Method and system for calculating non-along-orbit imaging visibility of agile optical remote sensing satellite

Abstract

The invention relates to the technical field of remote sensing satellite imaging calculation, and discloses a method and system for calculating non-along-orbit imaging visibility of an agile optical remote sensing satellite, and the method comprises the steps: S1, obtaining a visible information set S of a central point, and a visible information set E of a starting point and an ending point; s2, executing first judgment to obtain a first judgment result; if the first judgment result is yes, ending the process of the method, otherwise, executing S3, and removing unavailable elements from the set S; s4, removing elements which do not meet non-along-track imaging conditions from the set S; s5, setting visible window information for the remaining elements in the set S; obtaining visible window cloud amount data, judging whether the visible window cloud amount is met or not, removing corresponding elements from the set S to obtain a visible window set meeting all limiting conditions, and ending the process of the method. The method is not only suitable for calculation of strip windows in the longitude direction of non-along-rail imaging, but also suitable for calculation of strip windows in any straight line direction.

Description

Technical Field

[0001] The present invention relates to the field of remote sensing satellite imaging computing technology, and in particular to a method and system for computing off-track imaging visibility of an agile optical remote sensing satellite. Background Art

[0002] Traditional optical remote sensing satellites have very limited imaging modes to choose from when completing designated observation targets. They can only passively push-broom imaging at the subsatellite point along the trajectory or swing sideways / forward and backward in the roll / pitch direction to complete passive push-broom imaging of targets along the track strip. This along-track imaging mode is limited by the maneuverability of the satellite platform, resulting in limited satellite on-orbit application efficiency. Off-track imaging is an imaging mode that actively pushes and sweeps along the distribution of ground imaging targets. It can meet the flexible and rapid imaging requirements of complex-shaped targets such as coastlines, river banks, and border lines, and has important application prospects.

[0003] However, in this field, the primary task of the visibility calculation of on-track imaging is to calculate whether the target point is within the field of view of the satellite, and it is also necessary to calculate parameters such as the imaging side swing angle and the solar altitude angle; while off-track imaging is to achieve flexible observation of the target area by flexibly adjusting the imaging side swing angle, so the visibility calculation requirements of off-track imaging are higher than those of on-track imaging. The main reason is that the visibility calculation of off-track imaging needs to pay attention to the dynamic visibility of the target point, that is, to ensure the visibility of the target point during the entire imaging process by adjusting the satellite attitude, while the imaging process of the on-track imaging mode does not perform attitude adjustment, and only pays attention to the visibility of the imaging center point at a single moment. At the same time, because the side swing angle is dynamically adjusted during the imaging process of the off-track imaging mode, it is necessary to calculate the side swing angle at different time points to ensure that the target point is always within the field of view of the sensor during the entire imaging process. In addition, the visibility calculation of off-track imaging also needs to consider the limitations of the satellite attitude control capability. The satellite adjusts its own attitude during the imaging process so that the imaging sensor can be aimed at the target area. However, the greater the angle between the satellite's own trajectory and the imaging trajectory, the greater the amplitude of the satellite's attitude adjustment, which puts higher requirements on the satellite's attitude control system. If the angle exceeds a certain range, the satellite may not be able to maintain this attitude stably.

[0004] Based on this, how to ensure the accuracy and efficiency of visibility calculation and effectively cover the target area has become a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defects existing in the above-mentioned prior art, thereby providing a method and system for calculating the off-track imaging visibility of an agile optical remote sensing satellite. Under the premise of given the longitude and latitude of the imaging start and end points, the side swing angle of the satellite imaging at the imaging start and end points and other information are calculated, and then the visible window of the satellite to the target is calculated.

[0006] A method for calculating off-track imaging visibility of an agile optical remote sensing satellite comprises the following steps: S1. Pre-acquire the visible information set S of the center point, the visible information set E of the starting point and the end point; S2. Execute a first judgment for determining whether there is a visible window at the center of the target during the shooting period to obtain a first judgment result; if the first judgment result is yes, the method flow ends, otherwise, execute step S3; S3. Remove unavailable elements from set S; S4. Make judgments based on the non-along-track imaging conditions in sequence, and remove the unsatisfied elements that do not meet the non-along-track imaging conditions from the set S; S5. For the remaining elements in the set S, set the visible window information, and mark the window as satisfying the non-along-track imaging condition; obtain the visible window cloud amount data to determine whether the visible window cloud amount meets the condition. If not, mark it as unsatisfactory cloud amount, and remove the corresponding element from the set S to obtain a visible window set that meets all restrictions. The method process ends.

