Satellite stripe imaging method, satellite stripe imaging device and computer readable medium

Abstract

The invention provides a satellite stripe imaging method, a satellite stripe imaging device and a computer readable medium. The satellite stripe imaging method comprises the following steps: acquiring a target area, and dividing the target area into a plurality of stripes; selecting one strip from the plurality of strips as a current strip, wherein the current strip is internally provided with at least one control point; setting a satellite push-broom vector; the satellite push-scan vector is configured to have a first direction during forward push-scan and a second direction during reverse push-scan, and the first direction is parallel to the second direction; calculating a starting point coordinate of a current strip according to a push-broom speed, wherein the push-broom speed is a model of a satellite push-broom vector; obtaining a first control point coordinate of each control point according to the current strip starting point coordinate; correcting the first control point coordinate to obtain a current stripe control point coordinate; obtaining a satellite attitude quaternion according to the current strip control point coordinate; and completing current stripe imaging according to the satellite attitude quaternion and the satellite push-broom vector.

Description

Technical Field

[0001] The present application mainly relates to the field of satellites, and particularly to a satellite strip imaging method, a satellite strip imaging device, and a computer-readable medium. Background Art

[0002] In the prior art, during the strip imaging process of an optical imaging satellite, the satellite needs to perform pitch, roll, and yaw three-axis maneuvers to complete strip push-scanning, strip switching, drift angle correction, and strip stitching. However, some optical imaging satellites do not have the freedom of the yaw axis or have weak maneuverability of the yaw axis. For example, an optical imaging satellite with a turntable system. For these satellites, the three-axis maneuvering scheme in the prior art cannot be used to complete drift angle correction, strip imaging, and strip stitching, and thus the large-area observation task cannot be completed. Summary of the Invention

[0003] In view of the above problems, the present application provides a satellite strip imaging method, a satellite strip imaging device, and a computer-readable medium, which can solve the technical problem that some optical imaging satellites cannot use the three-axis maneuvering scheme to complete the large-area observation task.

[0004] To solve the above technical problems, the present application provides a satellite strip imaging method, including:

[0005] Obtain a target area, and divide the target area into a plurality of strips; select one strip from the plurality of strips as the current strip, and at least one control point is included in the current strip; set a satellite push-scan vector; the satellite push-scan vector is configured such that: the satellite push-scan vector has a first direction during forward push-scanning, and the satellite push-scan vector has a second direction during reverse push-scanning, and the first direction and the second direction are parallel; calculate the starting coordinates of the current strip according to the push-scan ground speed, and the push-scan ground speed is the modulus of the satellite push-scan vector.

[0006] Obtain the first control point coordinates of each control point according to the starting coordinates of the current strip; correct the first control point coordinates to obtain the current strip control point coordinates; obtain the satellite attitude quaternion according to the current strip control point coordinates; and complete the imaging of the current strip according to the satellite attitude quaternion and the satellite push-scan vector.

[0007] In an embodiment of the present application, the correcting the first control point coordinates to obtain the current strip control point coordinates includes: performing ground height correction and drift angle correction on the first control point coordinates.

[0008] In an embodiment of the present application, the calculating the starting coordinates of the current strip according to the push-scan ground speed includes: calculating the starting coordinates of the current strip by using the following formula:

[0009]

[0010] Among them, S tg is the target point coordinate, tg is the over-the-top moment of the target point, P tg is the satellite position vector at the over-the-top moment, N tg is the satellite velocity vector at the over-the-top moment, V G is the push-sweep speed mentioned above, t s is the push-sweep time of the current strip, L is the interval between strips, n is the number of strips, S j is the starting coordinate of the current strip corresponding to the j-th strip as the current strip, j = 1, 2,..., n, and n is a natural number.

[0011] In an embodiment of the present application, the obtaining of the first control point coordinates of each of the control points according to the starting coordinate of the current strip includes: using the following formula to obtain the first control point coordinates:

[0012]

[0013] Among them, is the first control point coordinate, t 1 is the moment when the satellite line of sight points to the control point; is the starting coordinate of the current strip, t 0 is the moment when the satellite line of sight points to the starting point of the current strip.

[0014] In an embodiment of the present application, the following formula is used to correct the ground height of the first control point coordinates:

[0015]

[0016] Among them, is the surface height corresponding to the control point, is the second control point coordinate, is the first control point coordinate.

[0017] In an embodiment of the present application, the correction of the drift angle includes: using the following formula, in the spherical coordinate system, correcting the second control point coordinate to the current strip control point coordinate

[0018] θ ′ = θ + δ,

[0019] where δ is the angle of the earth's rotation per second, is the current strip control point coordinate.

