Gaze mode imaging opportunity time window determination method and device, electronic equipment and storage medium

Abstract

The invention discloses a staring mode imaging opportunity time window determination method. The method comprises the following steps: calculating a push-scan time window for a target area in a push-scan mode; at the middle moment of the push-scan time window, the maximum side swing angle and the minimum side swing angle of the observation target area are calculated; determining an auxiliary area and an auxiliary center point according to the maximum side-sway angle, the minimum side-sway angle and the sub-satellite point trajectory; taking the middle moment of the push-broom time window as a starting point, and respectively calculating an auxiliary pitch angle and an auxiliary side swing angle forwards and backwards in sequence according to preset step length time; determining a staring moment and an out-of-staring moment according to the auxiliary pitch angle and the auxiliary side swing angle; and determining a staring time window starting moment and a staring time window ending moment between adjacent staring moments and staring outside moments by adopting a binary search method. According to the invention, the target area can be covered to the maximum extent in the staring mode, and the effective coverage area is maximum. The invention further discloses a device for implementing the method, electronic equipment and a computer readable storage medium.

Description

Technical Field

[0001] The present invention relates to the field of satellite observation technology, and in particular to a method, device, electronic device and storage medium for determining a staring mode imaging opportunity time window. Background Art

[0002] The imaging opportunity window of a remote sensing satellite for a regional target refers to the time range represented by the start and end time points during which the field of view payload carried by the satellite can observe the regional target. The calculation of the visible time window is the basis of satellite observation missions and the prerequisite for various tasks such as regional target coverage calculation and imaging mission planning.

[0003] The existing gaze mode is that the user gives a gaze point (specific longitude and latitude) of the target shooting area, then calculates the time window in which the gaze point can be gazed, and starts the gaze shooting within the time window. The shooting results of such gaze shooting are unstable in the effective coverage area of ​​the target shooting area, and cannot guarantee the maximum effective coverage area. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a method, device, electronic device and storage medium for determining a time window of opportunity for gaze mode imaging. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0005] A first aspect of an embodiment of the present invention provides a method for determining a gaze mode imaging opportunity time window, comprising the following steps:

[0006] Calculate the push-sweep time window start time, push-sweep time window end time and push-sweep time window middle time for the target area in the push-sweep mode;

[0007] At the middle moment of the push-scan time window, calculating the maximum roll angle and the minimum roll angle of the target area to be observed;

[0008] Determine the auxiliary area, the auxiliary center point and the longitude and latitude of the auxiliary center point according to the maximum roll angle, the minimum roll angle and the sub-satellite point trajectory;

[0009] Based on the longitude and latitude of the auxiliary center point, taking the middle moment of the push-scan time window as the starting point, the auxiliary pitch angle and the auxiliary roll angle of the satellite when staring at the auxiliary center point at the step boundary moment are calculated forward and backward respectively according to the preset step time;

[0010] Determine a gaze moment and a gaze-out moment according to the auxiliary pitch angle and the auxiliary roll angle;

[0011] The binary search method is used between adjacent gaze moments and out-of-gaze moments to determine the start and end moments of the gaze time window.

[0012] In one embodiment of the present invention, determining the auxiliary area, the auxiliary center point, and the longitude and latitude of the auxiliary center point according to the maximum roll angle, the minimum roll angle, and the sub-satellite point trajectory includes:

[0013] Draw a first straight line parallel to the sub-satellite point trajectory at the vertex of the target area corresponding to the maximum roll angle;

[0014] Draw a second straight line parallel to the sub-satellite point trajectory at the vertex of the target area corresponding to the minimum roll angle;

[0015] Draw two perpendicular lines respectively perpendicular to the first straight line and the second straight line; wherein the two perpendicular lines pass through the vertex of the target area, and the target area is located in the auxiliary area surrounded by the first straight line, the second straight line and the two perpendicular lines;

[0016] The auxiliary center point and the longitude and latitude of the auxiliary center point are determined according to the auxiliary area.

[0017] In one embodiment of the present invention, determining the gaze moment and the gaze-out moment according to the auxiliary pitch angle and the auxiliary roll angle comprises:

[0018] Determining whether the auxiliary pitch angle and the auxiliary roll angle are greater than a preset pitch angle and a preset roll angle;

[0019] When the auxiliary pitch angle or the auxiliary roll angle is greater than the preset pitch angle or the preset roll angle, marking the step boundary moment as the out-of-gaze moment;

[0020] When the auxiliary pitch angle and the auxiliary roll angle are smaller than the preset pitch angle and the preset roll angle, the step boundary moment is marked as a gaze moment;

[0021] The binary search method is used between adjacent gaze moments and out-of-gaze moments to determine the start and end moments of the gaze time window.

