Yangtze river channel ship flow segmentation quantification method based on inflection point identification

Abstract

The invention discloses a Yangtze River channel ship flow segmentation quantification method based on inflection point identification. The method comprises the following steps: abstracting a Yangtze River channel into a broken line by adopting a method of extracting a center line and generating a break point; the positions of the ships are associated with the positions of the Yangtze River channels, the position areas of the ships in the Yangtze River channels are judged, and mapping track data of the ships sorted according to time are obtained; according to the mapping trajectory data of each ship sorted according to the time, inflection point trajectory data of each ship sorted according to the time are obtained, wherein inflection points comprise a starting point, a turning point where the ship steers and an arrival point; and traversing the inflection point trajectory data of all ships in the Yangtze River channel within a preset time, analyzing to obtain the number of ships passing through each position area of the Yangtze River channel, and calculating to obtain the ship traffic flow of the Yangtze River channel. According to the method, the ship traffic flow in each 2km area in the Yangtze River channel can be quantified, and an important reference is provided for shipping safety, channel maintenance and ship dispatching of the Yangtze River channel.

Description

Technical Field

[0001] The invention belongs to the field of ship traffic flow estimation, and in particular relates to a segmented quantification method of ship flow in the Yangtze River waterway based on inflection point identification. Background Art

[0002] The Automatic Identification System (AIS) collects a large amount of near-real-time traffic data that can describe ship behavior. AIS data contains detailed and continuous spatiotemporal information of ships, as well as the actual maneuvering behavior of ships. Therefore, AIS data provides a more accurate and reliable data basis for ship traffic flow research, and then analyzes the ship traffic conditions in different regions.

[0003] The invention with application publication number CN116611552B discloses a method and system for predicting ship traffic flow based on target monitoring data. The method uses time series data, correlation analysis module and model building module to establish a model, thereby obtaining the predicted value of ship traffic. However, the invention requires modeling and a large amount of historical data support, otherwise the accuracy is low.

[0004] Maritime traffic research focuses on the traffic dynamics of ships. It starts from the spatiotemporal characteristics of ships and analyzes the navigation routes of ships, so as to understand the maritime traffic patterns and the traffic function characteristics of various maritime regions. The invention with application publication number CN110580388B discloses a waterway network extraction method based on multi-source trajectory data, which extracts waterways from a large amount of ship trajectory data from AIS, smoothes the waterway boundaries, triangulates the extracted waterways and performs triangle classification processing to filter out triangles that are useless to the waterway, extracts the centerline of the waterway, and constructs the waterway network to achieve a more accurate waterway network construction. Compared with the prior art, the invention not only extracts the boundaries of ocean waterways, but also extracts the centerline and intersections. The method proposed in the invention solves the problem of extracting a complete, continuous, and smooth waterway network from trajectory data with noise and uneven density through various methods such as curvature filtering, linear interpolation, and SMA boundary smoothing algorithm.

[0005] The waterways of maritime transportation are complex and diverse. Due to the geographical restrictions of inland waterways, the traffic flow trend along the route is relatively simple and mainly takes place along inland waterways. However, compared with open waters, the navigation environment of inland waterways presents a higher level of complexity.

[0006] At present, the research on inland waterway traffic is generally centered around the characteristics of inland waterways, and the analysis of inland waterway ship traffic flow is also carried out from a microscopic perspective. Through the ship travel time series of a single waterway cross section of AIS data, the complexity of water traffic flow in inland waterways is analyzed at different geographical locations and different time intervals. However, current research mainly focuses on the fine traffic flow analysis of small areas and short time scales, and lacks quantitative analysis of ship traffic flow on a large time scale in the overall area. Summary of the invention

[0007] Technical problem solved: The present invention discloses a segmented quantification method for ship traffic in the Yangtze River waterway based on inflection point identification. By combining the abstract Yangtze River waterway with the ship trajectory based on the inflection point, the ship traffic flow in each small area in the Yangtze River waterway is quantified according to the numbering calculation method, which provides an important reference for shipping safety, waterway maintenance and ship scheduling in the Yangtze River waterway.

