An AIS civil target display control method and device based on group identification

Abstract

This invention discloses an AIS civilian target display control method based on group identification, comprising the following steps: S1, Target Group Identification: Through target spatiotemporal consistency transformation, the collected AIS target latitude and longitude are uniformly extrapolated to the latitude and longitude of each current display cycle. Based on this latitude and longitude, a target feature matrix is ​​constructed and matrix transformation is performed. The difference degree obtained from the matrix transformation is used for group similarity calculation, thereby identifying group targets; S2, Group Target Display: Based on the identification of group targets, the group targets are displayed using group target symbols representing the group and group boundary lines representing the range of the target group. This invention also discloses an AIS civilian target display control device based on group identification. This invention achieves the replacement of a large number of AIS target displays within entity groups with special target group symbols and group boundary displays, thereby significantly reducing the number of target symbols displayed in the situation and optimizing the situation display effect. It can be widely applied in the field of ship information technology.

Description

Technical Field

[0001] This invention relates to ship information technology, and in particular to an AIS civilian target display control method and device based on group identification. It proposes an automatic target display control technology that combines target group identification and group boundary target judgment, which solves the problem of the impact of excessive AIS targets on the target situation display of the ship information system, and realizes an optimized target situation display method that takes into account both civilian ship targets reported by AIS equipment and radar-detected targets. Background Technology

[0002] AIS (Automatic Identification System) is a device that uses the VHF band to automatically transmit or receive information from shore (ship) between ships and between ships and shore. Because AIS helps in timely acquisition of maritime traffic conditions, prevents ship collisions, and ensures the safety of naval navigation, the International Maritime Organization (IMO) mandates that all international vessels of 300 gross tons or more, domestic vessels of 500 gross tons or more, and passenger ships of all sizes built after July 1, 2002, must be equipped with AIS. It is estimated that more than one million ships worldwide are currently equipped with AIS.

[0003] The information acquired by AIS equipment mainly includes two parts: dynamic and static information about the vessel. It can obtain information such as the vessel identification code (MMIS code), position, speed, heading, name, and call sign. On the one hand, it has advantages such as long operating range, high accuracy, and good real-time performance; on the other hand, since the number of vessels in daily maritime operations reaches 400,000 to 500,000, and each vessel typically broadcasts AIS information every 2 seconds to 6 minutes, the AIS target information is characterized by its massive volume and high update frequency.

[0004] Ship information systems typically need to process and display both AIS target information and radar target information detected by the ship's navigation radar simultaneously. Even after filtering out some AIS targets using nautical charts and eliminating duplicate targets by correlating them with radar targets, there is still usually a need to process and display four to five hundred batches of AIS targets. This massive amount of AIS target data not only excessively consumes the computer display and control resources of the ship information system, but also significantly reduces the readability of situational information.

[0005] AIS acquires targets primarily from civilian vessels, mainly fishing boats and merchant ships, which tend to sail in convoys, largely conforming to the movement trends of group targets. Therefore, by utilizing target group identification and group boundary target judgment methods, a large number of physical targets can be replaced by displaying specific group target symbols and group target area ranges, thereby significantly reducing the number of AIS targets displayed on the screen and optimizing the situational awareness display.

[0006] A target group must be a set of targets that coordinate and act together. Therefore, they must share similarities in their motion characteristics. Extracting these similarity parameters as a feature vector for a target group becomes crucial for identifying it. For two target groups, it is necessary to calculate the differences between the two groups. If the differences are sufficiently small, it indicates that the two groups are similar and can be merged into one. Through several iterations, several relatively stable sets of target groups will be formed, thus achieving target group identification.

[0007] The determination of the target group boundary involves two steps: first, obtaining the target points located on the group boundary by sorting by latitude and longitude; and second, eliminating the concave points on the boundary points so that the final boundary boundary outline formed by connecting the boundary points is a convex shell shape, which is the boundary of the target group. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the aforementioned background technology and provide an AIS civilian target display control method and device based on group recognition. This invention proposes a method for using AIS target information to determine the motion similarity between targets, identify target groups, and draw the boundary contours of target groups. It achieves the replacement of a large number of AIS target displays within entity groups with special target group symbols and group boundary displays, thereby significantly reducing the number of target symbols displayed in the situation and optimizing the situation display effect. The main technical problems solved include the algorithm for target group recognition using motion similarity judgment between targets and the method for drawing the convex point graphics of the target group boundary contours.

