School of Rural and Surveying Engineering

Numerous attempts have been made to generate semantic “mappings” between different ontologies, or create aligned/integrated ones. An essential step towards their success is the ability to compare the categories involved. This paper introduces a systematic methodology for comparing categories met in geographic ontologies. The methodology explores/extracts semantic information provided by categories’ definitions. The first step towards this goal is the recognition of syntactic and lexical patterns in definitions, which help to identify (a) semantic properties such as purpose, location, cover, and (b) semantic relations such as hypernym, part of, has-parts, etc. At the second step, a similarity measure among categories is applied, in order to explore how (the) extracted properties and relations interrelate. This framework enables us to (a) better understand the impact of context in cross-ontology “mappings”, (b) evaluate the “quality” of definitions as to whether they respect mere ontological aspects (such as unambiguous taxonomies), and (c) deal more effectively with the problem of semantic translation among geographic ontologies.

Traditional trip planning involves decisions made by tourists in order to explore an environment, such as a geographic area, usually without having any prior knowledge or experience with it. Contemporary technological development has facilitated not only human mobility but also has set the path for various applications to assist tourists in way-finding, event notification using location-based services etc. Our approach explores how the use of ontologies can assist tourists plan their trip, in a web-based environment. The methodology consists of building two separate ontologies, one for the users profile and another one concerning tourism information and data in order to assist visitors of an area plan their visit.

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Spatialization is a special kind of visualization that projects multidimensional data into low-dimensional representational spaces by making use of spatial metaphors. Spatialization methods face a dual challenge: on the one hand, to apply dimension reduction techniques in order to overcome the limitations of the representational space, and on the other hand, to provide a metaphoric framework for the visualization of information at different levels of granularity. This paper investigates how granularity is modeled and visualized by the existing spatialization methods, and introduces a new approach based on kernel density estimation and landscape metaphor. According to our approach, clusters of multidimensional data are revealed by landscape "relief", and are hierarchically organized into different levels of granularity through landscape "smoothness." In addition, it is demonstrated, herein, how the exploration of information at different levels of granularity is supported by appropriate operations in the framework of an interactive spatialization environment prototype. the exploration of information at different levels of granularity is supported by appropriate operations in the framework of an interactive spatialization environment prototype.

Definitions of categories in existent geospatial ontologies are an invaluable source of information because they provide us with essential knowledge about concepts and their properties. A closer examination reveals that definitions also contain supplementary linguistic items, which are mainly qualitative expressions, such as quantifiers. This inclusion of modifiers in definitions affects the way values are assigned to the categories' properties (semantic properties and relations). This paper introduces a methodology for: (1) representing the essence of qualitative information to clarify the identity relations among categories; and (2) assessing their semantic similarity in order to disambiguate the taxonomic structure of existent geospatial ontologies.

Geographic hypermedia systems include geospatial information from diverse sources. Meaningful access and utilization of such information is materialized only with semantic integration and proper documentation through ontologies. The present work presents a unified view of important research subdomains tasks related to geosemantics and ontologies, (as formal representations of geographic knowledge), such as ontology engineering, extraction of semantic information and ontology integration. Although there is a great degree of recent literature in the field, differences in (a) perspective -purpose, (b) the primary information available and (c) the methodologies and tools used, compose unrelated approaches that have not been put in the overall context. Therefore, it is extremely difficult for the wider audience to understand the difference and the applicability of available approaches in a given context. An attempt is made to draw the overall picture in order to assist users in defining their problem, selecting an appropriate approach and successfully undertaking a geosemantics or ontology-based task.

In this paper, we provide a web-based tool for building geographic ontologies. This work draws from a previously presented framework for building geographic ontologies utilizing Natural Language Understanding Semantics. Several special characteristics of geographic concepts have been tackled therein making it an appropriate framework for providing a generic ontology of geographic ontology design. The implementation process consists of two steps. The first step is to determine the generic schema of building a geographic ontology, while the second is to develop the interface where the users can build their own ontology based however on the predefined generic scheme. This tool has additional functions such as testing the ontology's consistency, assigning values to properties of geographic concepts and saving locally the ontology in OWL Full format. The current approach applies the specifications of W3C for ontology languages and tools.

Historical maps deliver valuable historical information which is applicable in several domains while they document the spatiotemporal evolution of the geographical entities that are depicted therein. In order to use the historical cartographic information effectively, the maps’ semantic documentation becomes a necessity for restoring any semantic ambiguities and structuring the relationship between historical and current geographical space. This paper examines cartographic ontologies as a proposed methodology and presents the first outcomes of the methodology applied for the historical map series «Carte de la nouvelle frontiθre Turco-Grecque» that sets the borderlines between Greece and Ottoman Empire in 1881. The map entities were modelled and compared to the current ones so as to record the changes in their spatial and thematic attributes and an ontology was developed in Protιgι OWL Editor 3.4.4 for the attributes that thoroughly define a historical map and the digitised spatial entities. Special focus was given on the Greek borderline and the changes that it caused to other geographic entities.

In this paper, we introduce the idea of documenting operational chains for land degradation assessment using ontologies. We believe that this process will help end users better understand the application domain characteristics and evaluate the results of the assessment process. Since the application domain is wide, various operational chains for land degradation assessment and their associated documentation exist, according to different options. This parameterization process causes the development of different ontologies, which nonetheless are, to a certain extent, linked because of the common software components of the corresponding operational chains. We therefore propose a hierarchical structure of these ontologies; so that several requirements such as understanding of expert knowledge interconnections and of application domain variety, documentation and assimilation of new expert knowledge, and reusability of software components become feasible.

In this paper, we examine how the notion of formalized context can be incorporated into a geographic ontology. It has been common ground that context is very crucial in Knowledge Representation [3]; however, a formal account of what context is or how it can be explicitly modeled has not yet been agreed on. On the other hand, up to now, research on generating ontologies has focused on assigning properties and their values to geographic concepts. It is also evident, that a domain ontology such as a geographic one, is context-driven.

SUMMARY This paper seeks to reveal the semantics of geospatial concepts as it can be elicited from text descriptions. So far, such an approach has dealt with the analysis of existent repositories of geographic information. Taking up with the study of the semantics of geospatial concepts, we turn to the analysis of the linguistic expressions of space and consequently of the “things” it includes. More specifically, we identify linguistic terms that people use when they locate themselves in space or when they move around it.

An important subject in geographic analysis is the representation of socioeconomic units (SEUs) on the basis of their characteristics. As a result, similarities and heterogeneities need to be revealed and portrayed accordingly. In this paper, we present a method for the analysis of a particular kind of socioeconomic units, which are the islands of the Greek archipelago. In order to facilitate the analysis but also to convey its results, SEUs are depicted using a two-dimensional “map” metaphor whose dimensions are not geographic but the dimensions of the socioeconomic analysis. The spatialization method used is multi-dimesional scaling (MDS). The resulted map can be actually considered as a cartogram for it does not preserve geographic location or topology but rather the semantic similarity of SEUs.

Spatial (and geospatial) thinking has been well studied and recognized as an important ability of humans and especially for young people and young adults, who most of the times use it subconsciously, from interpreting maps and diagrams to navigating in familiar and non-familiar environments. However, spatial thinking ability is not easy to estimate, because spatial thinking is an amalgam of different factors (e.g. spatial perception, spatial orientation, spatial visualization, mental rotation etc.). Various tests have been developed, especially from teachers and psychologists, which in their majority assess one factor of spatial thinking, either at small scales or large scales, but no test has been developed yet from researchers engaged in the Geographic Information field to assess spatial thinking in a holistic way. So, this paper underlines the need to develop such a test.