Automatic Geospatial Data Conflation Using Semantic Web Technologies

Duplicate geospatial data collections and maintenance are an extensive problem across Australia government organisations. This research examines how Semantic Web technologies can be used to automate the geospatial data conflation process. The research presents a new approach where generation of OWL ontologies based on output data models and presenting geospatial data as RDF triples serve as the basis for the solution and SWRL rules serve as the core to automate the geospatial data conflation processes

Spatial ontologies for architectural heritage

Informatics and artificial intelligence have generated new requirements for digital archiving, information, and documentation. Semantic interoperability has become fundamental for the management and sharing of information. The constraints to data interpretation enable both database interoperability, for data and schemas sharing and reuse, and information retrieval in large datasets. Another challenging issue is the exploitation of automated reasoning possibilities. The solution is the use of domain ontologies as a reference for data modelling in information systems. The architectural heritage (AH) domain is considered in this thesis. The documentation in this field, particularly complex and multifaceted, is well-known to be critical for the preservation, knowledge, and promotion of the monuments. For these reasons, digital inventories, also exploiting standards and new semantic technologies, are developed by international organisations (Getty Institute, ONU, European Union). Geometric and geographic information is essential part of a monument. It is composed by a number of aspects (spatial, topological, and mereological relations; accuracy; multi-scale representation; time; etc.). Currently, geomatics permits the obtaining of very accurate and dense 3D models (possibly enriched with textures) and derived products, in both raster and vector format. Many standards were published for the geographic field or in the cultural heritage domain. However, the first ones are limited in the foreseen representation scales (the maximum is achieved by OGC CityGML), and the semantic values do not consider the full semantic richness of AH. The second ones (especially the core ontology CIDOC – CRM, the Conceptual Reference Model of the Documentation Commettee of the International Council of Museums) were employed to document museums’ objects. Even if it was recently extended to standing buildings and a spatial extension was included, the integration of complex 3D models has not yet been achieved. In this thesis, the aspects (especially spatial issues) to consider in the documentation of monuments are analysed. In the light of them, the OGC CityGML is extended for the management of AH complexity. An approach ‘from the landscape to the detail’ is used, for considering the monument in a wider system, which is essential for analysis and reasoning about such complex objects. An implementation test is conducted on a case study, preferring open source applications

A GeoSPARQL Compliance Benchmark

We propose a series of tests that check for the compliance of RDF triplestores with the GeoSPARQL standard. The purpose of the benchmark is to test how many of the requirements outlined in the standard a tested system supports and to push triplestores forward in achieving a full GeoSPARQL compliance. This topic is of concern because the support of GeoSPARQL varies greatly between different triplestore implementations, and such support is of great importance for the domain of geospatial RDF data. Additionally, we present a comprehensive comparison of triplestores, providing an insight into their current GeoSPARQL support

A Web GIS-based Integration of 3D Digital Models with Linked Open Data for Cultural Heritage Exploration

This PhD project explores how geospatial semantic web concepts, 3D web-based visualisation, digital interactive map, and cloud computing concepts could be integrated to enhance digital cultural heritage exploration; to offer long-term archiving and dissemination of 3D digital cultural heritage models; to better interlink heterogeneous and sparse cultural heritage data. The research findings were disseminated via four peer-reviewed journal articles and a conference article presented at GISTAM 2020 conference (which received the ‘Best Student Paper Award’)

EAGLE—A Scalable Query Processing Engine for Linked Sensor Data

Recently, many approaches have been proposed to manage sensor data using semantic web technologies for effective heterogeneous data integration. However, our empirical observations revealed that these solutions primarily focused on semantic relationships and unfortunately paid less attention to spatio–temporal correlations. Most semantic approaches do not have spatio–temporal support. Some of them have attempted to provide full spatio–temporal support, but have poor performance for complex spatio–temporal aggregate queries. In addition, while the volume of sensor data is rapidly growing, the challenge of querying and managing the massive volumes of data generated by sensing devices still remains unsolved. In this article, we introduce EAGLE, a spatio–temporal query engine for querying sensor data based on the linked data model. The ultimate goal of EAGLE is to provide an elastic and scalable system which allows fast searching and analysis with respect to the relationships of space, time and semantics in sensor data. We also extend SPARQL with a set of new query operators in order to support spatio–temporal computing in the linked sensor data context.EC/H2020/732679/EU/ACTivating InnoVative IoT smart living environments for AGEing well/ACTIVAGEEC/H2020/661180/EU/A Scalable and Elastic Platform for Near-Realtime Analytics for The Graph of Everything/SMARTE