[0020] In an embodiment of the present application, obtaining the satellite attitude quaternion according to the current strip control point coordinates includes: obtaining the transformation matrix from the geocentric coordinate system to the satellite body coordinate system by using the following formula

[0021]

[0022] wherein, is the satellite coordinate in the geocentric coordinate system at time t 1 , is the corresponding coordinate in the satellite body coordinate system, and

[0023]

[0024] where q 1 , q 2 , q 3 , q 4 are the satellite attitude quaternions, and

[0025] In an embodiment of the present application, the satellite strip imaging method includes: imaging a plurality of different current strips to obtain a plurality of strip images; and

[0026] stitching the plurality of strip images.

[0027] The present application also provides a satellite strip imaging device, including: a memory for storing instructions executable by a processor; and a processor for executing the instructions to implement the above satellite strip imaging method.

[0028] The present application also provides a computer-readable medium storing computer program code, where the computer program code implements the above satellite strip imaging method when executed by a processor.

[0029] The satellite strip imaging method proposed in this application enables a satellite without a yaw axis degree of freedom or with a weak yaw axis maneuverability to complete strip imaging by setting the first direction and the second direction of the satellite push-scan vector to be parallel; by correcting the coordinates of the first control point to obtain the current strip control point coordinates, and obtaining the satellite attitude quaternion based on the current strip control point coordinates, the satellite can complete the drift angle correction without using the yaw axis, and then complete the strip imaging work. The satellite strip imaging method of this application solves the problem that a satellite without a yaw axis degree of freedom or with a weak yaw axis maneuverability cannot complete the task of large-area observation using the three-axis maneuvering scheme in the prior art. In addition, for an optical imaging satellite with a yaw axis, using the satellite strip imaging method of this application reduces the process of yaw axis maneuvering, can reduce the time required for strip switching, thereby shortening the time required to complete the entire imaging task and improving the task completion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are provided to further understand this application, and they are incorporated and constitute a part of this application. The accompanying drawings show embodiments of this application and, together with this specification, serve to explain the principles of this application. In the accompanying drawings:

[0031] Figure 1 is a flowchart of a satellite strip imaging method according to an embodiment of this application;

[0032] Figure 2a is a diagram of the relationship of satellite push-scan vectors during the forward push-scan of the satellite in a satellite strip imaging method;

[0033] Figure 2b is a diagram of the relationship of satellite push-scan vectors during the reverse push-scan of the satellite in a satellite strip imaging method;

[0034] Figure 3a is a diagram of the relationship of satellite push-scan vectors during the forward push-scan of the satellite in the satellite strip imaging method according to an embodiment of this application;

[0035] Figure 3b is a diagram of the relationship of satellite push-scan vectors during the reverse push-scan of the satellite in the satellite strip imaging method according to an embodiment of this application;

[0036] Figure 4a is this application Figure 2a and Figure 2b is a schematic diagram of the strip shape shown in the embodiment;

[0037] Figure 4b is this application Figure 2a and Figure 2b is a schematic diagram of the strip imaging process shown in the embodiment;

[0038] Figure 5a is this applicationFigure 3a and Figure 3b Schematic diagram of the strip shape of the embodiment shown;

[0039] Figure 5b This application Figure 3a and Figure 3b Schematic diagram of the strip imaging process of the embodiment shown;

[0040] Figure 6 Schematic diagram of the satellite three - axis angle change in the satellite strip imaging method of an embodiment of this application;

[0041] Figure 7 is Figure 6 Scene simulation diagram of the strip of the embodiment shown; and

[0042] Figure 8 System block diagram of the satellite strip imaging device of an embodiment of this application. Detailed implementation manners

[0043] In order to more clearly illustrate the technical solutions of the embodiments of this application, the following will briefly introduce the attached drawings required in the description of the embodiments. Obviously, the attached drawings in the following description are only some examples or embodiments of this application. For those of ordinary skill in the art, without creative efforts, this application can also be applied to other similar scenarios based on these attached drawings. Unless obvious from the language context or otherwise stated, the same reference numerals in the figures represent the same structure or operation.

[0044] As shown in this application, unless the context clearly indicates an exceptional situation, words such as "a", "an", "one" and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the clearly identified steps and elements, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0045] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that for the sake of convenience in description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the specification. In all examples shown and discussed herein, any specific values should be construed as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, further discussion thereof is not required in subsequent drawings.

[0046] In the present application, flowcharts are used to illustrate the operations performed by the systems according to the embodiments of the present application. It should be understood that the operations described above or below do not necessarily have to be performed precisely in sequence. On the contrary, various steps can be processed in reverse order or simultaneously. Also, other operations can be added to these processes, or one or more steps can be removed from these processes.

