Push-broom mode visibility determination method, imaging opportunity time window determination method, device and system

Abstract

The invention discloses a push-scan mode visibility determination method. The method comprises the following steps: acquiring moment ephemeris data of a satellite at a preset moment; determining a first conversion matrix for converting the instantaneous orbit coordinate system 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 time ephemeris data; determining a satellite line-of-sight boundary vector under the earth-fixed coordinate system according to the conversion matrix and the sidesway capability of the satellite at the preset moment; determining the view field projection of the satellite view field on the earth surface according to the satellite sight line boundary vector; and judging whether the field projection intersects with the target area, and if so, determining that the preset moment is a visible moment. The calculation method is simple and quick, and the calculation result is accurate. The invention further provides an imaging opportunity time window determination method, and the accuracy of imaging opportunity time window calculation is improved. The invention also discloses a device and a system for realizing the method.

Description

Technical Field

[0001] The present invention relates to the field of satellite observation technology, and in particular to a push-broom mode visibility determination method, an imaging opportunity time window determination method, a device and a system. Background Art

[0002] At present, all existing remote sensing satellite images in China form coverage strips along the satellite flight trajectory, that is, the satellite is kept stable in three axes to the ground or swung sideways in the roll direction to push-broom imaging of the subsatellite point or the strip target parallel to the subsatellite point. Push-broom imaging is a major imaging method for using satellites to obtain images. With the development of aerospace technology, satellite remote sensing observation technology for the earth has been widely used in many fields such as meteorological observation, environmental monitoring, disaster warning, and urban planning. The imaging opportunity time window of a remote sensing satellite for a regional target refers to the time range represented by the start time point and the end time point in which the field of view payload carried by the satellite can observe the regional target. The calculation of this visible window is the basis of satellite observation tasks and the premise of many tasks such as regional target coverage calculation and imaging task planning. The visibility determination of the target area at any time point is an important premise for calculating the imaging opportunity time window. The traditional visibility determination algorithm for the target area at any time point is complex and has limited calculation accuracy, and the calculation efficiency is low. Summary of the invention

[0003] In order to solve the above problems existing in the prior art, the present invention provides a push-broom mode visibility determination method, an imaging opportunity time window determination method, a device and a system. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0004] A first aspect of an embodiment of the present invention provides a push-broom mode visibility determination method and an imaging opportunity time window determination method, comprising the following steps:

[0005] Obtain satellite time and ephemeris data at a preset time;

[0006] Determine, based on the ephemeris data at the time, a first conversion matrix for converting the instantaneous orbital coordinate system of the satellite at the preset time into an inertial coordinate system and a second conversion matrix for converting the inertial coordinate system into an earth-fixed coordinate system;

[0007] Determine a satellite line of sight boundary vector in an earth-fixed coordinate system according to the first conversion matrix, the second conversion matrix and the sway capability of the satellite at a preset time;

[0008] Determining a projection of the satellite's field of view on the earth's surface according to the satellite's line of sight boundary vector;

[0009] It is determined whether the field of view projection intersects with the target area. If so, the preset time is the visible time.

[0010] In one embodiment of the present invention, determining the field of view projection of the satellite field of view on the earth's surface according to the satellite line of sight boundary vector includes:

[0011] Calculating a first intersection point and a second intersection point of the satellite line of sight boundary vector and the earth's surface;

[0012] The first intersection point and the second intersection point are connected to form the field of view projection.

[0013] In one embodiment of the present invention, the determining whether the field of view projection intersects with the target area includes:

[0014] It is determined whether 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 intersect.

[0015] In one embodiment of the present invention, the determining whether the field of view projection intersects with the target area includes: determining whether the first intersection point or the second intersection point is inside the target area.

[0016] In one embodiment of the present invention, the determining whether 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 intersect includes:

[0017] Calculate 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;

[0018] It is determined whether the plane-to-plane intersection line is within the first sector plane and the second sector plane at the same time.

[0019] In one embodiment of the present invention, the determining whether the first intersection point or the second intersection point is inside the target area includes:

[0020] Calculate whether the first ray or the second ray is inside the pyramid formed by the center of the earth and the target area; wherein 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.

