point, ω n Is a satellite orbit angular velocity vector with the size ofMu is the gravitational constant, p is the orbit half-diameter, r is the vector diameter of the earth-centered satellite, and the magnitude of the vector diameter is r +.>p＝a(1-e 2 ) A is the semi-long axis, e is the eccentricity, H is the satellite-to-target point distance vector, v r Is a radial component of the absolute velocity of the satellite, of size +.>ω b Is the angular velocity vector omega of the satellite b ＝ω n +ω s ，ω s Is the angular velocity caused by the attitude motion of the satellite itself.
Further, the calculating the integration time t of the camera according to the distance between the optical agile satellite and the real photographing point and the ground speed vector of the real photographing point in the camera body coordinate system specifically includes:
wherein v is cx The method is characterized in that the method is used for obtaining the component of the ground speed vector of a real photographing point in a camera body coordinate system along the push-broom direction of a TDICCD device on a camera, h is the distance between an optical agile satellite and the real photographing point, f is the focal length of the camera, and d is the pixel size of the TDICCD device of the camera.
Compared with the prior art, the invention has the advantages that:
(1) The method fully considers the influence of the satellite attitude angle and the satellite attitude angular speed in the active push-broom imaging process, calculates the velocity-height ratio, further obtains the integral time, and is suitable for the active push-broom imaging mode and the traditional passive push-broom imaging mode;
(2) The method of the invention has the advantages that on the premise of meeting the calculation precision, certain simplification is carried out, and only the earth time difference correction and the earth rotation two-time coordinate conversion are considered, so that the method is suitable for limiting the calculation speed and the storage size in the use of spaceborne;
(3) The method fully considers the influence of the attitude angle and the attitude angular speed of the satellite in the imaging process, and can be applied to both an active push-broom imaging mode and a traditional passive push-broom imaging mode.
Drawings
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a schematic diagram of the relationship between the J2000 inertial coordinate system and the satellite orbit coordinate system according to the present invention;
FIG. 3 is a diagram illustrating the transformation relationship of the coordinate system according to the present invention;
FIG. 4 is a schematic diagram of camera shooting geometry without taking geographic elevation into consideration in the present invention;
FIG. 5 is a schematic diagram of camera shooting geometry considering geographic elevation in accordance with the present invention;
fig. 6 is a schematic diagram of exemplary imaging scenes and integration time calculation in the active push-broom imaging process according to an embodiment of the present invention, where fig. 6 (a) is an active push-broom imaging scene, fig. 6 (b) is a satellite attitude angle change situation, and fig. 6 (c) is an integration time change situation in the exemplary scene.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The following coordinate systems will be used in the present invention:
j2000 inertial coordinate system (i)
Orbital coordinate system (o): the origin of coordinates is located at the mass center of the satellite, the z axis points to the earth center, the y axis points to the negative normal of the track surface, and the x axis, the y axis and the z axis form a right-hand system.
Satellite body coordinate system (b): the system is fixedly connected with a satellite, the origin of coordinates of the system is positioned at the mass center of the satellite, the x-axis points to the flight direction of the satellite, the z-axis points to the visual axis direction of the camera, and the y-axis, the x-axis and the z-axis form a right-hand system.
Camera body coordinate system (c): the origin of the coordinates is positioned at the mass center of the camera, the z axis points to the direction of the visual axis of the camera, and the x axis and the y axis are consistent with the satellite body coordinate system (b).
Ground fixed coordinate system (F): using the WGS84 coordinate system
As shown in fig. 1, which is a flow chart of the method of the present invention, the main steps are as follows:
s1, acquiring calculation time, orbit parameters and attitude data of an optical agile satellite and the position of a camera in a satellite body coordinate system.
Orbit parameters include the position of the satellite in the WGS84 coordinate system, and attitude data includes the roll angle, pitch angle and yaw angle of the satellite.
S2, determining a theoretical photographing point of the camera visual axis on the ground, and combining the geographical elevation data of the theoretical photographing point to obtain a real photographing point and a distance between a satellite and the real photographing point.