[0047] The present application uses specific terms to describe the embodiments of the present application. Terms such as "one embodiment", "an embodiment", and / or "some embodiments" mean a certain feature, structure, or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that the "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more at different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the present application can be appropriately combined.

[0048] During the imaging process of a satellite camera, due to the rotation of the Earth itself, the movement direction of the satellite and the actual imaging direction of the camera are not the same, and the angle between the two is the drift angle. The yaw axis is the axis of rotation around the satellite's vertical axis (usually the Z-axis), and by rotating around the yaw axis, the satellite can change its nose pointing direction.

[0049] For an optical imaging satellite with three axes of pitch, roll, and yaw, the strip imaging process often uses the yaw axis to correct the drift angle to ensure that the optical axis of the imaging system can accurately point to the target area. However, for an optical imaging satellite lacking a yaw axis or having a weak maneuvering ability of the yaw axis, it is impossible to use the three-axis maneuvering scheme in the prior art to complete the drift angle correction, strip imaging, and subsequent strip stitching work.

[0050] In view of the above technical problems, the present application proposes a satellite strip imaging method. Figure 1The flowchart of a satellite strip imaging method 10 according to an embodiment of the present application is shown.

[0051] As Figure 1 shown, the present application provides a satellite strip imaging method 10, including:

[0052] Step S1: Obtain a target area and divide the target area into multiple strips;

[0053] Step S2: Select one strip from the multiple strips as the current strip, and there is at least one control point in the current strip;

[0054] Step S3: Set the satellite push-scan vector; the satellite push-scan vector is configured such that when the satellite is pushing forward, the satellite push-scan vector has a first direction, and when the satellite is pushing backward, the satellite push-scan vector has a second direction, and the first direction and the second direction are parallel;

[0055] Step S4: Calculate the starting coordinates of the current strip according to the push-scan ground speed, and the push-scan ground speed is the modulus of the satellite push-scan vector;

[0056] Step S5: Obtain the first control point coordinates of each control point according to the starting coordinates of the current strip;

[0057] Step S6: Correct the first control point coordinates to obtain the control point coordinates of the current strip;

[0058] Step S7: Obtain the satellite attitude quaternion according to the control point coordinates of the current strip;

[0059] Step S8: Complete the imaging of the current strip according to the satellite attitude quaternion and the satellite push-scan vector.

[0060] The satellite strip imaging method of the present application enables a satellite without a yaw axis degree of freedom or with a weak yaw axis maneuvering ability to complete strip imaging by setting the first direction and the second direction of the satellite push-scan vector to be parallel; by correcting the first control point coordinates to obtain the control point coordinates of the current strip and obtaining the satellite attitude quaternion according to the control point coordinates of the current strip, the satellite can complete the drift angle correction without using the yaw axis, and then complete the strip imaging work. The satellite strip imaging method of the present application solves the problem that a satellite without a yaw axis degree of freedom or with a weak yaw axis maneuvering ability cannot complete the task of large-area observation using the three-axis maneuvering scheme in the prior art. In addition, for an optical imaging satellite with a yaw axis, using the satellite strip imaging method of the present application reduces the process of yaw axis maneuvering, can reduce the time required for strip switching, thereby shortening the time required to complete the entire imaging task and improving the task completion efficiency.

[0061] The above steps S1 to S8 are described in detail below.

[0062] In some embodiments, the target area in step S1 is the ground area to be imaged by the user. In some embodiments, the number of strip division lines in the target area in step S1 can be set according to the actual satellite configuration and the requirements of area imaging, and the present application does not limit this.

[0063] In some embodiments, in step S2, according to the actual imaging needs, there can be multiple control points in one strip. In the field of mathematics, a control point refers to a reference point used to define a curve, a surface, or other geometric shapes. Here, the control points in the present application refer to the reference points in the strip, which are used for high-precision mapping and positioning.

[0064] In some embodiments, the strip of the satellite strip imaging method 10 in the present application is a curved strip. This is determined by step S3 in the satellite strip imaging method 10 of the present application.

[0065] Next, step S3 in the satellite strip imaging method 10 will be described in detail in conjunction with Figures 2a to 3b Figure 1 shows a satellite push - sweep vector relationship diagram during the forward push - sweep of a satellite in a satellite strip imaging method.

[0066] Figure 2a Figure 1 shows a satellite push - sweep vector relationship diagram during the forward push - sweep of a satellite in a satellite strip imaging method. Figure 2b Figure 2 shows a satellite push - sweep vector relationship diagram during the reverse push - sweep of a satellite in a satellite strip imaging method. Figure 3a Figure 3 shows a satellite push - sweep vector relationship diagram during the forward push - sweep of a satellite in the satellite strip imaging method of an embodiment of the present application. Figure 3b Figure 4 shows a satellite push - sweep vector relationship diagram during the reverse push - sweep of a satellite in the satellite strip imaging method of an embodiment of the present application. Among them, Figure 2a and Figure 2b The satellite push - sweep vector relationships in Figures 1 and 2 are settings in the satellite strip imaging method with three - axis maneuvering. Figure 3a and Figure 3b The satellite push - sweep vector relationships in Figures 3 and 4 are settings in the satellite strip imaging method of the present application without using the yaw axis.