[0022] In one embodiment of the present invention, the calculation of the push-sweep time window start time, the push-sweep time window end time and the push-sweep time window middle time for the target area in the push-sweep mode includes:

[0023] Constructing a first circular area and a second circular area; wherein the target area is located in the first circular area, and the instantaneous field of view projection is located in the second circular area;

[0024] Divide the preset time period into equal parts linearly to obtain multiple equal-divided moments;

[0025] Determine whether the first circular area and the second circular area overlap at each of the equal division moments;

[0026] The moment when the first circular area and the second circular area overlap and are equally divided is a preliminary calculation result;

[0027] Calculating the visible time and the invisible time in the preliminary calculation result;

[0028] A binary search method is used between adjacent visible moments and invisible moments to determine the push-scan time window start moment and the push-scan time window end moment;

[0029] The middle time of the push-sweep time window is determined according to the start time of the push-sweep time window and the end time of the push-sweep time window.

[0030] A second aspect of an embodiment of the present invention provides a device for determining a gaze mode imaging opportunity time window, comprising:

[0031] A first calculation module is used to calculate the push-sweep time window start time, the push-sweep time window end time and the push-sweep time window middle time for the target area in the push-sweep mode;

[0032] A second calculation module is used to calculate the maximum roll angle and the minimum roll angle of the target area in the middle of the push-scan time window;

[0033] A first determination module is used to determine the auxiliary area, the auxiliary center point and the longitude and latitude of the auxiliary center point according to the maximum roll angle, the minimum roll angle and the sub-satellite point trajectory;

[0034] A third calculation module is used to calculate the auxiliary pitch angle and the auxiliary roll angle of the satellite when it is staring at the auxiliary center point at the step boundary time respectively forward and backward according to the preset step time based on the longitude and latitude of the auxiliary center point and taking the middle moment of the push-scan time window as the starting point;

[0035] A second determination module is used to determine the gaze moment and the gaze-out moment according to the auxiliary pitch angle and the auxiliary roll angle;

[0036] The third determination module is used to determine the start time of the gaze time window and the end time of the gaze time window by using a binary search method between adjacent gaze moments and gaze-out moments.

[0037] In one embodiment of the present invention, the first determining module is further configured to draw a first straight line parallel to the sub-satellite point trajectory at the vertex of the target area corresponding to the maximum roll angle;

[0038] Draw a second straight line parallel to the sub-satellite point trajectory at the vertex of the target area corresponding to the minimum roll angle;

[0039] Draw two perpendicular lines respectively perpendicular to the first straight line and the second straight line; wherein the two perpendicular lines pass through the vertex of the target area, and the target area is located in the auxiliary area surrounded by the first straight line, the second straight line and the two perpendicular lines;

[0040] The auxiliary center point and the longitude and latitude of the auxiliary center point are determined according to the auxiliary area.

[0041] In one embodiment of the present invention, the second determination module is further used to determine whether the auxiliary pitch angle and the auxiliary roll angle are greater than a preset pitch angle and a preset roll angle;

[0042] When the auxiliary pitch angle or the auxiliary roll angle is greater than the preset pitch angle or the preset roll angle, marking the step boundary moment as the out-of-gaze moment;

[0043] When the auxiliary pitch angle and the auxiliary roll angle are smaller than the preset pitch angle and the preset roll angle, the step boundary moment is marked as a gaze moment;

[0044] The binary search method is used between adjacent gaze moments and out-of-gaze moments to determine the start and end moments of the gaze time window.

[0045] In one embodiment of the present invention, the first calculation module is further used to construct a first circular area and a second circular area; wherein the target area is located in the first circular area, and the instantaneous field of view projection is located in the second circular area;

[0046] Divide the preset time period into equal parts linearly to obtain multiple equal-divided moments;

[0047] Determine whether the first circular area and the second circular area overlap at each of the equal division moments;

[0048] The moment when the first circular area and the second circular area overlap and are equally divided is a preliminary calculation result;

[0049] Calculating the visible time and the invisible time in the preliminary calculation result;

[0050] A binary search method is used between adjacent visible moments and invisible moments to determine the push-scan time window start moment and the push-scan time window end moment;

[0051] The middle time of the push-sweep time window is determined according to the start time of the push-sweep time window and the end time of the push-sweep time window.

[0052] A third aspect of an embodiment of the present invention provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, a method for determining a gaze mode imaging opportunity time window provided by the first aspect of an embodiment of the present invention is implemented.

[0053] A fourth aspect of an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for determining a gaze mode imaging opportunity time window provided by the first aspect of an embodiment of the present invention is implemented.

[0054] Beneficial effects of the present invention:

[0055] The present invention determines the auxiliary area and the auxiliary center point through the maximum roll angle, the minimum roll angle and the sub-satellite point trajectory in the target area specified by the user, and can maximize the coverage of the target area in the staring mode, with the largest effective coverage area.

[0056] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0057] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0059] Figure 1 This is a schematic diagram of the satellite conical field of view;

[0060] Figure 2 This is a schematic diagram of the satellite's rectangular field of view;

[0061] Figure 3 A schematic flow chart of a method for determining a gaze mode imaging opportunity time window provided by an embodiment of the present invention;

[0062] Figure 4 A schematic diagram of a target area and field of view projection provided by an embodiment of the present invention;

[0063] Figure 5 A schematic diagram of another target area and field of view projection provided by an embodiment of the present invention;

[0064] Figure 6A timing diagram of preliminary calculation results provided by an embodiment of the present invention;

[0065] Figure 7 A spatial schematic diagram of an auxiliary area provided for an embodiment of the present invention;

[0066] Figure 8 A block diagram of a device for determining a gaze mode imaging opportunity time window provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0067] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0068] Introduction to main concepts:

[0069] 1. The imaging opportunity window of a remote sensing satellite for a regional target refers to the time range represented by the start and end time points during which the field of view payload carried by the satellite can observe the regional target. The visible window calculation is the basis of satellite observation missions and the prerequisite for various tasks such as regional target coverage calculation and imaging mission planning.