[0008] Technical solution:

[0009] A Yangtze River waterway ship flow segmentation quantification method based on inflection point identification, the Yangtze River waterway ship flow segmentation quantification method comprising the following steps:

[0010] S1: The Yangtze River waterway is abstracted into a broken line by extracting the center line and regenerating the broken points; specifically, it includes:

[0011] S11: Extract the centerline of the Yangtze River channel;

[0012] S12: Generate multiple inflection points at preset intervals on the center line of the Yangtze River waterway, and connect them to generate an abstract Yangtze River waterway;

[0013] S2: Statistics on ship traffic flow on the Yangtze River waterway; specifically including:

[0014] S21: Correlate the ship position with the Yangtze River waterway position, determine the ship's position area within the Yangtze River waterway, and obtain time-ordered mapping trajectory data for each ship;

[0015] S22: obtaining the turning point trajectory data of each ship sorted by time according to the mapping trajectory data of each ship sorted by time, where the turning points include a starting point, a turning point where the ship turns, and an arrival point;

[0016] S23: Traversing the turning point trajectory data of all ships in the Yangtze River waterway within a preset time, analyzing to obtain the number of ships passing through each location area of ​​the Yangtze River waterway, and calculating the ship traffic flow of the Yangtze River waterway.

[0017] Furthermore, in step S11, the centerline extraction tool in ArcGIS is used to extract the centerline of the Yangtze River waterway according to the spatial position and shape of both banks of the Yangtze River main channel, and the extracted centerline of the Yangtze River waterway is abstracted into the basic waterway of the Yangtze River.

[0018] Furthermore, in step S12, the point generation tool along the line in ArcGIS is used to generate a breakpoint every 2 kilometers on the extracted centerline of the Yangtze River waterway, and each breakpoint is numbered in ascending order from upstream to downstream, the Yangtze River waterway is divided into N location areas, and the generated breakpoints are connected into broken lines to generate an abstract Yangtze River waterway.

[0019] Step S21 further comprises:

[0020] Determine the AIS data points P in the Yangtze River waterway i (X i ,Y i ), the coordinates of each AIS data point are compared with the coordinates of each equally spaced inflection point of the abstract Yangtze River waterway Compare and find the closest X to the AIS data point N <X i The inflection point coordinates are obtained and the numbers of the inflection point coordinates found are used as the location area of ​​the AIS data point in the Yangtze River waterway.

[0021] Step S22 further includes:

[0022] Get the mapping trajectory data of each ship in time order J = {P1, P2, ..., P n}, P i ={X i ,Y i ,t i ,N i}, i=1,2,...,n; P i Indicates the inflection point number obtained by mapping the i-th AIS data point in the ship track, (X i ,Y i ) represents the inflection point P i Coordinates of t i Indicates the timestamp of the ith AIS data point, N i Indicates the location area of ​​the Yangtze River waterway;

[0023] Get the starting point G according to the timestamp o and arrival point G d ;

[0024] The location area number of the Yangtze River waterway where the turning point from downstream to upstream is located is determined according to the maximum value of the location area number at consecutive adjacent time points, and the location area number is recorded as N d ; Calculate the AIS data points P at adjacent time points in sequence i(X i ,Y i ) and the coordinates of the nearest vertex The point with the largest distance is taken as the turning point G from downstream to upstream x ;

[0025] The location area number of the Yangtze River waterway where the turning point from upstream to downstream is located is determined according to the minimum value of the location area number at consecutive adjacent time points, and the location area number is recorded as N x ; Calculate the AIS data points P at adjacent time points in sequence i (X i ,Y i ) plus the coordinate number of the nearest vertex plus one The point with the largest distance is taken as the turning point G from upstream to downstream s ;

[0026] Sort the identified turning points by time to obtain the turning point trajectory data of each ship sorted by time and They respectively represent the first turning point and the second turning point from downstream to upstream or from upstream to downstream.

[0027] Furthermore, in step S23, the process of calculating the ship traffic flow of the Yangtze River waterway includes the following steps:

[0028] Traverse the turning point trajectory data of all ships in the Yangtze River waterway within a preset time, and obtain the turning point data of all ships' single trips;

[0029] Convert the inflection point trajectory data arranged in time into ship trajectory data with the inflection point position number as a subset;

[0030] Initialize ship traffic flow data;

[0031] Traverse each single trip of a ship and increase the ship traffic flow data of the location area of ​​the Yangtze River waterway corresponding to the inflection point contained therein by one;

[0032] The ship traffic flow data of all location areas of the Yangtze River waterway are obtained through statistics.