[0067] In Figures 2a to 3b Figure 5 shows the Earth's rotation vector α, the satellite push - sweep vector β, and the actual push - sweep vector γ. Among them, the Earth's rotation vector α refers to the Earth's rotation speed vector at the gazing point; the satellite push - sweep vector β refers to the moving speed vector of the gazing point caused by satellite maneuvering; the actual push - sweep vector γ refers to the actual moving speed vector of the gazing point. The Earth's rotation vector α, the satellite push - sweep vector β, and the actual push - sweep vector γ have the following relationship: γ = α + β.

[0068] During the satellite strip imaging process, in order to improve the imaging efficiency, expand the coverage area, and meet specific observation requirements, it is often necessary to alternate between forward pushbroom imaging and reverse pushbroom imaging. Among them, forward pushbroom imaging means that the satellite images along the orbital direction. Reverse pushbroom imaging means that the satellite adjusts its attitude so that the imaging direction is opposite to the orbital direction. In these two imaging methods, in order to ensure that the imaging direction of the satellite payload (such as an optical camera) is consistent with the target direction, drift angle correction is required.

[0069] In some embodiments, the number of forward pushbroom times and reverse pushbroom times of a strip imaging can be set according to the requirements of the strip imaging. This application does not make specific limitations on the specific number of pushbroom times. For example, it can be set to two forward pushbrooms and one reverse pushbroom, or two reverse pushbrooms and two reverse pushbrooms.

[0070] Such as Figure 2a and Figure 2b As shown in, the existing technical solution is: in order to ensure that the imaged strips after forward pushbroom and reverse pushbroom are parallel, the direction F1 of the actual pushbroom vector γ during forward pushbroom and the direction F2 of the actual pushbroom vector γ during reverse pushbroom are set to be parallel. At this time, there is an included angle between the satellite pushbroom vector β during forward pushbroom and the satellite pushbroom vector β during reverse pushbroom, that is, the direction of the satellite pushbroom vector β needs to be changed when switching between forward pushbroom and reverse pushbroom. In Figure 2a and Figure 2b Under the shown solution, the method for correcting the drift angle is: changing the yaw axis of the satellite to change the yaw angle of the satellite. Due to the influence of the earth's rotation vector α, when the satellite is in forward pushbroom, there is a deviation of θ1 between the actual pushbroom vector γ and the satellite pushbroom vector β. At this time, the drift angle correction is to rotate the yaw axis by θ1 degrees. When the satellite switches to reverse pushbroom, due to the influence of the earth's rotation vector α, there is a deviation of θ2 between the actual pushbroom vector γ and the satellite pushbroom vector β. At this time, the drift angle correction is to rotate the yaw axis by (θ1 + θ2) degrees again.

[0071] However, for satellites without a yaw axis or satellites with weak yaw axis maneuverability, it is difficult to change the direction of the satellite pushbroom vector β, and it is also impossible to complete the drift angle correction through the satellite yaw angle correction.

[0072] Such as Figure 3a and Figure 3b As shown in, in the satellite strip imaging method of this application, the satellite pushbroom vector β has a first direction D1 during forward pushbroom and a second direction D2 during reverse pushbroom, and the first direction D1 and the second direction D2 are parallel.

[0073] For satellites without a yaw axis or with weak yaw axis maneuverability, since the direction D1 of the satellite push sweep vector β during forward push sweep and the direction D2 of the satellite push sweep vector β during reverse push sweep are parallel, when the satellite switches between forward push sweep and reverse push sweep, it can complete the strip imaging task without rotating the angle.

[0074] In Figure 3a and Figure 3b Under the shown scheme, since the actual push sweep vectors γ during forward push sweep and reverse push sweep are not parallel, and since the Earth's rotation speed varies with latitude and the direction of the actual push sweep vector γ also changes slightly, the strip after imaging is actually a curve strip with a very large curvature, and there will be an angle between two adjacent strips.

