An Efficient Algorithm to Construct Connectivity Topology for Road Network Using R-tree and B-tree Indexes

Abstract

A road network with topology is the basis for optimal path finding.According to the definition of connectivity topology by ISOGDF4.0(Geographic Data File) model and the requirements of road network connectivity topology during the optimal path finding procedure,this paper presents an efficient algorithm to construct connectivity topology for road network using R-tree and B-tree indexes.The efficient algorithm contains two parts: the first part breaks the roads at intersections and generates anew road network;the second part constructs connectivity topology based on the new network.The procedure of building new road network breaks the roads into line segments and gets intersections at first,then reconstructs new roads with the line segments set and the intersections.During the procedure of getting intersections of any two line segments,the algorithm builds R-tree spatial index on the line segments to improve query operation efficiency significantly.What’s more,our algorithm also builds B-tree index on serialized data of the roads such as the identity codes while constructing connectivity topology to improve the query operation efficiency on serialized data.This paper also tests the time complexity of the algorithm using road networks with different scales.Experiment results show that our algorithm builds connectivity topology of large-scale road network in very short time.(For a road network that contains about 30 thousands line segments and 25 thousands points,the quick algorithm completes connectivity topology construction in no more than 3 seconds).The time cost of our algorithm increases slightly while the traditional algorithm increases tremendously,to be exact,our algorithm’s time cost grows at the rate of O(v log(v)) while the traditional one grows with the speed of O(v2),so we concluded that the quick algorithm has high efficiency and is valuable to practicable application.