[0007] Preferably, pre-acquiring a visible information set S of a center point and a visible information set E of a starting point and an end point specifically includes: Obtain imaging parameters; The visibility of the imaging start point, center point and end point within the shooting period is calculated based on the imaging parameters, and divided according to the orbital circles to obtain a visible information set S of the center point and a visible information set E of the start point and the end point.

[0008] Preferably, step 32 specifically includes: S31. Mark the elements in the set S whose side swing angles do not meet the restrictions and whose sun altitude angles do not meet the restrictions as unavailable; S32. Execute a first judgment for determining whether there is a visible window at the target center point within the shooting period, and obtain a first judgment result; if the first judgment result is yes, the method flow ends, otherwise execute step S3.

[0009] Preferably, step 4 includes: S41. Filter out the visible information set E' of the start and end points of the same cycle as the elements in the set S from the set E, and execute the A second judgment is performed to determine whether it is less than 2; if the second judgment result is no, the corresponding element is marked as not meeting the non-along-track imaging condition and is removed from the set S.

[0010] Preferably, step 4 further includes: if the second judgment result is yes, executing step S42; S42. Information visible from the starting point in set E and end point visible information Get the visible time of the corresponding starting point and the visible time of the end point , the maximum imaging time of the satellite is D; execution is used to judge The third judgment of whether it is less than D. If the result of the third judgment is no, the corresponding element is marked as not meeting the non-along-track imaging condition and is removed from the set S.

[0011] Preferably, step 4 further includes: if the third judgment result is yes, executing step S43; S43. Computational imaging begins To the end The trajectory of the satellite during the period, obtained in the satellite trajectory and Satellite position coordinates and , information visible from the starting point and end point visible information Get satellite in and The coordinates of the imaging point and ; Calculate the angle between the satellite's subsatellite point trajectory and the imaging trajectory ; Execution is used to judge Is it greater than The fourth judgment; if the result of the fourth judgment is no, the corresponding element is marked as not satisfying the non-along-track imaging condition and is removed from the set S; if the result of the fourth judgment is yes, execute step S5.

[0012] Preferably, computational imaging begins To the end The trajectory of the satellite during the period, obtained in the satellite trajectory and Satellite position coordinates and , information visible from the starting point and end point visible information Get satellite in and The imaging point coordinates and ; Calculate the angle between the satellite's subsatellite point trajectory and the imaging trajectory using the cosine theorem ; ; In the formula, Indicates the longitude of the subsatellite point when imaging begins; Indicates the latitude of the subsatellite point when imaging begins Indicates the longitude of the subsatellite point at the end of imaging; Indicates the latitude of the subsatellite point at the end of imaging; Indicates the longitude of the imaging point when imaging begins; Indicates the latitude of the imaging point when imaging begins; Indicates the longitude of the imaging point at the end of imaging; Indicates the latitude of the subsatellite point at the end of imaging.

[0013] A system for calculating off-track imaging visibility of an agile optical remote sensing satellite, which is implemented by applying the method for calculating off-track imaging visibility of an agile optical remote sensing satellite; The system comprises: A pre-acquisition module, used for pre-acquiring a visible information set S of a center point and a visible information set E of a start point and an end point; A first judgment module is used to perform a first judgment to determine whether there is a visible window at the target center point within the shooting period, and obtain a first judgment result; if the first judgment result is yes, the system ends the work, otherwise the first removal module continues to work; A first removal module, used to remove unavailable elements from the set S; A second removal module performs sequential judgment based on the non-along-track imaging condition and removes the unsatisfied elements that do not meet the non-along-track imaging condition from the set S; The comprehensive processing module is used to set the visible window information for the remaining elements in the set S, and mark the window as meeting the non-along-track imaging conditions; obtain the visible window cloud amount data to determine whether the visible window cloud amount meets the conditions. If not, it is marked as unsatisfactory cloud amount, and the corresponding elements are removed from the set S to obtain a visible window set that meets all restrictions, and the system ends.