[0070] 2. Target area: a convex polygonal area surrounded by a series of longitude and latitude points. The format is unified as follows: the points are arranged counterclockwise, and the first point is the same as the last point, thus forming a closed area.

[0071] 3. Field of view: Figure 1 As shown, let the satellite be point S, and project the center point of the satellite's imaging area (line of sight) onto the earth's surface to obtain an intersection point Q. Since the satellite or camera payload can be maneuvered, the activity range of SQ is a conical area, and its projection on the plane is a circle, which is called the conical field of view.

[0072] like Figure 2 As shown, for the sweep-push mode, its range of activity in pitch and roll is different, and is a quadrangular pyramid, and its projection on the plane is a rectangle, which is called a rectangular field of view.

[0073] 4. Coverage area and field of view are two concepts that are easily confused. The field of view focuses on the range of activity of the center point (line of sight) of the imaging area. Coverage area refers to the actual coverage area of ​​the ground imaging by the satellite at a certain moment when performing an imaging mission, which is determined by the satellite altitude, sensor type, and (imaging payload or satellite) attitude.

[0074] 5. Satellite ephemeris data refers to the position and motion information of the satellite in orbit, including the position, speed, acceleration, altitude of the satellite from the ground and other parameters in a certain coordinate reference system. It uses time as a variable to describe the motion state of the satellite in orbit.

[0075] 6. A satellite imaging strip is a long strip of image area formed by the continuous coverage area of ​​the imaging payload scanning the earth's surface in push-broom mode.

[0076] like Figure 3 As shown, a first aspect of an embodiment of the present invention provides a method for determining a gaze mode imaging opportunity time window, comprising the following steps:

[0077] Step 11, calculating the push-sweep time window start time, push-sweep time window end time and push-sweep time window middle time for the target area in the push-sweep mode.

[0078] Step 12: Calculate the maximum and minimum roll angles of the target area at the middle of the push-scan time window.

[0079] Step 13, determining the auxiliary area, the auxiliary center point, and the longitude and latitude of the auxiliary center point according to the maximum roll angle, the minimum roll angle, and the sub-satellite point trajectory.

[0080] Step 14, based on the longitude and latitude of the auxiliary center point, taking the middle moment of the push-scan time window as the starting point, calculate the auxiliary pitch angle and auxiliary roll angle of the satellite when it is staring at the auxiliary center point at the step boundary moment forward and backward respectively according to the preset step time.

[0081] Step 15, determining the gaze moment and the gaze-out moment according to the auxiliary pitch angle and the auxiliary roll angle.

[0082] Step 16: using a binary search method between adjacent gaze moments and gaze-out moments to determine the gaze time window start moment and the gaze time window end moment.

[0083] In this embodiment, the auxiliary area and the auxiliary center point are determined in the target area specified by the user through the maximum roll angle, the minimum roll angle and the sub-satellite point trajectory. The auxiliary center point is the required gaze point. The time window in the gaze mode is searched according to the auxiliary center point and the satellite attitude constraints, which can maximize the coverage of the target area in the gaze mode.

[0084] A second aspect of an embodiment of the present invention provides a method for determining a gaze mode imaging opportunity time window, comprising the following steps:

[0085] Step 21, calculating the push-sweep time window start time, push-sweep time window end time and push-sweep time window middle time for the target area in the push-sweep mode.

[0086] In a feasible implementation, the specific steps of step 21 include steps 211 to 217:

[0087] Step 211: construct a first circular area and a second circular area.

[0088] The target area is located in the first circular area, and the instantaneous field of view projection is located in the second circular area.

[0089] In this step, the first circular area encloses the target area, and the second circular area encloses the field of view projection. The first circular area is at least the circumscribed circle of the target area, and the second circular area is at least the circle with the field of view projection as the radius. For example, Figure 4 As shown, the center of the first circular area is P1, the geocentric angle corresponding to the radius is θ1, and the center of the first circular area is P s , the geocentric angle corresponding to the radius is θ s .

[0090] Here, for the instantaneous field of view projection, it can be pre-calculated according to the method of step A1 to step A4:

[0091] Step A1, obtaining satellite time ephemeris data at a preset time.

[0092] The visibility determination algorithm determines whether the satellite has an opportunity to shoot the target area at any time. We define the field of view model in push-broom mode as follows:

[0093] (1) The satellite camera only performs side-to-side maneuvers, and the pitch angle is fixed at 0.

[0094] (2) The target area is a convex polygon on the earth's surface (the number of edges n>=3).

[0095] (3) According to the satellite camera's side-swing maneuverability, the left and right boundaries of the camera's line of sight intersect with the Earth's surface at two points respectively. The line connecting these two points is the field of view (visibility) range at that moment.