[0033] Step S23 further comprises:

[0034] The inflection points are analyzed to divide the single trip of the ship; the single trip of the ship refers to the trip between adjacent inflection points;

[0035] The turning point trajectory data of all ships in the Yangtze River waterway within the preset time are traversed, and the number of ships and traffic types passing through each location area of ​​the Yangtze River waterway are obtained by combining the single trip analysis of the ships, and the ship traffic flow of the Yangtze River waterway is calculated; among which, the traffic types include the number of ship voyages to the upstream, the number of ship voyages to the downstream, and the number of voyages in the same location area.

[0036] Furthermore, in step S23, the process of calculating the ship traffic flow of the Yangtze River waterway includes the following steps:

[0037] Initialize the ship traffic flow data and set the number of ship voyages N to the upstream S , the number of ships sailing downstream N X and the number of ship voyages N in the same area T ;

[0038] Each single trip of the ship is taken as the basic object of study. If the position area number of two adjacent turning points of a single trip is N i >N i+1 , it means that the single trip leads to the upstream, and the number of ship voyages leading to the upstream in the corresponding position area of ​​two adjacent turning points is N s Add 1; if N i <N i+1 , it means that the single trip leads to the downstream, and the number of ship voyages to the upstream in the corresponding position area of ​​two adjacent turning points is N X Add 1; if N i =N i+1 , it means that the single trip is only navigable in a certain location area in the Yangtze River waterway, and the number of ships sailing in the same area of ​​the two adjacent turning points is N T Add 1;

[0039] The number of ships of different traffic types passing through each location area of ​​the Yangtze River waterway within a preset time is counted as the ship traffic flow of the Yangtze River waterway.

[0040] Beneficial effects:

[0041] First, the segmented quantification method of Yangtze River waterway ship traffic based on inflection point identification of the present invention abstracts the Yangtze River waterway as a broken line, does not consider the width of the Yangtze River waterway, and mainly focuses on the relative relationship between the various positions of the Yangtze River waterway and its spatial position relationship relative to the land. This makes the study of the Yangtze River waterway more flexible and simplifies the traffic flow calculation to a certain extent.

[0042] Second, the segmented quantification method of the Yangtze River waterway ship flow based on inflection point identification of the present invention selects 2 kilometers as the basic unit for dividing the Yangtze River, as the basic object for subsequent comparison of traffic flow in various regions of the Yangtze River, and assigns each unit a number in ascending order from upstream to downstream. This allows the specific area and its mileage within the Yangtze River waterway to be determined based on the number, and using 2 kilometers as the basic unit can make subsequent traffic flow statistics more detailed.

[0043] Third, the segmented quantification method of the Yangtze River waterway ship flow based on inflection point identification of the present invention abstracts the ship's navigation trajectory into a line between adjacent inflection points, which not only solves the problem of inconsistent data accuracy of different ships, but also compresses the trajectory data, and finally completes the division of the ship's single trip.

[0044] Fourth, the segmented quantification method of the Yangtze River waterway ship traffic based on inflection point identification of the present invention, the ship traffic flow statistics can not only obtain the ship traffic flow of each area, but also refine it into the ship traffic flow to the upstream, the ship traffic flow to the downstream and the ship traffic flow sailing in the same area.

[0045] Fifth, the segmented quantification method of the Yangtze River waterway ship traffic based on inflection point identification of the present invention can provide comprehensive data on the ship traffic flow in each area of ​​the Yangtze River waterway, providing an important reference for shipping safety, waterway maintenance and ship scheduling in the Yangtze River waterway. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a flow chart of the segmented quantification method of Yangtze River waterway ship flow based on inflection point identification of the present invention;

[0047] Figure 2 It is a schematic diagram of extracting the center line;

[0048] Figure 3 It is a schematic diagram of the abstract Yangtze River waterway, where (a) represents the inflection points of the generated polyline; (b) represents the inflection points generated at equal distances; (c) represents the secondary generated polyline; (d) represents the comparison diagram of the original polyline and the secondary generated polyline;

[0049] Figure 4 is a schematic diagram of inflection point recognition, wherein (a) represents before inflection point recognition; (b) represents after inflection point recognition;

[0050] Figure 5 This is a schematic diagram of the Yangtze River waterway location area;

[0051] Figure 6 This is the traffic flow statistics chart of the Yangtze River waterway in 2023. DETAILED DESCRIPTION

