ReQuLGD: Representation and Querying for Linked Geospatial Data


Tutorial at the 16th International Semantic Web Conference 2017

The Web of data has recently been populated with linked geospatial data as various geospatial data sources have been transformed into RDF and added to the linked data cloud (e.g., Geonames, Open Street Map, CORINE land cover etc.). Therefore, it is important to study how to represent geospatial data in RDF and how to query it using SPARQL. Researchers from the areas of Semantic Web and Linked Data have studied theses problems recently. The results of this research has been the development of geospatial extensions of RDF and SPARQL, and the implementation of geospatial RDF stores. In this tutorial, we present a comparative survey of current research in this area and point to directions for future work.

Tutorial Overview 

This is a half-day tutorial and will be held on Saturday, October 21st,  in the afternoon. A brief overview is provided below:
Part 1 Introduction
Part 2: Data models and query languages for linked geospatial data. We survey the recent geospatial extensions of RDF and SPARQL concentrating on the OGC standard GeoSPARQL and our own language stSPARQL. We also discuss proposals for geospatial Ontology Based Data Access (OBDA) with more emphasis on the OBDA framework of our system Ontop-spatial. Finally, we discuss the problem of querying incomplete geospatial information expressed using Semantic Web standards. 

Part 3: Implemented Systems. In this part of the tutorial, we present systems for storing and querying linked geospatial data. We distinguish these implementations into two categories: geospatial RDF stores and geospatially-enabled OBDA systems. We will describe the architectures of the surveyed systems and we will compare them in terms of functionality and performance. Demos of Strabon and Ontop-spatial will also be given by the presenters. 
Part 4: Open issues. This last part of this tutorial will be dedicated to the discussion of open issues. We will point out open problems in the area of data models and query languages, and we will discuss how we can improve the performance of GeoSPARQL query engines, both native and OBDA. For the latter problem, we will discuss how state-of-the-art approaches in the area of big geospatial data, and big RDF data query processing can be used to improve the performance of existing GeoSPARQL query engines. 


Tutorial material 

  • Github repository  with examples (software, datasets, etc.) that will be used in the tutorial. 

The slides for each part of the tutorial will be availalble soon in this section. 



References:

  • Open Geospatial Consortium. GeoSPARQL - A geographic query language for RDF data. OGC Candidate Implementation Standard, 2012.
  •  M. Koubarakis and K. Kyzirakos. Modeling and Querying Metadata in the Semantic Sensor Web: The Model stRDF and the Query Language stSPARQL. In Proceedings of the 7th Extended Semantic Web Conference, volume 6088 of LNCS, pages 425–439. Springer, 2010.
  • K. Kyzirakos, M. Karpathiotakis, and M. Koubarakis. Strabon: A Semantic Geospatial DBMS. In Proceedings of the 11th International Semantic Web Conference, volume 7649 of LNCS, pages 295–311. Springer, 2012.
  • C. Nikolaou and M. Koubarakis. Querying incomplete information in RDF with SPARQL. Artificial Intelligence, 237:138 – 171, 2016. K. Bereta and M. Koubarakis. Ontop of Geospatial databases. In Proceedings of the 15th International Semantic Web Conference, Kobe, Japan, October 17–21, pages 37–52. Springer International Publishing, 2016.
  • S. Br¨uggemann, K. Bereta, G. Xiao, and M. Koubarakis. Ontology-Based Data Access for Maritime Security. In Proceedings of the 13th Extended Semantic Web Conference, Heraklion, Crete, Greece, May 29 - June 2, 2016, pages 741–757, 2016
  •  D. Calvanese, G. De Giacomo, D. Lembo, M. Lenzerini, A. Poggi, and R. Rosati. Ontology-based Database Access. In Proceedings of the Fifteenth Italian Symposium on Advanced Database Systems, SEBD 2007, 17-20 June 2007, Torre Canne, Fasano, BR, Italy, pages 324–331, 2007.
  • G. Garbis, K. Kyzirakos, and M. Koubarakis. Geographica: A Benchmark for Geospatial RDF stores (long version). In Proceedings of the 12th International Semantic Web Conference, volume 8219 of Lecture Notes in Computer Science, pages 343–359. Springer, 2013.


Presenters


Manolis Koubarakis is a Professor in the Dept. of Informatics and Telecommunications, National and Kapodistrian University of Athens. He is a EurAI fellow. He previously held positions at the Dept. of Electronic and Computer Engineering , Technical University of Crete (Assistant and Associate Professor), the Dept. of Informatics, University of Athens (Visiting Researcher), the Dept. of Computation, UMIST(now University of Manchester) (Lecturer) and the Dept. of Computing, Imperial College, London (Research Associate). He has published more than 170 papers that have been widely cited in the areas of Artificial Intelligence (especially Knowledge Representation), Databases, Semantic Web and Linked Data. He previously held positions at the Dept. of Electronic and Computer Engineering , Technical University of Crete (Assistant and Associate Professor), the Dept. of Informatics, University of Athens (Visiting Researcher), the Dept. of Computation, UMIST(now University of Manchester) (Lecturer) and the Dept. of Computing, Imperial College, London (Research Associate). He currently teaches the following university courses: Artificial Intelligence, Knowledge Technologies and Data Structures and Programming Techniques. His research has been funded by the European Commission, the Greek General Secretariat for Research and Technology and industry sources.

Konstantina Bereta is a research associate at the Management of Data, Information and Knowledge group, in the Dept. of Informatics and Telecommunications, National and Kapodistrian University of Athens. She is also a PhD candidate under the supervision of prof. Manolis Koubarakis and holds a BSc. and MSc. from the same department. She has worked as a scientific programmer and research associate in several EU FP7 projects. Her research interests focus in the areas of spatiotemporal databases, Semantic Web and Cloud Computing. She is the developer of Ontop-spatial, a geospatial extension of the system Ontop, which is currently the most efficient OBDA solution for geospatial information.