Satellite-to-region target visible time window calculation method and system based on binary matrix row-column query
By using a binary matrix row and column query method, the global region is divided into grid cells, a binary matrix is constructed, and ground viewpoint information is calculated in real time. This solves the problem of low computational efficiency for targets in irregular areas and achieves efficient calculation of the visible time window.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI SATELLITE ENG INST
- Filing Date
- 2026-01-20
- Publication Date
- 2026-05-29
AI Technical Summary
Existing technologies suffer from problems such as low shape representation accuracy, high onboard storage overhead, or insufficient real-time computing efficiency when dealing with targets with irregular and complex shapes. They are difficult to balance the refinement of the description with the real-time performance of the solution.
A binary matrix row and column query method is adopted to divide the global region into grid cells. A binary matrix is established by determining the attributes of the grid cells. Ground viewpoint information is calculated in real time by combining the satellite SAR payload model, and the visible time window is determined by row and column query.
It effectively reduced the computational load on the onboard computer, improved the processing efficiency of on-orbit autonomous mission planning, and provided high-efficiency, low-power target visibility time window computing support.
Smart Images
Figure CN122110109A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of satellite observation technology, and more specifically, to a method and system for calculating the visible time window of a satellite for a regional target based on binary matrix row and column queries. Background Technology
[0002] Synthetic Aperture Radar (SAR) satellites, as active microwave remote sensing platforms, possess all-weather, all-day Earth observation capabilities, enabling them to image ground targets under various lighting and weather conditions. With the increasing intelligence of satellites, on-board autonomous mission planning has become a core means of reducing ground control workload and improving response efficiency. In the process of achieving on-orbit autonomous mission planning, real-time calculation of the visible time window for ground targets (especially complex, irregularly shaped targets) by the satellite payload is a crucial step.
[0003] In existing technologies, ground area targets are typically described using a four-point coordinate method, simplifying the target into a quadrilateral. Although this method can solve the observation window through algorithms such as tracking propagation, iterative correction, or geometric coordinate transformation, the four-point coordinate description suffers from significant geometric distortion when dealing with irregular areas such as islands, seas, and lakes, resulting in low observation efficiency. It is particularly difficult to meet accuracy requirements in specific scenarios such as the land-sea boundary.
[0004] Several improved solutions have been proposed for calculating the access window for regional targets. For example, Chinese invention patent application number 201310247258.7 discloses a method for obtaining the access time window for satellite imaging of ground target areas. This method uses the satellite's orbital period and the return orbit period of the satellite's nadir point to initially determine the access time window. Although this method has certain advantages in processing regularly shaped targets, for irregularly shaped target areas, a preprocessing procedure is still required to convert them into regular rectangles. This often introduces large calculation errors or leads to invalid observations when processing irregular areas with complex edge details.
[0005] Furthermore, the paper "A Fast Algorithm for Time Window of Target Access Area by Earth Observation Satellites" proposes a fast algorithm based on the great circle approximation, which improves the calculation speed by expanding the visible area and using orbital filtering. However, this method is highly dependent on the storage of vertex coordinates of the target area. When dealing with complex irregular polygons, the dramatic increase in the number of vertices will consume a large amount of onboard storage space. Meanwhile, the iterative correction-based method described in the paper "A Fast Calculation Method for Time Window of Satellite Access Area Targets" decomposes the area window into calculating and correcting the time window for each boundary. Its computational load is directly limited by the complexity of the target boundary. When there are many boundary feature points of irregular targets, the computational load on the onboard computer will increase significantly.
[0006] In summary, existing technologies generally suffer from drawbacks such as low shape representation accuracy, high onboard storage overhead, or insufficient real-time computing efficiency when dealing with large-scale, irregular, and complex shaped targets, making it difficult to balance the refinement of the description with the real-time performance of the solution. Summary of the Invention
[0007] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method and system for calculating the visible time window of satellite pairs for regional targets based on binary matrix row and column queries.