[0096] Get the satellite ephemeris data at the preset time, including the position coordinates (x, y, z) in the inertial coordinate system and the corresponding velocity vector v x 、v y 、v z and satellite altitude. The preset time is any time required by the user.

[0097] Step A2, determining a first conversion matrix for converting the instantaneous orbital coordinate system of the satellite at a preset time into an inertial coordinate system and a second conversion matrix for converting the inertial coordinate system into an earth-fixed coordinate system according to the ephemeris data at the time.

[0098] In this step, according to v x 、v y 、v z Construct the first transformation matrix of the satellite's instantaneous orbital coordinate system to the inertial coordinate system at the preset time According to the preset time, a second transformation matrix of the inertial coordinate system to the earth-fixed coordinate system is obtained.

[0099] Step A3, determining the satellite line of sight boundary vector in the earth-fixed coordinate system according to the first conversion matrix, the second conversion matrix and the roll capability of the satellite at a preset time.

[0100] In this step, the calculation formula of the satellite line of sight boundary vector is:

[0101]

[0102] Among them, θ represents the maximum value of the roll capability, and θ can be positive or negative. In actual calculation, the roll capability is ±θ. Therefore, the satellite line of sight boundary vector is two vectors, that is, two rays starting from the satellite S. For example, Figure 5 As shown, the center of the earth is O, the satellite is S, the target area is quadrilateral ABCD, and the left and right boundaries of the camera's line of sight intersect the earth's surface at two points M and N respectively.

[0103] Step A4, determining the projection of the satellite field of view on the earth's surface according to the satellite line of sight boundary vector. The specific steps of step A4 include step A41-step A42:

[0104] Step A41, calculating the first intersection point M and the second intersection point N between the satellite line of sight boundary vector and the earth's surface.

[0105] Step A42: The first intersection point M and the second intersection point N are connected to form a field of view projection.

[0106] Here, the field of view projection is the line connecting M and N. Specifically, the intersection of the two satellite line of sight boundary vectors and the earth's surface is calculated to obtain the intersection points M and N. MN is the field of view projection, and the rays where SM and SN are located are the two satellite line of sight boundary vectors.

[0107] Step 212, linearly divide the preset time period into equal parts to obtain a plurality of equally divided moments. The preset time period is a time period required by the user, for example, it can be a time period of the next 72 hours or a week. The preset time period is linearly divided into equal parts to obtain a plurality of time vectors, and the equal division points are also the equal division moments.

[0108] Step 213, determining whether the first circular area and the second circular area overlap at each equally divided moment. Specifically, at each equally divided moment, the first circular area and the second circular area are constructed according to step 211. If the two circular areas do not overlap, the target area must be invisible to the satellite at this moment. If the two circular areas have overlapping parts, the target area may be visible to the satellite at this moment.

[0109] Specifically, the specific steps of step 213 include determining the distance between the first center P1 of the first circular area and the center O of the earth, and between the center O of the earth and the second center P1 of the second circular area at each equally divided moment. sThe first angle θ s1 , is it smaller than the first geocentric angle θ1 corresponding to the radius of the first circular area and the second geocentric angle θ corresponding to the radius of the second circular area s The sum of ; if less than, then they overlap; if greater than, then they do not overlap.

[0110] Here, the question of whether the two circular areas overlap can be transformed into the problem of calculating the angle between the vectors. For example, Figure 4 As shown, calculate P at each equally divided moment s Angle θ of OP1 s1 Is it less than θ s +θ1; if it is less than, then it overlaps and the equally divided moments are marked as preliminary calculation results; if it is greater than, then it does not overlap.

[0111] Step 214: The time when the first circular area and the second circular area overlap is the preliminary calculation result. This step performs a preliminary screening of the time, and can exclude most of the areas that do not need further calculation, thereby reducing the subsequent calculation amount.

[0112] Step 215, calculating the visible time and the invisible time in the preliminary calculation result.

[0113] In this step, first determine the time required for calculation of the push-broom mode visibility determination method: the preliminary calculation results include multiple equally divided time points, and for each two adjacent equally divided time points, the calculation time points are divided according to a fixed time step. For each calculation time point, determine whether the time point is a visible moment according to the push-broom mode visibility determination method of step B1 of this embodiment.

[0114] Here, the specific steps of step B1 are: determine whether the field of view projection of each calculation time point intersects with the target area; if so, the calculation time point is the push-scan visible moment.

[0115] Specifically, there are two methods to determine whether the field of view projection intersects with the target area: Figure 5 For example, the first method is to determine whether the field of view projection MN intersects with any side of the target area ABCD. As long as one side intersects, it is considered that the field of view projection intersects with the target area; the second method is to determine whether the first intersection point M or the second intersection point N is inside the target area ABCD.

