E. Stefanakis | The University of New Brunswick (original) (raw)

Papers by E. Stefanakis

Lecture Notes in Computer Science, 2005

Nowadays new applications ask for enriching the semantics associated to geographical information ... more Nowadays new applications ask for enriching the semantics associated to geographical information in order to support a wide variety of tasks including data integration, interoperability, knowledge reuse, knowledge acquisition, knowledge management, spatial reasoning and many others. Examples of such semantic issues are temporal and spatio-temporal data management, 3D manipulation, spatial granularity and multiple resolutions, multiple representations (providing different perspectives of

Proceedings 14th International Conference on Data Engineering, 1998

The join query is one of the fundamental operations in Data Base Management Systems (DBMSs). Mode... more The join query is one of the fundamental operations in Data Base Management Systems (DBMSs). Modern DBMSs should be able to support non-traditional data, including spatial objects, in an efficient manner. Towards this goal, spatial data structures can be adopted in order to support the execution of join queries on sets of multidimensional data. This paper introduces analytical models that estimate the cost (in terms of node or disk accesses) of join queries involving two multidimensional indexed data sets using R-tree-based structures. In addition, experimental results are presented, which show the accuracy of the analytical estimations when compared to actual runs on both synthetic and real data sets. It turns out that the relative error rarely exceeds 15% for all combinations, a fact that makes the proposed cost models useful tools for efficient spatial query optimization.

Abstract. Content Management Systems [1] are widely used in web sites and portals lately, promoti... more Abstract. Content Management Systems [1] are widely used in web sites and portals lately, promoting collaboration among groups of users. Collaboration applies to many fields and storytelling in the Web is one of them. When a group of users can contribute into telling a ...

International Journal of Geographical Information Science, 1999

ABSTRACT

Proceedings of the 23rd International …, 2007

... Emmanuel Stefanakis 1 and Poulicos Prastacos 2. ... scope of these standards and specificatio... more ... Emmanuel Stefanakis 1 and Poulicos Prastacos 2. ... scope of these standards and specifications is to enable an application developer to use any geospatial content (data and services) available on the net within a single environment and a single workflow (McKee and Buehler ...

... 5. Data quality: It is a measure of the quality of data collected to ... of entities, the com... more ... 5. Data quality: It is a measure of the quality of data collected to ... of entities, the completeness and logical consistency among data elements, and the temporal information assigned ... geographic entities (eg, Greece should be accompanied by the national anthem, several pictures ...

The methods used in commercial GIS packages for both the representation and analysis of geographi... more The methods used in commercial GIS packages for both the representation and analysis of geographic data are inadequate, because they do not handle uncertainty. This leads to information loss and inaccuracy in analysis with adverse consequences in the spatial decision-making process. The incorporation of fuzzy set methodologies into a DBMS repository for the application domain of GIS should be beneficial and will improve its level of intelligence. Focusing on this direction the paper addresses both a representation and a reasoning issue. Specifically, it extends a general spatial data model to deal with the uncertainty of geographic entities, and shows how the standard data interpretation operations available in GIS packages may be extended to support the fuzzy spatial reasoning. Representative geographic operations, such as the fuzzy overlay, fuzzy distance and fuzzy select, are examined, while a real world situation involving spatial decision making is presented.