A Method and System for Rapid Coverage of Remote Sensing Satellites in a Large Area over a Long Period

Abstract

The present invention provides a method and system for rapid coverage of remote sensing satellites in a large area over a long period. By establishing a visible schedule of ground targets for remote sensing satellites; determining a set of satellites with the earliest visible opportunities for the ground targets to be covered during their life cycles; sorting the satellites in the set, and successively simulating the shooting of each of the sorted satellites on the current remaining target area to obtain the shooting strips of each satellite and adding them to the coverage plan; calculating the remaining target area after the simulated shooting of all satellites on the target area; repeating the previous steps until the remaining targets are all covered, and outputting the coverage plan. By pre-establishing the visible schedule, the real-time calculation is converted into data query, the satellites visible on the same day are sorted according to the optimization objective, and then the target area is simulated and shot by the satellites visible on the same day to obtain the earliest strip coverage plan, reducing the calculation complexity and improving the calculation performance by narrowing the calculation period and calculation resources.

Description

Technical Field

[0001] The present invention relates to the technical field of satellite remote sensing technology, and in particular to a method and system for rapid coverage of remote sensing satellites in a large area over a long period of time. Background Art

[0002] With the increasingly wide application of remote sensing data in various fields, the number of remote sensing satellites at home and abroad has developed rapidly in recent years. In the case of sufficient imaging satellite resources, how to reasonably conduct multi-satellite and multi-payload coverage analysis for large-area targets is a key and difficult problem that urgently needs to be solved in remote sensing satellite mission planning.

[0003] At present, the main process of multi-satellite and multi-payload coverage analysis in the observation area is to convert the area target into a point target, calculate the window for the point target, and then select the coverage according to strategies such as coverage priority, time priority, and imaging quality priority for the calculated window, so as to form a multi-satellite and multi-payload coverage plan for the area target. The methods for converting area targets into point targets mainly include equal-width division and grid division. Equal-width division, as the name implies, divides the area target parallel to the satellite sub-track according to the width of the satellite payload's swath. The multi-satellite area coverage plan is obtained through window calculation and optimized selection based on the single-satellite equal-width division (as shown in Figure 1 ); Grid division is to divide the area target into grids with a grid granularity smaller than the swath size (as shown in Figure 2 ), and then obtain the coverage strip through grid point visibility calculation, and obtain the multi-satellite area coverage plan through optimized selection of the coverage strip. Although the above two area coverage methods can obtain multi-satellite area coverage plans, they require high computing resources and long computing time, and can only adapt to short-term and limited area targets, and there is a problem of incomplete coverage for long-cycle and large-area targets. Summary of the Invention

[0004] The technical problem to be solved by the present invention is how to quickly cover long-cycle and large-area targets, and a method and system for rapid coverage of remote sensing satellites in a large area over a long period of time are proposed.

[0005] To solve the above technical problem, the technical solution adopted by the present invention is:

[0006] A method for rapid coverage of remote sensing satellites in a large area over a long period of time, comprising the following steps:

[0007] Step 1: Establish a visible time table of ground area targets for remote sensing satellites;

[0008] Step 2: Determine the satellite set O' with the earliest visible opportunity during the life cycle of the ground area target to be covered according to the visible time table of the ground area target for remote sensing satellites t min ;

[0009] Step 3: Sort the satellites in the satellite set O′ according to the optimization objective, and successively simulate the shooting of each sorted satellite on the current remaining target area to obtain the shooting strips of each satellite and add them to the coverage plan; the current remaining target area refers to the target area remaining after subtracting the remaining target area and the already covered strips by the previous satellite. tmin

[0010] Step 4: Calculate the remaining target area after the satellites in the satellite set O′ simulate shooting on the target area. tmin

[0011] Step 5: Repeat Steps 1 to 3 for the remaining target area until the remaining target area is completely covered or the end time of the regional target life cycle is reached, and output the coverage plan F.

[0012] Furthermore, the method for determining the satellite set with the earliest visible opportunity for the ground area target during its life cycle in Step 2 is as follows:

[0013] Step 2.1: Determine the set of grid points of the target area.

[0014] Step 2.2: Calculate the visibility of the grid points of the target area within the satellite orbit period according to the determined set of grid points of the target area.

[0015] Step 2.3: Calculate the set of visible satellites of the target area at time t according to the visibility of the target area within the satellite orbit period.