[0116] Among them, the problem of judging whether the field of view projection MN intersects with any side of the target area ABCD in the first method can be converted into judging whether the first fan plane formed by the center of the earth O and any side of the target area ABCD and the second fan plane MON formed by the center of the earth O and the field of view projection MN intersect. For example, taking the side AB of the target area as an example, judging whether the fan plane AOB intersects with the fan plane MON, here, the specific method of judging whether the two fan planes intersect includes steps B11-B12:

[0117] Step B11, calculating the surface intersection lines of a first fan plane formed by the center of the earth and any side of the target area and a second fan plane formed by the center of the earth and the projection of the field of view.

[0118] Step B12, determine whether the plane-to-plane intersection line is within the first fan plane and the second fan plane at the same time. If the plane-to-plane intersection line is within the first fan plane and the second fan plane at the same time, the field of view projection intersects with the target area, and the calculation time point is the push-scan visible moment. If it is not within the first fan plane and the second fan plane at the same time, the field of view projection does not intersect with the target area, and the calculation time point is the push-scan invisible moment.

[0119] In step B11 and step B12, corresponding results are obtained by using a solid geometry calculation method, and the calculation accuracy is improved.

[0120] For the second method, the problem of judging whether the first intersection point M or the second intersection point N is inside the target area ABCD can be converted into calculating whether the first ray or the second ray is inside the pyramid formed by the center of the earth and the target area; the first ray is the ray from the center of the earth to the first intersection point, and the second ray is the ray from the center of the earth to the second intersection point. For example, judging whether OM or ON is inside the pyramid OABCD, since A, B, C, D, M, and N are all points on the surface of the earth, if OM or ON is inside the pyramid OABCD, it means that M or N must be inside the surface of the target area ABCD. Here, if a two-dimensional calculation method is used to calculate whether point M or point N is inside the surface ABCD, a large error will be generated in high-latitude areas. However, converting it to using a three-dimensional geometric calculation method to calculate whether OM or ON is inside the pyramid OABCD can avoid this error, so that the calculation result is more accurate. If the first ray or the second ray is inside the pyramid formed by the center of the earth and the target area, the field of view projection intersects with the target area, and the calculation time point is the push-scan visible moment. Otherwise, the calculation time point is the push-scan invisible moment.

[0121] In this embodiment, under the condition that the satellite camera only performs a side swing maneuver and the pitch angle is fixed at 0, the projection of the satellite field of view on the earth's surface is a small arc. At this time, the problem of determining the visibility of the target area at any point in time can be converted into the satellite field of view (arc) inside the target area or the satellite field of view (arc) intersecting with any side of the target area. The calculation method is simple and fast and improves the accuracy of the calculation results.

[0122] Step 216: Use a binary search method to determine the push-scan time window start time T between adjacent visible moments and invisible moments. start and the end time of the push-scan time window T end The calculation in this step obtains the precise start and end times of the push-sweep time window.

[0123] Here, the calculation result of step 215 is as follows Figure 6 As shown, blue is the invisible moment, orange is the visible moment, the corresponding time window's precise start time is between T2 and T3, and the precise push-scan time window end time is between T8 and T9. The binary search method steps are: calculate whether it is visible at time point T2.5, if it is visible, then the precise push-scan time window start time is between T2 and T2.5, continue to calculate whether T2.25 is visible, if it is visible, continue to calculate whether T2.125 is visible, if it is not visible at time point T2.5, then the precise start time is between T2.5 and T3, continue to calculate whether T2.75 is visible, and so on, you can calculate until the required accuracy is achieved, the calculation of the push-scan time window end time is the same.

[0124] In this embodiment, the calculation of whether the circular areas overlap can exclude most of the data that is not needed for the next step of calculation, reducing the amount of subsequent calculations and improving calculation efficiency. At the same time, combined with the push-scan mode visibility judgment method, the accuracy of the push-scan time window calculation is further improved.

[0125] In a feasible implementation, other methods may also be used to calculate the push-sweep time window start time and the push-sweep time window end time for the target area in the push-sweep mode.

[0126] Step 217, according to the push-scan time window start time T start and the end time of the push-scan time window T end , determine the middle time T of the push-scan time window mid The middle time of the push-sweep time window is the middle time point between the start time of the push-sweep time window and the end time of the push-sweep time window.

[0127] Step 22: at the middle time T of the push-scan time window mid , calculate the maximum and minimum roll angles of the target area. Here, at T mid At the moment, the included angle of all vertices in the target area in the YOZ plane in the OZ direction in the satellite instantaneous orbit coordinate system is calculated, that is, the maximum and minimum side swing angle range required to wrap the target area. The target area is a convex polygon. At the middle moment T of the push-scan time window, mid Among all the vertices in the target area, the one that requires the largest roll angle to observe one vertex and the one that requires the smallest roll angle to observe one vertex, that is, the vertex that requires the largest roll angle to observe and the vertex that requires the smallest roll angle to observe, such as Figure 7 As shown, these are point B and point D.

[0128] Step 23, according to the maximum roll angle, the minimum roll angle and the sub-satellite point trajectory, determine the auxiliary area, the auxiliary center point and the longitude and latitude of the auxiliary center point. The specific steps of step 23 include steps 231 to 234:

[0129] Step 231: Draw a first straight line parallel to the sub-satellite point trajectory at the vertex of the target area corresponding to the maximum roll angle.

