Study On The GIS And GPS Data Pretreatment Key Technology For Traffic Condition Detection

Real-time traffic condition detection for the urban road is essential to traffic management, controls, guidance, and improvement road traffic condition. And will be valuable for residential journey, public transportation dispatching, urban planning and so on.As the vehicles equipped with GPS receiver have increased in past few years, a new way to detect traffic condition is the use of GPS equipped floating vehicle method. The GIS and GPS data pretreatment is the basis of realization floating vehicle technology, which can provide high reliable data pool for traffic condition detection and will directly affect the efficiency and accuracy of traffic condition detection. Therefore, it is necessary to research the key technology of pretreatment in order to detect traffic condition based on GPS equipped floating vehicle.According to the analysis of MapInfo format electronic map, GPS raw data, the existing map-matching algorithm, this paper presents a scheme of the GPS and GIS data pretreatment in view of the research background and application demand. The research emphasis described in this paper is concerned with electronic map pretreatment, GPS Unusual data processing and map-matching algorithm.Considering the core issues of the map pretreatment, there are several key technologies need to study: according to application demand, the map database is designed to realized the connection of spatial data and attribute data; The algorithm based on pretreatment for constructing topological structure of urban road network can solve the problem that MapInfo format electronic map does not have topology structure and the road network does not connect; Simultaneously, the automatically generated algorithm of road link sideline nodes can provide the basis data to support the realization of the new proposed map-matching algorithm and the GIS dynamic demonstration of traffic condition.In GPS data pretreatment aspect, considering the measurement errors of GPS data gathering by GPS receiver, the pretreatment methods are presented to patch flaw data and repair the erroneous data, in order to increase the reliability of the primary data; Because the goal, object scale, speed and matching rate of this topic map matching are entirely different with vehicles guidance map matching and the existing guidance map matching algorithm does not suit this topic, a new map-matching algorithm based on the map pretreatment is proposed, which is different to the existing algorithms and is a map-matching algorithm of the point to the face (regional); The method of traffic direction judgment is proposed to classify the vehicles of different directions of the two-way road.Finally, with the use of Chongqing Municipality electronic map and vehicle real-time positioning data, the above several key technologies are implemented by VB & MapX platform. The experimental results show that, the precision and efficiency of the algorithm based on pretreatment for constructing topological structure of urban road network improves more significantly than other algorithms; the automatically generated algorithm of road sideline nodes is simple and effective; the efficiencies of the map matching algorithm based on the map pretreatment and the vehicle traveling direction judge judgment method are higher, and their accuracies can satisfy the demand of the road link speed estimation.