[0008] According to one aspect of the present invention, a method for calculating the visible time window of a satellite pair for a regional target based on a binary matrix row and column lookup includes:
[0009] Step S1: Divide the global region into several unit grids according to the grid division method to complete the creation of the global grid; Step S2: Based on the center point coordinates of the grid cell and the preset target area set, determine the attributes of each grid cell; if the grid cell is determined to be within the target area, assign a value of 1 to the grid cell; if the grid cell is determined to be outside the target area, assign a value of 0 to the grid cell, and then establish a binary matrix representing the attributes of the target area. Step S3: Using the preset satellite SAR payload Earth observation model, calculate in real time the geodetic latitude and longitude information of each SAR payload wave position at the current forecast time for the ground viewpoint; Step S4: Based on the ground viewpoint's geodetic latitude and longitude information, calculate the row and column numbers of the corresponding grid cells in the binary matrix using a preset conversion formula; Step S5: Based on the calculated row and column numbers, query the binary matrix to determine the attribute values of the corresponding grid cells; Step S6: Based on the attribute values of the corresponding grid cells, calculate the visible time window of the satellite for the target area during its single-orbit operation.
[0010] Preferably, step S1 specifically includes: The global region is divided into several areas of a predetermined latitude and longitude resolution. The cell grid, and the cell located at the first line, number The grid cells of a column are characterized as .
[0011] Preferably, in step S2, determining the attributes of each grid cell specifically includes: Determine the target mesh cell center point The relative positional relationship with the target region set, if the center point If it coincides with the target region set, then the target grid cell is determined. Located within the target area, if the center point If the target region set does not overlap, then the target grid cell is determined. Located outside the target area.
[0012] Preferably, in step S2, establishing the binary matrix representing the attributes of the target region specifically includes: Build size OK The zero matrix of the column; if the grid cell is determined center point If the target cell is located within the target area or on the boundary of the target area, the corresponding element in the zero matrix is assigned a value of 1. After the center point of all the grid cells is determined, a binary matrix representing the attributes of each grid cell is obtained.
[0013] Preferably, step S3 specifically includes: Sub-step S3.1: Obtain the predicted satellite orbit position information, pre-stored payload wave position information, and satellite attitude information transmitted by the navigation receiver. The payload wave position information includes the wave position center view, far-end view, and near-end view. The predicted satellite orbit position information includes the orbit parameters of the J2000 inertial coordinate system and the position in the Earth-fixed coordinate system. Sub-step S3.2: Obtain the wave position orientation in the satellite's own coordinate system based on the payload wave position information; Sub-step S3.3: Combine satellite attitude information to obtain the wave position pointing in the orbital coordinate system; Sub-step S3.4: Combine the predicted satellite orbital position information to obtain the wave position pointing in the J2000 geocentric inertial coordinate system; Sub-step S3.5: Combine time information and the transformation matrix between the J2000 geocentric inertial coordinate system and the Earth-fixed coordinate system to obtain the wave position orientation in the Earth-fixed coordinate system; Sub-step S3.6: Combine the equations of the Earth ellipsoid model to obtain the positioning information of the intersection point of the wavefront pointing and the ground in the Earth-fixed coordinate system; Sub-step S3.7: Based on the positioning information of the ground intersection point, obtain the geodetic latitude and longitude of the ground viewpoint; Sub-step S3.8: Repeat sub-steps S3.1 to S3.7 to obtain the geodetic latitude and longitude information corresponding to each wave position of the SAR payload at all times.
[0014] Preferably, the conversion formula in step S4 is as follows:
[0015]
[0016] in, Indicates rounding up. The latitude is the ground viewpoint. The longitude is the ground viewpoint. The longitude resolution of the divided grid cells. The latitude resolution of the divided grid cells.
[0017] Preferably, step S5 specifically includes: According to line number With column number Query the attribute values of the corresponding cell grid in the binary matrix. If determined Then it is characterized in If the ground viewpoint of the target beam is not within the target area at any given time, set a status word indicating whether the target beam is within the target area. If determined This indicates that the ground viewpoint of the target wave position at time t is located within the target area, and the state word is set. Among them, subscript , This represents the total number of SAR payload positions.