[0016] Step 2.4: Calculate the set of satellites and time visible to the target area according to the set of visible satellites of the target area at time t.

[0017] Furthermore, the method for determining the set of grid points of the target area in Step 2.1 is as follows:

[0018] Take the grid points covered by the target area as the grid point set P, and then select characteristic grid points from the target area grid point set P according to the orbital inclination of the satellite and the minimum swath width of the satellite to form the characteristic grid point set P', where the characteristic grid points refer to the latitudes passing through the geometric center point of the target area, and the grid points in the target area grid point set P whose distance from the above latitudes is less than or equal to one grid size;

[0019] P′ = {p′1, p′2, p′3,..., p′ n},

[0020] n is the number of characteristic grid points.

[0021] ​​Further, the method for calculating the visibility of the target area within the satellite orbital period in step 2.2 is as follows:

[0022] Query the remote sensing satellite visibility schedule to obtain the characteristic grid point p'. i |p' i ∈P' for the visibility schedules M of all satellites P′i ;

[0023] Then the set M of visibility schedules of the ground area target characteristic grid point set P' for all satellites P′ is the union of the visibility schedules of each characteristic grid point

[0024] M P′ = M p′1 ∪M p′2 ∪M p′3 ...∪M p′n |p' n ∈P'.

[0025] Further, the method for calculating the set of visible satellites of the target area at time t in step 2.3 is as follows:

[0026] Step 2.3.1: Calculate the set of satellites that have a visibility opportunity for the characteristic grid point p' at time t i ;

[0027] Traverse the visibility schedule M of each satellite for the characteristic grid point p' i for all satellites P′i , M P′i for each element V in m which represents the visibility time of the characteristic grid point p' for the satellite s i at time t, calculate the offset t' of the visibility schedule reference time t of the characteristic grid point p' for the satellite s m ; i t' = (t - t m ) / T 0m , where T

[0028] is the orbital regression period of the satellite s 0m in days; sm If t' ∈ D sm |D m ∈ V m , then the satellite s m is visible to the characteristic grid point p' at time t, and the satellite s m is added to the set S of satellites visible to the characteristic grid point p' at time point t m ; i ; m ; i ; p′i ;p′i , add p' i to the satellite s m at the set of grid points visible at time point t D m denote the satellite S m for the characteristic grid points based on time t 0m the visible offset within one orbital period is a set of several natural numbers less than the orbital regression period;

[0030] Step 2.3.2: Calculate the set of satellites that have a visible opportunity for the regional target at time point t.

[0031] Traverse each element in M P′ and perform the calculation of the visible satellite set according to the steps of Step 2.3.1. Then, the set of satellites that have a visible opportunity for the regional target at time point t is the intersection of the visible satellite sets of each characteristic grid point, denoted as O t = S p′1 ∩ S p′2 ∩ S p′2 ∩... ∩ S p′n .

[0032] Furthermore, the method for calculating the set of satellites and the time that are earliest visible to the regional target in Step 2.4 is as follows:

[0033] If there are elements in the result O t , then this calculation ends. The set of satellites that are earliest visible to the regional target is denoted as O' t min , and the earliest visible time is denoted as t min ;

[0034] If there are no elements in O t , assign t + 1 to t and repeat the calculation in Step 2.3, where t + 1 ≤ t e , t e represents the end time of the period that needs to be collected for the current target area, with 1 unit being a day, indicating 1 day. The visible set O t+1 of the regional target, until it is calculated that there are elements in O t+1 or the time condition is not satisfied.

[0035] Furthermore, the optimization objective described in Step 3 refers to: coverage priority, time priority, and imaging quality priority.

[0036] Furthermore, the specific method of Step 3 is:

[0037] Step 3.1: If coverage is prioritized, sort the satellites in the set O' t min of the satellites that are earliest visible to the regional target in descending order of satellite swath width;

[0038] If time is prioritized, for O′ t min Sort in ascending order of the local time of the descending node from early to late;

[0039] If image quality is prioritized, for O′ t min Sort in descending order of resolution;

[0040] Step 3.2: Traverse the satellites in O′ t min in sequence, and mark the current satellite as s c , using the orbital inclination of s c as the tilt angle, and passing through the visible grid points p′ c of s at time t min to create a straight line l and add it to the set of straight lines L, forming a set of straight lines L with the orbital inclination of satellite s c as the tilt angle and passing through the visible grid points; c |p′ sct min ∈P c ;