[0130] Step 232: Draw a second straight line parallel to the sub-satellite point trajectory at the vertex of the target area corresponding to the minimum roll angle.

[0131] For example, Figure 7 As shown, two straight lines EL and FK are drawn through points B and D respectively and are parallel to the sub-satellite point trajectory.

[0132] Step 233, draw two perpendicular lines perpendicular to the first straight line and the second straight line respectively.

[0133] The two vertical lines pass through the vertex of the target area, and the target area is located in an auxiliary area surrounded by the first straight line, the second straight line and the two vertical lines.

[0134] In this step, the auxiliary area is the smallest rectangular area that encloses the target area. For example, perpendicular lines EF and LK are drawn through points A and C to EL and FK to obtain the auxiliary area EFKL.

[0135] Step 234, determine the auxiliary center point and the longitude and latitude of the auxiliary center point according to the auxiliary area. For example, the auxiliary area is a rectangle, so the auxiliary center point δ can be obtained, that is, the center point of the rectangle EFKL, and the longitude and latitude coordinates of the auxiliary center point δ can be obtained according to the longitude and latitude coordinates of the vertices of the target area and the auxiliary area.

[0136] Step 24, based on the longitude and latitude of the auxiliary center point, taking the middle moment of the push-scan time window as the starting point, calculate the auxiliary pitch angle and auxiliary roll angle of the satellite when it is staring at the auxiliary center point at the step boundary moments forward and backward respectively according to the preset step time.

[0137] In this step, the pitch angle and roll angle required by the satellite at the auxiliary center point δ are calculated from the middle moment of the push-scan time window as the starting point to the "past" and "future" according to the preset step time. The preset step time forward is the past time, and the preset step time backward is the future time. The pitch angle and roll angle are calculated forward and backward respectively with the preset step time, and the forward time point is calculated first, and then the backward time point is calculated, or the backward time point is calculated first, and then the forward time point is calculated.

[0138] The purpose of calculating the time into the past is to obtain the range of the initial start time of the gaze time window, and the purpose of calculating the time into the future is to obtain the range of the initial end time of the gaze time window.

[0139] Step 25, determining the gaze moment and the gaze-out moment according to the auxiliary pitch angle and the auxiliary roll angle.

[0140] Step 25 includes step 251-step 252:

[0141] Step 251, determining whether the auxiliary pitch angle and auxiliary roll angle at the step boundary moment are greater than the preset pitch angle and preset roll angle. The preset pitch angle and preset roll angle are corresponding pitch angle and roll angle requirements set according to the image accuracy and resolution and other requirements required by the user.

[0142] Step 252: When the auxiliary pitch angle or the auxiliary roll angle is greater than the preset pitch angle or the preset roll angle, the step boundary moment is marked as the out-of-gaze moment.

[0143] When the auxiliary pitch angle is less than the preset pitch angle and the auxiliary roll angle is less than the preset roll angle, the step boundary moment is marked as the gaze moment.

[0144] Here, if the auxiliary pitch angle at the step boundary moment is greater than the preset pitch angle, or the auxiliary roll angle is greater than the preset roll angle, then the step boundary moment is the gaze-out moment. If the auxiliary pitch angle at the step boundary moment is less than the preset pitch angle, and the auxiliary roll angle is less than the preset roll angle, then the step boundary moment is the gaze moment. When two adjacent step boundary moments are calculated, one is gaze and the other is gaze-out, the range of the gaze time window start time and the range of the preliminary gaze time window end time are determined.

[0145] When calculating toward the past time point, if the current step boundary moment is the out-of-gaze moment and the previous step boundary moment is the gaze moment, the two adjacent step boundary moments at this time are the range of the start time of the gaze time window. Correspondingly, when calculating toward the future time point, if the current step boundary moment is the out-of-gaze moment and the previous step boundary moment is the gaze moment, the two adjacent step boundary moments at this time are the range of the end time of the gaze time window.

[0146] Step 26, using a binary search method between adjacent gaze moments and gaze-out moments to determine the gaze time window start moment and the gaze time window end moment.

[0147] Here, the binary search method is to calculate whether the midpoint of the range of the start time of the gaze time window is the gaze moment. If it is the gaze moment, the precise start time is between the start point and the midpoint of the range, and continue to calculate whether the midpoint between the start point and the midpoint of the range is the gaze moment, and so on. If the midpoint time point is a gaze-out moment, then the precise start time is the midpoint between the midpoint and the end point of the range. Whether it is the gaze moment, and so on, can be calculated to the required accuracy. The calculation of the end time is the same.