[0052] The following examples will enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0053] The present invention discloses a Yangtze River waterway ship flow segmentation quantification method based on inflection point recognition, and the Yangtze River waterway ship flow segmentation quantification method comprises the following steps:

[0054] S1: The Yangtze River waterway is abstracted into a broken line by extracting the center line and regenerating the broken points; specifically, it includes:

[0055] S11: Extract the centerline of the Yangtze River channel;

[0056] S12: Generate multiple inflection points at preset intervals on the center line of the Yangtze River waterway, and connect them to generate an abstract Yangtze River waterway;

[0057] S2: Statistics on ship traffic flow on the Yangtze River waterway; specifically including:

[0058] S21: Correlate the ship position with the Yangtze River waterway position, determine the ship's position area within the Yangtze River waterway, and obtain time-ordered mapping trajectory data for each ship;

[0059] S22: obtaining the turning point trajectory data of each ship sorted by time according to the mapping trajectory data of each ship sorted by time, where the turning points include a starting point, a turning point where the ship turns, and an arrival point;

[0060] S23: Traversing the turning point trajectory data of all ships in the Yangtze River waterway within a preset time, analyzing to obtain the number of ships passing through each location area of ​​the Yangtze River waterway, and calculating the ship traffic flow of the Yangtze River waterway.

[0061] See also Figure 1 The Yangtze River waterway ship flow segmentation quantification method specifically includes the following steps:

[0062] S1: Abstract Yangtze River Channel

[0063] Since this study does not consider the width of the Yangtze River channel, it mainly focuses on the relative relationship between the various positions of the Yangtze River channel and its spatial position relationship relative to the land, so the Yangtze River channel is abstracted as a broken line. In addition, due to the limitations of navigation conditions, only the ship navigation in the Yangtze River main channel is continuous and stretching, so the Yangtze River channel extraction in this study is only for the Yangtze River main channel, and does not consider the Yangtze River tributaries. Figure 5 is the research area of ​​this study.

[0064] S11: Extract the centerline of the Yangtze River channel

[0065] This study first uses the method of extracting the centerline to extract the centerline of the Yangtze River waterway based on the spatial position and shape of both sides of the Yangtze River main channel, and abstracts this center line into the basic waterway of the Yangtze River. Figure 2 As shown in the figure, the blue polyline is the two sides of the Yangtze River main channel, and the pink polyline is the basic channel of the Yangtze River generated based on the two sides of the channel. However, in order to facilitate the subsequent analysis of traffic flow in different areas of the Yangtze River channel, this study needs to divide the Yangtze River channel into spatial areas of equal length, which is equivalent to dividing the polyline into equal intervals.

[0066] S12: Generate an abstract Yangtze River waterway

[0067] In order to better preserve the original shape of the central broken line of the Yangtze River, so that the broken line can have a unified shape trend with the Yangtze River waterway and can be divided into equally spaced areas, we choose 2 kilometers as the basic unit for dividing the central broken line, that is, every two kilometers in the Yangtze River waterway is divided into a research unit, which serves as the basic object for subsequent research on comparing traffic flow in various regions of the Yangtze River. Therefore, first generate inflection points every 2 kilometers of the previously extracted central broken line, and assign each inflection point a number in ascending order from upstream to downstream. The starting point is numbered 0 and the end point is numbered N. Different numbers divide the Yangtze River waterway into N location areas. Moreover, the number of each research unit has its geographical meaning, that is, the mileage from the starting point of the Yangtze River waterway is about 2N (km). As a result, each inflection point or each research unit can determine its geographical location in the Yangtze River waterway according to the number. For example Figure 5 As shown, the Yangtze River waterway in this study is divided into 1376 research units, and the overall mileage of the Yangtze River waterway is 2750 km.

[0068] Finally, the generated inflection points are connected into a broken line, and the second generated broken line is the abstract Yangtze River waterway in this study. Figure 3 The blue broken lines in a and b are the extracted central broken lines, the pink points in figure b are the broken points generated every 2 kilometers of the extracted central broken lines, and the red broken line in figure c is the secondary generated broken line, which is the abstract Yangtze River waterway in this study.

[0069] S2: Vessel traffic statistics

[0070] S21: Ship position area determination

[0071] This paper determines the relative position of each ship on the Yangtze River waterway at different time points by associating the ship position with the position of each area of ​​the Yangtze River waterway.