[0041] Step 3.3: Traverse L, calculate the distance of the intersecting line segment between the straight line l|l ∈ L and the target area (if it is tangent, the length of the intersecting line segment is 0), find the longest intersecting line segment, and use the endpoints of the intersecting line segment as the center points, perpendicular to the intersecting line segment, and extend it by half of the width of the satellite s c to generate a strip q containing four vertices sc . If the vertices of the strip are within the regional target, then extend the strip in the direction of the line segment until the four vertices are not within the regional target. Finally, the determined strip is marked as q′ sc , and add this strip to the coverage scheme F′;

[0042] Step 3.4: Subtract the target area from the calculated strip area to obtain the remaining uncovered area, and then use the other satellites in O′ t min to simulate and photograph the uncovered area to calculate the coverage strip, and further obtain the coverage scheme F′ t min of O′ for the area, and add the scheme F′ to the scheme F. If there is no remaining area, then F is the multi-satellite coverage scheme for this area and output it. If there is a remaining area, go to step 4.

[0043] The present invention also provides a fast coverage system for remote sensing satellites in a large area over a long period, including the following steps:

[0044] Remote sensing satellite visible time table construction module: used to establish the visible time table of the ground area target for the remote sensing satellite;

[0045] Calculation of visible opportunity satellite module: used to determine the set of satellites O′ with the earliest visible opportunities during the life cycle of the ground area target to be covered according to the visible time table of the ground area target for the remote sensing satellite t min ;

[0046] Simulated shooting strip coverage module: used to sort the satellites in the satellite set O' according to the optimization target, and successively make each sorted satellite simulate shooting the current remaining target area, obtain the shooting strip of each satellite and add it to the coverage plan; the remaining target area refers to the remaining target area after subtracting the remaining target area from the already covered strip by the previous satellite; t min The remaining target area calculation module: used to calculate the remaining target area after the satellites in the satellite set O' simulate shooting the target area;

[0047] Remaining target area calculation module: used to calculate the remaining target area after all satellites in the satellite set O' simulate shooting the target area; t min in the target area;

[0048] Coverage plan output module: used to calculate the remaining target area using the remote sensing satellite visibility schedule construction module, visible opportunity satellite calculation module, and simulated shooting strip coverage module until the remaining target area is completely covered or the end time of the regional target life cycle is reached, and output the coverage plan F.

[0049] Adopting the above technical solution, the present invention has the following beneficial effects:

[0050] A long-duration large-area remote sensing satellite rapid coverage method and system provided by the present invention, by establishing and maintaining a global grid remote sensing satellite visibility schedule and grid feature points of the grid-shaped ground area target, determines the satellite set with the earliest visible opportunity for the ground area target during its life cycle. Here, by pre-establishing the visibility schedule, real-time calculation is transformed into data query, reducing the calculation complexity during regional target coverage analysis and improving the calculation performance; then, according to the optimization target, the satellites visible on the same day are sorted, and the target area is successively simulated and shot by the sorted satellites visible on the same day to obtain the earliest strip coverage plan. Here, by reducing the calculation period and calculation resources, the calculation complexity is reduced and the calculation performance is improved; then, the remaining target area that has not been shot after the target area is simulated and shot is continued to be simulated and shot according to the previous method to obtain the coverage strip. Here, by gradually solving and shrinking the problem, the overall calculation complexity is reduced and the calculation performance is improved. Using the method of the present invention, rapid full coverage division of remote sensing observation area targets in long cycles and large areas can be carried out. Description of the Drawings

[0051] Figure 1 It is a schematic diagram of equal-width division;

[0052] Figure 2 It is a schematic diagram of grid division;

[0053] Figure 3 It is a system flow chart of the present invention;

[0054] Figure 4Flowchart for determining the set of satellites with the earliest visible opportunities for a regional target during its life cycle as shown in the embodiments of the present invention;

[0055] Figure 5 Schematic diagram of strip division. Detailed implementation manners

[0056] The technical solutions of the present invention will be described clearly and completely below with reference to the accompanying drawings. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0057] Figures 1 to 5 A specific embodiment of a method for rapid coverage of remote sensing satellites in a large area over a long period of time according to the present invention is shown, as Figure 3 shown.

