=Paper=
{{Paper
|id=Vol-2088/paper6
|storemode=property
|title=Geospatial Data Integration and Visualisation Using Linked Data
|pdfUrl=https://ceur-ws.org/Vol-2088/paper6.pdf
|volume=Vol-2088
|authors=Weiming Huang,Ali Mansourian,Lars Harrie,Sebastian Hunger,Azimjon Sayidov,Robert Weibel,Kiran Zahra
|dblpUrl=https://dblp.org/rec/conf/agile/Huang17
}}
==Geospatial Data Integration and Visualisation Using Linked Data==
https://ceur-ws.org/Vol-2088/paper6.pdf
Geospatial data integration and visualisation using Linked Data
Weiming Huang Ali Mansourian Lars Harrie
GIS Centre, Department of GIS Centre, Department of GIS Centre, Department of
Physical Geography and Physical Geography and Physical Geography and
Ecosystem Science, Lund Ecosystem Science, Lund Ecosystem Science, Lund
University University University
Sölvegatan 12, 223 62 Sölvegatan 12, 223 62 Sölvegatan 12, 223 62
Lund, Sweden Lund, Sweden Lund, Sweden
weiming.huang@nateko.lu.se ali.mansourian@nateko.lu.se lars.harrie@nateko.lu.se
Abstract
Geospatial data are increasingly available nowadays, and this leads to more analyses and visualisation of geospatial data from several
sources. To enable this, we need homogenous data as well as proper integration methods. Geospatial data integration has been a long-
standing research topic for decades, and this paper discusses the utilisation of Linked Data technology stack to alleviate the geospatial
data integration, particularly in the multi-scale context. Furthermore, this paper also discusses the possibilities of incorporating
symbolisation information in Linked Data along with the integrated linked geospatial data for visualisation.
Keywords: geospatial data integration; multi-scale; Linked Data; visualisation; symbolisation.
1 Introduction web map), the thematic data are usually simply
overlaid on the top of a base map without explicit
The rapid development of the Internet, together links and integration. However, the scales of the
with the incentives from legislation, commence, thematic data and the base map are generally not
and the open data trend, has led to the improvement synchronised because unlike the thematic layer, the
of the availability of geospatial data, including both base map is usually a multi-scale map from an
the authoritative geospatial data accessible from authoritative mapping agency and has multiple
governmental Spatial Data Infrastructures (SDIs) representations (for details, see Huang et al., 2016).
and the prevalent Volunteered Geographic In this context, the Semantic Web technologies,
Information (VGI). For example, in Europe, the particularly the ones concerning Linked Data,
INSPIRE1 directive formulated that in a few years’ provide a promising technical framework to ease
time, several authorities that are responsible for the integration and linking between geospatial data.
creating and maintaining geospatial data are obliged “Linked Data” is the term for the collection of
to set up download services to facilitate the access design principles and technologies centred around a
and sharing of geospatial data. The substantial paradigm to publish, retrieve, reuse, and integrate
improvement of data availability will enable cross- data on the Web (Kuhn et al. 2014). The adoption
data set analysis and visualisation, in which the and application of Linked Data in the geospatial
integration of geospatial data from different sources community have developed considerably in recent
is indispensable. years. A number of geospatial data sets have been
The productions of geospatial data from different released as Linked Data, and some of them have
sources are generally isolated, and this causes the made up an indispensable portion in the linking
syntactic and semantic heterogeneity that are two open data (LOD) cloud (The Linking Open Data
significant obstacles for geospatial data integration. cloud diagram, 2017; Figure 1). On the other hand,
Furthermore, the links between multi-source the visualisation and symbolisation of linked
geospatial data that are of relevance are often geospatial data has been rarely exploited, and it is
lacking. The absence of links between data sets even trickier in a multi-scale context. Hence, this
impedes the integration of geospatial data for project mainly concentrates on investigating the
visualisation and analysis, and this impediment is integration and visualisation of multi-source
especially significant in a multi-scale environment. geospatial data utilising the Linked Data technology
For example, in a map mashup (a common form of stack, in particular in a multi-scale context. The
AGILE PhD school 2017
following research questions will be addressed Data integration is a long-standing research theme
Figure 1. The central part of LOD cloud of November, 2017
within the work: in the geospatial domain where geometric,
• How to organise geospatial data in different topological as well as semantic information are
scales in Linked Data, the design of unique resource used (see e.g. , Walter and Fritch 1999, Du et al.
