{"title":"A Dynamic Data Structure for Approximate Proximity Queries in Trajectory Data","authors":"M. D. Berg, Joachim Gudmundsson, Ali D. Mehrabi","doi":"10.1145/3139958.3140023","DOIUrl":"https://doi.org/10.1145/3139958.3140023","url":null,"abstract":"Let S be a set of n polygonal trajectories in the plane and k be a fixed constant. We present a data structure to store S so that, given a k-vertex query trajectory Q, we can answer the following queries approximately: • Nearest neighbor query: given a query trajectory Q, report the trajectory in S with minimum Fréchet distance to Q. • Top-j query: given a query trajectory Q and a positive integer j, report the j trajectories in S with minimum Fréchet distance to Q. • Range reporting query: given a query trajectory Q and a number δmax, report all trajectories in S with Fréchet distance at most δmax to Q. • Similarity query: given a query trajectory Q and a trajectory τ ∈ S, report the Fréchet distance between Q and τ. Our data structure answers these queries approximately with an additive error that is at most ϵ · reach(Q) for a given fixed constant ϵ > 0, where reach(Q) is the maximum distance between the start vertex of Q and any other vertex of Q. Furthermore, our query procedures ignore trajectories whose Fréchet distance to the query Q is very large. That is, if no trajectory is close to the query trajectory then no answer might be returned. The data structure uses O(n/ϵ2k) space and answers each of the queries above in time O(1 + #answers). Our data structure is the first one that can answer all these queries with provable error guarantees. Moreover, it is fully dynamic: inserting and deleting a trajectory with m vertices takes O(1/ϵ2k (m + log(1/ϵ))) and O(1/ϵ2k) amortized time, respectively. Finally, we empirically evaluate our data structure.","PeriodicalId":270649,"journal":{"name":"Proceedings of the 25th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115371899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Krittika D’Silva, A. Noulas, Mirco Musolesi, C. Mascolo, Max Sklar
{"title":"If I build it, will they come?: Predicting new venue visitation patterns through mobility data","authors":"Krittika D’Silva, A. Noulas, Mirco Musolesi, C. Mascolo, Max Sklar","doi":"10.1145/3139958.3140035","DOIUrl":"https://doi.org/10.1145/3139958.3140035","url":null,"abstract":"Estimating revenue and business demand of a newly opened venue is paramount as these early stages often involve critical decisions such as first rounds of staffing and resource allocation. Traditionally, this estimation has been performed through coarse measures such as observing numbers in local venues. The advent of crowdsourced data from devices and services has opened the door to better predictions of temporal visitation patterns for locations and venues. In this paper, using mobility data from the location-based service Foursquare, we treat venue categories as proxies for urban activities and analyze how they become popular over time. The main contribution of this work is a prediction framework able to use characteristic temporal signatures of places together with k-nearest neighbor metrics capturing similarities among urban regions to forecast weekly popularity dynamics of a new venue establishment. Our evaluation shows that temporally similar areas of a city can be valuable predictors, decreasing error by 41%. Our findings have the potential to impact the design of location-based technologies and decisions made by new business owners.","PeriodicalId":270649,"journal":{"name":"Proceedings of the 25th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129707762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. K. M. M. R. Khan, Oscar Correa, E. Tanin, L. Kulik, K. Ramamohanarao
{"title":"Ride-sharing is About Agreeing on a Destination","authors":"A. K. M. M. R. Khan, Oscar Correa, E. Tanin, L. Kulik, K. Ramamohanarao","doi":"10.1145/3139958.3139972","DOIUrl":"https://doi.org/10.1145/3139958.3139972","url":null,"abstract":"Ride-sharing is rapidly becoming an alternative form of transportation mainly due to its economic benefits. Existing research on ridesharing aims to optimally match trajectories between people with pre-selected destinations. In this paper, we show better ride-sharing arrangements are possible when users are presented with more destinations and agree on a common destination. Given a set of points of interest (POIs) and a set of users, our approach presents destination POIs and computes ride-sharing plans. Each arrangement for a subset of users that fit in a car can be presented as a minimum Steiner tree (MST) problem. An optimal solution of the overall problem minimizes the total length of all the MSTs. The problem is a version of the set cover problem and is NP-hard. We first develop a series of baseline methods which use a popular MST algorithm. Then, we propose our method which uses constraints on intermediary points where users can meet to share rides. These constraints reduce the time complexity significantly and our method is up to two orders of magnitude faster than the best baseline method. Since our algorithm finds the subsets of users and POIs for each arrangement, we define and solve a new type of MST problem as a first step. Our experiments show that