Retrieval tasks
Description
The Data Management group has targeted points-based search where trajectories are returned based on their proximity to a set of query points; i.e., given a collection of trajectories and a set query points, the goal is to retrieve the top-k trajectories that pass as close as possible to all query points. We advanced the nearest-neighbor based state-of-the-art by proposing a novel and more efficient, spatial range-based approach. In addition, a practical variant of this points-based search was proposed, which additionally takes into account other qualitative characteristics of the searched trajectories, e.g., the temporal span. Besides one-time or snapshot search. our recent work also introduced continuous points-based trajectory search where the query is long-standing and the result set must be maintained whenever updates to the query parameters and/or the data, i.e., the trajectories, occur.
Publications
- Shuyao Qi, Dimitris Sacharidis, Panagiotis Bouros and Nikos Mamoulis:
Snapshot and Continuous Points-based Trajectory Search
International Journal on Advances of Computer Science for Geographic Information Systems (GeoInformatica), Vol 21, No 4, October 2017 - Shuyao Qi:
Advanced Ranking Queries on Composite Data
PhD thesis, Department of Computer Science, University of Hong Kong, China PR, 2016 - Shuyao Qi, Panagiotis Bouros, Dimitris Sacharidis and Nikos Mamoulis:
Efficient Point-based Trajectory Search
Proceedings of the 14th International Symposium on Spatial and Temporal Databases (SSTD), Hong Kong, China, August 26-28, 2015
Received the Best Paper Award
Path finding
Description
This line of work is captured by Prof. Bouros' doctorate studies. Prof. Bouros addressed new challenges that arise in path-finding problems, given the availability of trajectory collections; in prarticulal, whether path queries traditionally targeting graphs can be posed on trajectory collections, and even more importantly, if the evaluation of these queries can be enhanced by the special characteristics of the trajectories. For instance, a trajectory can be seen as a set of precomputed answers. Under this perspective, a novel framework was proposed for evaluating path queries on large disk resident collections that are frequently updated by adding and removing trajectories. The thesis introduced two evaluation paradigms that enjoy the benefits of search algorithms (i.e., fast index maintenance) while utilizing transitivity information to terminate the search sooner. In addition, efficient indexing schemes and appropriate updating procedures were also introduced.
Publications
- Panagiotis Bouros, Dimitris Sacharidis, Theodore Dalamagas, Spiros Skiadopoulos and Timos Sellis:
Evaluating Path Queries over Frequently Updated Route Collections
IEEE Transactions on Knowledge and Data Engineering (TKDE), Vol 24, No 7, July 2012 - Panagiotis Bouros:
Evaluating Queries over Route Collections
Doctorate dissertation, School of Electrical and Computer Engineering, National Technical University of Athens, Greece, 2011 - Panagiotis Bouros and Yiannis Vassiliou:
Evaluating Path Queries over Route Collections
Proceedings of the PhD Workshop in conjunction with the 26th IEEE International Conference on Data Engineering (ICDE), Long Beach, California, USA, March 5, 2010 - Panagiotis Bouros, Spiros Skiadopoulos, Theodore Dalamagas, Dimitris Sacharidis and Timos Sellis:
Evaluating reachability queries over path collections
Proceedings of the 21st International Conference on Scientific and Statistical Database Management (SSDBM), New Orleans, Louisiana, USA, June 2-4, 2009 - Panagiotis Bouros, Theodore Dalamagas, Spiros Skiadopoulos and Timos Sellis:
Evaluating “Find a Path” Reachability Queries
Proceedings of the ECAI Workshop on Spatial and Temporal Reasoning (STRWS), Patras, Greece, July 22, 2008