[0075] Figure 4a Shows Figure 2a and Figure 2b The strip shape 40 of the shown embodiment. Figure 4b Shows Figure 2a and Figure 2b The strip imaging process of the shown embodiment. As Figure 4a and Figure 4b Shown, since the direction F1 of the actual push sweep vector γ during forward push sweep and the direction F2 of the actual push sweep vector γ during reverse push sweep are set to be parallel, along the direction F3 of the actual push sweep vector γ of the satellite, the strip is a rectangular strip. In this kind of scheme, the linear arrays 41 are not parallel to each other, and the linear arrays 41 rotate around the optical axis continuously during push sweep. When switching strips, the satellite needs to switch by a large angle, seriously affecting the maneuverability.

[0076] Figure 5a Shows Figure 3a and Figure 3b The strip shape 50 of the shown embodiment. Figure 5b Shows Figure 3a and Figure 3b The strip imaging process of the shown embodiment. As Figure 5a and Figure 5b Shown, since the direction D1 of the satellite push sweep vector β during forward push sweep and the direction D2 of the satellite push sweep vector β during reverse push sweep are set to be parallel, along the direction D3 of the actual push sweep vector γ of the satellite, the shape of the strip is a curvilinear quadrilateral. In this kind of scheme, the linear arrays 51 are parallel to each other, and the linear arrays 51 do not need to rotate around the optical axis during push sweep.

[0077] After setting the satellite push sweep vector in step S3, step S4 is executed.

[0078] In some embodiments, in step S4, calculating the current strip starting point coordinates according to the push sweep ground speed includes: calculating the current strip starting point coordinates using the following formula (1):

[0079]

[0080] Among them, S tg is the target point coordinate, tg is the over-the-top moment of the target point, and P tg is the satellite position vector at the over-the-top moment, and N tg is the satellite velocity vector at the over-the-top moment, and V G is the push-sweep speed, t s is the push-sweep time of the current strip, L is the interval between strips, n is the number of strips, and S j is the starting coordinate of the current strip corresponding to the j-th strip when the j-th strip is used as the current strip, j = 1, 2,..., n, and n is a natural number.

[0081] In some embodiments, the coordinates in formula (1) of the present application may be coordinates in a common satellite imaging coordinate system, such as the Earth-fixed coordinate system and the J2000 geocentric inertial coordinate system. Preferably, the coordinates of the present application are coordinates in the Earth-fixed coordinate system.

[0082] In formula (1), the target point S tg refers to: the position point that the satellite user is interested in and expects the satellite to image. During the strip imaging process, the satellite images around the target point and its nearby areas. In some embodiments, the target point is set at the center position between two adjacent strips. Among them, the center position is generally the geometric center position of a quadrilateral area on the ground covered by all the spliced strips. The over-the-top moment tg of the target point refers to: the specific moment when the satellite passes directly above (or close to directly above) the target point on the orbit. The push-sweep speed V G is the modulus of the satellite push-sweep vector described above, specifically referring to: the speed at which the imaging optical axis of the satellite sweeps across the ground during the push-sweep imaging process. In some embodiments, the magnitude of the push-sweep speed V G is set by the satellite user within a reasonable range according to the actual imaging requirements and the configuration of the satellite.

[0083] In some embodiments, after the imaging area is divided into n strips and arranged in order, the starting coordinates of each strip in the n strips are calculated using formula (1) respectively.

[0084] The calculation scheme in the prior art is applicable to the case where the strips are parallel. If the calculation scheme in the prior art is used, there will be gaps between the adjacent strips after imaging. For the strips with odd and even terms in the order, the strip starting point calculation method of the present application uses different formulas to calculate, solving the problem that there will be an included angle between adjacent strips when setting the satellite push-sweep vector in step S3, and there are no gaps between the strips after imaging and the overlapping area is minimized.

[0085] After obtaining the strip starting point in step S4, step S5 is executed: obtaining the first control point coordinates of each control point according to the current strip starting point coordinates.

[0086] In some embodiments, obtaining the first control point coordinates of each control point according to the current strip starting point coordinates includes: using the following formula (2) to obtain the first control point coordinates:

[0087]

[0088] where is the first control point coordinate, and t 1 is the moment when the satellite line of sight points to the control point; is the current strip starting point coordinate, and t 0 is the moment when the satellite line of sight points to the current strip starting point.

[0089] In this embodiment, the first control point coordinates of the present application are calculated based on the strip starting point coordinates calculated by formula (1) in step S4 and the push-broom ground speed V G and are calculated.

[0090] After obtaining the first control point coordinates of each control point in step S5 step S6 is executed: correcting the first control point coordinates to obtain the current strip control point coordinates.

[0091] In some embodiments, correcting the first control point coordinates to obtain the current strip control point coordinates includes: performing ground height correction and drift angle correction on the first control point coordinates

[0092] In some embodiments, the following formula (3) is used to perform ground height correction on the first control point coordinates:

[0093]

[0094] where is the surface height corresponding to the control point, is the second control point coordinate, is the first control point coordinate.