identifiers and ontologies is important to link the 2012, Yang et al. 2014). With a few exceptions
multiple representations of each geographic object; (e.g., Mustière and Devogele. 2008), these studies
• How to establish the links between different have concentrated on the integration of data of
geospatial Linked Data sets, particularly in a multi- similar levels of detail.
scale context; In the abovementioned environment of map
• How the links between data sets can be utilised mashup, in which multi-source geospatial data are
for the synchronisation of scales between multi- generally simply overlaid together without any
source geospatial data sets; links established between each other, the
• How the linked geospatial data sets should be integration usually is about multi-scale data sets.
visualised and symbolised, namely how the Stern and Sester (2013) studied mashups of natural
symbolisation information should be defined and protected areas on top of a base map, where the
organised, and on which level (feature level, feature protected areas often have common geometries with
collection level, etc.) it should be defined. the base map. To overcome the problem of
• How the linked geospatial data sets would inconsistencies in the multi-scale representation,
benefit the SDI. they argued that the base map should act as
constraints for generalising the thematic data.
2 Related work Toomanian et al. (2013) used Semantic Web
technologies to integrate multi-source data in map
2.1 Geospatial data integration using Linked mashups. They defined the semantic relationships
Data between feature types in the thematic data and the
base map in the map mashups using ontologies.
AGILE PhD school 2017
These semantic relationships were then used to of multi-scale geospatial data sets has been rarely
enable real-time adjustment of the thematic features explored, and this is the focus of this project.
to the base map.
Linked Data technology has been adopted to 2.2 Visualisation of geospatial linked data
facilitate geospatial data integration in some other
The linked geospatial data are situated at rather
studies. For instance, Wiemann and Bernard (2016)
central places in the LOD because geospatial and
investigated possibilities for the integration of SDI
location data often serve as nexus and linkage
and Linked Data paradigm in terms of spatial data
between different data items and sets (Janowicz,
integration. They implemented a prototype system
2012). However, the portrayal and symbolisation of
where the spatial relationships were explored by the
linked geospatial data have been seldom discussed.
OGC Web Processing Service (WPS) and then
When it comes to the visualisation of linked
explicitly and separately stored using Linked Data,
geospatial data, the providers of such data generally
including the information of involved features,
use external styling service or hard-coded
relationship types and conducted relationship
symbolisation parameters. The LinkedGeoData
measurements. Lutz et al. (2009) addressed a
(LGD) project which released OpenStreetMap
hybrid ontology-based solution for overcoming the
(OSM) data in Linked Data used separate renderer
semantic heterogeneity in SDI. They designed a
service where the symbolisation rules are settled to
shared vocabulary on top of which the application
render the LGD data (Stadler et al. 2012). The
ontologies were designed, then they used the
GeoNames2 has an online portal in which the
ontology reasoner (DL query) to identify the
entities can be shown on the top of either a digital
subsumption relationships between concepts, thus
base map or satellite images; the entities are simply
the corresponding concepts in different
shown as labels with numerical signs or bounding
classification systems were recognised; they also
boxes with uniform symbology. In these cases, the
used semantic annotations to label the data services
portrayal information is not explicit and can be
to enable the data requestor to use a tailored
hardly reused by the users or other organisations
language to retrieve data. The tailored language was
which are interested in the geospatial data in RDF
then translated into DL query and subsequently the
and the visualisation of the data.
WFS requests were invoked.
There have been some studies using ontologies to
In the framework of Linked Data technology,
organise and semantically annotate the symbology
some techniques have been extended in order to
information in Linked Data. For example, the OGC
improve the handling of linked geospatial data. For
(Open Geospatial Consortium) explored semantic
example, SPARQL, as the query protocol for RDF,
mediation of portrayal information of geospatial
has a standardised geospatial extension –
data using ontology in their testbed 11 and 12
GeoSPARQL (Perry and Herring, 2011).