[0021] A second aspect of an embodiment of the present invention provides a method for determining an imaging opportunity time window, comprising the following steps:

[0022] 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;

[0023] Divide the preset time period into equal parts linearly to obtain multiple equal-divided moments;

[0024] Determine whether the first circular area and the second circular area overlap at each of the equal division moments;

[0025] The moment when the first circular area and the second circular area overlap and are equally divided is a preliminary calculation result;

[0026] Determine the visible time and the invisible time in the preliminary calculation result according to the push-broom mode visibility determination method described in the first aspect of the embodiment of the present invention;

[0027] A binary search method is used between adjacent visible moments and invisible moments to determine the start and end moments of the time window.

[0028] In one embodiment of the present invention, the determining whether the first circular area and the second circular area overlap at each equally divided moment includes:

[0029] Determine, at each equal division moment, whether a first angle formed by a first center of the first circular area to the center of the earth and by a first angle formed by a center of the earth to the second center of the second circular area is less than a sum of a first geocentric angle corresponding to the radius of the first circular area and a second geocentric angle corresponding to the radius of the second circular area;

[0030] If it is less than, then it overlaps;

[0031] If greater, there is no overlap.

[0032] A third aspect of an embodiment of the present invention provides a push-broom mode visibility determination device, comprising:

[0033] An acquisition module is used to acquire the satellite time ephemeris data at a preset time;

[0034] A first determination module is used to determine, according to the ephemeris data at the time, a first conversion matrix for converting the instantaneous orbital coordinate system of the satellite at the preset time into an inertial coordinate system and a second conversion matrix for converting the inertial coordinate system into an earth-fixed coordinate system;

[0035] A second determination module is used to determine 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 sway capability of the satellite at a preset time;

[0036] A third determination module is used to determine the field of view projection of the satellite field of view on the earth's surface according to the satellite line of sight boundary vector;

[0037] The first judgment module is used to judge whether the field of view projection intersects with the target area. If so, the preset moment is the visible moment.

[0038] A fourth aspect of an embodiment of the present invention provides a system for determining an imaging opportunity time window, including:

[0039] A construction module, 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;

[0040] A division module is used to linearly divide the preset time period into equal parts to obtain multiple equal-divided moments;

[0041] A second judging module is used to judge whether the first circular area and the second circular area overlap at each of the equal division moments;

[0042] A fourth determination module, used for taking the moment of equal division of the overlap of the first circular area and the second circular area as a preliminary calculation result;

[0043] a push-broom mode visibility determination device, used to determine the visible time and the invisible time in the preliminary calculation result;

[0044] The fifth determination module is used to determine the time window start time and the time window end time by using a binary search method between adjacent visible moments and invisible moments.

[0045] Beneficial effects of the present invention:

[0046] The present invention uses the condition that when 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 time point 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 the calculation result is accurate. The present invention also provides an imaging opportunity time window determination method based on the above-mentioned visibility determination method combined with the calculation of whether the circular areas overlap to obtain an accurate imaging opportunity time window range, thereby improving the accuracy of the imaging opportunity time window calculation.

[0047] 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.

[0048] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] 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:

[0050] Figure 1 This is a schematic diagram of the satellite conical field of view;

[0051] Figure 2 This is a schematic diagram of the satellite's rectangular field of view;

[0052] Figure 3 A schematic flow chart of a push-broom mode visibility determination method provided by an embodiment of the present invention;

[0053] Figure 4 A schematic diagram of the projection of the target area and satellite field of view provided by an embodiment of the present invention;

[0054] Figure 5 A schematic flow chart of a method for determining an imaging opportunity time window provided by an embodiment of the present invention;

[0055] Figure 6 A schematic diagram of a target area and field of view projection of a method for determining an imaging opportunity time window provided by an embodiment of the present invention;

[0056] Figure 7 A timing diagram of preliminary calculation results provided by an embodiment of the present invention;

[0057] Figure 8 A schematic diagram of a structural block diagram of a push-broom mode visibility determination device provided by an embodiment of the present invention;

[0058] Fig. 9 A schematic structural block diagram of a system for determining an imaging opportunity time window provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0059] 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.

[0060] Introduction to main concepts:

[0061] 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.

[0062] 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.

[0063] 3. Field of view: Figure 1As 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 P. Since the satellite or camera payload can maneuver, the activity range of SP is a conical area, and its projection on the plane is a circle, which is called a conical field of view.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] like Figure 3 As shown, a first aspect of an embodiment of the present invention provides a push-broom mode visibility determination method, which is applied to a satellite under the condition that the satellite camera only performs a side swing maneuver and the pitch angle is fixed at 0, comprising the following steps:

[0069] Step 11, obtaining the satellite time ephemeris data at a preset time.

[0070] Step 12: Determine, based on the ephemeris data, 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.