[0095] By adopting ground height correction, the obtained second control point coordinates can be closer to the actual coordinates of the control points on the real ground.

[0096] In some embodiments, the drift angle correction includes: using the following formula (4), in the spherical coordinate system, correcting the second control point coordinate to the current strip control point coordinate

[0097] θ ′ ​= θ + δ (4)

[0098] where δ is the angle of the Earth's rotation per second is the current strip control point coordinate

[0099] Since the Earth-fixed coordinate system is generally represented in the form of a Cartesian coordinate system, in some embodiments, for the convenience of calculation, the second control point coordinate in the Cartesian coordinate system can be converted to the second control point coordinate in the spherical coordinate system and then the formula (4) is used for drift angle correction. After that, the obtained current strip control point coordinate in the spherical coordinate system is converted back to the Cartesian coordinate system for subsequent processing

[0100] In some embodiments, δ is calculated using the following formula (5):

[0101]

[0102] where 360 in the numerator above is the angle of one full rotation of the Earth, and the denominator below calculates the number of seconds for one full rotation of the Earth, that is: the duration of one full rotation of the Earth is 23 hours 56 minutes and 4 seconds

[0103] By using the above formula (4) for drift angle correction to obtain the current control point coordinate, it is possible to avoid the influence of the drift angle in subsequent strip imaging and there is no need to use the yaw axis

[0104] After obtaining the current strip control point coordinate in step S6, step S7 is executed: obtaining the satellite attitude quaternion according to the current strip control point coordinate

[0105] In some embodiments, obtaining the satellite attitude quaternion according to the current strip control point coordinate includes: obtaining the transformation matrix from the Earth-fixed coordinate system to the satellite body coordinate system using the following formula (6)

[0106]

[0107] where is the satellite coordinate in the Earth-fixed coordinate system at time t 1 and is the corresponding coordinate in the satellite body coordinate system and

[0108] is the current strip control point coordinate. It can be understood that the strip imaging process is controlled by the satellite, and according to the coordinates in the body coordinate system, the satellite can better adjust its attitude

[0109] In some embodiments, if the above coordinates are J2000 geocentric inertial system coordinates, the conversion method from the J2000 geocentric inertial system to the satellite body coordinate system needs to be used.

[0110] In some embodiments, obtaining the satellite attitude quaternion based on the current strip control point coordinates further includes: calculating the satellite attitude quaternion using the following formula (7):

[0111]

[0112] where q 1 , q 2 , q 3 , q 4 are the satellite attitude quaternions, is the transformation matrix from the geodetic coordinate system to the satellite body coordinate system.

[0113] In some embodiments, after obtaining the quaternion, the satellite attitude is represented by the following formula (8):

[0114]

[0115] where is the satellite attitude represented by the satellite attitude quaternion.

[0116] In step S8, the attitude control system of the satellite adjusts the satellite attitude according to the satellite attitude quaternion, and the satellite bus system correspondingly sets the camera parameters and completes the imaging task of the current strip according to the previously set satellite push-scan vector to obtain the current strip image data.

[0117] In some embodiments, the satellite strip imaging method of the present application further includes: imaging multiple different current strips to obtain multiple strip images; and stitching the multiple strip images.

[0118] It can be understood that since the target area includes multiple strips, the imaging of the target area requires the completion of the imaging of multiple strips and the stitching of multiple strip images.

[0119] In some embodiments, the calculation can be completed strip by strip and then the imaging can be performed strip by strip. For example, calculate the starting point coordinates of the first strip and set the moment when the satellite line of sight points to the strip starting point as t 0 ; assuming the satellite control frequency is 4 hz, then the first control point coordinates of the control points within the strip corresponding to the moments of t 0 +0.25 s, t 0 +0.5 s, t 0 +0.75 s,..., t 0 +t s can be calculated using the above formula (2). After that, according to the above formulas (3) to (7), the coordinates of the control points are obtained. and a series of satellite attitudes represented by satellite attitude quaternions corresponding thereto Subsequently, the attitude control system of the satellite adjusts the satellite attitude according to this series of satellite attitudes The satellite bus management system correspondingly sets the camera parameters to complete the imaging task of one strip. Repeat the above steps to complete the imaging tasks of other strips. After obtaining multiple strip images, splice the multiple strip images to complete strip splicing.

[0120] In some embodiments, the calculations for multiple strips can be completed first and then the multiple strips can be imaged one by one. For example: calculate the starting coordinates of multiple strips Obtain a series of first control point coordinates of multiple strips Obtain a series of control point coordinates of multiple strips After that, obtain a series of control point coordinates of multiple strips a series of satellite attitudes of After that, the attitude control system of the satellite adjusts the satellite attitude according to this series of satellite attitudes The satellite bus management system correspondingly sets the camera parameters, images multiple strips one by one and obtains multiple strip images, and then splices the multiple strip images to complete strip splicing.