[0018] Preferably, step S6 specifically includes: Sub-step S6.1: For each wave position of the SAR payload, perform attribute query operations on the cell grid to obtain the corresponding status word within the preset forecast time interval. Within this framework, construct a visible time window matrix for all wavelengths relative to the target region:
[0019] Sub-step S6.2: For the visible time window matrix Perform row detection operation: For each matrix row corresponding to each detection time, if the element values from the 2nd column to the last column in the target matrix row are not all 0, then it is determined that the target SAR payload is visible to the target area at the target time t, and the corresponding imaging enable state word is set. The current time t is recorded; if all elements from the second column to the last column in the target matrix row are 0, the target SAR payload is determined to be invisible to the target area, and the corresponding imaging enable state word is set. ; Sub-step S6.3: If the imaging enable state word When the value changes from 0 to 1, the corresponding time is determined as the start time of the visible time window of the target area. If the imaging enable state word If the value changes from 1 to 0, the corresponding time is determined as the end time of the visible time window of the target area. Based on the aforementioned start time With the end time The visible time window of the SAR satellite over the target area is obtained. .
[0020] According to another aspect of the present invention, a satellite-to-regional target visibility time window calculation system based on binary matrix row and column lookup is characterized in that it includes: Module M1: Divides the global region into several unit grids according to the grid division method, completing the creation of the global grid; Module M2: Based on the center point coordinates of the grid cell and the preset target area set, determine the attributes of each grid cell; if the grid cell is determined to be within the target area, assign a value of 1 to the grid cell; if the grid cell is determined to be outside the target area, assign a value of 0 to the grid cell, and then establish a binary matrix representing the attributes of the target area. Module M3: Through a preset satellite SAR payload Earth observation model, it calculates in real time the geodetic latitude and longitude information of each wave position of the SAR payload at the current forecast time of the ground viewpoint; Module M4: Based on the ground viewpoint's geodetic latitude and longitude information, it calculates the row and column numbers of the corresponding grid cells in the binary matrix using a preset conversion formula; Module M5: Based on the calculated row and column numbers, query the binary matrix to determine the attribute values of the corresponding grid cells; Module M6: Based on the attribute values of the corresponding grid cells, calculates the visible time window of the satellite for the target area during its single-orbit operation.
[0021] Preferably, the module M1 specifically includes: The global region is divided into several areas of a predetermined latitude and longitude resolution. The cell grid, and the cell located at the first line, number The grid cells of a column are characterized as .
[0022] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes ground-based discretization modeling preprocessing to map irregularly shaped regional targets such as islands, specific sea areas, and lakes into two-dimensional logical matrices representing spatial attributes. This technical solution transforms the highly complex spatial geometric topology determination process in traditional computation into a fast row and column addressing operation on the two-dimensional logical matrix, effectively avoiding the computational overhead of real-time analysis of complex boundaries by onboard computers. Based on the retrieval mechanism of the two-dimensional logical matrix, this invention provides SAR satellites with highly efficient and low-power target visibility time window computation support when performing multi-mode on-orbit autonomous mission planning and resource scheduling. Attached Figure Description
[0023] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a flowchart illustrating the method for calculating the visible time window of regional targets by SAR satellites based on row and column queries of a binary matrix.
[0024] Figure 2 Example diagram for calculating the location attribute of the center point of a grid cell.
[0025] Figure 3 The flowchart for step 2 is shown.
[0026] Figure 4 The flowchart for step 3 is shown. Detailed Implementation
[0027] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.
[0028] Example 1: This embodiment provides a satellite-based method for calculating the visible time window of regional targets based on binary matrix row and column lookup. This method divides the global region into discrete grid cells and uses a geometric inclusion determination algorithm to identify the topological relationship between the center point of each grid cell and the irregular target area. If a grid cell is determined to be within the target area, it is assigned a specific logical value, thereby constructing a complete attribute matrix characterizing the target's shape features, which is pre-stored in the onboard storage device. During satellite operation, the system acquires orbit and attitude data in real time, and combines this with the payload's imaging geometry model to calculate the latitude and longitude of the instantaneous observation viewpoint formed by each radar beam position on the ground. Subsequently, using a linear quantization mapping mechanism, the dynamic geodetic coordinates are converted into row and column addressing indices of the attribute matrix in real time. The satellite extracts the attribute states of the corresponding grid cells through table lookup operations and continuously monitors the temporal imaging enable states. By identifying the critical moments when attribute states switch, the start and end nodes of the observation window are determined. This scheme significantly reduces the computational load on the onboard computer and improves the processing efficiency of mission planning by transforming complex analytical geometric calculations into an efficient storage addressing process.
