POSITION _ I am an associate professor at the Department of Geography and Geoinformation Science, George Mason University, USA.

EMPLOYMENT _ I received a PhD degree in Computer Science from Aalborg University, Denmark in 2000 and a degree in Information Systems (Magister) from Johannes Kepler Universität (JKU) Linz, Austria. I had the privilege to work as a research assistant at Department of Spatial Information Science and Engineering, University of Maine, USA (1996-97), assistant professor at the Department of Computer Science, Aalborg University, Denmark (2000-02), a researcher at the Computer Technology Institute, Greece (2002-2008), and a senior researcher and head of the Geoinformatics dept. at IMIS, Research Center “ATHENA” in Athens, Greece (2008-2012).

RESEARCH _ My research has addressed various aspects of spatial database research as well as related areas such as computational geometry and transportation research. He produced theoretical research results as well as practical work that are now used in actual applications and products. His early work focused on spatiotemporal databases and specifically on the modeling of such data as well as query optimization including indexing. He developed a spatiotemporal index, the TB-tree for trajectory data and a framework for capturing the uncertainty related to trajectory data and on query processing for moving objects’ data.
Later, the focus of his work shifted towards data management for fleet management applications. The main result was a robust map-matching algorithm that translated large amounts of vehicle-tracking data to travel times. Additional work addressed data management techniques that allow for a live assessment of the traffic situations in urban areas as well as a shortest-path algorithm that exploits network hierarchies. This technology was commercialized and is currently used in fleet management products.
Recent work addresses user-generated geospatial content, i.e., how to exploit geospatial data sets generated by Web users (point cloud data, travel blogs). This domain is tightly coupled with language processing problems, i.e., how do users express spatial relationships in natural language terms, and data fusion, i.e., how to integrate and improve the quality of user-generated data.

PUBLICATIONS _ My research has been documented in more than 90 articles in international journals and refereed conferences attracting more than 3400 citations based on Google Scholar.

SCIENTIFIC SERVICE _ I have served on many program committees, organized conferences and workshops (organizer: GEOCROWD workshops 2013 and 2012, pc co-chair – ACM GIS 2004 and SSTD 2011, W2GIS 2014, MDM demo chair 2008, SIGMOD publicity chair 2011) and acted as a reviewer for the NSF, the Swiss National Science Foundation, the Icelandic Center for Research, the Research Grants Council, Hong Kong, China, the European Commission and the European Research Council (ERC).

PROJECTS _ Over the years my research has been supported by DOD, GMU, the European Commission and the Greek General Secretariat of Science and Technology.