[0014] The technical solution of the present invention has the following advantages: Regarding the visibility calculation problem of remote sensing satellites, in the existing technology, E Zhibo proposed a fast algorithm in "A Fast Calculation Method for the Visibility of Remote Sensing Satellites to Regional Targets", which calculates the visible time window by combining discrete time steps with binary search methods. However, this method is based on the along-track imaging mode and belongs to passive push-broom imaging. It cannot be customized according to the shape and geographical direction of the area, thereby reducing the number of imaging times. Shen Ying designed a method for enabling satellites to push-broom along specific meridians in "A Method for Autonomously Planning the Push-Broom Time and Attitude of Satellites Along Meridians". By calculating the imaging time and expected attitude of each target point in the strip in real time, this method can actively push-broom a section of geographical target strips along the meridian direction, thereby improving the efficiency of satellite use, but it is not applicable to other geographical targets in any other straight line direction. The technical solution of the present invention solves the technical problems that are not solved in the above two articles: how to ensure the accuracy and efficiency of visibility calculation and effectively cover the target area, which becomes a technical problem that technical personnel in this field urgently need to solve. It is also applicable to the strip window calculation along the meridian direction of non-along-track imaging, and is also applicable to the strip window calculation method along any straight line direction. According to different imaging requirements, the shape and direction of the strip can be flexibly adjusted to achieve accurate and efficient image acquisition. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 It is a detailed schematic diagram of the method of the present invention; Figure 2 This is a schematic diagram of along-track imaging; Figure 3 This is a schematic diagram of non-along-track imaging of the present invention; Figure 4 This is a simulation diagram of the push-scan imaging results along the track; Figure 5 This is a simulation diagram of the non-along-track push-scanning imaging result of the present invention; Figure 6 It is a schematic diagram of the method flow of the present invention. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0019] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] With the rapid development of remote sensing technology, optical remote sensing satellites are playing an increasingly important role in the fields of earth observation, environmental monitoring, disaster warning, etc. Traditional optical remote sensing satellites mostly use along-track imaging, that is, the satellite observes at a fixed side swing angle according to the predetermined orbit, and the observation strip is consistent with the trajectory direction of the sub-satellite point. This method is suitable for situations where the geographical orientation of the target scene is relatively consistent with the direction of the satellite track, and can efficiently image a large area of ​​the surface. However, when the geographical orientation of the target scene is inconsistent with the direction of the satellite track, along-track imaging may require observation through the splicing of multiple imaging strips, which may result in a long data acquisition cycle, reduced resolution, or waste of storage and computing resources.

[0022] The off-track imaging mode generates observation strips in different directions from the sub-satellite point trajectory by flexibly adjusting the side swing angle during the observation process to match the actual geographical direction of the target scene. For target scenes with complex geographical directions or not extending along the direction of the satellite track, such as rivers, coastlines, seismic zones and railway lines, a more customized observation solution is provided. The off-track imaging mode achieves flexible observation of the target area by adjusting the satellite's attitude without changing the satellite's orbit. This flexibility enables the satellite to respond quickly to emergencies, achieve real-time monitoring, and significantly improve observation efficiency.

[0023] Example 1 like Figure 6 Schematic diagram of the method flow of this embodiment; A method for calculating off-track imaging visibility of an agile optical remote sensing satellite comprises the following steps: S1. Pre-acquire the visible information set S of the center point and the visible information set E of the starting point and the end point, specifically including: Acquire imaging parameters; in this embodiment, the imaging parameters include but are not limited to the coordinates of the imaging start and end points, satellite imaging parameter information, satellite orbit information and target shooting period; The visibility of the imaging start point, center point, and end point in the shooting cycle is calculated based on the imaging parameters, and divided according to the orbital circles to obtain a visible information set S of the center point and a visible information set E of the start point and the end point. In this embodiment, the visibility information includes but is not limited to the imaging position coordinates, side swing, solar altitude angle, and visible time; S2. Execute a first judgment for determining whether there is a visible window at the center point of the target within the shooting period, and obtain a first judgment result; if the first judgment result is yes, the method flow ends, otherwise, execute step S3; specifically: In this embodiment, the first judgment of whether there is a visible window for the target center point within the shooting period is achieved by judging whether the set S or the set E is empty; when the set S or the set E is empty, it means that there is no visible window for the target center point within the shooting period.