our method can provide a fast and readily deployable solution for real world large city scenarios.","PeriodicalId":270649,"journal":{"name":"Proceedings of the 25th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126819877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Network Model for the Utility Domain","authors":"P. Bakalov, E. Hoel, Sangho Kim","doi":"10.1145/3139958.3139980","DOIUrl":"https://doi.org/10.1145/3139958.3139980","url":null,"abstract":"The existing network models in geographic information systems that are used to support the utility domain (e.g., water, wastewater, sewer, gas, electric, and telecommunications) have limitations and constraints that restrict the ability of these utility companies to effectively and accurately model the rapidly increasing complexity and sophistication of their networks. This is caused by the fact that utility domain places a very different set of requirements on a network model and the associated analytic operations compared to those, commonly found in transportation and social networks. Although many utilities have succeeded in implementing production systems on top of simple graph models, the solutions have often involved either having to author considerable amounts of custom application code to go with the model (an expensive and cumbersome proposition), or modifying their workflows in order to compensate for the limitations of the underlying graph model. This paper introduces a new utility-centric graph information model that is designed to directly support the complex modeling of utility infrastructures. The model is focused on supporting additional requirements for improved performance and scalability (by optimized data storage layouts), efficiency and productivity (by modeling of real-world concepts like devices with multiple terminals, inside-plant, etc.), data quality (by enforcing a business rule-based framework which prevents bad data from entering the system), real-time data acquisition (by supporting for field-based telemetry such as Advanced Meter Infrastructure -- AMI, and Supervisory Control","PeriodicalId":270649,"journal":{"name":"Proceedings of the 25th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132357856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Best-Compromise In-Route Nearest Neighbor Queries","authors":"E. Ahmadi, Camila F. Costa, M. Nascimento","doi":"10.1145/3139958.3140007","DOIUrl":"https://doi.org/10.1145/3139958.3140007","url":null,"abstract":"Humans are animals of habit, e.g., people follow typical and/or familiar paths in their daily routines. With that in mind we investigate the problem where a user, traveling on his/her preferred path, needs to visit one of many available points-of-interest while (1) minimizing his/her total travel distance and also (2) minimizing the detour distance incurred to reach the chosen point-of-interest. We call this new problem the \"Best-Compromise In-Route Nearest Neighbor\" query in order to emphasize that a route cannot typically optimize both criteria at the same time, but rather find a compromise between them. In fact, the competing nature of these two criteria resembles the notion of skyline queries. In that context, we propose a solution based on using suitable upper-bounds to both cost criteria to prune uninteresting paths. It returns all linearly non-dominated paths that are optimal under any given linear combination of the two competing criteria. Our experiments using real data sets of different sizes show that our proposal can be orders of magnitude faster than a straightforward alternative.","PeriodicalId":270649,"journal":{"name":"Proceedings of the 25th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134497747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Sobue, Yukihiro Fukushima, T. Kashiyama, Y. Sekimoto
{"title":"Flying Object Detection and Classification by Monitoring Using Video Images","authors":"H. Sobue, Yukihiro Fukushima, T. Kashiyama, Y. Sekimoto","doi":"10.1145/3139958.3140026","DOIUrl":"https://doi.org/10.1145/3139958.3140026","url":null,"abstract":"In recent years, there has been remarkable development in unmanned aerial vehicle UAVs); certain companies are trying to use the UAV to deliver goods also. Therefore, it is predicted that many such objects will fly over the city, in the near future. This study proposes a system for monitoring objects flying over a city. We use multiple 4K video cameras to capture videos of the flying objects. In this research, we combine background subtraction and a state-of-the-art tracking method, the KCF, for detection and tracking. We use deep learning for classification and the SfM for calculating the 3-dimensional trajectory. A UAV is flown over the inner-city area of Tokyo and videos are captured. The accuracy of each processing is verified, using the videos of objects flying over the city. In each processing, we obtain a certain measure of accuracy; thus, there is a good prospect of creating a system to monitor objects flying, over a city.","PeriodicalId":270649,"journal":{"name":"Proceedings of the 25th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133035839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Johannes Oehrlein, Benjamin Niedermann, J. Haunert