[0029] The following is combined Figure 1 The following is a detailed explanation of each step of the method: Step S1: Divide the global region into several unit grids according to the grid division method to complete the creation of the global grid; It is understood that step S1 specifically includes: The global region is divided into several areas of a predetermined latitude and longitude resolution. The cell grid, and the cell located at the first line, number The grid cells of a column are characterized as .
[0030] Step S2: As Figure 3 As shown, based on the center point coordinates of the grid cell and the preset target area set, the attributes of each grid cell are determined; if the grid cell is determined to be within the target area, the grid cell is assigned a value of 1; if the grid cell is determined to be outside the target area, the grid cell is assigned a value of 0, thereby establishing a binary matrix representing the attributes of the target area. It is understood that, in step S2, determining the attributes of each mesh element specifically includes: like Figure 2 As shown, the target mesh cell is determined. center point The relative positional relationship with the target region set, if the center point If it coincides with the target region set, then the target grid cell is determined. Located within the target area, if the center point If the target region set does not overlap, then the target grid cell is determined. Located outside the target area.
[0031] It is understood that, in step S2, establishing the binary matrix representing the attributes of the target region specifically includes: Build size OK The zero matrix of the column; if the grid cell is determined center point If the target cell is located within the target area or on the boundary of the target area, the corresponding element in the zero matrix is assigned a value of 1. After the center point of all the grid cells is determined, a binary matrix representing the attributes of each grid cell is obtained.
[0032] Step S3: As Figure 4 As shown, the ground viewpoint latitude and longitude information corresponding to each wave position of the SAR payload at the current forecast time is calculated in real time using the preset satellite SAR payload Earth observation model. It is understood that step S3 specifically includes: Sub-step S3.1: Obtain the predicted satellite orbit position information, pre-stored payload wave position information, and satellite attitude information transmitted by the navigation receiver. The payload wave position information includes the wave position center view, far-end view, and near-end view. The predicted satellite orbit position information includes the orbit parameters of the J2000 inertial coordinate system and the position in the Earth-fixed coordinate system. Sub-step S3.2: Obtain the wave position orientation in the satellite's own coordinate system based on the payload wave position information; Sub-step S3.3: Combine satellite attitude information to obtain the wave position pointing in the orbital coordinate system; Sub-step S3.4: Combine the predicted satellite orbital position information to obtain the wave position pointing in the J2000 geocentric inertial coordinate system; Sub-step S3.5: Combine time information and the transformation matrix between the J2000 geocentric inertial coordinate system and the Earth-fixed coordinate system to obtain the wave position orientation in the Earth-fixed coordinate system; Sub-step S3.6: Combine the equations of the Earth ellipsoid model to obtain the positioning information of the intersection point of the wavefront pointing and the ground in the Earth-fixed coordinate system; Sub-step S3.7: Based on the positioning information of the ground intersection point, obtain the geodetic latitude and longitude of the ground viewpoint; Sub-step S3.8: Repeat sub-steps S3.1 to S3.7 to obtain the geodetic latitude and longitude information corresponding to each wave position of the SAR payload at all times.
[0033] Step S4: Based on the ground viewpoint's geodetic latitude and longitude information, calculate the row and column numbers of the corresponding grid cells in the binary matrix using a preset conversion formula; It is understood that the conversion formula in step S4 is as follows:
[0034]
[0035] in, Indicates rounding up. The latitude is the ground viewpoint. The longitude is the ground viewpoint. The longitude resolution of the divided grid cells. The latitude resolution of the divided grid cells.
[0036] Step S5: Based on the calculated row and column numbers, query the binary matrix to determine the attribute values of the corresponding grid cells; It is understood that step S5 specifically includes: According to line number With column number Query the attribute values of the corresponding cell grid in the binary matrix. If determined Then it is characterized in If the ground viewpoint of the target beam is not within the target area at any given time, set a status word indicating whether the target beam is within the target area. If determined This indicates that the ground viewpoint of the target wave position at time t is located within the target area, and the state word is set. Among them, subscript , This represents the total number of SAR payload positions.
