CN107564289B - Road network preprocessing method for merging traffic nodes - Google Patents

Abstract

The invention discloses a road network preprocessing method for merging traffic nodes, which comprises the following steps of firstly, constructing a basic file for representing urban road network information on the basis of a road network to be processed; secondly, determining a node merging radius according to the road network characteristics and an expected target; then, generating a reference node according to a specified rule, and searching a node to be merged in the merging radius range; and finally, deleting the searched nodes to be merged and processing the basic file, so that the road network of the intersection consisting of a plurality of traffic nodes can be optimized, and the smoothness and readability of the road network are improved.

Description

Road network preprocessing method for merging traffic nodes

Technical Field

The invention relates to a road network preprocessing method for merging traffic nodes, and belongs to the technical field of urban road network preprocessing.

Background

In recent years, under the condition that problems such as urban traffic congestion aggravation, serious pollution, frequent occurrence of safety accidents and the like are increasingly prominent, the call for smart traffic city construction is more intense, various integrated application systems which are based on urban traffic big data and can realize functions of making, implementing, evaluating and the like of auxiliary schemes are continuously proposed, popularized and applied, wherein the integrated application systems include urban traffic virtual platforms built by southeast university.

With the continuous development of network information technology, open road traffic information provides accurate mass road network data for promoting the construction of urban traffic virtual platforms. At present, the real-time downloading of network road traffic data and the rapid analysis of the network traffic data into a road network are realized from the technical aspect. However, in a road network analyzed based on open source road information, a plurality of traffic nodes represent a common intersection, which is not only helpful for road traffic analysis, but also occupies a calculation memory space and increases calculation time.

Disclosure of Invention

The invention provides a road network preprocessing method for merging traffic nodes, which aims to improve the smoothness and readability of a road network formed by analyzing open source road information and shorten the time consumption of traffic operation analysis.

In order to solve the technical problem, the invention provides a road network preprocessing method for merging traffic nodes, which comprises the following steps:

step one, constructing a basic file for representing urban road network information on the basis of a road network to be processed, wherein the basic file comprises a node basic information file, a node connection directory list file and a road section basic information file;

step two, determining a node merging radius according to the road network characteristics and the expected target;

step three, generating a reference node according to a specified rule, searching nodes to be merged in the step two within the merging radius range, if the nodes to be merged exist, turning to step four, otherwise, turning to step three;

and step four, deleting the searched nodes to be merged and processing the basic files.

Further, in the first step, the node basic information file includes a node number and a node coordinate, the road section basic information file includes a road section number, a road section starting point and a road section ending point, and the node connection directory list file includes a sending node number, a receiving node number and a receiving node number.

Further, the determining the node merging radius in the step two includes: according to the density degree of traffic nodes needing to be merged in a road network, two traffic nodes which are far away from each other and represent one intersection are selected, and the distance between the two traffic nodes is used as a node merging radius.

Further, the rule for generating the reference node in step three includes: the sending node numbers are generated in the descending order, the sending node numbers are generated in the descending order or are randomly selected from all the sending nodes by adopting equal probability.

Further, the step four includes the following steps:

(4.1) traversing the first column of the basic information file of the traffic node, and deleting the row containing the node to be merged;

(4.2) searching whether the following road sections exist in the road section basic information table: deleting the road sections from the reference nodes to the nodes to be merged and/or the road sections from the nodes to be merged to the reference nodes if the road sections exist;

(4.3) searching nodes to be merged in the first column and the third column of the road section basic information table respectively, and replacing the searched nodes to be merged with reference nodes;

(4.4) adding the third column element and the last column element of the row with the first column element as the nodes to be merged into the receiving node number column with the first column element as the row with the reference node, deleting the nodes to be merged in the row with the first column element as the reference node, and arranging the new receiving nodes in the order from small to large; replacing nodes to be merged in other rows with reference nodes;

and (4.5) repeating the steps (4.1) - (4.4) until all the searched nodes to be merged are executed.

Has the advantages that: compared with the prior art, the method can effectively reduce the number of nodes and road sections at the intersection, thereby directly reducing the data occupation space of the storage nodes and the road sections, and having positive effects on optimizing the road network structure and improving the traffic analysis speed.

Drawings

FIG. 1 is a basic flow diagram of the process of the present invention;

FIG. 2 is a road network diagram used for analysis by an embodiment of the method of the present invention;

FIG. 3 is a road network graph after nodes 10 are merged in the analysis of the embodiment of the method of the present invention;

FIG. 4 is a road network graph after nodes are sequentially merged in the analysis of the embodiment of the method of the present invention;

FIG. 5 is a final road network graph after node merging in the analysis of the method embodiment of the present invention.

Detailed Description

The process of the invention is further illustrated below with reference to the examples.