(1) And acquiring a vector of the camera visual axis in the satellite body coordinate system, and obtaining a vector representation of the camera visual axis in the ground fixed coordinate system through coordinate system conversion.
Let the vector representation form of the camera visual axis in the satellite body coordinate system be C C ＝[X C Y C Z C ]' the vector representation of the camera visual axis in the ground fixed coordinate system is C F ＝[X F Y F Z F ]′，C F The method comprises the following steps:
C F ＝L ECF,ECI ·L ECI,o ·L ob ·C C
wherein L is ECF,ECI For the transformation matrix from the J2000 inertial coordinate system to the ground-fixed coordinate system,
the method is used on the satellite, and has requirements on calculation speed and storage size, so that the method is properly simplified on the premise of meeting calculation accuracy, and only the earth time difference correction and the earth rotation two-time coordinate conversion are considered.
Three equatorial moment parameters ζ transformed between standard epoch and equatorial coordinate system of calculated epoch A ,z A ,θ A The method comprises the following steps:
when Greenning flat fixed starThe method comprises the following steps:
where t is the julian day time interval from J2000.0, also known as julian century:JD (t) is the julian day corresponding to the calculation time, JD (J2000.0) = 2451545.0 is the julian day corresponding to epoch J2000.0.
The result units of (2) are time units, which are converted into angular units in use, the correspondence being 1 hour corresponding to 15 °.
L ECI,o For the transformation matrix from the satellite orbit coordinate system to the J2000 inertial coordinate system, the relationship of the J2000 inertial coordinate system and the satellite orbit coordinate system is shown in fig. 2.
L-shaped memory x ，L y ，L z In the form of:
L ECI,o can be expressed as:
L ECI,o ＝L z (-Ω)L x (π/2-i)L y (π/2+u)
wherein omega is the right ascent point of the satellite orbit, i is the orbit inclination angle,for latitudinal argument, ω is the paraxial argument, +.>Is the true near point angle.
For true near point anglesThe average and close point angle M and the eccentricity e in six satellite orbits are obtained through iteration. First, a close point angle E, E-E sin e=m is found from the close point angle M and the eccentricity E. Then adopt simple iteration method E (k+1) ＝e sin E (k) +M solves the above equation. The error accuracy is set to sigma (e.g. 10 -6 rad), the maximum number of iterations is set to cal_num (e.g., 100 times), and when the accuracy reaches the requirement or the number of iterations reaches the maximum number of iterations, the iteration is stopped. Calculating the true near point angle +.>
L ob For a transformation matrix from the satellite body coordinate system to the orbital coordinate system, if a pose transformation of 1-2-3 (roll-pitch-yaw) is employed,wherein->The roll angle, θ is the pitch angle, and ψ is the yaw angle.
According to the installation relation of the camera on the satellite platform, a conversion matrix L from the satellite body coordinate system to the camera body coordinate system can be obtained cb . The entire coordinate system conversion process is shown in fig. 3.
(2) And obtaining a space linear equation of the camera visual axis vector in the ground fixed coordinate system according to the position of the satellite in the ground fixed coordinate system (WGS 84 coordinate system) and the position of the camera visual axis vector obtained in the last step in the ground fixed coordinate system.
Assuming that the satellite's position component in the WGS84 coordinate system isThe position component of the camera visual axis vector in the ground-fixed coordinate system is +.>According to->The space linear equation of the star-ground connection line in the ground-solid coordinate system can be obtained, and the space linear equation is based on the camera visual axis vector +.>A spatial linear equation of the camera visual axis vector in the geodetic coordinate system can be obtained.
By combining the space linear equation and the earth ellipsoid equation, the intersection point between the camera visual axis vector and the earth ellipsoid can be obtained, namely the initial photographing points x, y and z.
(3) And obtaining the corrected photographing point elevation slant distance according to the initial photographing point position obtained in the previous step and the geographical elevation data of the photographing point.