[0058] Step 1: Establish a visible schedule of the ground regional target for remote sensing satellites;

[0059] In this embodiment, the Earth's surface is divided into grids by the GeoSOT partitioning method to obtain a grid set P, and a visible schedule V of each grid point for each satellite is constructed m , and then a visible schedule M of the grid points for all satellites is formed;

[0060] M = {V1, V2, V3,..., V y};

[0061] V m = {s m , t 0m , D m}

[0062] D m represents the visible offset of the satellite s m for the grid point based on the time t 0m within one orbital period, and is a set of several natural numbers less than the orbital regression period; s m represents a satellite with only one effective payload for earth observation; t 0m represents the reference time of the visible time offset of the satellite s m (any past time point can be selected); y represents the number of satellites.

[0063] Step 2: Determine the set of satellites O′ with the earliest visible opportunities for the ground regional target to be covered during its life cycle according to the visible schedule of the ground regional target for remote sensing satellites, as t min shown; Figure 4 shown.

[0064] In this embodiment, the method for determining the set of satellites that have the earliest visible opportunity for the ground area target during its life cycle in step 2 is as follows:

[0065] Step 2.1: Determine the set of grid points in the target area.

[0066] In this embodiment, the method for determining the set of grid points in the target area is as follows:

[0067] Take the grid points covered by the target area as the grid point set P, and then select characteristic grid points from the target area grid point set P according to the orbital inclination of the satellite and the minimum width of the satellite to form the characteristic grid point set P', where The characteristic grid points refer to the latitudes passing through the geometric center point of the target area, and the grid points in the target area grid point set P that are less than or equal to one grid size away from the above latitudes.

[0068] P′ = {p′1, p′2, p′3,..., p′ n},

[0069] n is the number of characteristic grid points.

[0070] Step 2.2: Calculate the visibility of the grid points in the area within the satellite orbit period according to the determined set of grid points in the target area.

[0071] In this embodiment, the method for calculating the visibility of the target area within the satellite orbit period is as follows:

[0072] Query the visible time schedule of the remote sensing satellite to obtain the visible time schedule M of the characteristic grid point p′ i |p′ i ∈ P′ for all satellites; P′i ;

[0073] Then the set of visible time schedules M of the ground area target characteristic grid point set P' for all satellites P′ is the union of the visible time schedules of each characteristic grid point

[0074] M P′ = M p′1 ∪ M p′2 ∪ M p′3 ... ∪ M p′n |p′ n ∈ P′.

[0075] Step 2.3: Calculate the set of visible satellites of the target area at time t according to the visibility of the target area within the satellite orbit period;

[0076] In this embodiment, the method for calculating the set of visible satellites of the target area at time t is as follows: Step 2.3.1: Calculate the visible situation of the characteristic grid point p′ at time t iSatellite set with visible opportunities;

[0077] Traverse the feature grid point p′ i Visibility schedule M for all satellites P′i , M P′i Each element V in m represents the visible time of the feature grid point p′ i for satellite s m Calculate the offset t′ of the feature grid point p′ i for satellite s m from the reference time t of the visibility schedule; 0m t′ = (t - t

[0078] ) / T 0m ), where T sm is the orbital regression period of satellite s sm in days; m

[0079] If t′ ∈ D m |D m ∈ V m , then satellite s m is visible to the feature grid point p′ i at time t. Add satellite s m to the satellite set S i visible to the feature grid point p′ p′i at time point t, and add p′ i to the set of grid points visible to satellite s m at time point t D m represents the visible offset of satellite S m from the feature grid point based on time t 0m within one orbital period, which is a set of several natural numbers less than the orbital regression period;

[0080] Step 2.3.2: Calculate the satellite set with visible opportunities for the regional target at time point t.

[0081] Traverse each element in M P′ and perform the calculation of the visible satellite set according to the steps in Step 2.3.1. Then, the satellite set with visible opportunities for the regional target at time point t is the intersection of the visible satellite sets for each feature grid point, denoted as O t = S p′1 ∩ S p′2 ∩ S p′2 ∩... ∩ S p′n .

[0082] ​Step 2.4: Calculate the satellite set and time visible to the target area based on the set of visible satellites in the target area at time t.