[0009] This invention provides an AIS civilian target display control method based on group identification, comprising the following steps: S1, Target group identification: Through target spatiotemporal consistency transformation, the collected AIS target latitude and longitude are uniformly extrapolated to the latitude and longitude of each current display cycle. Based on the latitude and longitude, a target feature matrix is ​​constructed and matrix transformation is completed. The difference degree obtained by matrix transformation is used for group similarity calculation, thereby identifying group targets; S2, Group target display: Based on the identification of group targets, the group targets are displayed by group target symbols representing the group and group boundary lines representing the range of the target group.

[0010] In the above technical solution, the specific process of step S1 is as follows: S11, Target spatiotemporal consistency conversion: Obtain the latest AIS reported targets according to the ship information system situation display update cycle, and use the linear extrapolation method to uniformly extrapolate the latitude and longitude of the AIS targets to the latitude and longitude of each current display cycle; S12, Matrix construction and transformation: Construct a target feature matrix for a group with n targets, and obtain the difference transformation matrix and the difference degree y between the i-th target and the j-th target in the difference matrix by centering, standardizing and differentiating the target feature matrix. ijS13, Group similarity calculation: If y ij If the value is less than the threshold U, then target i and target j are grouped into the same group G. ij =(X i ,X j ), take target X i and target X j The average value of each element represents the group objective. , and another group Similarly, the group target after average transformation Repeat the matrix transformation steps above to perform difference transformation comparison; if the difference is less than the threshold U, merge the two groups, and use the average value of each element of the target in the new group to represent the target of this group and compare the difference with other groups again, and so on, until there are no groups that can be merged, thus completing the identification of the group target.

[0011] In the above technical solution, step S12 includes step S121, constructing the target feature matrix, the specific process of which is as follows: Let there be n targets, and the i-th target among the n targets is... , , ,in, To characterize the target If we have m feature parameters, then the feature matrix of these n targets can be represented as:

[0012] .

[0013] In the above technical solution, the matrix transformation process in step S12 is as follows: S122, matrix centering transformation , ,in, The transformed central matrix; S123, matrix normalization transformation ,in, The transformed standard matrix; S124, the difference matrix transformation is set to... , ;

[0014] These are weighting coefficients. ,make , Then we can obtain n matrices containing n elements; sequentially arrange Y1 to Y... n If each column of n elements in a matrix is ​​rearranged from top to bottom to left to right, we obtain an n×n symmetric matrix with zeros on the diagonal. This matrix can then be converted into an upper triangular or lower triangular matrix, i.e., a difference matrix. , where y ij This represents the degree of difference between the i-th objective and the j-th objective.

[0015] In the above technical solution, the specific process of step S2 is as follows: S21, Obtain the minimum bounding rectangle: The latitude and longitude of each target in the group are approximated as planar coordinates for calculation. By sorting the latitude and longitude values ​​of each target in the group, the maximum latitude and longitude values ​​and the minimum latitude and longitude values ​​L are obtained. max B max L min B min and with (L min B max ) and (L max B min S21, Boundary Point Selection: Divide the minimum bounding rectangle into four equal parts, and determine whether each region contains only one target point. If so, stop dividing the region into four equal parts; otherwise, continue dividing the region into four equal parts until each cell contains only one target point. A cell containing a target point is represented by 1, and a cell not containing a target point is represented by 0. This results in an n×m 0-1 matrix. The criterion for determining internal points is: in the 0-1 matrix, if an element... If a point is in the i-th row or j-th column, there must be at least one 1 on both sides of it. That is, in the same row, there must be at least one 1 on the left and right sides of the j-th column; or in the same column, there must be at least one 1 on the top and bottom sides of the i-th row. If all internal points are changed from 1 to 0, a boundary point matrix is ​​formed, and the 1 points in the matrix are the corresponding boundary points.