[0037] Step S6: Based on the attribute values of the corresponding grid cells, calculate the visible time window of the satellite for the target area during its single-orbit operation.
[0038] It is understood that step S6 specifically includes: Sub-step S6.1: For each wave position of the SAR payload, perform attribute query operations on the cell grid to obtain the corresponding status word within the preset forecast time interval. Within this framework, construct a visible time window matrix for all wavelengths relative to the target region:
[0039] Sub-step S6.2: For the visible time window matrix Perform row detection operation: For each matrix row corresponding to each detection time, if the element values from the 2nd column to the last column in the target matrix row are not all 0, then it is determined that the target SAR payload is visible to the target area at the target time t, and the corresponding imaging enable state word is set. The current time t is recorded; if all elements from the second column to the last column in the target matrix row are 0, the target SAR payload is determined to be invisible to the target area, and the corresponding imaging enable state word is set. ; Sub-step S6.3: If the imaging enable state word When the value changes from 0 to 1, the corresponding time is determined as the start time of the visible time window of the target area. If the imaging enable state word If the value changes from 1 to 0, the corresponding time is determined as the end time of the visible time window of the target area. Based on the aforementioned start time With the end time The visible time window of the SAR satellite over the target area is obtained. .
[0040] Example 2: Step 1: Divide the global region into unit grids using the grid method to complete the creation of the global grid.
[0041] When creating a global grid, the grid resolution must first be determined, dividing the globe into an m°×n° grid, where m and n are the latitude and longitude resolutions of the grid cells, respectively. A common approach is to use equal latitude and longitude division, with intervals of m°. This results in a grid of 180 / m rows and 360 / m columns. For example, dividing a global region (longitude range -180°~180°, latitude range -90°~90°) into 1°×1° 180×360 grid cells, denoted as the nth... line, number Column grid cells are ,in It represents the grid enclosed by the longitude range of -180° to -179° and the latitude range of 90° to 89°.
[0042] Step 2: Using the center point of the grid cell and the target area set, determine the attributes of the grid cell, determine whether the grid cell is the target area, if so, assign the value 1 to the grid cell, otherwise assign the value 0 to the grid cell, and establish a binary matrix.
[0043] Using the center point of the grid cell and target area set Complete the determination of grid cell attributes, determine whether the grid cell is the target area, if so, assign the value 1 to the grid cell, otherwise assign the value 0 to the grid cell, and establish a binary matrix.
[0044] Grid cell center point The center point is calculated using latitude and longitude coordinates, and its coordinates are... ,in Longitude of the center point of the grid cell The latitude of the center point of the grid cell is calculated using the following formula:
[0045] in, , The first line, number Column grid cell longitude upper and lower limits, , The first line, number Upper and lower limits of latitude for each grid cell.
[0046] The target region is the set of latitude and longitude coordinates of a series of feature points on the boundary of the region. It means that among them For the target area The latitude and longitude coordinates of each point are used to form an irregular polygon by arranging the feature points in a clockwise or counterclockwise order. This polygon is the target area.
[0047] The determination of grid cell attributes is equivalent to judging the grid cell. center point Set of target regions Relative positional relationships; Establish OK Column zero matrix:
[0048] when When it is within the target area or on the boundary of the target area, the assignment matrix is... .
[0049] The judgment grid unit center point Set of target regions The relative positional relationship between the point and the polygon is determined using the ray casting method, i.e., the bounding box pre-detection is performed to exclude targets located within the given polygon. Data outside the circumscribed rectangle. First, calculate the target region. The upper and lower limits of latitude and longitude, if In the target area Outside the upper and lower limits of latitude and longitude, outside the target region, assign values. ;like In the target area Within the upper and lower limits of latitude and longitude, the ray method is further used for further analysis. Enclosure detection with polygons. After determining the center points of all mesh elements, a binary matrix representing the properties of each mesh element is obtained. .