(Fellah, 2015; 2017). They designed symbology
GeoSPARQL also provides an ontology as a
ontologies during the testbeds, and the ontologies in
standardised exchange basis for geospatial RDF
testbed 11 was more inclined to the ISO 19117
data (Battle and Kolas, 2012) and this has been
standard (Kresse and Fadaie, 2004) and the
adopted in several studies in which the geospatial
ontology in testbed 12 was better aligned to
data sets are published as Linked Data and linked to
Symbology Encoding (SE; Müller, 2006) and
other data sets. For example, Patroumpas et al.
Styled Layer Descriptor (SLD; Lupp, 2007). In
(2015) exposed the INSPIRE-compliant data and
outline, the ontologies that they developed were
metadata as Linked Data by transforming them into
modularised to avoid huge-sized ontology and
the data model of resource description framework
foster the reusability, specifically the vocabulary
(RDF) using XSLT transformations and then
was modularised into style ontology, symbol
exposing them through (Geo)SPARQL endpoints,
ontology, symbolizer ontology and graphic
they adopted the GeoSPARQL ontology for the
ontology. However, there still very few study
geometric representation of their RDF data sets.
concerning how the symbolisation information
These technical advances enable the geospatial data
should be associated with geospatial information in
to be linked and referenced. However, the linking
the LOD cloud, and how the multi-scale
AGILE PhD school 2017
symbolisation should be arranged if the data are in The PhD study of the Weiming Huang at GIS
several different levels of detail. Centre, Lund University is jointly funded by China
Scholarship Council (CSC) and Lund University.
3 Method
Notes
The Linked Data technology will be leveraged in
this project. Specifically, the data will be 1.https://inspire.ec.europa.eu/
constructed upon their connections with the 2.http://www.geonames.org/
reference data sets. For example, the natural
protected areas are generally defined by their
connections with other geographic objects (e.g., Reference
river, lake, road, etc.). Assuming that the reference
geospatial data that have the topographic and Abele, A., McCrae, J.P., Buitelaar, P., Jentzsch, A.
cadastral objects are released in Linked Data, then and Cyganiak, R. (2017) Linking open data cloud
the natural protected areas can be defined upon their diagram 2017 [online]. Available from: http://lod-
relations with the objects in base map, and the cloud.net/ [accessed 15 February 2017]
scales between the reference data and the thematic
data that are built upon the reference data can be Battle, R. and Kolas, D. (2012) Enabling the
automatically synchronised. Several case studies geospatial semantic web with parliament and
will be performed to verify the feasibility of the GeoSPARQL. Semantic Web, 3(4), 355-370.
approach. In addition to this, the symbolisation
information of both thematic and reference data will Du, H., Anand, S., Alechina, N., Morley, J., Hart,
also be incorporated into the Linked Data sets to G., Leibovici, D., Jackson, M. and Ware, M. (2012)
enable tailored visualization. The symbolisation of Geospatial information integration for authoritative
thematic data also can be dependent on the styling and crowd sourced road vector data. Transactions
or other information in reference data. in GIS, 16 (4), 455–476.
To realise this idea, we need:
• Multiple representation databases that are released Fellah, S. (ed.) (2015) OGC Testbed-11 Symbology
as Linked Data to serve as reference data sets, the Mediation Engineering Report, Open Geospatial
GeoSPARQL can be employed to act as vocabulary Consortium.
for geometries; and the design of URI still needs to
be explored; Fellah, S. (ed.) (2017) Testbed-12 Semantic
• Ontologies that define the formal semantics of the Portrayal, Registry and Mediation Engineering
relations between thematic and reference data, these Report, Open Geospatial Consortium.
can be extended from GeoSPARQL;
• Ontologies that define the styling information of Huang, W., Harrie, L. and Mansourian, A. (2016).
linked geospatial data, some concepts from SE and On-demand mapping and integration of thematic
SLD can serve as reference; data. In ICA Workshop on Generalisation and
• A mechanism for generating thematic data from Multiple Representation, 14 June, Helsinki,
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