[0024] like Figure 1 FIG. 4 is a detailed flow chart of the method of this embodiment, S3. Removing unavailable elements from the set S, specifically comprising: S31. Mark the elements in the set S whose side swing angles do not meet the restrictions and whose sun altitude angles do not meet the restrictions as unavailable; S32. Execute a first judgment for determining whether there is a visible window at the center point of the target within the shooting cycle, and obtain a first judgment result; if the first judgment result is yes, the method flow ends, otherwise execute step S3. For example: when the side swing angle does not meet the restriction, the captured image will deviate from the vertical state, resulting in increased geometric distortion of the image, affecting the accurate expression of the true shape and size of the object. This effect is particularly significant, especially in mountainous terrain or areas with tall objects. When the solar altitude angle is too small, such as below 30°, it will cause blurred colors and increased shadow areas in the image, reducing the clarity and quality of the image. Especially in high latitudes or winter months, the problem of low solar altitude angle is particularly prominent.

[0025] S4. Based on the non-along-track imaging condition, sequential judgments are made, and the unsatisfied elements that do not satisfy the non-along-track imaging condition are removed from the set S; specifically, the following steps are included: S41. Filter out the visible information set E' of the start and end points of the same cycle as the elements in the set S from the set E, and execute the A second judgment is performed to determine whether it is less than 2; if the second judgment result is no, the corresponding element is marked as not meeting the non-along-track imaging condition and is removed from the set S.

[0026] Step 4 also includes: if the second judgment result is yes, executing step S42; S42. Information visible from the starting point in set E and end point visible information Get the visible time of the corresponding starting point and the visible time of the end point , the maximum imaging time of the satellite is D; execution is used to judge The third judgment of whether it is less than D. If the result of the third judgment is no, the corresponding element is marked as not meeting the non-along-track imaging condition and is removed from the set S.

[0027] Step 4 also includes: if the third judgment result is yes, executing step S43; S43. Computational imaging begins To the end The trajectory of the satellite during the period, obtained in the satellite trajectory and Satellite position coordinates and , information visible from the starting point and end point visible information Get satellite in and The coordinates of the imaging point and ; Calculate the angle between the satellite's subsatellite point trajectory and the imaging trajectory ; Execution is used to judge Is it greater than The fourth judgment; if the fourth judgment result is no, mark the corresponding element as not satisfying the non-along-track imaging condition and remove it from the set S; if the fourth judgment result is yes, execute step S5; specifically: Computational imaging begins To the end The trajectory of the satellite during the period, obtained in the satellite trajectory and Satellite position coordinates and , information visible from the starting point and end point visible information Get satellite in and The coordinates of the imaging point and ; Calculate the angle between the satellite's subsatellite point trajectory and the imaging trajectory using the cosine theorem ; ; In the formula, Indicates the longitude of the subsatellite point when imaging begins; Indicates the latitude of the subsatellite point when imaging begins Indicates the longitude of the subsatellite point at the end of imaging; Indicates the latitude of the subsatellite point at the end of imaging; Indicates the longitude of the imaging point when imaging begins; Indicates the latitude of the imaging point when imaging begins; Indicates the longitude of the imaging point at the end of imaging; Indicates the latitude of the subsatellite point at the end of imaging.

[0028] S5. For the remaining elements in the set S, set the visible window information, and mark the window as satisfying the non-along-track imaging condition; obtain the visible window cloud amount data to determine whether the visible window cloud amount meets the condition. If not, mark it as unsatisfactory cloud amount, and remove the corresponding element from the set S to obtain a visible window set that meets all restrictions. The method process ends.