[0016] In the above technical solution, step S2 further includes step S23, concave point removal: If a concave point graph appears during the connection of boundary points, the concave points are removed so that the boundary line becomes a closed convex point graph. The specific process is as follows: S231, Given the coordinates of n boundary points (x... i ,y i (i=0..n-1), first select y i The point with the smallest coordinate is used as the starting point a0 for sorting. If multiple points have the same y-coordinate, the point with the smallest x-coordinate is selected. The angle between the line connecting the other points relative to a0(x0,y0) and the x-axis is calculated. , .when At that time, if but ;like but ,make ,according to Sort the other (n-1) points in ascending order, then insert point a0 at the beginning of the sorted list, finally obtaining a0...a0 sorted clockwise. nBoundary point list; S232, among all sorted boundary points, given the initial connection between points a0 and a1, for points a2 and a3 to be connected in order, if If a2 is a concave point, it should be removed from the boundary point set. Connect a0, a1, and a3 directly to form the boundary line. Then, using a1 and a3 as the initial connection, determine the subsequent points a4 and a5. If a2 is a convex point, then a0, a1, and a2 should be connected to form a boundary line. Then, using a1 and a2 as the initial connection, the subsequent points a3 and a4 are judged; and so on, the subsequent two points to be connected are judged again until all boundary points are traversed; S233, for the first point a0 and the last point a2 in the boundary point set... n , will a n-1 a n-2 Two points are used as the initial connection points. Then, points a and b need to be connected sequentially. n The two points, a and a0, are used to determine the concave point.

[0017] In the above technical solution, in step S11, the time corresponding to each target ship motion parameter is used as the primary key value for sorting, and the maximum time value is rounded up to T'=RoundUp(T max Each target motion parameter is linearly extrapolated to its latitude and longitude at that moment using the following method: S111, distance If the azimuth angle θ = heading, then the extrapolated target point's coordinates in the geocentric Earth-fixed coordinate system (X...) t Y t )for: , where L s B s These are the target's current longitude and latitude, respectively. , a and b are the Earth's major and minor semi-axes, respectively; S112, then the extrapolated target's latitude and longitude in the geodetic coordinate system are: .

[0018] In the above technical solution, after removing the concave points and obtaining a convex point image in step S2, the method further includes step S24, display principle, the specific process of which is as follows: S241, for a 2-point boundary set, the midpoint of the line connecting the two points is taken to display the group target symbol, and the range of the group target is represented by a dashed circle with the midline segment as the radius; S242, for a 3-point or more boundary set, the coordinates of the center point of the convex point boundary polygon are obtained according to the method of obtaining the position of the polygon mass point, and the range of the group target is represented by a dashed convex point boundary polygon; let (x i ,y i Let i = 1..n be the coordinates of the n vertices of the convex boundary polygon in the ship's coordinate system with the ship's position as the origin. Then the position of the center point of the polygon (C) is given. x C y)for: , S is the area of ​​the polygon. .

[0019] In the above technical solution, step S2 further includes S25, displaying group target labels, specifically: the group target label displays the group target batch number, group target quantity, type, country / region / province (state), latitude and longitude of the group indicator location, as well as group speed and heading; wherein, the group target batch number adopts a 4-digit decimal serial number, with the uppercase letter "G" before the number to indicate the group target batch number, the group speed is displayed as the two-dimensional vector average of the absolute speed of the targets in the group, and the group heading is displayed as the mean square error of the heading of the targets in the group; S26, updating the group target batch number, specifically: S261, the target group is updated and displayed according to the situation update cycle, defining the group density β=n / s, where n is the number of targets in the group, and S is the area of ​​the convex point boundary polygon; S262, if the group density changes between previous and subsequent cycles If the percentage is ≤50%, the batch number will not be renumbered and will still be used to represent the group; otherwise, it will be considered a new group, and the unused numbers from 0000 to 9999 will be renumbered sequentially, and the original batch number will be replaced as the group batch number.

[0020] The present invention also provides an AIS civilian target display control device based on group identification, which has a computer program capable of executing an AIS civilian target display control method based on group identification.

[0021] The present invention provides a civilian target display control method and device based on group identification for AIS, which has the following beneficial effects:

[0022] First, special target group symbols and group boundary displays replace the display of a large number of AIS targets within entity groups, thereby significantly reducing the number of target symbols displayed in the situation, optimizing the situation display effect, and making it easier for users to observe and grasp the target situation.