[0083] In this embodiment, the method for calculating the earliest visible satellite set and time for the regional target is as follows:

[0084] If there are elements in the result O t then this calculation ends, the earliest visible satellite set for the regional target is denoted as O′ t min , and the earliest visible time is denoted as t min ;

[0085] If there are no elements in O t , assign t + 1 to t, and repeat step 2.3 for calculation, where t + 1 ≤ t e , t e represents the end time of the period that needs to be collected for the current target area, with 1 unit being a day, indicating 1 day. The visible set O t+1 of the regional target, until there are elements in O t+1 is calculated, or the time condition is not met.

[0086] Step 3: Sort the satellites in the satellite set O′ t min according to the optimization objective, and successively simulate the shooting of each satellite in the sorted order for the current remaining target area to obtain the shooting strip of each satellite and add it to the coverage plan; the current remaining target area refers to the target area remaining after subtracting the remaining target area and the already covered strips by the previous satellite.

[0087] The optimization objective in this embodiment refers to: coverage priority, time priority, and imaging quality priority.

[0088] Step 3.1: If coverage is prioritized, sort the satellites in the earliest visible satellite set O′ t min for the regional target in descending order of satellite swath width;

[0089] If time is prioritized, sort O′ t min in descending order of local time of descending node from early to late;

[0090] If imaging quality is prioritized, sort O′ t min in descending order of resolution.

[0091] Step 3.2: Traverse the satellites in O′ t min in turn, and mark the current satellite as s c , use the orbital inclination of s c as the tilt angle, and through s c at time t min to obtain the visible grid point p′ c |p′ c∈P sct min Create a straight line l and add it to the set L to form a satellite s c The orbital inclination is used as the inclination angle and the set L of straight lines passing through the visible grid points is as follows Figure 5 as shown

[0092] Step 3.3: Traverse L, calculate the distance of the intersecting line segment between the straight line l|l ∈ L and the target area (if it is tangent, the length of the intersecting line segment is 0), find the longest intersecting line segment, and take the endpoints of the intersecting line segment as the center points, perpendicular to the intersecting line segment, and extend the satellite s c Half of the swath width to generate a strip q containing four vertices sc , if the strip vertices are within the regional target, then extend the strip in the direction of the line segment until the four vertices are not within the regional target, and the finally determined strip is marked as q′ sc , add this strip to the coverage scheme F′;

[0093] Step 3.4: Subtract the calculated strip area from the target area to obtain the remaining uncovered area, and then use the other satellites in O′ t min to simulate the shooting calculation of the coverage strip for the uncovered area, and then obtain the coverage scheme F′ of O′ t min for the area. And add the scheme F′ to the scheme F. If there is no remaining area, then F is the multi-satellite coverage scheme for this area and output. If there is a remaining area, go to step 4.

[0094] In this embodiment, by sorting the satellites in the visible satellite set according to the optimization target, and then traversing each satellite in turn to simulate the shooting of the current satellite on the target area to obtain the coverage strip, and using other satellites to simulate the shooting of the remaining area to obtain the multi-satellite coverage scheme, a strip with the largest coverage can be quickly selected.

[0095] Step 4: Repeat steps 1 to 3 for the remaining target area until the remaining target area is completely covered or the end time of the regional target life cycle is reached.

[0096] The present invention also provides a fast coverage system for long-duration large-area remote sensing satellites, including the following steps:

[0097] Remote sensing satellite visible time table construction module: used to establish the visible time table of remote sensing satellites for the ground area target to be covered;

[0098] Calculation of visible opportunity satellite module: used to determine the set O′ of satellites with the earliest visible opportunities of the ground area target during its life cycle according to the visible time table of the ground area target for remote sensing satellites t min ;

[0099] Simulation shooting strip coverage module: used to simulate the shooting strip coverage of the satellite set O′ according to the optimization targett min Sort the satellites in [the satellite set], and sequentially simulate the shooting of each sorted satellite on the current remaining target area to obtain the shooting strips of each satellite and add them to the coverage plan; the remaining target area refers to the target area remaining after subtracting the remaining target area from the already covered strips by the previous satellite.

[0100] Remaining target area calculation module: used to calculate the remaining target area after the satellites in the satellite set O' t min simulate shooting on the target area.

