In this paper, we propose an efficient approach to tackle ann queries in road networks. Motivated by this, we introduce a new type of query called group nearest compact poi set gncs query for a user group who wishes to. In spatial database and road network applications, the search for the nearest neighbor nn from a given query object q is the most. Abstract aggregate nearest neighbor queries return the object that minimizes an aggregate distance function with respect to a set of query points. Nearest neighbor queries have been studied extensively in settings where the euclidean distance is assumed and rtrees are used. Motivated by applications in computer vision and databases, we introduce and study the simultaneous nearest neighbor search snn problem. Pdf aggregate nearest neighbor queries in road networks. The pro posed techniques can be easily extended for directed road networks e. Given a set o of data objects, a set q of query points, a positive integer k, and an aggregate function f e. Voronoibased aggregate nearest neighbor query processing. Aggregate nearest neighbor queries in spatial databases. Query processing, ann, voronoi diagram, road networks.
Enforcing k nearest neighbor query integrity on road networks. Approximate aggregate nearest neighbor queries on road networks saranya sadasivam asif iqbal baba weishinn ku haiquan chen dept. The space perspective covers euclidean space and spatial road network space. Aggregate nearest neighbor queries in road networks core. Topk spatial preference queries in directed road networks. Pois are typically obtained by using a range query or a k nearest neighbors knn query. In spatial database and road network applications, the search for the nearest neighbor nn from a given query object q is the most fundamental and important problem. Geographic information system near neighbor query point network distance spatial query. Most related to our work are the group nearest neighbor query gnn and the aggregate nearest neighbor query ann. Aggregate nearest neighbor ann query has been studied in both the euclidean space and road networks. Let v p be the voronoi cell of p on a road network, the nearest neighbor of a query point q is p,ifand only if q. Path nearest neighbor, road networks, spatial databases. The islands approach to nearest neighbor querying in spatial.
Given a set of data points, the goal of snn is to design a data structure that, given a collection of queries, finds a collection of. Aggregate nearest neighbor queries return the object that minimizes an aggregate distance function with respect to a set of query points. Consider, for example, several users at specific locations query points that want to find the restaurant data point, which leads to the minimum sum of distances that they have to travel in order to meet. Note that, gnn query with aggregate distance function is also called aggregate nearest neighbor ann query in 18. Aggregate knearest neighbors queries in timedependent. The ann query aggregates on the distances of a group of points, di. Pdf a survey on nearest neighbor search methods semantic. In this paper we present an algorithm for processing aggregate nearest neighbor queries in timedependent road networks, i.
Proceedings of the 185th annual acm international symposium on advances in geographic information systems gis, 2010, pp. At the same time, yiu 22 applied the ann query to the road. Consider, for example, several users at specific locations query points that want to find the restaurant data point, which leads to the minimum sum of distances that they have to travel in. Efficient knearest neighbor search in timedependent spatial.
Aggregate nearest neighbor queries in road networks. Citeseerx aggregate nearest neighbor queries in road networks. There are some scholars 4 6 that consider the directionaware query of moving objects in euclidean space. Flexible aggregate nearest neighbor queries in road. Aggregate nearest neighbor query, which returns an optimal target point that minimizes the aggregate distance for a given query point set, is one of the most important operations in spatial databases and their application domains. In particular, we first continuously compute the nearest neighbors nns for each query point in. Furthermore, an aggregate nearest neighbor query algorithm based on strategy.
Monitoring path nearest neighbor in road networks citeseerx. Aggregate keyword nearest neighbor queries on road networks. Voronoibased kaggregate nearest neighbor query processing. Abstract aggregate nearest neighbor ann query has been studied in both the euclidean space and road networks. On topk weighted sum aggregate nearest and farthest. A taxonomy for nearest neighbour queries in spatial databases. Asif baba, instructor, computer science publications and. In a road network, given a distance value r, the island of a data point dp is the subset of the road network covered by a network expansion from dp with the range r. During backtracking to the upper level node n 1, the algorithm prunes entries whose mindist is equal to or larger than the distance best distofthe nearest neighbor already. The first one is a road network dataset derived from the city of san juan, ca. Queries in road networks man lung yiu, nikos mamoulis, and dimitris papadias abstract aggregate nearest neighbor queries return the object that minimizes an aggregate distance function with.
This ever increasing information volume has led to time and computation complexity. Take a road network consisting of a set of edges and a set of nodes shown in fig. Flexible aggregate nearest neighbor queries and its keywordaware variant on road networks zhongpu chen, bin yao, zhijie wang, xiaofeng gao, shuo shang, shuai ma, and minyi guo, fellow, ieee abstract aggregate nearest neighbor ann query in both the euclidean space and road networks has been extensively studied, and. In all above mentioned queries, the aim is to minimize the total sum of the distances to the query points from a point. Probabilistic flexible aggregate nearest neighbor search.