[0023] Secondly, it simultaneously reduces the excessive use of computer hardware display resources by AIS target display, thereby improving system operating efficiency.

[0024] Third, this method can be used for both civilian and military information systems to process and display AIS targets, and has a wide range of applications. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the AIS civilian target display control method based on group identification according to the present invention.

[0026] Figure 2 This is a flowchart illustrating step S13 in Embodiment 1 of the AIS civilian target display control method based on group identification of the present invention.

[0027] Figure 3 This is a schematic diagram of the concave point that appears in step S23 of Embodiment 1 of the AIS civilian target display control method based on group recognition of the present invention;

[0028] Figure 4 This is a schematic diagram of the group target icon displayed in step S241 of Embodiment 2 of the AIS civilian target display control method based on group identification of the present invention;

[0029] Figure 5 This is a schematic diagram of a two-point boundary group target after step S241 is completed in Embodiment 2 of the AIS civilian target display control method based on group recognition of the present invention;

[0030] Figure 6 This is a schematic diagram of step S242 completing the three-point boundary group target in Embodiment 2 of the AIS civilian target display control method based on group recognition of the present invention;

[0031] Figure 7 This is a schematic diagram of step S242 completing the four-point boundary group target in Embodiment 2 of the AIS civilian target display control method based on group recognition of the present invention;

[0032] Figure 8 This is a schematic diagram illustrating the completion of a five-point boundary group target in step S242 of Embodiment 2 of the AIS civilian target display control method based on group recognition of the present invention;

[0033] Figure 9 This is a schematic diagram of the architecture of the AIS civilian target display control device based on group recognition according to the present invention. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments, but these embodiments should not be construed as limiting the present invention.

[0035] See Figure 1 The present invention, an AIS civilian target display control method based on group identification, requires the following steps to achieve target group identification and group target display of massive AIS targets:

[0036] Example 1

[0037] S1, Target Group Identification

[0038] S11. Selection of target feature parameters

[0039] AIS target data for civilian vessels typically includes the target vessel's longitude, latitude, turning rate, absolute speed, track heading, MMSI code (Maritime Mobility Service Identifier), vessel name, length, beam, draft, vessel type code, destination, and estimated time of arrival.

[0040] The first three digits of the MMSI code are the MID code, representing the country / region / province (state) to which the ship belongs, as shown in Table 1:

[0041] Table 1. MID Number Correspondence with Ship Country / Region / Province (State)

[0042]

[0043] The ship type codes are shown in Table 2:

[0044] Table 2 Ship Type Code Comparison Table

[0045]

[0046] Ships in the same group are generally of the same type and from the same country / region / province (and their destinations and estimated arrival times are also likely to be the same). Therefore, the AIS ship target information can be pre-filtered using information such as MID code and ship type code. Then, the ship motion parameters such as longitude, latitude, turning rate, absolute speed, and course angle of the filtered targets can be used as target feature parameters to construct a main matrix for calculation.

[0047] The length, beam, and draft of ships in the same group should not differ much. They can also be constructed as a target feature auxiliary matrix and calculated in the same way as reference values ​​for weighting coefficients.

[0048] S12, Target Spatiotemporal Consistency Transformation

[0049] The latest AIS reported targets are obtained according to the ship information system status display update cycle. A linear extrapolation method is used to uniformly extrapolate the latitude and longitude of the AIS targets to the latitude and longitude of each current display cycle.

[0050] S13, Matrix Construction and Transformation (see...) Figure 2 )

[0051] S131. Construct the target feature matrix

[0052] Suppose there are n targets, and the i-th target among the n targets is... , , , For a characterizable target Given m characteristic parameters (such as longitude, latitude, speed, and heading), the feature matrix of these n targets can be represented as:

[0053]

[0054] S132, Matrix centering transformation

[0055]

[0056] , This is the transformed center matrix.

[0057] S133, Matrix Normalization Transformation

[0058] , This is the transformed standard matrix.

[0059] S134, Difference Matrix Transformation

[0060] make , ;

[0061] These are weighting coefficients. .