Fig. 1 is a basic flow chart of a road network preprocessing method for merging traffic nodes, which specifically includes the following steps:

step 1: based on the road network to be processed, a basic file for representing urban road network information is constructed, and the road network shown in fig. 2 is adopted for explanation:

1.1, constructing a traffic node basic information file, wherein the result is shown in a table 1;

TABLE 1 traffic node basic information Table

1.2, constructing a road section basic information file, wherein the result is shown in a table 2;

TABLE 2 basic information Table of road section

Road segment numbering	Starting point of a road section	End of road section	Road segment numbering	Starting point of a road section	End of road section
						1	2	10	7	8	9
2	10	11	8	9	10
						3	11	5	9	10	3
4	6	12	10	4	11
						5	12	9	11	11	12
6	9	1	12	12	7

1.3, constructing a node connection directory table, wherein the result is shown in a table 3;

TABLE 3 node connection directory Table

Step 2: determining a node merging radius according to the road network characteristics and an expected target;

it can be known from the network diagram to be processed that the nodes 9, 10, 11 and 12, the total of four nodes, need to be merged, and according to the node coordinates, the distance between the nodes 9 and 11 is calculated to be 1.414, the node merging radius can be slightly larger than the value, and the node merging radius is taken to be 1.5;

and step 3: generating a reference node according to a specified rule, and searching whether a node to be merged exists or not;

here, a mode of randomly generating a reference node by equal probability is selected, and one node is selected from the sending nodes connected with the directory list file, and the selected node is set to be 9 in the embodiment;

taking the node 9 as the center of a circle and the node combination radius 1.5 as the search radius, finding 3 nodes to be combined, which are respectively 10, 11 and 12;

and 4, step 4: deleting the searched nodes to be merged and processing the basic files;

and combining the nodes to be combined one by one according to the increasing sequence of the node serial numbers, taking the combining node 10 as an example to perform the file processing in the step 4:

4.1, traversing a first column of the basic information file of the traffic node, and deleting a row containing a node to be merged, wherein the new basic information file of the traffic node is shown in a table 4;

table 4 basic information table of traffic nodes after merging node 9

4.2, deleting the road sections from the reference nodes to the nodes to be merged and/or the road sections from the nodes to be merged to the reference nodes, wherein the updated road section basic information table is shown in a table 5;

table 5 basic information table of links after performing step D2

Road segment numbering	Starting point of a road section	End of road section	Road segment numbering	Starting point of a road section	End of road section
						1	2	10	7	8	9
2	10	11	9	10	3
						3	11	5	10	4	11
4	6	12	11	11	12
						5	12	9	12	12	7
6	9	1

4.3, searching nodes to be merged in the first column and the third column of the road section basic information table respectively, replacing the searched nodes to be merged with the reference nodes, and displaying the updated road section basic information table as shown in table 6;

table 6 basic information table of links after performing step D3

4.4, adding the third column element to the last column element of the row with the first column element as the node to be merged into the receiving node with the first column element as the row with the reference node, deleting the node to be merged in the row with the first column element as the reference node, and arranging the new receiving nodes in the descending order; replacing nodes to be merged in other rows with reference nodes, wherein the updated connection directory table file is shown in table 7; FIG. 3 is a road network graph with nodes 9 merged into nodes 10;

table 7 node connection directory table

Replacing nodes to be merged, and repeatedly executing steps 4.1, 4.2, 4.3 and 4.4 to merge nodes 11 and 12, wherein fig. 4 is a road network graph set after three nodes 10, 11 and 12 are respectively merged;

repeating the steps 3 and 4 to obtain a final merged road network diagram, as shown in fig. 5;

the final link basic information file, the link basic information file and the node connection directory file are shown in tables 8, 9 and 10, respectively;

table 8 final traffic node basic information table

Node numbering	Node coordinate x	Node coordinate y
			2	-5	0
4	1	-5
			6	6	1
8	0	6
			9	0	1

TABLE 9 Final basic information Table for road section

Table 10 final nodal connection directory table

。

Claims (1)

1. A road network preprocessing method for merging traffic nodes is characterized by comprising the following steps: the method comprises the following steps:

step one, constructing a basic file for representing urban road network information on the basis of a road network to be processed, wherein the basic file comprises a node basic information file, a node connection directory list file and a road section basic information file;

step two, determining a node merging radius according to the road network characteristics and the expected target;

step three, generating a reference node according to a specified rule, searching a node to be merged in the merging radius range of the step two, if the node to be merged exists, turning to the step four, otherwise, turning to the step three;

deleting the searched nodes to be merged and processing the basic files;

in the first step, the node basic information file comprises a node number and a node coordinate, the road section basic information file comprises a road section number, a road section starting point and a road section finishing point, and the node connection directory list file comprises a sending node number, a receiving node number and a receiving node number;

the step two of determining the node merging radius comprises the following steps: selecting two traffic nodes with a longer distance in an intersection according to the density of the traffic nodes needing to be merged in a road network, and taking the distance between the two traffic nodes as a node merging radius;

the rule for generating the reference node in the third step includes: generating according to the sequence of the numbers of the sending nodes from small to large, generating according to the sequence of the numbers of the sending nodes from large to small, or randomly selecting from all the sending nodes by adopting equal probability;

the fourth step comprises the following steps:

(4.1) traversing the first column of the basic information file of the traffic node, and deleting the row containing the node to be merged;

(4.2) searching whether the following road sections exist in the road section basic information table: deleting the road sections from the reference nodes to the nodes to be merged and/or the road sections from the nodes to be merged to the reference nodes if the road sections exist;

(4.3) searching nodes to be merged in the first column and the third column of the road section basic information table respectively, and replacing the searched nodes to be merged with reference nodes;

(4.4) adding the third column element and the last column element of the row with the first column element as the nodes to be merged into the receiving node number column with the first column element as the row with the reference node, deleting the nodes to be merged in the row with the first column element as the reference node, and arranging the new receiving nodes in the order from small to large; replacing nodes to be merged in other rows with reference nodes;

and (4.5) repeating the steps (4.1) - (4.4) until all the searched nodes to be merged are executed.

Images