[0121] Figure 6 FIG. shows a schematic diagram of the satellite three-axis angle change in the satellite strip imaging method according to an embodiment of the present application. Among them, the abscissa is time, with the unit of second; the ordinate is the satellite three-axis angle, with the unit of degree. Figure 6 In the shown embodiment, the satellite orbital altitude is 500 km, the camera swath width is 15 km, the number of spliced strips is 5, and the length of each strip is 100 km.

[0122] As Figure 6 shown, as time progresses, when the satellite is performing strip imaging, only the pitch and roll axes are maneuvered, and the yaw axis always remains stationary with an angle of zero all the time, which can be applicable to an optical imaging satellite with a turntable system. Figure 7 FIG. shows Figure 6 a scene simulation diagram of the strip in the shown embodiment. Among them, Figure 7 the bar-shaped areas where 71, 72, 73, 74, and 75 are located in respectively correspond to five strips. As Figure 7 shown, by using the satellite strip imaging method of the present application, the imaging of multiple strips can be completed without using the yaw axis, and the subsequent strip splicing task can be completed.

[0123] For a satellite with a yaw axis, after adopting the satellite strip imaging method of the present application, the yaw axis maneuvering process during the strip switching process can be reduced, the time required for strip switching can be reduced, thereby shortening the time required to complete the entire imaging task and improving the task completion efficiency.

[0124] The present application also proposes a satellite strip imaging device, including: a memory for storing instructions executable by a processor; a processor for executing the instructions to implement the above satellite strip imaging method.

[0125] Figure 8 It is a system block diagram of a satellite strip imaging device according to an embodiment of the present application. Refer to Figure 8 As shown, the satellite strip imaging device 800 may include an internal communication bus 801, a processor 802, a read-only memory (ROM) 803, a random access memory (RAM) 804, and a communication port 805. When applied to a personal computer, the satellite strip imaging device 800 may further include a hard disk 806. The internal communication bus 801 can enable data communication between the components of the satellite strip imaging device 800. The processor 802 can make judgments and issue prompts. In some embodiments, the processor 802 may be composed of one or more processors. The communication port 805 can enable data communication between the satellite strip imaging device 800 and the outside. In some embodiments, the satellite strip imaging device 800 can send and receive information and data from a network through the communication port 805. The satellite strip imaging device 800 may further include different forms of program storage units and data storage units, such as a hard disk 806, a read-only memory (ROM) 803, and a random access memory (RAM) 804, which can store various data files used for computer processing and / or communication, as well as possible program instructions executed by the processor 802. The processor executes these instructions to implement the main part of the method. The result processed by the processor is transmitted to the user device through the communication port and displayed on the user interface.

[0126] The above satellite strip imaging method can be implemented as a computer program, stored in the hard disk 806, and loaded into the processor 802 for execution to implement the satellite strip imaging method of the present application.

[0127] The present application also proposes a computer-readable medium storing computer program code, and the computer program code implements the above satellite strip imaging method when executed by a processor.

[0128] Some aspects of the present application may be executed entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. The above-mentioned hardware or software may be referred to as a "data block", "module", "engine", "unit", "component", or "system". The processor may be one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DAPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, or combinations thereof. In addition, aspects of the present application may be embodied as a computer product located in one or more computer-readable media, the product including computer-readable program code. For example, the computer-readable media may include, but is not limited to, magnetic storage devices (such as hard disks, floppy disks, magnetic tapes...), optical disks (such as compact disks CD, digital versatile disks DVD...), smart cards, and flash memory devices (such as cards, sticks, key drives...).

[0129] The computer-readable media may include a propagated data signal having computer program code embodied therein, for example, on a baseband or as part of a carrier wave. The propagated signal may take many forms, including electromagnetic, optical, or the like, or any suitable combination thereof. The computer-readable media may be any computer-readable media other than a computer-readable storage media that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. The program code located on the computer-readable media may be propagated through any appropriate medium, including radio, cable, fiber optic cable, radio frequency signal, or similar media, or any combination of the above media.

[0130] Similarly, it should be noted that, in order to simplify the presentation of the disclosure of the present application and thus assist in the understanding of one or more embodiments of the invention, in the foregoing description of the embodiments of the present application, sometimes multiple features are grouped into one embodiment, drawing, or description thereof. However, this disclosure method does not mean that the features required by the subject matter of the present application are more than the features mentioned. In fact, the features of the embodiment are less than all the features of the single embodiment disclosed above.