Efficient reverse knearest neighbor estimation lmu munich. Liu, voronoibased aggregate nearest neighbor query processing in road networks, in. Most of the current studies on the k nearest neighbor queries utilize spatial index structures and hence are based on the euclidean distances between the points. Continuous nearest neighbor monitoring in road networks. Fast optimal aggregate point search for a merged set on road. Given a group qof mquery objects, it retrieves from a database the objects most similar to q, where the similarity is. Probabilistic flexible aggregate nearest neighbor search in road. Nearest neighbour queries or knn have been used in many disciplines. Aggregate nearest neighbor ann query in both the euclidean space and road networks has been extensively studied, and the flexible. An aggregate nearest neighbor ann query returns a point of interest poi that minimizes an aggregate function for multiple query points. Citeseerx document details isaac councill, lee giles, pradeep teregowda.
Among them,k aggregate nearest neighbor kann query returns a common interesting data object that minimizes an aggregate distance for multiple query points,so it has high research value and broad application prospects. In realworld road networks, however, the shortest distance between two points depends on the actual path connecting the points and cannot be com. Up to the authors knowledge, the problem of continuous k aggregate nearest neighbors has not been addressed before. Any node can be pruned if where is the minimum distance between the node and a query point. Aggregate nearest neighbor query, which returns a common interesting point that minimizes the aggregate distance for a given query point set, is one of the most important operations in spatial databases and their application domains. In this scenario, mobile service users are moving in a road network. The proximity queries in general search for data objects that minimize a distancebased function with reference to.
Furthermore, the following property holds for the k nearest neighbors of a query point q on a road network. Considering the road network in the introduction, the graph nodes generated by this. Asif iqbal baba, hua lu, torben bach pedersen and xike xie, handling false negatives in indoor rfid data, in proceedings of the 15th ieee international conference on mobile data management. Merged aggregate nearest neighbor query processing in road networks. Aggregate nearest neighbor queries in road networks man lung yiu, nikos mamoulis, and dimitris papadias abstract aggregate nearest neighbor queries return the object that minimizes an aggregate distance function with respect to a set of query points. Nearest neighbor queries in network databases springerlink. Sorry, we are unable to provide the full text but you may find it at the following locations. A number of facilities or socalled points of interest, e. After touching the border of dp2, the 3nn search process can stop. However, the problem does not involve road network constraints.
Flexible aggregate nearest neighbor queries and its keyword. Hierarchical graph traversal for aggregate k nearest neighbors search in road networks tenindra abeywickrama,1,2 muhammad aamir cheema,2 sabine storandt3 1grabnus ai lab, national university of singapore, singapore 2faculty of information technology, monash university, melbourne, australia 3department of computer and information science, university of konstanz, konstanz, germany. A trajectory privacy preserving scheme in the cannq service for iot. Ieee transactions on knowledge and data engineering 16 1, 8296, 2004.
In this paper, we propose a novel approach to efficiently process ann queries in road networks. Recently, different methods to solve such problems are proposed. The k gnn query allows a group of n users to retrieve top k locations from the lsps database to minimize some aggregate cost function f over all n users. Several types of queries have been studied in the road network, such as knn queries 7, range queries 9, aggregate nearest neighbor queries 11, reverse nearest neighbor queries 12. Proceedings of the 22nd acm international conference on information and knowledge management, 27 october 1 november 20, san francisco. Due to their popularity and importance, k nearest neighbor knn queries, which find the k closest points of interest objects to a given query location, have been. Merged aggregate nearest neighbor query processing in road. Abstract nowadays, the need to techniques, approaches, and algorithms to search on data is increased due to improvements in computer science and increasing amount of information. Given a destination where a user is going to, this new query returns the knn with respect to the shortest path connecting the destination and the users current location, and thus provides a list of nearest candidates for reference by considering the whole coming journey. On efficiently monitoring continuous aggregate k nearest. Directionaware continuous moving knearestneighbor query in. Processing locationbased aggregate queries in road networks. Figure 1 gives an example of a krnn query in a road network, where each line.
During backtracking to the upper level node n 1, the algorithm prunes entries whose mindist is equal to or larger than the distance best distofthe nearest neigh bor already retrieved. Pdf privacy and location anonymization in locationbased. The flexible aggregate nearest neighbor fann problem further generalizes ann by introducing an extra flexibility. In this paper, we focus on the problem of dynamic density queries for moving objects in road networks. Citeseerx aggregate nearest neighbor queries in road. Group nearest compact poi set queries in road networks. There are three types of objects in this road network, hotels, restaurants, and theaters. P and q queries, an aggregate nearest neighbor ann query 19 retrieves the points in p that have the smallest aggregate distances to the points in q. Pdf simultaneous nearest neighbor search semantic scholar. Retrieve the trajectories of people with the minimum aggregated distance to a set of query points publications.
