Virtual road network missing road section automatic identification method based on bus GPS track
Technical Field
The invention relates to an automatic identification method for a missing road section, in particular to an automatic identification method for a virtual road network missing road section based on a bus GPS track.
Background
The rapid development of the information technology provides the possibility of electronization for the analysis of urban traffic problems, the big data technology provides real-time road traffic data information, and the construction of an urban virtual traffic system platform based on big data is an effective method for analyzing the urban traffic problems at present. The urban virtual traffic system platform can centralize multi-source traffic data in one system, reproduce complex traffic phenomena on the virtual platform, and an analyst can perform various operations according to different research targets to solve problems in time.
The urban traffic problem analysis can not be carried out without constructing an urban road network, the urban road network is used as a framework and a foundation of an urban traffic system, and the integrity of road network basic data provides guarantee for the reliability of subsequent traffic analysis. However, there are certain obstacles to the current further research into urban traffic problems. On one hand, due to the hysteresis and timeliness of information updating, the urban road network electronic map often has the problem of local deletion. On the other hand, some traffic analysis processes have high requirements on road network accuracy, the existing road network accuracy is difficult to guarantee, the problem of the existing traffic analysis processes is solved mainly by manual observation, relevant materials of government departments are obtained through early-stage traffic investigation, missing roads are perfected and supplemented, and the method not only consumes a large amount of manpower, material resources and financial resources, but also depends on personal judgment of workers, so that the analysis result is poor.
Research shows that the GPS track point data of the ground public transport line has the advantages of being timely in updating and relatively high in position precision, and therefore possibility is provided for matching urban road data through the GPS track point data of the public transport line, and therefore missing road sections are identified.
Disclosure of Invention
The purpose of the invention is as follows: aiming at the practical problems and the defects of the prior art, the invention provides a method for automatically identifying the missing road sections of the virtual network.
The technical scheme is as follows: in order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows: a virtual road network missing road section automatic identification method based on a GPS track comprises the following steps:
(1) recording GPS data recorded at intervals of a certain time by buses as bus GPS track points, wherein the time interval is usually 30s, loading the bus GPS track points and a road network into a city virtual traffic system platform, and displaying a city road network and a city bus line and analyzing the city traffic demand by the platform;
(2) starting from the bus, along the driving direction, the bus will be on the routeThe measured GPS track points are sequentially recorded as a detection point b1,b2,…,bnThus forming a detection point set B, wherein n is the number of times of last detection on the bus line;
(3) for all detection points B in detection point set B i1, n, from b1Starting with b1Drawing a circle by taking the custom distance l as a radius as a circle center, and taking all road network topological points surrounded by the circular area as candidate points so as to form a candidate point set R, wherein l can be set according to actual needs and is usually 100 m;
(4) if no candidate point exists in the step (3), entering a step (8), otherwise, entering a step (5);
(5) based on a comprehensive traffic network topology connection table in an urban virtual traffic system platform, with each road section as a unit, sequentially storing candidate points contained in the road section, including road network nodes and inflection points, judging whether any two candidate points in a candidate point set R are adjacent, if so, judging that a connection relation exists, otherwise, traversing all candidate points in the R, selecting topological point pairs with the connection relation, and forming a detection point b1A set of peripheral road segments D;
(6) separately calculating the detection points b1The distance D to each segment in the set D is given by the following formula:
wherein r is a calculation index, M, N is two endpoints of a certain road segment in the set D, and P is b1A vertical point to the MN; selecting the smallest distance dminThe maximum allowable deviation d is used as the judgment index0Comparison, d0Can be set according to actual needs, and can be 15m in general, if dmin<d0Then, it indicates the detection point b1On the road section, it is moved out of the detection point set B(ii) a If d ismin>d0Then, it indicates the detection point b1Roads do not exist around the detection point set B, and the detection point set B is reserved with the roads;
(7) if the detection point b is detected in the step (6)1If the detection point set B is moved out, the step (9) is carried out, otherwise, the step (8) is carried out;
(8) adding a fixed radius increment iteration value delta l to l, recording the value as l again, and judging whether l exceeds a given upper limit llimitIf not, repeating the step (3) and the step (4); if a given upper limit l is exceededlimitThen B is reserved in the detection point set B1Wherein Δ l and llimitCan be set according to actual needs, and the delta l is usually 100m and llimitTypically 1000 m;
(9) in sequence with b2,b3,…,bnRepeating the steps (3) to (8) by taking the GPS track points as the circle center until all the GPS track points on the bus line are traversed;
(10) and outputting the remaining detection points in the B, and judging the road sections corresponding to the detection points as missing road sections, wherein the missing road sections comprise:
(a) road middle section missing: the first situation is that a certain section of road between two road nodes is missing in the advancing direction of the road, and the situation mainly occurs in a block with dense branch networks or a newly built development area, and the reason for the situation is mainly new road building; the second condition is that in the advancing direction of the road, the road has local lane change and the lane after lane change is lost, which mainly appears on the road along the subway and is a temporary measure for facilitating the subway construction;
(b) end segment missing of road: the terminal point or the starting point of the bus line can be arranged on a branch road with a relatively far position, and some branch roads are omitted in the road network data because of being communicated with only one road;
(c) the intersection right-turn special lane is absent: this is often the case at large intersections, and the additional right-turn lanes are not updated in the road network in time due to the intersection reconstruction and the like.