[0071] Step 13, 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.

[0072] Step 14, determining the field of view projection of the satellite field of view on the earth surface according to the satellite line of sight boundary vector.

[0073] Step 15, determine whether the field of view projection intersects with the target area; if so, the preset time is the visible time.

[0074] In this embodiment, the field of view projection is determined when 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 time point can be converted into whether the field of view projection and the target area intersect. Therefore, the result of whether they intersect can be obtained through geometric calculation. If the field of view projection intersects with the target area, the preset moment is the visible moment. If they do not intersect, it is the invisible moment. The calculation method is simple and fast, and the calculation result is accurate.

[0075] Based on the first aspect of the embodiment of the present invention, the push-broom mode visibility determination method is specifically described: the second aspect of the embodiment of the present invention provides a push-broom mode visibility determination method, which is applied to a satellite under the condition that the satellite camera only performs a side swing maneuver and the pitch angle is fixed at 0, comprising the following steps:

[0076] Step 21, obtaining the satellite time ephemeris data at a preset time.

[0077] 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:

[0078] (1) The satellite camera only performs side-to-side maneuvers, and the pitch angle is fixed at 0.

[0079] (2) The target area is a convex polygon on the earth's surface (the number of edges n>=3).

[0080] (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.

[0081] 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.

[0082] Step 22, according to the ephemeris data, determine 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.

[0083] 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.

[0084] Step 23, 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.

[0085] In this step, the calculation formula of the satellite line of sight boundary vector is:

[0086]

[0087] 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 4 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.

[0088] Step 24, 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 24 include step 241-step 242:

[0089] Step 241, calculating a first intersection point M and a second intersection point N between the satellite sight line boundary vector and the earth's surface.

[0090] Step 242: The first intersection point M and the second intersection point N are connected to form a field of view projection.

[0091] 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.

[0092] Step 25, determining whether the field of view projection intersects with the target area; if so, the preset time is the visible time.

[0093] Specifically, there are two methods to determine whether the field of view projection intersects with the target area: Figure 4 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.

[0094] 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 251-252:

[0095] Step 251, 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.

[0096] Step 252, determine whether the plane-to-plane intersection line is in the first fan plane and the second fan plane at the same time. If the plane-to-plane intersection line is in 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 preset moment is the visible moment. If it is not in 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 preset moment is the invisible moment.

[0097] In step 251 and step 252, corresponding results are obtained by using a solid geometry calculation method, and the accuracy of the calculation is improved.

[0098] 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 to 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 preset time is a visible time. Otherwise, the preset time is an invisible time.

[0099] 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.

[0100] like Figure 5 As shown, a third aspect of an embodiment of the present invention provides a method for determining an imaging opportunity time window, comprising the following steps:

[0101] Step 31, constructing a first circular area and a second circular area.

[0102] The target area is located in the first circular area, and the field of view projection is located in the second circular area.

[0103] Step 32: divide the preset time period into equal linear parts.

[0104] Step 33, determining whether the first circular area and the second circular area overlap at each equally divided moment.

[0105] Step 34, the time when the first circular area and the second circular area overlap and are equally divided is a preliminary calculation result.

[0106] Step 35 , determining the visible moment and the invisible moment in the preliminary calculation result according to the push-broom mode visibility determination method of the first aspect or the second aspect of the embodiment of the present invention.

[0107] Step 36, using a binary search method between adjacent visible moments and invisible moments to determine the time window start moment and the time window end moment.

[0108] In this embodiment, based on the above visibility determination method and combined with the calculation of whether the circular areas overlap, an accurate imaging opportunity time window range is obtained, thereby improving the accuracy of the imaging opportunity time window calculation.

[0109] On the basis of the third aspect of the embodiment of the present invention, a method for determining an imaging opportunity time window is specifically described: A fourth aspect of the embodiment of the present invention provides a method for determining an imaging opportunity time window, comprising the following steps:

[0110] Step 41, constructing a first circular area and a second circular area.

[0111] The target area is located in the first circular area, and the instantaneous field of view projection is located in the second circular area.

[0112] 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 6 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 .

[0113] Here, for the instantaneous field of view projection, it can be pre-calculated according to the method of step 11 to step 14 or step 21 to step 24.

[0114] Step 42, 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.

[0115] Step 43, determining whether the first circular area and the second circular area overlap at each equally divided moment. At each equally divided moment, the first circular area and the second circular area are constructed according to step 41. 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.