[0072] The specific method is as follows: First, determine the AIS data points P in the Yangtze River waterway. i (X i ,Y i ), the coordinates of each AIS data point are compared with the coordinates of each equally spaced inflection point of the abstract Yangtze River waterway Compare and find the closest X to the AIS data point N <X iThe inflection point coordinates, the number N of the inflection point coordinates is the location area of ​​the AIS data point in the Yangtze River waterway.

[0073] S22: Ship single trip division

[0074] Since the navigation mode of ships on the water is different from that of road traffic, they will not take detours during a clear-purpose navigation process, but will only travel one way along the waterway. Therefore, this paper regards the journey between the turning points of the ship as a single journey of the ship. The turning point G here includes the ship's departure point, turning point and final arrival point in the entire navigation trajectory of the ship. This study abstracts the trajectory between navigations into a line between adjacent turning points, which not only solves the problem of inconsistent data accuracy of different ships, but also compresses the trajectory point data, and finally completes the division of the ship's single journey. The specific division process is as follows:

[0075] 1. Inflection point identification:

[0076] Inflection point G includes three types of points: starting point G o , turning point G x / s And the final destination G d .

[0077] (1) Starting point G o : The first departure point of the ship is the earliest point in the ship trajectory data.

[0078] (2) Arrival point G d : The latest arrival point of the ship is the latest point in the ship trajectory data.

[0079] (3) Turning point G x / s : The turning point of a ship is the point where the ship turns. It is divided into two cases, namely the point where the ship turns to sail upstream and the point where the ship turns to sail downstream.

[0080] Starting point G o and arrival point G d can be determined based on the timestamp of the ship data point, and the turning point G x / s It needs to be determined based on the spatial changes in the ship's trajectory. x / s According to the different directions of the ship's navigation, it is divided into the turning point G from downstream to upstream x and the turning point G from upstream to downstream s The specific identification method is as follows:

[0081] (1) Turning point G from downstream to upstream x :Since the location number of the Yangtze River waterway increases from upstream to downstream, the location area number of the Yangtze River waterway where the turning point from downstream to upstream is the maximum value of the location area numbers at adjacent time points, and this location area number is recorded as N dThen calculate the AIS data points at adjacent time points in sequence

[0082] P i (X i ,Y i ) and the coordinates of the nearest vertex The point farthest from the nearest inflection point, i.e. the point with the largest distance, is the turning point G from downstream to upstream. 1 .

[0083] (2) Turning point G from upstream to downstream s :The location area number of the Yangtze River channel where the turning point from upstream to downstream is located is the smaller value of the location area numbers at adjacent time points, and this location area number is recorded as N x Then calculate the AIS data points P at adjacent time points in sequence i (X i ,Y i ) plus the coordinate number of the nearest vertex plus one The point with the largest distance is the turning point G from upstream to downstream. s .

[0084] The ship trajectory data can be compressed into inflection point trajectory data through the inflection point recognition algorithm, which greatly compresses the trajectory data volume while retaining the ship trajectory direction.

[0085]

[0086] 2. Itinerary division:

[0087] According to the inflection point identification method, each inflection point is found in the trajectory data of each ship in turn, that is, two inflection points "G i —>G i+1 "As a single trip of the ship, all turning points are connected in time sequence"G o →G x / s →G d " is regarded as a whole trip of the ship. After the original trajectory data J is identified by inflection points and divided into trips, its overall trajectory data can be used as J G replace.

[0088] J={P1,P2,……,P n}, P i =[X i ,Y i ,t i ,N i ]

[0089]

[0090] Among them, (X i ,Y i), t i and N i P i The coordinates, timestamp and location area of ​​the point in the Yangtze River waterway.

[0091] Figure 4 The red trajectory data points are the trajectories leading to the downstream and then to the upstream. The points with red halo and N=2 are 2 The green trajectory data points are the trajectories leading to the upstream and then to the downstream. The points with red halo and N=3 are farthest from P. 4 It is the farthest, so it is an inflection point here. And it can be seen from the figure that after the inflection point is identified, the red original trajectory data points are compressed into 3 data points to represent the original journey.