Geotriples: a tool for publishing earth observation and geospatial data as rdf graphs using the r2rml mapping language

Τα τελευταία χρόνια ένας ολοένα αυξανόμενος όγκος δεδομένων παρατήρησης γης γίνεται διαθέσιμος στην Ευρώπη και την Αμερική. Τα συνδεδεμένα δεδομένα είναι ένα μοντέλο το οποίο μελετάει τον τρόπο με τον οποίο τα δεδομένα μπορούν να γίνουν διαθέσιμα στον παγκόσμιο ιστό και να διασυνδεθούν με άλλα δεδομένα, δημιουργώντας επομένως έναν "Ιστό Δεδομένων". Ωστόσο τα δεδομένα παρατήρησης γης που διατίθενται από υπηρεσίες όπως η ESA \gt και η NASA δεν ακολουθούν το μοντέλο των συνδεδεμένων δεδομένων. Κατά συνέπεια, προκειμένου κάποιος χρήστης κάποιος χρήστης να ικανοποιήσει διαφόρου τύπου ανάγκες για πληροφορίες, θα πρέπει να συλλέξει γεωχωρικά δεδομένα και δεδομένα παρατήρησης γης από διαφορετικά σιλό. Δημοσιεύοντας τα δεδομένα των σιλό αυτών ως γράφους RDF, καθίσταται δυνατή η ανάπτυξη εφαρμογών ανάλυσης δεδομένων με μεγάλη περιβαλλοντολογική και οικονομική αξία. Στην παρούσα διπλωματική, παρουσιάζεται το εργαλείο GeoTriples για το μετασχηματισμό δεδομένων παρατήρησης γης και γεωχωρικών δεδομένων σε γράφους RDF. To GeoTriples επεκτείνει τη γλώσσα αντιστοίχησης R2RML ώστε να λάβει υπόψιν και τις ιδιαιτερότητες που παρουσιάζουν τα γεωχωρικά δεδομένα. Αποτελεί μία ημι-αυτόματη εφαρμογή για μετατροπή γεωχωρικής πληροφορίας σε RDF χρησιμοποιώντας δημοφιλή λεξιλόγια όπως GeoSPARQL και stSPARQL, χωρίς ταυτόχρονα να δεσμεύεται αποκλειστικά με κάποιο από αυτά.A plethora of Earth Observation data that is becoming available at no charge in Europe and the US recently reflects the strong push for more open Earth Observation data. Linked Data is a paradigm which studies how one can make data available on the Web and interconnect it with other data with the aim of making the value of the resulting "Web of data" greater than the sum of its parts. Open Earth Observation data that are currently made available by space agencies such as ESA and NASA are not following the linked data paradigm. Therefore, Earth Observation data and other kinds of geospatial data that are necessary for a user to satisfy her information needs can only be found in different data silos, where each silo may contain only part of the needed data. Publishing the content of these silos as RDF graphs, enables the development of data analytics applications with great environmental and financial value. In this thesis, we present the tool GeoTriples that allows for the transformation of Earth Observation data and geospatial data into RDF graphs. GeoTriples goes beyond the state of the art by extending the R2RML mapping language to be able to deal with the specificities of geospatial data. GeoTriples is a semiautomated tool that allows the publication of geospatial information into an RDF graph using the state of the art vocabularies like GeoSPARQL and stSPARQL, but at the same time it is not tightly coupled to a specific vocabulary