[0101] Coverage plan output module: used to calculate the remaining target area using the remote sensing satellite visibility schedule construction module, the visible opportunity satellite calculation module, and the simulated shooting strip coverage module until the remaining target area is completely covered or the end time of the regional target life cycle is reached, and output the coverage plan F.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for rapid coverage of a large area by a remote sensing satellite over a long period, characterized in that, Including the following steps: Step 1: Establish a visible schedule of ground area targets for remote sensing satellites; Step 2: Determine the set of satellites with the earliest visibility opportunities during the life cycle of the ground area target to be covered according to the remote sensing satellite visibility schedule for the ground area target ; Step 3: Sort the satellites in the satellite set according to the optimization objective, and successively simulate the shooting of each satellite in the sorted order for the current remaining target area to obtain the shooting strips of each satellite and add them to the coverage plan; ; The optimization objectives refer to: coverage priority, time priority, and imaging quality priority; the current remaining target area refers to the remaining target area after subtracting the already covered strips from the remaining target area of the previous satellite; The specific method of Step 3 is: Step 3.1: If coverage is prioritized, sort the satellites in the set of satellites that are earliest visible to the regional target in descending order of satellite swath width; If time is prioritized, for sort in descending order of local time of descending node from early to late; If image quality is prioritized, sort in descending order of resolution; Step 3.2: Traverse the satellites in one by one. Mark the current satellite as , and use the orbital inclination of as the tilt angle. Through , create a straight line at the visible grid points at time and add it to the set of straight lines . represents the set of visible grid points of satellite at the time point , forming a set of straight lines with the orbital inclination of the satellite as the tilt angle and passing through the visible grid points ;​ Step 3.3: Traverse and calculate the distance of the intersecting line segment between the straight line and the target area. If the length of the intersecting line segment is 0 when it is tangent, find the longest intersecting line segment, and take the endpoints of the intersecting line segment as the center points, perpendicular to the intersecting line segment, and extend the satellite by half of the width to generate a strip with four vertices . If the strip vertices are within the regional target, then extend the strip along the line segment direction until the four vertices are not within the regional target. The finally determined strip is marked as and add this strip to the coverage plan ; Step 3.4: Subtract the calculated strip area from the target area to obtain the remaining uncovered area, and then use other satellites in to simulate shooting the uncovered area and calculate the coverage strip, so as to obtain the coverage plan for the area , and add the plan to the plan . If there is no remaining area, then is the multi-satellite coverage plan for this area and output it. If there is a remaining area, go to Step 4; Step 4: Calculate the remaining target area after all satellites in the satellite set simulate photographing the target area; Step 5: Repeat Steps 1 to 3 for the remaining target area until the remaining target area is completely covered or the end time of the target area life cycle is reached, and output the coverage plan .

2. The covering method according to claim 1, wherein The determination method for the set of satellites with the earliest visible opportunities for ground area targets within their life cycles in Step 2 is: Step 2.1: Determine the set of target area grid points; Step 2.2: Calculate the visibility of the target area grid points within the satellite orbit period based on the determined set of target area grid points; Step 2.3: Calculate the set of visible satellites in the target area at time according to the visibility of the target area within the satellite orbit period; Step 2.4: Calculate the set of satellites visible to the target area and the time based on the set of visible satellites in the target area at time .

3. The covering method according to claim 2, wherein The method for determining the set of target area grid points in Step 2.1 is: Take the grid points covered by the target area as the grid point set , and then select characteristic grid points from the target area grid point set to form a characteristic grid point set , where , the characteristic grid points refer to the latitudes passing through the geometric center point of the target area, and the grid points in the target area grid point set whose distance to the above-mentioned latitudes is less than or equal to one grid size; ， n is the number of characteristic grid points.

4. The covering method according to claim 2, wherein The method for calculating the visibility of the target area within the satellite orbit period in Step 2.2 is: Query the visible schedule of remote sensing satellites to obtain characteristic grid points For the visible schedules of all satellites ; Then the set of target feature grid points in the ground area The set of visibility schedules for all satellites Is the union of the visibility schedules for each feature grid point 。 5. The covering method according to claim 2, characterized in that The method for calculating the set of visible satellites in the target area at the moment in Step 2.3 is as follows: ​ Step 2.3.1: Calculate at time For the feature grid points Set of satellites with visible opportunities; Traverse the characteristic grid points Visibility schedule for all satellites , For each element in Represents the characteristic grid point For the satellite Visibility time, calculate at the moment Characteristic grid point For the satellite Visibility schedule reference time Offset of ; , is the orbital regression period of the satellite , in days; If , then the satellite at the moment is visible to the feature grid point . Adding the satellite to the set of satellites visible to the feature grid point at the moment point , adding to the set of grid points visible to the satellite at the moment point ; ; represents the visible offset of the satellite to the feature grid point based on time within one orbital period, which is a set of several natural numbers less than the orbital regression period; Step 2.3.2: Calculate the set of satellites that have the opportunity to be visible to the regional target at the time point ​ Traverse each element in, and perform the calculation of the visible satellite set according to the steps in Step 2.3.