[0116] Specifically, the specific steps of step 43 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. s The 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.

[0117] 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 6 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.

[0118] Step 44, multiple equally divided moments where the first circular area and the second circular area overlap are preliminary calculation results. 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.

[0119] Step 45 , determining the visible moment and the invisible moment in the preliminary calculation result according to the method of step 15 or step 25 in the push-broom mode visibility determination method of the first aspect or the second aspect of the embodiment of the present invention.

[0120] In this step, the time required for the push-broom mode visibility determination method to calculate is first determined: the preliminary calculation result includes multiple equally divided time points, and for each adjacent equally divided time point, the calculation time point is divided according to a fixed time step, and for each calculation time point, the above push-broom mode visibility determination method is used to determine whether the calculation time point is a visible time point. The preset time in the push-broom mode visibility determination method is also the calculation time point here.

[0121] Step 46: Use binary search method to determine the time window start time and the time window end time between adjacent visible time and invisible time. The final accurate time window start time and end time are obtained through calculation in this step.

[0122] Here, the calculation result of step 45 is as follows Figure 7 As shown, blue is the invisible moment, orange is the visible moment, and the corresponding time window has an exact start time between T2 and T3, and an exact end time between T8 and T9. The binary search method is to calculate whether it is visible at time point T2.5. If it is visible, the exact 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, the exact 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 end time is the same.

[0123] In this embodiment, the calculation of the satellite-region midpoint geocentric vector angle in step 43 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-broom mode visibility determination method, the accuracy of the imaging opportunity time window calculation is further improved.

[0124] like Figure 8 As shown, a fifth aspect of an embodiment of the present invention provides a push-broom mode visibility determination device 50, comprising:

[0125] An acquisition module 51 is used to acquire the satellite time ephemeris data at a preset time;

[0126] A first determination module 52 is used to determine, according to the ephemeris data, 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;

[0127] A second determination module 53 is used to determine 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 sway capability of the satellite at a preset time;

[0128] A third determination module 54 is used to determine the field of view projection of the satellite field of view on the earth's surface according to the satellite line of sight boundary vector;

[0129] The first judgment module 55 is used to judge whether the field of view projection intersects with the target area. If so, the preset time is the visible time.

[0130] In one embodiment of the present invention, determining a projection of a satellite field of view on the earth's surface according to a satellite line of sight boundary vector includes:

[0131] Calculate the first and second intersection points of the satellite line of sight boundary vector and the earth's surface;

[0132] The first intersection point and the second intersection point are connected to form a field of view projection.

[0133] In one embodiment of the present invention, determining whether the field of view projection intersects with the target area includes:

[0134] It is determined whether 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 intersect.

[0135] In one embodiment of the present invention, determining whether the field of view projection intersects with the target area includes: determining whether the first intersection point or the second intersection point is inside the target area.

[0136] In one embodiment of the present invention, determining whether 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 intersect includes:

[0137] Calculate 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;

[0138] Determine whether the face-to-face intersection line is within both the first sector and the second sector.

[0139] In one embodiment of the present invention, determining whether the first intersection point or the second intersection point is inside the target area includes:

[0140] Calculate whether the first ray or the second ray is inside the pyramid formed by the center of the earth and the target area; wherein 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.

[0141] A sixth 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 push-broom mode visibility determination method provided in the above-mentioned embodiment of the present invention is implemented.

[0142] A seventh 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 push-broom mode visibility determination method provided in the above-mentioned embodiment of the present invention are implemented.

[0143] like Fig. 9 As shown, an eighth aspect of an embodiment of the present invention provides an imaging opportunity time window determination system, comprising:

[0144] A construction module 61 is 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;

[0145] A division module 62, used to linearly divide the preset time period into equal parts to obtain a plurality of equally divided moments;

[0146] A second judging module 63 is used to judge whether the first circular area and the second circular area overlap at each equally divided moment;

[0147] A fourth determination module 64, for preliminarily calculating the moment when the first circular area and the second circular area overlap and are equally divided;

[0148] A push-broom mode visibility determination device 50, for determining the visible moment and the invisible moment in the preliminary calculation result;

[0149] The fifth determining module 65 is used to determine the time window start time and the time window end time by using a binary search method between adjacent visible moments and invisible moments.

[0150] In one embodiment of the present invention, determining whether the first circular area and the second circular area overlap at each equally divided moment includes:

[0151] Determine whether, at each equal division moment, a first angle formed by the first center of the first circular area to the center of the earth and by the center of the earth to the second center of the second circular area is less than the sum of a first geocentric angle corresponding to the radius of the first circular area and a second geocentric angle corresponding to the radius of the second circular area;

[0152] If it is less than, then it overlaps;

[0153] If greater, there is no overlap.