Has the advantages that: compared with the prior art, the invention has the following advantages: the traditional process of manually identifying the virtual road network missing road sections is replaced by computer automatic identification, so that the labor, material resources and financial resources are saved, the defect of experience in manual identification is overcome, and the accuracy of road network identification is improved.
Drawings
FIG. 1 is a flow chart of the present invention;
fig. 2(a), (b), and (c) are schematic diagrams showing three positional relationships between the detection point and the link.
Detailed Description
The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.
As shown in fig. 1, the method for automatically identifying a virtual road network missing road section based on a bus GPS track according to the present invention comprises the steps of:
(1) and recording GPS data recorded by buses at intervals of 30s as bus GPS track points, and loading the bus GPS track points and the road network into the urban virtual traffic system platform.
The present embodiment selects 41 bus routes GPS track points and urban road network data in wuhan city as experimental data, the bus route name and the number of GPS track points of each route, i.e., the number of detection points, as shown in table 1 below.
TABLE 1
(2) Taking the bus number 201 as an example, 324 GPS track points measured on the line along the driving direction from the start of the bus are sequentially marked as b1,b2,…,b324And forming a detection point set B.
(3) For all detection points B in detection point set B i1.., 324 from b1Starting with b1And drawing a circle with the distance of 100m as a radius as a circle center, and regarding all road network topological points surrounded by the circular area as candidate points to form a candidate point set R.
(4) If no candidate point exists in the step (3), entering a step (8), otherwise, entering a step (5);
(5) for the candidate point set R, judging the connection relation between any two candidate points, traversing all the candidate points in the R, selecting a topological point pair with the connection relation, and forming a detection point b1A set of peripheral road segments D;
the basis for judging the connection relation between any two candidate points is as follows: and a comprehensive traffic network topology connection table in the urban virtual traffic system platform. The table takes each road section as a unit, and sequentially stores topological points contained in the road section, including road network nodes and inflection points, wherein a connection relation exists between two adjacent topological points, and two non-adjacent topological points do not have a connection relation. Detection point b1The comprehensive traffic network topology connection table of the peripheral road segment set D is shown in Table 2.
TABLE 2
It can be seen that 6 road topology points with serial numbers of 0-5 exist in D, and 20 road sections are formed.
(6) Separately calculating the detection points b1Selecting the distance D to each road section in the set D, wherein the minimum distance DminIs compared with the maximum allowable deviation d0Comparison, if dmin<d0Then, it indicates the detection point b1On the road section, removing the road section from the detection point set B; if d ismin>d0Then, it indicates the detection point b1Roads do not exist around the detection point set B, and the detection point set B is reserved with the roads;
calculating the detection point b1The method for the distance to each road section in the set D comprises the following steps: to detect point b1And section MN in set D as an example: b1The vertical point to the MN is denoted as point P, b1The position relation with the MN is divided into three cases:
(a)b1is within the line segment MN, as shown in fig. 2 (a);
(b)b1is outside the point N of the line segment MN, as shown in fig. 2 (b);
(c)b1is projected outside of point M of line segment MN, e.g.FIG. 2(c) shows.
In consideration of the directivity of the road section MN, a calculation index r is introduced as shown in the following formula:
then b is1The distance d to the segment MN is:
in the present embodiment, the maximum allowable deviation d0Taking 15m as the minimum distance d found by calculationmin15.8m, point b is indicated1The periphery has no road and is retained in the detection point set B.
(7) If the detection point b is detected in the step (6)1If the detection point set B is moved out, the step (9) is carried out, otherwise, the step (8) is carried out;
(8) selecting an area radius of 100m for the initial candidate point, increasing the radius of 100m each time, repeating iteration, judging whether the radius size after iteration exceeds a given radius upper limit of 1000m, and if not, repeating the step (3) and the step (4); if the given upper limit is exceeded, B is reserved in the detection point set B1。
In this embodiment, when the radius is 300m, the candidate point exists in R, and the process proceeds to step (5).
(9) In sequence with b2,b3,…,b324Repeating the steps (3) to (8) by taking the GPS track points as the circle center until all the GPS track points on the bus line are traversed;
(10) and outputting the remaining detection points in the B, and judging the road sections corresponding to the detection points as missing road sections, wherein the missing road sections comprise:
(a) road middle section missing: the first situation is that a certain section of road between two road nodes is missing in the advancing direction of the road, and the situation mainly occurs in a block with dense branch networks or a newly built development area, and the reason for the situation is mainly new road building; the second condition is that in the advancing direction of the road, the road has local lane change and the lane after lane change is lost, which mainly appears on the road along the subway and is a temporary measure for facilitating the subway construction;
(b) end segment missing of road: the terminal point or the starting point of the bus line can be arranged on a branch road with a relatively far position, and some branch roads are omitted in the road network data because of being communicated with only one road;
(c) the intersection right-turn special lane is absent: this is often the case at large intersections, and the additional right-turn lanes are not updated in the road network in time due to the intersection reconstruction and the like.
In this embodiment, the remaining detection points B are 8, respectively1,b63,b67,b106,b177,b191,b245,b307And the road sections corresponding to the detection points are missing road sections, and the missing type of the road sections is further found to be newly-built road missing by comparing the map.
The method for identifying the missing road sections of the other lines is similar to the method for identifying the missing road sections of the other lines, wherein the method is only one bus line and adjacent roads.