Under the condition that the earth elevation data is not considered, the geometric relationship between the shooting of the point under the satellite and the shooting under the condition of the general gesture is shown in fig. 4, the point S represents an on-satellite camera, the shooting point is T1 when the point under the satellite is shot, and the image plane is perpendicular to ST1; after the general attitude of the satellite is maneuvered, the included angle between the satellite-ground connection line and the visual axis of the camera is phi, the photographing point is T, the image plane is perpendicular to ST, and the ST direction is the direction of the z axis of the satellite body coordinate system. The angle of the earth center isWhere R is the satellite geocentric distance and R is the geodetic distance of the point of photography without regard to the geographic elevation data.
After the elevation data is taken into account, as shown in fig. 5, the photographing point of the camera visual axis is changed from point P to point P ', and the three points P' and S, P are collinear. In the figure, OP is the local radius of the earth without considering the geographical elevation data, OP' is the local radius of the earth after correcting the photographing point by considering the geographical elevation data, and the value of OP is the sum of the value of OP and the geographical elevation data. According to the cosine law, the calculation formula considering the size of the slant distance h of the geographic elevation of the photographing point is as follows:
s3, calculating the ground speed vector of the real photographing point in the camera body coordinate system.
(1) In the J2000 inertial coordinate system, calculating a relative speed vector v of a photographing point relative to an on-board camera:
the speed of the ground imaging target point T relative to the camera body coordinate system is
v＝ω e ×R-(ω n ×r+ω b ×H+v r )
Wherein omega e Is the earth angular velocity vector, R is the vector from the earth's center to the target point, ω n Is a satellite orbit angular velocity vector with the size ofMu is the gravitational constant, p is the orbit half-diameter, r is the vector diameter of the earth-centered satellite, and the magnitude of the vector diameter is r +.>p＝a(1-e 2 ) A is the semi-long axis, e is the eccentricity, H is the satellite-to-target point distance vector, v r Is a radial component of the absolute velocity of the satellite, of size +.>ω b Is the angular velocity vector omega of the satellite b ＝ω n +ω s Comprising angular velocity omega due to orbital motion n As well as the satellite's own attitudeAngular velocity ω due to motion s . In the traditional passive imaging mode, the satellite attitude angular speed omega is not considered s =0, ω in active push-broom imaging mode s ≠0。
According to the above formula explanation, the velocity formula of the ground imaging target point T with respect to the camera body coordinate system can be developed as:
v＝ω e ×R-[ω n ×r+(ω n +ω s )×H+v r ]＝ω e ×R-ω n ×R-ω s ×H-v r
(2) According to the ground speed v, J2000 inertial coordinate system to satellite orbit coordinate system conversion matrix L obtained in the last step oi Transformation matrix L from orbit coordinate system to satellite body coordinate system bo Converting to obtain the ground speed vector v of the ground speed in the satellite body coordinate system b
v b ＝L bo ·L oi ·v
(3) According to the transformation matrix L from the satellite body coordinate system to the camera body coordinate system cb The vector projection v of the ground speed in the camera body coordinate system can be calculated c ：
v c ＝L cb ·v b 。
S4, calculating the integration time of the camera according to the magnitude h of the distance vector h between the satellite and the real shooting point and the ground speed vector in the camera body coordinate system. According to the imaging principle of TDICCD, the integration time is the movement time of the imaged ground object on a single detector, namely the product of the detector size divided by the focal length of the camera and the speed-height ratio.
(1) V obtained from the previous step c Obtaining v c Component v along push-broom direction of TDICCD device on camera cx ；
(2) According to v cx And h, calculating to obtain a speed-height ratio B:
(3) Calculating the integration time corresponding to the TDICCD device of the camera according to the speed-to-height ratio B, the focal length f of the camera and the pixel size d of the TDICCD device of the camera, which are obtained above:
examples
An active push-broom scene is created, and a section of vertical orbit active push-broom imaging process is selected, namely the observation strip is perpendicular to the satellite point track below the satellite. The satellite in the scene needs to adjust a larger drift angle to ensure that the focal plane image shift direction is perpendicular to the TDICDD linear array.