[0062] make , Then we can obtain n matrices containing n elements;

[0063] Sequentially Y1 to Y n If each column of n elements in a matrix is ​​rearranged from top to bottom to left to right, we obtain an n×n symmetric matrix with zeros on the diagonal. This matrix can then be converted into an upper triangular or lower triangular matrix, i.e., a difference matrix.

[0064] y ij This represents the degree of difference between the i-th objective and the j-th objective.

[0065] S14, Group Similarity Calculation

[0066] Using spatiotemporally consistent target point feature parameters within the same update cycle, a target feature matrix is ​​constructed. Then, group similarity class calculation is performed according to the method described above, thereby transforming the target set into a cluster.

[0067] If y ij Less than the threshold U (usually y can be selected) ij When the root mean square is used as the threshold, target i and target j are grouped into the same group G. ij =(X i ,X j Take these two targets X. i ,X j The average value of each element represents the group objective. , and another group Similarly, the group target after average transformation Repeat steps S132, S133, and S134 to perform difference transformation and comparison. If the difference is less than the threshold, merge the two groups. Similarly, use the average value of each element of the target in the new group to represent the target of this group and compare the differences with other groups again. Continue in this manner until there are no more groups to merge, thus completing the identification of the group target.

[0068] S2, Display of group targets

[0069] The display of the group objective consists of two elements: a group objective icon representing the group, whose objective parameters are... The other is the group boundary line, which represents the extent of the target group. The group boundary line is drawn primarily through the following steps:

[0070] S21. Find the minimum bounding rectangle.

[0071] Since the distances between the targets in a group are not too far, the latitude and longitude of each target within the group can be approximated as planar coordinates for calculation. By sorting the latitude and longitude values ​​of each target within the group, the maximum and minimum latitude and longitude values ​​L can be obtained. max B max L min B min With (L) min B max ) and (L max B min The top left and bottom right corners of the rectangle are respectively used to obtain the minimum bounding rectangle of a certain group of targets.

[0072] S22, Boundary Point Selection

[0073] Divide the smallest bounding rectangle into four equal parts and determine if each region contains only one target point. If yes, stop dividing the region into four equal parts; otherwise, continue dividing the region into four equal parts until each cell contains only one target point.

[0074] If a target point is in a cell, it is represented by 1; if no target point is in a cell, it is represented by 0. This results in an n×m 0-1 matrix.

[0075] The criterion for determining interior points is: In a 0-1 matrix, if a certain element... If a cell is in the i-th row or j-th column, there must be at least one 1 on both sides of it. That is, in the same row, there must be at least one 1 on the left and right sides of the j-th column; or in the same column, there must be at least one 1 on the top and bottom sides of the i-th row.

[0076] If all interior points are changed from 1 to 0, a boundary point matrix is ​​formed, and the grid points with a value of 1 in the matrix are the corresponding boundary points.

[0077] S23, Depression Removal

[0078] During the process of connecting boundary points, the following may occur: Figure 3 The concave dot plot shown is used for collision avoidance calculations, in addition to display. Therefore, the concave dots need to be removed so that the boundary line can become a closed convex dot plot.

[0079] The procedure for determining concave points is as follows:

[0080] S231. Given the coordinates of n boundary points (x... i ,y i ), i=0..n-1. First, select y i The point with the smallest y-coordinate is used as the starting point a0 for sorting. If multiple points have the same y-coordinate, the point with the smallest x-coordinate is selected. Calculate the angle between the line connecting the other points relative to a0(x0,y0) and the x-axis. , .when At that time, if but ;like but .make ,according to Sort the other (n-1) points in ascending order, then insert point a0 at the beginning of the sorted list, finally obtaining a0...a0 sorted clockwise. n List of boundary points.

[0081] S232. Among all the sorted boundary points, given the initial connection between points a0 and a1, and the points a2 and a3 to be connected in sequence, if... If a2 is a concave point, it should be removed from the boundary point set. Connect a0, a1, and a3 directly to form the boundary line. Then, using a1 and a3 as the initial connection, determine the subsequent points a4 and a5. If a2 is a convex point, then a0, a1, and a2 should be connected to form a boundary line. Then, using a1 and a2 as the initial connection, the subsequent two points a3 and a4 are judged. This process is repeated for the next two points to be connected, until all boundary points are traversed.