{"title":"Inferring the Parametric Weight of a Bicriteria Routing Model from Trajectories","authors":"Johannes Oehrlein, Benjamin Niedermann, J. Haunert","doi":"10.1145/3139958.3140033","DOIUrl":"https://doi.org/10.1145/3139958.3140033","url":null,"abstract":"Finding a shortest path between two nodes in a graph is a well-studied problem whose applicability in practice crucially relies on the choice of the applied cost function. Especially, for the key application of vehicle routing the cost function may consist of more than one optimization criterion (e.g., distance, travel time, etc.). Finding a good balance between these criteria is a challenging and essential task. We present an approach that learns that balance from existing GPS-tracks. The core of our approach is to find a balance factor α for a given set of GPS-tracks such that the tracks can be decomposed into a minimum number of optimal paths with respect to α. In an experimental evaluation on real-world GPS-tracks of bicyclists we show that our approach yields an appropriate balance factor in a reasonable amount of time.","PeriodicalId":270649,"journal":{"name":"Proceedings of the 25th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115797311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Deriving Double-Digitized Road Network Geometry from Probe Data","authors":"O. H. Dørum","doi":"10.1145/3139958.3139966","DOIUrl":"https://doi.org/10.1145/3139958.3139966","url":null,"abstract":"Increasing availability of probe data sources has the potential for enabling automatic map updates, refine the shape of existing map road geometry as well as estimate basic map attributes. The present paper proposes a comprehensive end-to-end unsupervised method based on principal curves for creating bi-directional road geometry from sparse probe data yielding a complete double-digitized road network from raw probe sources without prior map information. The resulting road segments in the road network graph enable conflation with existing map data to identify map changes including basic map attributes such as direction of travel, turn restrictions and traveled speed.","PeriodicalId":270649,"journal":{"name":"Proceedings of the 25th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems","volume":"426 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115920920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ardavan Afshar, Joyce Ho, B. Dilkina, Ioakeim Perros, Elias Boutros Khalil, Li Xiong, V. Sunderam
{"title":"CP-ORTHO: An Orthogonal Tensor Factorization Framework for Spatio-Temporal Data","authors":"Ardavan Afshar, Joyce Ho, B. Dilkina, Ioakeim Perros, Elias Boutros Khalil, Li Xiong, V. Sunderam","doi":"10.1145/3139958.3140047","DOIUrl":"https://doi.org/10.1145/3139958.3140047","url":null,"abstract":"Extracting patterns and deriving insights from spatio-temporal data finds many target applications in various domains, such as in urban planning and computational sustainability. Due to their inherent capability of simultaneously modeling the spatial and temporal aspects of multiple instances, tensors have been successfully used to analyze such spatio-temporal data. However, standard tensor factorization approaches often result in components that are highly overlapping, which hinders the practitioner's ability to interpret them without advanced domain knowledge. In this work, we tackle this challenge by proposing a tensor factorization framework, called CP-ORTHO, to discover distinct and easily-interpretable patterns from multi-modal, spatio-temporal data. We evaluate our approach on real data reflecting taxi drop-off activity. CP-ORTHO provides more distinct and interpretable patterns than prior art, as measured via relevant quantitative metrics, without compromising the solution's accuracy. We observe that CP-ORTHO is fast, in that it achieves this result in 5x less time than the most accurate competing approach.","PeriodicalId":270649,"journal":{"name":"Proceedings of the 25th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121806608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Next place prediction in unfamiliar places considering contextual factors","authors":"Takashi Nicholas Maeda, K. Tsubouchi, F. Toriumi","doi":"10.1145/3139958.3139970","DOIUrl":"https://doi.org/10.1145/3139958.3139970","url":null,"abstract":"This research aims to develop a method for maximizing the accuracy of next place prediction (NPP) in places that are unfamiliar to each mobile phone users. NPP is a problem of predicting the next place of the user given his/her current place and current time. In places that are unfamiliar to the person, it is difficult to predict the next place based on the person's historical location data because there are just a few or no data in such places for each user. Furthermore, it is also difficult to rely on the regularity of human mobility because tourists' mobility is easily affected by many external factors, such as weather. Our research aims to solve the difficulties in NPP in unfamiliar places by focusing on contextual factors such as weather, transportation means, place of residence, and time.","PeriodicalId":270649,"journal":{"name":"Proceedings of the 25th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126231487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}