[0029] Example 2 A system for calculating off-track imaging visibility of an agile optical remote sensing satellite, which is implemented by applying a method for calculating off-track imaging visibility of an agile optical remote sensing satellite described in Example 1; The system comprises: A pre-acquisition module, used for pre-acquiring a visible information set S of a center point and a visible information set E of a start point and an end point; A first judgment module is used to perform a first judgment to determine whether there is a visible window at the target center point within the shooting period, and obtain a first judgment result; if the first judgment result is yes, the system ends the work, otherwise the first removal module continues to work; A first removal module, used to remove unavailable elements from the set S; A second removal module performs sequential judgment based on the non-along-track imaging condition and removes the unsatisfied elements that do not meet the non-along-track imaging condition from the set S; The comprehensive processing module is used to set the visible window information for the remaining elements in the set S, and mark the window as meeting the non-along-track imaging conditions; obtain the visible window cloud amount data to determine whether the visible window cloud amount meets the conditions. If not, it is marked as unsatisfactory cloud amount, and the corresponding elements are removed from the set S to obtain a visible window set that meets all restrictions, and the system ends.

[0030] Example 3 To further introduce the technical solution of Example 1, this embodiment also discloses the following contents based on Example 1; like Figure 2 is a schematic diagram of along-track imaging; Figure 3 This is a schematic diagram of non-along-track imaging; Figure 2 and Figure 3 In the figure, point A is the imaging point at the beginning of imaging, point A' is the sub-satellite point of the satellite at the beginning of imaging, point M is the imaging center point, point B is the imaging point at the end of imaging, and point B' is the sub-satellite point of the satellite at the end of imaging.

[0031] The application scenario of this embodiment is to select a part of a river as the target, select a satellite to shoot the target, and perform simulation calculations in the along-track push-scanning mode and the non-along-track push-scanning mode respectively. The orbit parameters of the simulation scenario are shown in Table 1, and the scanning strip parameters are shown in Table 2 and Table 3 respectively. The imaging scene diagram is the result obtained by software simulation, as shown in Table 1 and Table 2 respectively. Figure 4 , Figure 5 shown.

[0032] Table 1 Simulation scenario orbit parameters

[0033] Table 2 Parameters of along-track push-scanning strips

[0034] Table 3 Non-on-track push-scanning strip parameters

[0035] From the simulation results, it can be seen that imaging in the along-track push-scanning mode requires 12 passes and 11 days to complete; imaging in the off-track imaging mode requires 5 passes and 5 days to complete. It can be seen that for targets that do not extend along the direction of the satellite track, shooting in the off-track push-scanning imaging mode can reduce the problem of long data acquisition cycles caused by geographical mismatch, and the observation efficiency is significantly improved. At the same time, in the calculated windows, optimization can be performed based on the side swing angle, solar altitude angle and cloud cover to reduce geometric distortion, resolution degradation and cloud obstruction caused by large-angle deviation or atmospheric interference.

[0036] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for calculating off-track imaging visibility of an agile optical remote sensing satellite, characterized in that: The following steps are involved: S1. Pre-acquire the visible information set S of the center point, the visible information set E of the starting point and the end point; S2. Execute a first judgment for determining whether there is a visible window at the center of the target during the shooting period to obtain a first judgment result; if the first judgment result is yes, the method flow ends, otherwise, execute step S3; S3. Remove unavailable elements from set S; S4. Make judgments based on the non-along-track imaging conditions in sequence, and remove the unsatisfied elements that do not meet the non-along-track imaging conditions from the set S; S5. For the remaining elements in the set S, set the visible window information, and mark the window as satisfying the non-along-track imaging condition; obtain the visible window cloud amount data to determine whether the visible window cloud amount meets the condition. If not, mark it as unsatisfactory cloud amount, and remove the corresponding element from the set S to obtain a visible window set that meets all restrictions. The method process ends.

2. The method for calculating the off-track imaging visibility of an agile optical remote sensing satellite according to claim 1, characterized in that: Pre-acquire the visible information set S of the center point and the visible information set E of the start point and the end point, specifically including: Obtain imaging parameters; The visibility of the imaging start point, center point and end point within the shooting period is calculated based on the imaging parameters, and divided according to the orbital circles to obtain a visible information set S of the center point and a visible information set E of the start point and the end point.