[0082] S233. For the first point a0 and the last point a0 in the boundary point set... n , will a n-1 a n-2 Two points are used as the initial connection points. Then, points a and b need to be connected sequentially. n The two points, a and a0, are used to determine the concave point.

[0083] Example 2

[0084] This embodiment is basically the same as Embodiment 1, except that:

[0085] In step S12, the specific process of target spatiotemporal consistency transformation is as follows:

[0086] Sort by the time corresponding to each target ship motion parameter as the primary key value, round up the maximum time value T'=RoundUp(Tmax), and linearly extrapolate each target motion parameter to the latitude and longitude of that time using the following method:

[0087] S121, Distance If the azimuth angle θ = heading, then the extrapolated target point's coordinates in the geocentric Earth-fixed coordinate system (X...) t Y t )for:

[0088]

[0089] Among them, L s B s These are the target's current longitude and latitude, respectively. , ,

[0090] a and b are the major and minor semi-axis of the Earth, respectively. In this embodiment, in the WGS-84 coordinate system, a = 6378137m and b = 6356752m.

[0091] S122, then the extrapolated target's latitude and longitude in the geodetic coordinate system are:

[0092]

[0093] Step S2, group target display, also includes the following steps:

[0094] S24. Display Principles: Obtain boundary points for targets within the target cluster as described above, and remove concave points to obtain a convex point map, which is then displayed according to the following principles:

[0095] S241. For a 2-point boundary set, display the group target icon by taking the midpoint of the line connecting the two points (e.g., ...). Figure 4 As shown), the range of the group of targets is represented by a dashed circle with the centerline segment as the radius. Figure 5 As shown;

[0096] S242. For a boundary set with 3 or more points, the coordinates of the center point of the convex boundary polygon are obtained using the following method for determining the position of polygonal mass points. The range of the group target is represented by a dashed convex boundary polygon. Figures 6-8 As shown.

[0097] (x i ,y iLet i = 1..n, be the coordinates of the n vertices of the convex boundary polygon in the ship's coordinate system with the ship's position as the origin. Then the position of the polygon's center point (C x C y )for:

[0098] ,

[0099] S is the area of ​​the polygon.

[0100] The range of group targets represented by dashed lines can be manually selected to be displayed or hidden.

[0101] S25, Group Target Tag Display

[0102] The group target label can display the group target batch number, number of group targets, type, country / region / province (state) to which it belongs, latitude and longitude of the location of the group indicator, as well as group speed and heading.

[0103] Among them, the target batch number adopts a 4-digit decimal serial number, and the uppercase letter "G" before the number indicates the target batch number (such as G1043). The group speed is displayed as the two-dimensional vector average of the absolute speed of the targets in the group (i.e., eastward speed and northward speed). The group heading is displayed as the mean square error of the heading of the targets in the group.

[0104] S26. Group target batch number update

[0105] S261. The target group is updated and displayed according to the situation update cycle. During the update process, the target group will change as targets join or leave the group, and as the group merges or splits. The group density β can be defined as β = n / s, where n is the number of targets in the group and S is the area of ​​the convex boundary polygon.

[0106] S262, If the change in group density before and after the periodic period If the percentage is ≤50%, the batch number will not be renumbered and will still be used to represent the group; otherwise, it will be considered a new group, and the unused numbers from 0000 to 9999 will be renumbered sequentially, and the original batch number will be replaced as the group batch number.

[0107] Example 3

[0108] See Figure 9 The present invention relates to an AIS civilian target display control device based on group identification, comprising the following components:

[0109] Target group identification module: Through target spatiotemporal consistency transformation, the collected AIS target latitude and longitude are uniformly extrapolated to the latitude and longitude of each current display cycle. Based on the latitude and longitude, a target feature matrix is ​​constructed and matrix transformation is completed. The difference obtained by matrix transformation is used to calculate group similarity, thereby identifying group targets.

[0110] Group target display module: Based on the identification of group targets, the group targets are displayed by group target symbols that represent the group and group boundary lines that indicate the range of the target group.

[0111] This invention proposes a situational awareness optimization method that utilizes group target identification and boundary judgment algorithms to replace a large number of physical group targets with special group target symbols and boundary lines. This method can significantly reduce the number of elements displayed in the situational awareness display while maintaining real-time control over the movement elements of the group targets.