Given a set of data points p, a set of query points q, and a userdefined flexibility parameter. In this paper we study knn monitoring in road networks, where the distance between a query and a data object is determined by the length of the shortest. Second observation provides a tighter pruning bound. Furthermore, the following property holds for the k nearest neighbors of a query point q on a road network 4. Aggregate nearest neighbor queries in road networks ieee.
Exact and approximate flexible aggregate similarity search. Consider, for example, several users at specific locations query points that want to find the restaurant data point, which leads to the minimum sum of distances that. Recently,k nearest neighbor knn query and its variants in road networks have received more and more attention in the research community. Throughout this paper, however, we always name this kind of query with aggregates as gnn, unless otherwise specified. A range query b knn point query c knn trajectory query r p 2 q 1 q 2 tr 1 tr 2 tr 3 tr 1 tr 2 tr 3 tr 1 tr 2 tr 3 q t a range query b knn point query c knn trajectory query r p 2 e. Most of them only consider the nearest objects in the dimension of distance. On efficiently monitoring continuous aggregate k nearest neighbors in road networks abstract. All existing methods, however, assume the euclidean distance metric. The problem of computing knn queries in spatial network databases has only been addressed more recently.
Approximate aggregate nearest neighbor queries on road networks saranya sadasivamy asif iqbal babaz weishinn kuy haiquan chen ydept. Abstract aggregate similarity search, also known as aggregate nearest neighbor ann query, nds many useful applications in spatial and multimedia databases. Papadias, aggregate nearest neighbor queries in road networks, ieee trans. The input of the query consists of four parameters. Existing location privacy techniques mainly consider the euclidean space where users can move freely. Hierarchical graph traversal for aggregate k nearest. Some recent works consider both the spatial closeness of objects to the query object and the neighboring relationship between objects. This paper proposes two algorithms to process mann query on road networks when aggregate function. On efficient aggregate nearest neighbor query processing in. Continuous aggregate nearest neighbor queries purdue. Processing locationbased aggregate queries in road.
Voronoibased aggregate nearest neighbor query processing in. Assume that the user q wants to stay in a hotel, have lunch in a restaurant, and go to the movies. Aggregate knearest neighbors queries in timedependent road. This paper addresses the problem of monitoring the k nearest neighbors to a dynamically changing path in road networks. At the same time, yiu 22 applied the ann query to the roa. Approximate aggregate nearest neighbor queries on road. Aggregate nearest neighbor queries on road networks, in acm sigspatial mobigis 2015, seattle, washington, usa, november 36, 2015. Given a set of data points, the goal of snn is to design a data structure that, given a collection of queries, finds a collection of close points that are compatible with each other. Efficient evaluation of krange nearest neighbor queries in road. Therefore, the algorithms for ann queries cannot apply. Merged aggregate nearest neighbor query processing in road networks by weiwei sun, chong chen, baihua zheng, chunan chen, liang zhu, weimo liu and yan huang cite. Probabilistic group nearest neighbor queries in uncertain. A reverse knearest neighbor rknn query returns the data objects that have the.
One of the future directions is to extend existing frameworks to support other kinds of locationbased queries, e. Given a set of data points p, a set of query points q, and a userde. Hierarchical graph traversal for aggregate k nearest neighbor. Continuous aggregate nearest neighbor queries user personal. Flexible aggregate nearest neighbor queries in road networks.
Given a group qof mquery objects, it retrieves from a database the objects most similar to q, where the similarity is an aggregation e. However, most of the existing applications are limited to traditional spatial queries, which return objects based on their distances from the query point. On efficient aggregate nearest neighbor query processing. Aggregate nearest neighbor queries in spatial databases 533 fig. Flexible aggregate nearest neighbor queries in road networks abstract. Fast optimal aggregate point search for a merged set on.
The term aggregate nearest neighbor query is coined in the literature in the. Among the others, nearest neighbor search is one of the best. A range query b knn point query c knn trajectory query r p 2 q 1 q 2 tr 1 tr 2 tr 3 tr 1 tr 2 tr 3 tr tr 2 tr 3 q t a range query b knn point query c knn trajectory query r p 2 e. Thus, spatial queries such as k nearest neighbor, range queries and reverse nearest neighbor 15 have received a signi. Aggregate nearest neighbor ann query returns a common interesting data object that minimizes an aggregate distance for multiple query points.
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