[0050] In a specific embodiment, steps 1 and 2 are ground preprocessing processes, through which a binary matrix representing the target region is obtained. , the binary matrix The matrix is stored in the onboard computer and queried during the real-time calculation window on the satellite.
[0051] Step 3: Based on the satellite SAR payload Earth observation model, calculate the geodetic latitude and longitude of the ground viewpoint corresponding to each SAR wave position.
[0052] Sub-step S3.1: Obtain the predicted satellite orbit position information, pre-stored payload wave position information, and satellite attitude information transmitted by the navigation receiver. The payload wave position information includes the wave position center view, far-end view, and near-end view. The predicted satellite orbit position information includes the orbit parameters of the J2000 inertial coordinate system and the position in the Earth-fixed coordinate system. Sub-step S3.2: Obtain the wave position orientation in the satellite's own coordinate system based on the payload wave position information; In one specific embodiment, the wave position orientation in the satellite's own coordinate system can be calculated through coordinate transformation based on the payload wave position angle and its relationship with the satellite's own coordinate system.
[0053] Sub-step S3.3: Combine satellite attitude information to obtain the wave position pointing in the orbital coordinate system; In one specific embodiment, after obtaining the satellite attitude information, the coordinate transformation matrix from the satellite body coordinate system to the orbit coordinate system can be calculated, and then the wave position pointing in the orbit coordinate system can be calculated based on the wave position pointing in the satellite body coordinate system.
[0054] Sub-step S3.4: Combine the predicted satellite orbital position information to obtain the wave position pointing in the J2000 geocentric inertial coordinate system; In a specific embodiment, by combining the orbital parameters of the J2000 inertial coordinate system, the coordinate transformation matrix from the orbital coordinate system to the J2000.0 geocentric inertial coordinate system can be calculated, and then the wave position pointing in the J2000 geocentric inertial coordinate system can be calculated based on the wave position pointing in the orbital coordinate system.
[0055] Sub-step S3.5: Combine time information and the transformation matrix between the J2000 geocentric inertial coordinate system and the Earth-fixed coordinate system to obtain the wave position orientation in the Earth-fixed coordinate system; In one specific embodiment, the Julian century number is calculated based on the time information, and then the Greenwich Mean Time (GMT) is calculated; the sidereal time rotation matrix is then calculated based on the GMT. Precession matrix Nucleation matrix The polar motion matrix can be calculated based on the Earth's polar motion parameters. Then, the coordinate transformation matrix from the inertial coordinate system (J2000) to the Earth-fixed coordinate system (WGS84) is calculated:
[0056] The wave position in the Earth-fixed coordinate system is calculated based on the coordinate transformation matrix and the wave position in the J2000 geocentric inertial coordinate system.
[0057] Sub-step S3.6: Combine the equations of the Earth ellipsoid model to obtain the positioning information of the intersection point of the wavefront pointing and the ground in the Earth-fixed coordinate system; Sub-step S3.7: Based on the positioning information of the ground intersection point, obtain the geodetic latitude and longitude of the ground viewpoint; Sub-step S3.8: Repeat sub-steps S3.1 to S3.7 to obtain the geodetic latitude and longitude information corresponding to each wave position of the SAR payload at all times.
[0058] Step 4: Calculate the row number of the corresponding grid cell based on the geodetic latitude and longitude of the SAR payload ground viewpoint. With column number .
[0059] line number With column number The calculation formula is:
[0060]
[0061] in, Indicates rounding up. The latitude is the ground viewpoint. The longitude is the ground viewpoint. The longitude resolution of the divided grid cells. The latitude resolution of the divided grid cells.
[0062] Step 5: Query the corresponding grid cell attributes in the binary matrix based on the row and column numbers.
[0063] According to line number With column number Query binary matrix Corresponding grid cell attribute values For a certain SAR payload position ( , (Total number of wave positions), if the calculation time When querying a binary matrix Acquired , then indicates the time. At that time, the ground viewpoint was not in the target area. In the middle, determine whether the wave position is within the target area. internal status word ;like , then indicates the time. At that time, the ground viewpoint of that wavelength was in the target area. In the middle, determine whether the wave position is within the target area. internal status word The SAR payload was acquired at each wave position separately. At the predicted time Interval, with time window matrix
[0064] Step 6: Calculate the visible time window of the target area for a single track based on the grid cell properties.