[0092] S23: Traffic flow calculation

[0093] This study calculates the number of the location area of ​​all turning points in the overall itinerary of the ship to complete the traffic flow statistics. After the turning point is identified, the overall itinerary trajectory of each ship can be compressed into a trajectory J where the turning points are arranged according to the timestamp. G , calculate the position change of each ship turning point over time J N The number of ships passing through each location area of ​​the Yangtze River waterway within a certain period of time can be counted. This study takes each single trip of a ship as the basic object of research. Assuming that the two turning points of a single trip of a ship are G1 and G2, and its location area numbers in the Yangtze River waterway are N1 and N2, the traffic flow of the Yangtze River waterway in area numbers N1 and N2 is increased by one. This is determined by the characteristics that inland ships only sail along the waterway.

[0094]

[0095] Among them, J N is the ship trajectory with the position number of the turning point as the subset, They are the location numbers of the starting point, turning point and arrival point respectively.

[0096] In order to study the ship traffic flow in various areas of the Yangtze River waterway in more detail, this study is divided into the following four types:

[0097] (1) Traffic flow statistics to the upstream N S :If the location area numbers of the two turning points of a single trip It means that the single trip is to the upstream, denoted by N S .

[0098] (2) Traffic flow statistics to the downstream NX :like This means that the single trip is to the downstream, recorded as

[0099] N X .

[0100] (3) Traffic flow statistics N in the same area T :like This means that the single trip is only navigable in a small area within the Yangtze River waterway, denoted by N T .

[0101] (4) Overall traffic flow statistics N Z : Overall traffic flow in a certain area of ​​the Yangtze River waterway.

[0102] Through the traffic flow statistics algorithm, the trajectory data of all the Yangtze River waterway within a certain period of time can be traversed to obtain the ship traffic flow of each research unit in the Yangtze River waterway.

[0103]

[0104] The more detailed formulas and variable meanings are shown in Table 1.

[0105] Table 1

[0106]

[0107]

[0108] The present invention applies the AIS data in the Yangtze River waterway in 2023 to the present method, and the ship traffic flow in the Yangtze River waterway in 2023 can be obtained, such as Figure 6 The ship traffic flow in every 2km area of ​​the Yangtze River waterway in 2023 is displayed in detail, which shows the feasibility and superiority of the method of the present invention.

[0109] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A segmented quantification method for Yangtze River waterway ship flow based on inflection point identification, characterized in that: The Yangtze River waterway ship flow segmentation quantification method comprises the following steps: S1: The Yangtze River waterway is abstracted into a broken line by extracting the center line and regenerating the broken points; specifically, it includes: S11: Extract the centerline of the Yangtze River channel; S12: Generate multiple inflection points at preset intervals on the center line of the Yangtze River waterway, and connect them to generate an abstract Yangtze River waterway; S2: Statistics on ship traffic flow on the Yangtze River waterway; specifically including: S21: Correlate the ship position with the Yangtze River waterway position, determine the ship's position area within the Yangtze River waterway, and obtain time-ordered mapping trajectory data for each ship; S22: obtaining the turning point trajectory data of each ship sorted by time according to the mapping trajectory data of each ship sorted by time, where the turning points include a starting point, a turning point where the ship turns, and an arrival point; S23: Traversing the turning point trajectory data of all ships in the Yangtze River waterway within a preset time, analyzing to obtain the number of ships passing through each location area of ​​the Yangtze River waterway, and calculating the ship traffic flow of the Yangtze River waterway.

2. The Yangtze River waterway ship flow segmentation quantification method based on inflection point identification according to claim 1 is characterized in that: In step S11, the centerline extraction tool in ArcGIS is used to extract the centerline of the Yangtze River waterway according to the spatial position and shape of both banks of the Yangtze River main channel, and the extracted centerline of the Yangtze River waterway is abstracted into the basic waterway of the Yangtze River.

3. The Yangtze River waterway ship flow segmentation quantification method based on inflection point identification according to claim 1 is characterized in that: In step S12, the point generation tool along the line in ArcGIS is used to generate a breakpoint every 2 kilometers on the extracted centerline of the Yangtze River waterway, and each breakpoint is numbered in ascending order from upstream to downstream, the Yangtze River waterway is divided into N location areas, and the generated breakpoints are connected into broken lines to generate an abstract Yangtze River waterway.