3. The method for calculating the off-track imaging visibility of an agile optical remote sensing satellite according to claim 1, characterized in that: Step S3 specifically includes: S31. Mark the elements in the set S whose side swing angles do not meet the restrictions and whose sun altitude angles do not meet the restrictions as unavailable; S32. Execute a first judgment for determining whether there is a visible window at the target center point within the shooting period, and obtain a first judgment result; if the first judgment result is yes, the method flow ends, otherwise execute step S3.

4. The method for calculating the off-track imaging visibility of an agile optical remote sensing satellite according to claim 1, characterized in that: For step 4, include: S41. Filter out the visible information set E' of the start and end points of the same cycle as the elements in the set S from the set E, and execute the A second judgment is performed to determine whether it is less than 2; if the second judgment result is no, the corresponding element is marked as not meeting the non-along-track imaging condition and is removed from the set S.

5. The method for calculating the off-track imaging visibility of an agile optical remote sensing satellite according to claim 4, characterized in that: Step 4 also includes: if the second judgment result is yes, executing step S42; S42. Information visible from the starting point in set E and end point visible information Get the visible time of the corresponding starting point and the visible time of the end point , the maximum imaging time of the satellite is D; execution is used to judge The third judgment of whether it is less than D. If the result of the third judgment is no, the corresponding element is marked as not meeting the non-along-track imaging condition and is removed from the set S.

6. The method for calculating the off-track imaging visibility of an agile optical remote sensing satellite according to claim 5, characterized in that: Step 4 also includes: if the third judgment result is yes, executing step S43; S43. Computational imaging begins To the end The trajectory of the satellite during the period, obtained in the satellite trajectory and Satellite position coordinates and , information visible from the starting point and end point visible information Get satellite in and The imaging point coordinates and ; Calculate the angle between the satellite's subsatellite point trajectory and the imaging trajectory ; Execution is used to judge Is it greater than The fourth judgment; if the result of the fourth judgment is no, the corresponding element is marked as not satisfying the non-along-track imaging condition and is removed from the set S; if the result of the fourth judgment is yes, execute step S5.

7. The method for calculating the off-track imaging visibility of an agile optical remote sensing satellite according to claim 6, characterized in that: Computational imaging begins To the end The trajectory of the satellite during the period, obtained in the satellite trajectory and Satellite position coordinates and , information visible from the starting point and end point visible information Get satellite in and The imaging point coordinates and ; Calculate the angle between the satellite's subsatellite point trajectory and the imaging trajectory using the cosine theorem ; ； In the formula, Indicates the longitude of the subsatellite point when imaging begins; Indicates the latitude of the subsatellite point when imaging begins Indicates the longitude of the subsatellite point at the end of imaging; Indicates the latitude of the subsatellite point at the end of imaging; Indicates the longitude of the imaging point when imaging begins; Indicates the latitude of the imaging point when imaging begins; Indicates the longitude of the imaging point at the end of imaging; Indicates the latitude of the subsatellite point at the end of imaging.

8. A system for calculating off-track imaging visibility of an agile optical remote sensing satellite, characterized in that: The method for calculating the off-track imaging visibility of an agile optical remote sensing satellite according to any one of claims 1 to 7 is implemented; The system comprises: A pre-acquisition module, used for pre-acquiring a visible information set S of a center point and a visible information set E of a start point and an end point; A first judgment module is used to perform a first judgment to determine whether there is a visible window at the target center point within the shooting period, and obtain a first judgment result; if the first judgment result is yes, the system ends the work, otherwise the first removal module continues to work; A first removal module, used to remove unavailable elements from the set S; A second removal module performs sequential judgment based on the non-along-track imaging condition and removes the unsatisfied elements that do not meet the non-along-track imaging condition from the set S; The comprehensive processing module is used to set the visible window information for the remaining elements in the set S, and mark the window as meeting the non-along-track imaging conditions; obtain the visible window cloud amount data to determine whether the visible window cloud amount meets the conditions. If not, it is marked as unsatisfactory cloud amount, and the corresponding elements are removed from the set S to obtain a visible window set that meets all restrictions, and the system ends.

Images