The length of the selected strip is 170km, and the active push-broom imaging ground speed is 7 km/s. Simulation is realized by adopting C++ programming.
A typical scene simulation result of the satellite active push-broom imaging process is shown in fig. 6. In fig. 6 (a), the red line represents the satellite's sub-satellite point track, and the blue line represents the satellite's shooting point track, i.e., the imaging scan stripe of the camera. The real-time changes of roll angle, pitch angle and yaw angle during satellite imaging are shown in fig. 6 (b). In this imaging mode, the yaw angle of the satellite is large, up to about-78 °. Fig. 6 (c) shows the variation of integration time during active push broom imaging calculated using the method, and it can be seen that in this example the integration time of the satellites varies in real time during imaging, decreasing from 1.027 mus to 1.003 mus and then increasing to 1.022 mus.
What is not described in detail in the present specification is a well known technology to those skilled in the art.

Claims (10)

1. The method for determining the integration time of the active push-broom imaging of the optical agile satellite is characterized by comprising the following steps:
(1) Acquiring the calculation time, orbit parameters and attitude data of an optical agile satellite and the position of a camera in a satellite body coordinate system;
(2) Determining a theoretical photographing point of a camera visual axis on the ground, and combining the theoretical photographing point geographical elevation data to obtain a real photographing point and a distance between an optical agile satellite and the real photographing point;
(3) Calculating the ground speed vector of a real photographing point in a camera body coordinate system;
(4) And calculating the integration time of the camera according to the distance between the optical agile satellite and the real photographing point and the ground speed vector of the real photographing point in the camera body coordinate system.
2. The method for determining the integration time of active push-broom imaging of an optical agile satellite according to claim 1, wherein the method comprises the following steps: the orbit parameters comprise the position of the optical agile satellite under the WGS84 coordinate system, and the attitude data comprise the roll angle, the pitch angle and the yaw angle of the optical agile satellite.
3. The method for determining the integration time of active push-broom imaging of an optical agile satellite according to claim 2, wherein the method comprises the following steps: the method for determining the theoretical photographing point of the camera visual axis on the ground specifically comprises the following steps:
(31) Acquiring a vector of a camera visual axis in a satellite body coordinate system, and obtaining a vector representation of the camera visual axis in a ground fixed coordinate system through coordinate system conversion;
(32) According to the position of the optical agile satellite in the ground fixed coordinate system and the position of the camera visual axis vector in the ground fixed coordinate system, a space linear equation of the camera visual axis vector in the ground fixed coordinate system is obtained, and an intersection point between the camera visual axis vector and an earth ellipsoid is obtained by combining the space linear equation and the earth ellipsoid equation, namely a theoretical photographing point;
(33) And obtaining the corrected real photographing point according to the theoretical photographing point position and the geographic elevation data of the theoretical photographing point, thereby obtaining the distance between the optical agile satellite and the real photographing point.
4. A method for determining an integration time of active push-broom imaging of an optical agile satellite according to claim 3, wherein: the method comprises the steps of obtaining a vector of a camera visual axis in a satellite body coordinate system, and obtaining a vector representation of the camera visual axis in a ground fixed coordinate system through coordinate system conversion, wherein the vector representation comprises the following specific steps:
C F ＝L ECF,ECI ·L ECI,o ·L ob ·C C
wherein C is C ＝[X C Y C Z]′ C C is the vector representation of the camera visual axis in the satellite body coordinate system F ＝[X F Y F Z F ]'is a vector representation of the camera's visual axis in a geodetic fixed coordinate system, where L ECF,ECI L is a transformation matrix from a J2000 inertial coordinate system to a ground-fixed coordinate system ECI,o L is a transformation matrix from a satellite orbit coordinate system to a J2000 inertial coordinate system ob Is a transformation matrix from the satellite body coordinate system to the orbital coordinate system.