4. The Yangtze River waterway ship flow segmentation quantification method based on inflection point identification according to claim 1 is characterized in that: Step S21 further includes: Determine the AIS data points P in the Yangtze River waterway i (X i , Y i ), the coordinates of each AIS data point are compared with the coordinates of each equally spaced inflection point of the abstract Yangtze River waterway The superscript N represents the area number where the inflection point is located. Find the area closest to the AIS data point and X N <X i The inflection point coordinates are obtained and the numbers of the inflection point coordinates found are used as the location area of ​​the AIS data point in the Yangtze River waterway.

5. The Yangtze River waterway ship flow segmentation quantification method based on inflection point identification according to claim 1 is characterized in that: Step S22 further includes: Get the mapping trajectory data J = {P1, P2, ..., P n }, P i ={X i , Y i , t i , N i }, i = 1, 2, ..., n; P i Indicates the inflection point number obtained by mapping the i-th AIS data point in the ship track, (X i , Y i ) represents the inflection point P i Coordinates of t i Indicates the timestamp of the ith AIS data point, N i Indicates the location area of ​​the Yangtze River waterway; Get the starting point G according to the timestamp o and arrival point G d ; The location area number of the Yangtze River waterway where the turning point from downstream to upstream is located is determined according to the maximum value of the location area number at consecutive adjacent time points, and the location area number is recorded as N d ; Calculate the AIS data points P at adjacent time points in sequence i (X i , Y i ) and the coordinates of the nearest vertex The point with the largest distance is taken as the turning point G from downstream to upstream x ; The location area number of the Yangtze River waterway where the turning point from upstream to downstream is located is determined according to the minimum value of the location area number at consecutive adjacent time points, and the location area number is recorded as N x ; Calculate the AIS data points P at adjacent time points in sequence i (X i , Y i ) plus the coordinate number of the nearest vertex plus one The point with the largest distance is taken as the turning point G from upstream to downstream s ; Sort the identified inflection points by time to obtain the inflection point trajectory data of each ship sorted by time and Represent the first and second turning points respectively.

6. The Yangtze River waterway ship flow segmentation quantification method based on inflection point identification according to claim 1 is characterized in that: In step S23, the process of calculating the ship traffic flow of the Yangtze River waterway includes the following steps: Traverse the turning point trajectory data of all ships in the Yangtze River waterway within a preset time, and obtain the turning point data of all ships' single trips; Initialize ship traffic flow data; Traverse each single trip of a ship and increase the ship traffic flow data of the location area of ​​the Yangtze River waterway corresponding to the inflection point contained therein by one; The ship traffic flow data of all location areas of the Yangtze River waterway are obtained through statistics.

7. The Yangtze River waterway ship flow segmentation quantification method based on inflection point identification according to claim 1 is characterized in that: Step S23 further comprises: The inflection points are analyzed to divide the single trip of the ship; the single trip of the ship refers to the trip between adjacent inflection points; The turning point trajectory data of all ships in the Yangtze River waterway within the preset time are traversed, and the number of ships and traffic types passing through each location area of ​​the Yangtze River waterway are obtained by combining the single trip analysis of the ships, and the ship traffic flow of the Yangtze River waterway is calculated; among which, the traffic type includes the number of ship voyages to the upstream, the number of ship voyages to the downstream, and the number of voyages in the same location area.

8. The Yangtze River waterway ship flow segmentation quantification method based on inflection point identification according to claim 7 is characterized in that: In step S23, the process of calculating the ship traffic flow of the Yangtze River waterway includes the following steps: Initialize the ship traffic flow data and set the number of ship voyages N to the upstream S , the number of ships sailing downstream N X and the number of ship voyages N in the same area T ; Each single trip of the ship is taken as the basic object of study. If the position area number of two adjacent turning points of a single trip is N i >N i+1 , it means that the single trip leads to the upstream, and the number of ship voyages leading to the upstream in the corresponding position area of ​​two adjacent turning points is N S Add 1; if N i <N i+1 , it means that the single trip leads to the downstream, and the number of ship voyages to the upstream in the corresponding position area of ​​two adjacent turning points is N x Add 1; if N i =N i+1 , it means that the single trip is only navigable in a certain location area in the Yangtze River waterway, and the number of ships sailing in the same area of ​​the two adjacent turning points is N T Add 1; The number of ships of different traffic types passing through each location area of ​​the Yangtze River waterway within a preset time is counted as the ship traffic flow of the Yangtze River waterway.

Images