[0154] A ninth 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, an imaging opportunity time window determination method provided in the above-mentioned embodiment of the present invention is implemented.

[0155] A tenth aspect of an embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of a method for determining an imaging opportunity time window provided in the above-mentioned embodiment of the present invention are implemented.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] As for the device / system / electronic device embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiments.

[0160] 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 / system that has the functions specified in a block or multiple blocks.

[0161] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including an instruction device / system that implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0162] 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.

[0163] 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 push-broom mode visibility determination method, characterized in that: The following steps are involved: Obtain satellite time and ephemeris data at a preset time; Determine, based on the ephemeris data at the time, a first conversion matrix for converting the instantaneous orbital coordinate system of the satellite at the preset time into an inertial coordinate system and a second conversion matrix for converting the inertial coordinate system into an earth-fixed coordinate system; Determine a satellite line of sight boundary vector in an earth-fixed coordinate system according to the first conversion matrix, the second conversion matrix and the sway capability of the satellite at a preset time; Determining a projection of the satellite's field of view on the earth's surface according to the satellite's line of sight boundary vector; It is determined whether the field of view projection intersects with the target area. If so, the preset time is the visible time.

2. The method according to claim 1, characterized in that The step of determining a projection of a satellite field of view on the earth's surface according to the satellite line of sight boundary vector comprises: Calculating a first intersection point and a second intersection point of the satellite line of sight boundary vector and the earth's surface; The first intersection point and the second intersection point are connected to form the field of view projection.

3. The method according to claim 1, characterized in that The determining whether the field of view projection intersects with the target area includes: It is determined whether 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 intersect.

4. The method according to claim 2, characterized in that The determining whether the field of view projection intersects with the target area includes: determining whether the first intersection point or the second intersection point is inside the target area.

5. The method according to claim 3, characterized in that The determining whether 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 intersect includes: Calculate 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; It is determined whether the plane-to-plane intersection line is within the first sector plane and the second sector plane at the same time.

6. The method according to claim 4, characterized in that The determining whether the first intersection point or the second intersection point is inside the target area includes: Calculate whether the first ray or the second ray is inside the pyramid formed by the center of the earth and the target area; wherein 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.

7. A method for determining an imaging opportunity time window, characterized in that: The following steps are involved: 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; Determine the visible time and the invisible time in the preliminary calculation result according to the push-broom mode visibility determination method of claim 1; A binary search method is used between adjacent visible moments and invisible moments to determine the start and end moments of the time window.

8. The method according to claim 7, characterized in that The determining, at each equally divided moment, whether the first circular area and the second circular area overlap comprises: Determine, at each equal division moment, whether a first angle formed by a first center of the first circular area to the center of the earth and by a first angle formed by a center of the earth to the second center of the second circular area is less than a sum of a first geocentric angle corresponding to the radius of the first circular area and a second geocentric angle corresponding to the radius of the second circular area; If it is less than, then it overlaps; If greater, there is no overlap.

9. A push-broom mode visibility determination device, characterized in that: include: An acquisition module is used to acquire the satellite time ephemeris data at a preset time; A first determination module is used to determine, according to the ephemeris data at the time, a first conversion matrix for converting the instantaneous orbital coordinate system of the satellite at the preset time into an inertial coordinate system and a second conversion matrix for converting the inertial coordinate system into an earth-fixed coordinate system; A second determination module is used to determine 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 sway capability of the satellite at a preset time; A third determination module is used to determine the field of view projection of the satellite field of view on the earth's surface according to the satellite line of sight boundary vector; The first judgment module is used to judge whether the field of view projection intersects with the target area. If so, the preset moment is the visible moment.

10. A system for determining an imaging opportunity time window, characterized in that: include: A construction module, 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; A division module is used to linearly divide the preset time period into equal parts to obtain multiple equal-divided moments; A second judging module is used to judge whether the first circular area and the second circular area overlap at each of the equal division moments; A fourth determination module, used for taking the moment of equal division of the overlap of the first circular area and the second circular area as a preliminary calculation result; a push-broom mode visibility determination device, used to determine the visible time and the invisible time in the preliminary calculation result; The fifth determination module is used to determine the time window start time and the time window end time by using a binary search method between adjacent visible moments and invisible moments.

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