constructing inspire compliant ontologies for geospatial data

Ο στόχος αυτής της πτυχιακής είναι η ανάπτυξη οντολογιών για γεωχωρικά δεδομένα συμβατών με το INSPIRE, που ανήκουν στις εξής κατηγορίες του: Ελληνική Διοικητική Γεωγραφία, Δημόσιες Συγκοινωνίες, Δημόσια Κτήρια, Χρήση Γης. Το πρώτο ζήτημα, ήταν να σχεδιαστούν τέσσερις οντολογίες που περιέχουν όλες τις απαραίτητες πληροφορίες για την αναπαράσταση των δεδομένων του κάθε θέματος. Το επόμενο βήμα, ήταν να μελετηθεί κάθε υπάρχουσα οντολογία, να εισαχθεί στην αντίστοιχη του INSPIRE και να γίνουν αλλαγές και επεκτάσεις οπουδήποτε αυτό χρειαζόταν. Έπειτα από αυτή τη διαδικασία, χρησιμοποιήθηκε το εργαλείο Geotriples για τη μετατροπή των δεδομένων των shapefile σε μορφή RDF, ξανά αξιοποιώντας κάθε οντολογία. Τέλος, με σκοπό να παρουσιαστούν τα αποτελέσματα τα τέσσερα dataset αποθηκεύτηκαν στο Strabon, στον οποίο έγιναν ενδεικτικές επερωτήσεις.The objective of this thesis is to develop INSPIRE compliant ontologies for datasets that belong to the following INSPIRE themes: Greek Administrative Geography, Public Trans- port, Public Buildings and Land Use. The first task was to construct four ontologies that contain all information needed to represent data related to each of the themes. The next step was to study each existing ontology, import it to its INSPIRE equivalent and proceed to making changes or expansions wherever it was necessary. Following that process, the Geotriples tool was used to convert the shapefile data to RDF form, again using each ontology. Finally, in order to demonstrate the results the four datasets have been stored in the spatiotemporal RDF store Strabon, and indicative queries where performed against each dataset

Spatial ontologies for architectural heritage

Informatics and artificial intelligence have generated new requirements for digital archiving, information, and documentation. Semantic interoperability has become fundamental for the management and sharing of information. The constraints to data interpretation enable both database interoperability, for data and schemas sharing and reuse, and information retrieval in large datasets. Another challenging issue is the exploitation of automated reasoning possibilities. The solution is the use of domain ontologies as a reference for data modelling in information systems. The architectural heritage (AH) domain is considered in this thesis. The documentation in this field, particularly complex and multifaceted, is well-known to be critical for the preservation, knowledge, and promotion of the monuments. For these reasons, digital inventories, also exploiting standards and new semantic technologies, are developed by international organisations (Getty Institute, ONU, European Union). Geometric and geographic information is essential part of a monument. It is composed by a number of aspects (spatial, topological, and mereological relations; accuracy; multi-scale representation; time; etc.). Currently, geomatics permits the obtaining of very accurate and dense 3D models (possibly enriched with textures) and derived products, in both raster and vector format. Many standards were published for the geographic field or in the cultural heritage domain. However, the first ones are limited in the foreseen representation scales (the maximum is achieved by OGC CityGML), and the semantic values do not consider the full semantic richness of AH. The second ones (especially the core ontology CIDOC – CRM, the Conceptual Reference Model of the Documentation Commettee of the International Council of Museums) were employed to document museums’ objects. Even if it was recently extended to standing buildings and a spatial extension was included, the integration of complex 3D models has not yet been achieved. In this thesis, the aspects (especially spatial issues) to consider in the documentation of monuments are analysed. In the light of them, the OGC CityGML is extended for the management of AH complexity. An approach ‘from the landscape to the detail’ is used, for considering the monument in a wider system, which is essential for analysis and reasoning about such complex objects. An implementation test is conducted on a case study, preferring open source applications

A Brokering Approach to Federating Spatial Data in a Semantic Web Environment

This thesis proposes a broker approach to federate Australia and New Zealand’s spatial data using Semantic Web technologies and ontologies. The proposed approach improves the current methods of integrating and accessing spatial data in Australia and New Zealand by enabling on-demand access to concurrent data, removing the need for a data warehouse to maintain and store the integrated data, and allowing the semantic reconciliation of heterogeneous spatial datasets