[0065] Based on the results obtained in step 5 The matrix can be used to calculate the visible time window of a target area for a single track. For different wave positions, there are cases where some wave positions are located within the target area and some are located outside the target area, i.e. In each row of the matrix Not all values are equal to 1. Here, it is assumed that imaging is possible when any wavefront is located within the target area. The matrix performs row detection operations, and for each detection time... The corresponding matrix row, if If the second to last columns of the matrix are not all zeros, then the SAR is considered visible to the target area, and the imaging enable state word is set. And record the time. ;like If all columns from the second to the last in the matrix are 0, then the SAR is considered to be invisible to the target area, and the imaging enable state word is set. .when When it changes from 0 to 1, the corresponding time can be obtained. The start time of the visible time window for regional targets ;when When it changes from 1 to 0, return the corresponding time. Start time of the visible time window for regional targets The visible time window for SAR satellites of regional targets can be obtained. .
[0066] This invention also provides a satellite-to-regional target visibility time window calculation system based on binary matrix row and column query. The satellite-to-regional target visibility time window calculation system based on binary matrix row and column query can be implemented by executing the process steps of the satellite-to-regional target visibility time window calculation method based on binary matrix row and column query. That is, those skilled in the art can understand the satellite-to-regional target visibility time window calculation method based on binary matrix row and column query as a preferred embodiment of the satellite-to-regional target visibility time window calculation system based on binary matrix row and column query.
[0067] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.
[0068] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.
Claims
1. A method for calculating the visible time window of satellite pairs for regional targets based on binary matrix row and column lookup, characterized in that, include: Step S1: Divide the global region into several unit grids according to the grid division method to complete the creation of the global grid; Step S2: Based on the center point coordinates of the grid cell and the preset target area set, determine the attributes of each grid cell; if the grid cell is determined to be within the target area, assign a value of 1 to the grid cell; if the grid cell is determined to be outside the target area, assign a value of 0 to the grid cell, and then establish a binary matrix representing the attributes of the target area. Step S3: Using the preset satellite SAR payload Earth observation model, calculate in real time the geodetic latitude and longitude information of each SAR payload wave position at the current forecast time for the ground viewpoint; Step S4: Based on the ground viewpoint's geodetic latitude and longitude information, calculate the row and column numbers of the corresponding grid cells in the binary matrix using a preset conversion formula; Step S5: Based on the calculated row and column numbers, query the binary matrix to determine the attribute values of the corresponding grid cells; Step S6: Based on the attribute values of the corresponding grid cells, calculate the visible time window of the satellite for the target area during its single-orbit operation.
2. The method according to claim 1, characterized in that, Step S1 specifically includes: The global region is divided into several areas of a predetermined latitude and longitude resolution. The cell grid, and the cell located at the first line, number The grid cells of a column are characterized as .
3. The method according to claim 2, characterized in that, In step S2, determining the attributes of each mesh element specifically includes: Determine the target mesh cell center point The relative positional relationship with the target region set, if the center point If it coincides with the target region set, then the target grid cell is determined. Located within the target area, if the center point If the target region set does not overlap, then the target grid cell is determined. Located outside the target area.
4. The method according to claim 3, characterized in that, In step S2, establishing the binary matrix representing the attributes of the target region specifically includes: Build size OK The zero matrix of the column; if the grid cell is determined center point If the target cell is located within the target area or on the boundary of the target area, the corresponding element in the zero matrix is assigned a value of 1. After the center point of all the grid cells is determined, a binary matrix representing the attributes of each grid cell is obtained.