[0148] like Figure 8As shown, a third aspect of an embodiment of the present invention provides a device for determining a gaze mode imaging opportunity time window, comprising:

[0149] The first calculation module 31 is used to calculate the push-sweep time window start time, the push-sweep time window end time and the push-sweep time window middle time for the target area in the push-sweep mode;

[0150] The second calculation module 32 is used to calculate the maximum roll angle and the minimum roll angle of the observation target area in the middle of the push-scan time window;

[0151] A first determination module 33 is used to determine the auxiliary area, the auxiliary center point and the longitude and latitude of the auxiliary center point according to the maximum roll angle, the minimum roll angle and the sub-satellite point trajectory;

[0152] The third calculation module 34 is used to calculate the auxiliary pitch angle and the auxiliary roll angle of the satellite when it is staring at the auxiliary center point at the step boundary time respectively forward and backward according to the preset step time based on the longitude and latitude of the auxiliary center point and taking the middle moment of the push-scan time window as the starting point;

[0153] A second determination module 35, for determining the gaze moment and the gaze-out moment according to the auxiliary pitch angle and the auxiliary roll angle;

[0154] The third determination module 36 is used to determine the start time of the gaze time window and the end time of the gaze time window by using a binary search method between adjacent gaze moments and gaze-out moments.

[0155] In one embodiment of the present invention, the first determining module is further used to draw a first straight line parallel to the sub-satellite point trajectory at the vertex of the target area corresponding to the maximum roll angle;

[0156] Draw a second straight line parallel to the subsatellite point trajectory at the vertex of the target area corresponding to the minimum roll angle;

[0157] Draw two perpendicular lines perpendicular to the first straight line and the second straight line respectively; wherein the two perpendicular lines pass through the vertex of the target area, and the target area is located in the auxiliary area surrounded by the first straight line, the second straight line and the two perpendicular lines;

[0158] The auxiliary center point and the longitude and latitude of the auxiliary center point are determined based on the auxiliary area.

[0159] In one embodiment of the present invention, the second determination module is further used to determine whether the auxiliary pitch angle and the auxiliary roll angle are greater than the preset pitch angle and the preset roll angle;

[0160] When the auxiliary pitch angle or the auxiliary roll angle is greater than the preset pitch angle or the preset roll angle, the step boundary moment is marked as the out-of-gaze moment;

[0161] When the auxiliary pitch angle and the auxiliary roll angle are less than the preset pitch angle and the preset roll angle, the step boundary moment is marked as the gaze moment;

[0162] The binary search method is used between adjacent gaze moments and out-of-gaze moments to determine the start and end moments of the gaze time window.

[0163] In one embodiment of the present invention, the first calculation module is further used to construct a first circular area and a second circular area; wherein the target area is located in the first circular area, and the instantaneous field of view projection is located in the second circular area;

[0164] Divide the preset time period into equal parts linearly to obtain multiple equal-divided moments;

[0165] Determine whether the first circular area and the second circular area overlap at each equally divided moment;

[0166] The moment when the first circular area and the second circular area overlap is the preliminary calculation result;

[0167] Calculate the visible time and the invisible time in the preliminary calculation results;

[0168] A binary search method is used between adjacent visible moments and invisible moments to determine the push-scan time window start moment and the push-scan time window end moment;

[0169] The middle time of the push-sweep time window is determined according to the start time of the push-sweep time window and the end time of the push-sweep time window.

[0170] A fourth aspect of an embodiment of the present invention provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, a method for determining a gaze mode imaging opportunity time window provided in the above-mentioned embodiment of the present invention is implemented.

[0171] A fifth aspect of an embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of a method for determining a gaze mode imaging opportunity time window provided in the above embodiment of the present invention are implemented.

[0172] The memory may include a random access memory (RAM) or a non-volatile memory (NVM), such as at least one disk memory. Optionally, the memory may also be at least one storage device located away from the aforementioned processor.

[0173] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware systems.

[0174] The method provided in the embodiment of the present invention can be applied to electronic devices. Specifically, the electronic device can be: a desktop computer, a portable computer, an intelligent mobile terminal, a server, etc. This is not limited here, and any electronic device that can implement the present invention belongs to the protection scope of the present invention.

[0175] As for the device / electronic device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0176] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0177] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0178] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0179] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for determining a time window of opportunity for staring mode imaging, characterized in that: The following steps are involved: Calculate the push-sweep time window start time, push-sweep time window end time and push-sweep time window middle time for the target area in the push-sweep mode; At the middle moment of the push-scan time window, calculating the maximum roll angle and the minimum roll angle of the target area to be observed; Determine the auxiliary area, the auxiliary center point and the longitude and latitude of the auxiliary center point according to the maximum roll angle, the minimum roll angle and the sub-satellite point trajectory; Based on the longitude and latitude of the auxiliary center point, taking the middle moment of the push-scan time window as the starting point, the auxiliary pitch angle and the auxiliary roll angle of the satellite when staring at the auxiliary center point at the step boundary moment are calculated forward and backward respectively according to the preset step time; Determine a gaze moment and a gaze-out moment according to the auxiliary pitch angle and the auxiliary roll angle; The binary search method is used between adjacent gaze moments and out-of-gaze moments to determine the start and end moments of the gaze time window.

2. The method according to claim 1, characterized in that Determining the auxiliary area, the auxiliary center point, and the longitude and latitude of the auxiliary center point according to the maximum roll angle, the minimum roll angle, and the sub-satellite point trajectory includes: Draw a first straight line parallel to the sub-satellite point trajectory at the vertex of the target area corresponding to the maximum roll angle; Draw a second straight line parallel to the sub-satellite point trajectory at the vertex of the target area corresponding to the minimum roll angle; Draw two perpendicular lines perpendicular to the first straight line and the second straight line respectively; wherein the two perpendicular lines pass through the vertex of the target area, and the target area is located in the auxiliary area surrounded by the first straight line, the second straight line and the two perpendicular lines; The auxiliary center point and the longitude and latitude of the auxiliary center point are determined according to the auxiliary area.

