| With the rapid development of modern transportation,the information of urban road network has become very complex.In real life,people are increasingly demanding the application of geographic information based on road network.The related problems have also attracted the attention of many spatial database researchers.In the field of spatial database,the evaluation and query of spatial location influence is a classical problem.The existing research on spatial location influence aims at a spatial point object.In this paper,the problem of evaluating the spatial influence of road sections is proposed.The spatial point objects are extended to linear sections,which can be widely used in commercial propaganda,traffic path planning,site selection and other fields.Consider the following application scenarios:First,advertisers plan to put outdoor billboards along both sides of the road,hoping to maximize the impact of the limited number of billboards and radiate as many target groups as possible within a certain cost range.In addition,the propaganda department intends to carry out propaganda activities on a certain theme,passing through a certain section of the city within a certain period of time,and the propaganda route rules hope to choose the section related to the theme.All the above applications can be solved by evaluating the spatial influence of road sections.Firstly,this paper defines the spatial influence of road sections.For practical application,this paper takes traffic network as evaluation object,spatial interest point and mobile object as reference object,and takes into account the distance characteristics of spatial influence,projecting reference object to traffic network to generate projection network.At the same time,the spatial influence of the section is related to the theme,and the evaluation method of the theme-related influence is designed.Secondly,this paper designs an efficient spatial influence query algorithm.Because of the complexity of traffic network structure and the mass of reference objects,it is a challenge to calculate the influence of road sections efficiently.In order to improve the efficiency of influential query,this paper proposes a new structured index projection network and reference object.A stroke algorithm is used to serialize the segment of projected road network.An index structure composed of side table structure and hierarchical tree structure is designed.The side table structure stores the jump relations of each segment,and the hierarchical structure stores the statistical information of reference objects on the segment.Based on the proposed index structure,a query algorithm for spatial influence of road segments is designed.Thirdly,this paper designs a dynamic object-oriented impact query algorithm.Some spatial reference objects are mobile,such as people in check-in data and mobile vehicles.Because of the mobility of reference objects,the influence of road segments may change with time,so this paper studies the influence query problem of dynamic object-oriented.Because the location of the moving reference object changes frequently,it is impossible to update the statistical information of the reference object in the fine-grained index structure.This paper designs an approximate query algorithm based on the coarse-grained index structure,updates the reference object to the upper nodes of the index structure,and calculates the influence by pruning and various estimation methods.Finally,the query efficiency and accuracy of the proposed algorithm are analyzed through real data sets,and the effectiveness of the proposed method is verified.At the same time,this paper designs a prototype system,which includes data preprocessing,section influence query and online query,result display and other functions.The research content of this paper can be widely used in the existing geographic information application platform,enriching and expanding the spatial database query algorithm. |
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