[0131] In some embodiments, numbers are used to describe components and the quantity of attributes. It should be understood that such numbers used in the description of embodiments are, in some examples, modified by the modifiers "about", "approximately" or "substantially". Unless otherwise stated, "about", "approximately" or "substantially" indicate that the said numbers are allowed to have a variation of ±20%. Accordingly, in some embodiments, the numerical parameters adopted in the present application are all approximate values, and such approximate values may change according to the characteristics required by individual embodiments. In some embodiments, the numerical parameters should consider the specified significant digits and adopt the method of retaining the general number of digits. Although the numerical ranges and parameters used to confirm the breadth of their scope in some embodiments of the present application are approximate values, in specific embodiments, the setting of such numerical values is as precise as possible within the feasible range.

Claims

1. A satellite strip imaging method, comprising: Acquire a target area, and divide the target area into a plurality of strips; Selecting a stripe from the plurality of stripes as a current stripe, wherein the current stripe has at least one control point; Setting a satellite push-broom vector; the satellite push-broom vector is configured such that: the satellite push-broom vector has a first direction in a forward push-broom direction, and the satellite push-broom vector has a second direction in a reverse push-broom direction, and the first direction is parallel to the second direction; Calculate the coordinates of the starting point of the current strip according to the push-sweep ground speed, where the push-sweep ground speed is the modulus of the satellite push-sweep vector; Acquire the first control point coordinates of each control point according to the starting point coordinates of the current strip; Correcting the coordinates of the first control point to obtain the coordinates of the current strip control point; Obtaining satellite attitude quaternion according to the coordinates of the current strip control point; The current strip imaging is completed according to the satellite attitude quaternion and the satellite push-scan vector.

2. The satellite strip imaging method according to claim 1, characterized in that: The step of correcting the first control point coordinates to obtain the current strip control point coordinates includes: performing ground height correction and drift angle correction on the first control point coordinates.

3. The satellite strip imaging method according to claim 1, characterized in that: Calculating the coordinates of the starting point of the current strip according to the sweeping ground speed includes: calculating the coordinates of the starting point of the current strip using the following formula: Among them, S tg is the target point coordinate, tg is the time when the target point passes the top, P tg is the satellite position vector at the moment of passing, N tg is the satellite velocity vector at the time of passing the top, V G is the sweeping speed, t s is the sweep time of the current strip, L is the interval between strips, n is the number of strips, S j are the starting point coordinates of the current stripe corresponding to the jth stripe as the current stripe, j = 1, 2, ..., n, where n is a natural number.

4. The satellite strip imaging method according to claim 1, characterized in that: The acquiring the first control point coordinates of each control point according to the current strip starting point coordinates comprises: acquiring the first control point coordinates by using the following formula: in, is the coordinate of the first control point, and t1 is the moment when the satellite visual axis points to the control point; are the coordinates of the starting point of the current strip, and t0 is the moment when the satellite visual axis points to the starting point of the current strip.

5. The satellite strip imaging method according to claim 4, characterized in that: The following formula is used to correct the ground height of the coordinates of the first control point: in, is the ground height corresponding to the control point, are the coordinates of the second control point, are the coordinates of the first control point.

6. The satellite strip imaging method according to claim 5, characterized in that: The deviation angle correction includes: using the following formula to convert the coordinates of the second control point into Corrected to the current strip control point coordinates i ′ =θ+δ, Where δ is the angle at which the Earth rotates per second, are the coordinates of the current strip control point.

7. The satellite strip imaging method as claimed in claim 6, characterized in that: The obtaining of the satellite attitude quaternion according to the coordinates of the current strip control point includes: obtaining the transformation matrix of the earth-fixed coordinate system to the satellite body coordinate system by using the following formula in, is the satellite coordinate in the earth-fixed coordinate system at time t1, for The corresponding satellite coordinates in this system are: are the coordinates of the current strip control point.

8. The satellite strip imaging method according to claim 7, wherein the step of obtaining the satellite attitude quaternion according to the coordinates of the current strip control point further comprises: The satellite attitude quaternion is calculated using the following formula: Among them, q1, q2, q3, q4 are satellite attitude quaternions, is the transformation matrix from the earth-fixed coordinate system to the satellite body coordinate system.

9. The satellite strip imaging method according to any one of claims 1 to 8, characterized in that: include: Imaging a plurality of different current strips to obtain a plurality of strip images; as well as The multiple strip images are stitched together.

10. A satellite strip imaging device, comprising: a memory for storing instructions executable by a processor; A processor, configured to execute the instructions to implement the satellite strip imaging method as described in any one of claims 1 to 9.

11. A computer-readable medium storing computer program codes, wherein the computer program codes, when executed by a processor, implement the satellite strip imaging method according to any one of claims 1 to 9.

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