3. The method according to claim 2, characterized in that The determining of the gaze moment and the gaze-out moment according to the auxiliary pitch angle and the auxiliary roll angle comprises: Determining whether the auxiliary pitch angle and the auxiliary roll angle are greater than a preset pitch angle and a preset roll angle; When the auxiliary pitch angle or the auxiliary roll angle is greater than the preset pitch angle or the preset roll angle, marking the step boundary moment as the out-of-gaze moment; When the auxiliary pitch angle and the auxiliary roll angle are smaller than the preset pitch angle and the preset roll angle, the step boundary moment is marked as a gaze moment; The binary search method is used between adjacent gaze moments and out-of-gaze moments to determine the start and end moments of the gaze time window.

4. The method according to claim 3, characterized in that The calculation of the push-sweep time window start time, the push-sweep time window end time and the push-sweep time window middle time for the target area in the push-sweep mode includes: Constructing a first circular area and a second circular area; wherein the target area is located in the first circular area, and the instantaneous field of view projection is located in the second circular area; Divide the preset time period into equal parts linearly to obtain multiple equal-divided moments; Determine whether the first circular area and the second circular area overlap at each of the equal division moments; The moment when the first circular area and the second circular area overlap and are equally divided is a preliminary calculation result; Calculating the visible time and the invisible time in the preliminary calculation result; A binary search method is used between adjacent visible moments and invisible moments to determine the push-scan time window start moment and the push-scan time window end moment; The middle time of the push-sweep time window is determined according to the start time of the push-sweep time window and the end time of the push-sweep time window.

5. A device for determining a time window of opportunity for gaze mode imaging, characterized in that: include: A first calculation module is used to calculate the push-sweep time window start time, the push-sweep time window end time and the push-sweep time window middle time for the target area in the push-sweep mode; A second calculation module is used to calculate the maximum roll angle and the minimum roll angle of the target area in the middle of the push-scan time window; A first determination module is used to determine the auxiliary area, the auxiliary center point and the longitude and latitude of the auxiliary center point according to the maximum roll angle, the minimum roll angle and the sub-satellite point trajectory; A third calculation module is used to calculate the auxiliary pitch angle and the auxiliary roll angle of the satellite when it is staring at the auxiliary center point at the step boundary time respectively forward and backward according to the preset step time based on the longitude and latitude of the auxiliary center point and taking the middle moment of the push-scan time window as the starting point; A second determination module is used to determine the gaze moment and the gaze-out moment according to the auxiliary pitch angle and the auxiliary roll angle; The third determination module is used to determine the start time of the gaze time window and the end time of the gaze time window by using a binary search method between adjacent gaze moments and gaze-out moments.

6. The method according to claim 5, characterized in that The first determination module is further used to draw a first straight line parallel to the sub-satellite point trajectory at the vertex of the target area corresponding to the maximum roll angle; Draw a second straight line parallel to the sub-satellite point trajectory at the vertex of the target area corresponding to the minimum roll angle; Draw two perpendicular lines perpendicular to the first straight line and the second straight line respectively; wherein the two perpendicular lines pass through the vertex of the target area, and the target area is located in the auxiliary area surrounded by the first straight line, the second straight line and the two perpendicular lines; The auxiliary center point and the longitude and latitude of the auxiliary center point are determined according to the auxiliary area.

7. The method according to claim 5, characterized in that The second determination module is further used to determine whether the auxiliary pitch angle and the auxiliary roll angle are greater than a preset pitch angle and a preset roll angle; When the auxiliary pitch angle or the auxiliary roll angle is greater than the preset pitch angle or the preset roll angle, marking the step boundary moment as the out-of-gaze moment; When the auxiliary pitch angle and the auxiliary roll angle are smaller than the preset pitch angle and the preset roll angle, the step boundary moment is marked as a gaze moment; The binary search method is used between adjacent gaze moments and out-of-gaze moments to determine the start and end moments of the gaze time window.

8. The method according to claim 5, characterized in that The first calculation module is further used to construct a first circular area and a second circular area; wherein the target area is located in the first circular area, and the instantaneous field of view projection is located in the second circular area; Divide the preset time period into equal parts linearly to obtain multiple equal-divided moments; Determine whether the first circular area and the second circular area overlap at each of the equal division moments; The moment when the first circular area and the second circular area overlap and are equally divided is a preliminary calculation result; Calculating the visible time and the invisible time in the preliminary calculation result; A binary search method is used between adjacent visible moments and invisible moments to determine the push-scan time window start moment and the push-scan time window end moment; The middle time of the push-sweep time window is determined according to the start time of the push-sweep time window and the end time of the push-sweep time window.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the method for determining the gaze mode imaging opportunity time window as described in any one of claims 1 to 4 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for determining a gaze mode imaging opportunity time window according to any one of claims 1 to 4 is implemented.

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