5. The method for determining the integration time of active push-broom imaging of an optical agile satellite according to claim 4, wherein the method comprises the following steps: the transformation matrix L from the J2000 inertial coordinate system to the ground fixed coordinate system ECF,ECI The method comprises the following steps:
three equatorial moment parameters ζ transformed between standard epoch and equatorial coordinate system of calculated epoch A ,z A ,θ A The method comprises the following steps:
when Greenning flat fixed starIs that
t is the julian day time interval from J2000.0,JD (t) is the julian day corresponding to the calculation time, JD (J2000.0) = 2451545.0 is the julian day corresponding to epoch J2000.0; />The result units of (2) are time units, which are converted into angular units in use, the correspondence being 1 hour corresponding to 15 °.
6. The method for determining the integration time of active push-broom imaging of an optical agile satellite according to claim 4, wherein the method comprises the following steps: the transformation matrix L from the satellite orbit coordinate system to the J2000 inertial coordinate system ECI,o The method comprises the following steps: l (L) ECI,o ＝L z (-Ω)L x (π/2-i)L y (pi/2+u), wherein Ω is the ascent point of satellite orbit, i is the orbital tilt,for latitudinal argument, ω is the paraxial argument, +.>For true near point angle, L x ，L y ，L z The following forms respectively:
7. a according to claim 6The method for determining the integration time of the active push-broom imaging of the optical agile satellite is characterized by comprising the following steps of: said true near point angleThe average and close point angle M and the eccentricity e in six satellite orbits are utilized to obtain through iteration; firstly, solving a close point angle E, E-esine=M according to a close point angle M and an eccentricity E; then adopting a simple iteration methodSolving an equation, setting the error precision as sum of the maximum iteration times, stopping iteration when the precision reaches the requirement or the maximum iteration times, and calculating to obtain the true near point angle +.>
8. The method for determining the integration time of active push-broom imaging of an optical agile satellite according to claim 4, wherein the method comprises the following steps: the distance between the optical agile satellite and the real photographing point is as follows:
wherein the method comprises the steps ofPhi is the included angle between the star-earth connection and the camera visual axis, R is the satellite earth center distance, R is the theoretical photographing point earth center distance, and OP' is the local radius of the earth of the real photographing point.
9. The method for determining the integration time of active push-broom imaging of an optical agile satellite according to claim 4, wherein the method comprises the following steps: the ground speed vector of the real photographing point in the camera body coordinate system is as follows:
v c ＝L cb ·L bo ·L oi ·v
wherein L is cb L is a transformation matrix from a satellite body coordinate system to a camera body coordinate system bo L is a transformation matrix from an orbit coordinate system to a satellite body coordinate system oi The transformation matrix from the J2000 inertial coordinate system to the satellite orbit coordinate system is shown as v, the relative velocity vector of the real photographing point relative to the on-board camera in the J2000 inertial coordinate system,
v＝ω e ×R-ω n ×R-ω s ×H-v r
wherein omega e Is the earth angular velocity vector, R is the vector from the earth's center to the real photographing point, ω n Is a satellite orbit angular velocity vector with the size ofMu is the gravitational constant, p is the orbit half-diameter, r is the vector diameter of the earth-centered satellite, and the magnitude of the vector diameter is r +.>p＝a(1-e 2 ) A is the semi-long axis, e is the eccentricity, H is the satellite-to-target point distance vector, v r Is a radial component of the absolute velocity of the satellite, of size +.>ω b Is the angular velocity vector omega of the satellite b ＝ω n +ω s ，ω s Is the angular velocity caused by the attitude motion of the satellite itself.
10. The method for determining the integration time of active push-broom imaging of an optical agile satellite according to claim 4, wherein the method comprises the following steps: according to the distance between the optical agile satellite and the real photographing point and the ground speed vector of the real photographing point in the camera body coordinate system, the integral time t of the camera is calculated, and specifically, the integral time t is as follows:
wherein v is cx The method is characterized in that the method is used for obtaining the component of the ground speed vector of a real photographing point in a camera body coordinate system along the push-broom direction of a TDICCD device on a camera, h is the distance between an optical agile satellite and the real photographing point, f is the focal length of the camera, and d is the pixel size of the TDICCD device of the camera.
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