5. The method according to claim 1, characterized in that, Step S3 specifically includes: Sub-step S3.1: Obtain the predicted satellite orbit position information, pre-stored payload wave position information, and satellite attitude information transmitted by the navigation receiver. The payload wave position information includes the wave position center view, far-end view, and near-end view. The predicted satellite orbit position information includes the orbit parameters of the J2000 inertial coordinate system and the position in the Earth-fixed coordinate system. Sub-step S3.2: Obtain the wave position orientation in the satellite's own coordinate system based on the payload wave position information; Sub-step S3.3: Combine satellite attitude information to obtain the wave position pointing in the orbital coordinate system; Sub-step S3.4: Combine the predicted satellite orbital position information to obtain the wave position pointing in the J2000 geocentric inertial coordinate system; Sub-step S3.5: Combine time information and the transformation matrix between the J2000 geocentric inertial coordinate system and the Earth-fixed coordinate system to obtain the wave position orientation in the Earth-fixed coordinate system; Sub-step S3.6: Combine the equations of the Earth ellipsoid model to obtain the positioning information of the intersection point of the wavefront pointing and the ground in the Earth-fixed coordinate system; Sub-step S3.7: Based on the positioning information of the ground intersection point, obtain the geodetic latitude and longitude of the ground viewpoint; Sub-step S3.8: Repeat sub-steps S3.1 to S3.7 to obtain the geodetic latitude and longitude information corresponding to each wave position of the SAR payload at all times.
6. The method according to claim 1, characterized in that, The conversion formula in step S4 is as follows: in, Indicates rounding up. The latitude is the ground viewpoint. The longitude is the ground viewpoint. The longitude resolution of the divided grid cells. The latitude resolution of the divided grid cells.
7. The method according to claim 1, characterized in that, Step S5 specifically includes: According to line number With column number Query the attribute values of the corresponding cell grid in the binary matrix. If determined Then it is characterized in If the ground viewpoint of the target beam is not within the target area at any given time, set a status word indicating whether the target beam is within the target area. If determined This indicates that the ground viewpoint of the target wave position at time t is located within the target area, and the state word is set. Among them, subscript , This represents the total number of SAR payload positions.
8. The method according to claim 1, characterized in that, Step S6 specifically includes: Sub-step S6.1: For each wave position of the SAR payload, perform attribute query operations on the cell grid to obtain the corresponding status word within the preset forecast time interval. Within this framework, construct a visible time window matrix for all wavelengths relative to the target region: Sub-step S6.2: For the visible time window matrix Perform row detection operation: For each matrix row corresponding to each detection time, if the element values from the 2nd column to the last column in the target matrix row are not all 0, then it is determined that the target SAR payload is visible to the target area at the target time t, and the corresponding imaging enable state word is set. The current time t is recorded; if all elements from the second column to the last column in the target matrix row are 0, the target SAR payload is determined to be invisible to the target area, and the corresponding imaging enable state word is set. ; Sub-step S6.3: If the imaging enable state word When the value changes from 0 to 1, the corresponding time is determined as the start time of the visible time window of the target area. If the imaging enable state word If the value changes from 1 to 0, the corresponding time is determined as the end time of the visible time window of the target area. Based on the aforementioned start time With the end time The visible time window of the SAR satellite over the target area is obtained. .
9. A satellite-based regional target visibility time window calculation system based on binary matrix row and column lookup, characterized in that, include: Module M1: Divides the global region into several unit grids according to the grid division method, completing the creation of the global grid; Module M2: Based on the center point coordinates of the grid cell and the preset target area set, determine the attributes of each grid cell; if the grid cell is determined to be within the target area, assign a value of 1 to the grid cell; if the grid cell is determined to be outside the target area, assign a value of 0 to the grid cell, and then establish a binary matrix representing the attributes of the target area. Module M3: Through a preset satellite SAR payload Earth observation model, it calculates in real time the geodetic latitude and longitude information of each wave position of the SAR payload at the current forecast time of the ground viewpoint; Module M4: Based on the ground viewpoint's geodetic latitude and longitude information, it calculates the row and column numbers of the corresponding grid cells in the binary matrix using a preset conversion formula; Module M5: Based on the calculated row and column numbers, query the binary matrix to determine the attribute values of the corresponding grid cells; Module M6: Based on the attribute values of the corresponding grid cells, calculates the visible time window of the satellite for the target area during its single-orbit operation.
10. The system according to claim 9, characterized in that, The module M1 specifically includes: The global region is divided into several areas of a predetermined latitude and longitude resolution. The cell grid, and the cell located at the first line, number The grid cells of a column are characterized as .