1. Then, at the time point the satellite set that has the visible opportunity for the regional target is the intersection of the visible satellite sets of each characteristic grid point, denoted as .

6. The covering method according to claim 2, characterized in that The method for calculating the set of satellites and time with the earliest visibility for the area target in Step 2.4 is: If the result contains elements, then this calculation ends, and the set of satellites that are earliest visible to the regional target is denoted as , and the earliest visible time is denoted as ; If has no elements, assign to , and repeat the calculation in step 2.3, where , represents the end time of the period to be collected in the current target area, with 1 unit being a day, representing 1 day, and the visible set of the regional target , until elements are calculated in , or the time condition is not met.

7. A rapid coverage system for remote sensing satellites in a large area over a long period, characterized in that, Including the following steps: Remote sensing satellite visible schedule construction module: used to establish a visible schedule of ground area targets for remote sensing satellites; Calculating Visible Opportunity Satellite Module: Used to determine, based on the ground area target, the set of satellites with the earliest visible opportunities during the life cycle of the ground area target to be covered in the remote sensing satellite visible schedule ; Simulated shooting strip coverage module: used to sort the satellites in the satellite set according to the optimization goal, and successively make each sorted satellite simulate shooting the current remaining target area, obtain the shooting strip of each satellite and add it to the coverage plan; the optimization goal refers to: coverage priority, time priority, imaging quality priority; the remaining target area refers to the target area remaining after subtracting the remaining target area from the already covered strip by the previous satellite; the specific method of obtaining the shooting strip of each satellite and adding it to the coverage plan in the simulated shooting strip coverage module is: Sort the satellites in the satellite set according to the optimization goal, and successively make each sorted satellite simulate shooting the current remaining target area, obtain the shooting strip of each satellite and add it to the coverage plan; the optimization goal refers to: coverage priority, time priority, imaging quality priority; the remaining target area refers to the target area remaining after subtracting the remaining target area from the already covered strip by the previous satellite; the specific method of obtaining the shooting strip of each satellite and adding it to the coverage plan in the simulated shooting strip coverage module is: 1): If coverage is prioritized, sort the satellites in the set of satellites that are earliest visible to the regional target in descending order of satellite swath width; among the satellites; If time is prioritized, sort in descending order of local time of the descending node from early to late; If image quality is prioritized, sort in descending order of resolution; 2): Traverse the satellites in in sequence. Mark the current satellite as , and use the orbital inclination of as the tilt angle. Through , at time , create a straight line from the visible grid points and add it to the set of straight lines to form a set of straight lines with the orbital inclination of the satellite as the tilt angle and passing through the visible grid points ; 3): Traverse , calculate the distance of the intersecting line segment between the straight line and the target area. If the length of the tangent intersecting line segment is 0, find the longest intersecting line segment, and take the endpoints of the intersecting line segment as the center points, perpendicular to the intersecting line segment, and extend the satellite by half of the width, and generate a strip containing four vertices . If the strip vertices are within the regional target, then extend the strip along the line segment direction until the four vertices are not within the regional target. The finally determined strip is marked as , and add this strip to the coverage plan ; 4): Subtract the calculated strip area from the target area to obtain the remaining uncovered area, and then use other satellites in to simulate shooting the uncovered area and calculate the coverage strip, so as to obtain the coverage plan for the area , and add the plan to the plan . If there is no remaining area, then is the multi-satellite coverage plan for this area and output. If there is a remaining area, go to the remaining target area calculation module to calculate the remaining target area; Remaining target area calculation module: used to calculate the remaining target area after all satellites in the satellite set simulate photographing the target area; Coverage plan output module: used to calculate the remaining target area using the remote sensing satellite visibility schedule construction module, visible opportunity satellite calculation module, and simulated shooting strip coverage module until the remaining target area is completely covered or the end time of the regional target life cycle is reached, and output the coverage plan .

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