[0112] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0113] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A civilian target display control method based on group recognition in AIS, characterized in that: Includes the following steps: S1. Target Group Identification: Through target spatiotemporal consistency transformation, the collected AIS target latitude and longitude are uniformly extrapolated to the latitude and longitude of each current display cycle. Based on this latitude and longitude, a target feature matrix is ​​constructed and matrix transformation is performed. The difference degree obtained from the matrix transformation is used for group similarity calculation to identify group targets. The specific process of step S1 is as follows: S11, Target Spatiotemporal Consistency Transformation According to the ship information system status display update cycle, the latest AIS reported targets are obtained, and the latitude and longitude of the AIS targets are uniformly extrapolated to the latitude and longitude of each current display cycle using a linear extrapolation method. S12, Matrix Construction and Transformation For a group of n targets, construct a target feature matrix. Obtain the difference transformation matrix and the difference degree y between the i-th target and the j-th target in the difference matrix by centering, standardizing, and differentiating the target feature matrix. ij The specific process of step S12 is as follows: S121. Construct the target feature matrix. The specific process is as follows: Suppose there are n objectives, and the i-th objective among the n objectives is... , , ,in, To characterize the target If we have m feature parameters, then the feature matrix of these n targets can be represented as: ； S122, Matrix centering transformation ， ,in, This is the transformed central matrix; S123, Matrix Normalization Transformation ,in, This is the transformed standard matrix; S124, Difference Matrix Transformation make , ; These are weighting coefficients. , make , Then we can obtain n matrices containing n elements; Sequentially Y1 to Y n If each column of n elements in a matrix is ​​rearranged from top to bottom to left to right, we obtain an n×n symmetric matrix with zeros on the diagonal. This matrix can then be converted into an upper triangular or lower triangular matrix, i.e., a difference matrix. , where y ij This represents the degree of difference between the i-th objective and the j-th objective; S13, Group Similarity Calculation If y ij If the value is less than the threshold U, then target i and target j are grouped into the same group G. ij =(X i ,X j ), take target X i and target X j The average value of each element represents the group objective. , and another group Similarly, the group target after average transformation Repeat the matrix transformation steps above to perform difference transformation comparison; if the difference is less than the threshold U, merge the two groups, and use the average value of each element of the target in the new group to represent the target of this group and compare the difference with other groups again, and so on, until there are no groups that can be merged, then the identification of the group target is completed. S2. Display of group targets: Based on the identification of group targets, the group targets are displayed by group target symbols that represent the group and group boundary lines that indicate the range of the target group.

2. The AIS civilian target display control method based on group identification according to claim 1, characterized in that: The specific process of step S2 is as follows: S21. Find the minimum bounding rectangle. The latitude and longitude of each target within the group are approximated as planar coordinates for calculation. By sorting the latitude and longitude values ​​of each target within the group, the maximum and minimum latitude and longitude values ​​L are obtained. max B max L min B min and with (L min B max ) and (L max B min The left and right corners of the rectangle are respectively the top left and bottom right corners, to obtain the minimum bounding rectangle of a certain group of targets; S22, Boundary Point Selection Divide the smallest bounding rectangle into four equal parts. Determine if each region contains only one target point. If it does, stop dividing the region into four equal parts. If not, continue dividing the region into four equal parts until each cell contains only one target point. If a target point is in a cell, it is represented by 1; if no target point is in a cell, it is represented by 0. This results in an n×m 0-1 matrix. The criterion for determining interior points is: in a 0-1 matrix, if a certain element... If a cell is in the i-th row or j-th column, there must be at least one 1 on both sides of it, meaning that in the same row, there must be at least one 1 on the left and right sides of the j-th column; or in the same column, there must be at least one 1 on the top and bottom sides of the i-th row. If all interior points are changed from 1 to 0, a boundary point matrix is ​​formed, and the grid points with a value of 1 in the matrix are the corresponding boundary points.

3. The AIS civilian target display control method based on group identification according to claim 2, characterized in that: Step S2 further includes step S23, concave point removal: If concave points appear during the process of connecting boundary points, these concave points are removed so that the boundary line becomes a closed convex point map. The specific process is as follows: S231. Given the coordinates of n boundary points (x... i ,y i (i=0..n-1), first select y i The point with the smallest coordinate is used as the starting point a0 for sorting. If multiple points have the same y-coordinate, the point with the smallest x-coordinate is selected. The angle between the line connecting the other points relative to a0(x0,y0) and the x-axis is calculated. , ,when At that time, if but ;like but ,make ,according to Sort the other (n-1) points in ascending order, then insert point a0 at the beginning of the sorted list, finally obtaining a0...a0 sorted clockwise. n List of boundary points; S232. Among all the sorted boundary points, given the initial connection between points a0 and a1, and the points a2 and a3 to be connected in sequence, if... If a2 is a concave point, it should be removed from the boundary point set. Connect a0, a1, and a3 directly to form the boundary line. Then, using a1 and a3 as the initial connection, determine the subsequent points a4 and a5. If a2 is a convex point, then a0, a1, and a2 should be connected to form a boundary line. Then, using a1 and a2 as the initial connection, the subsequent two points a3 and a4 should be judged. This process is repeated for the next two points to be connected until all boundary points have been traversed. S233. For the first point a0 and the last point a0 in the boundary point set... n , will a n-1 a n-2 Two points are used as the initial connection points. Then, points a and b need to be connected sequentially. n The two points, a and a0, are used to determine the concave point.

4. The AIS civilian target display control method based on group identification according to claim 3, characterized in that: In step S11, the time corresponding to each target ship motion parameter is used as the primary key value for sorting, and the maximum time value is rounded up to T'=RoundUp(T max Each target motion parameter is linearly extrapolated to its latitude and longitude at that moment using the following method: S111, Distance If the azimuth angle θ = heading, then the extrapolated target point's coordinates in the geocentric Earth-fixed coordinate system (X...) t Y t )for: ， Among them, L s B s These are the target's current longitude and latitude, respectively. , , a and b are the Earth's major and minor semi-axises, respectively; S112, then the extrapolated target's latitude and longitude in the geodetic coordinate system are: 。 5. The AIS civilian target display control method based on group identification according to claim 4, characterized in that: In step S2, after removing the concave points and obtaining a convex point image, the process further includes step S24, display principles, as follows: S241. For a 2-point boundary set, take the midpoint of the line connecting the two points to display the group target symbol, and use a dashed circle with the midline segment as the radius to represent the range of the group target. S242. For a boundary set of 3 points or more, the coordinates of the center point of the convex boundary polygon are obtained by the method of determining the position of the polygon mass point, and the range of the group target is represented by the dashed convex boundary polygon. set up (x i ,y i Let i = 1..n be the coordinates of the n vertices of the convex boundary polygon in the ship's coordinate system with the ship's position as the origin. Then the position of the center point of the polygon (C) is given. x C y )for: ， S is the area of ​​the polygon. .

6. The AIS civilian target display control method based on group identification according to claim 5, characterized in that: Step S2 further includes S25, displaying group target tags, the specific content of which is as follows: The group target label displays the group target batch number, number of group targets, type, country / region / province (state) to which it belongs, latitude and longitude of the location of the group identifier, as well as group speed and heading; Among them, the target batch number adopts a 4-digit decimal serial number, and the uppercase letter "G" before the number indicates the target batch number. The group speed is displayed as the two-dimensional vector average of the absolute speed of the targets in the group, and the group heading is displayed as the mean square error of the heading of the targets in the group. S26. Group target batch number update, details are as follows: S261. The target group is updated and displayed according to the situation update cycle. The group density is defined as β=n / s, where n is the number of targets in the group and S is the area of ​​the convex point boundary polygon. S262, If the change in group density before and after the periodic period If the percentage is ≤50%, the batch number will not be renumbered and will still be used to represent the group; otherwise, it will be considered a new group, and the unused numbers from 0000 to 9999 will be renumbered sequentially, and the original batch number will be replaced as the group batch number.

7. A civilian target display and control device based on group recognition, comprising a computer program, characterized in that: The computer program is capable of executing the AIS civilian target display control method based on group identification as described in any one of claims 1 to 6.

Images