Publication of spatial data as Linked Open Data

Abstract

For many years, issues associated with sharing of public information have been one of the major topics. The initiatives undertaken all over the world, with the purpose of providing governmental data – including spatial data – have proven that there are significant benefits from the opening of these resources. The fact that more and more governments start to make efforts to “liberate” their data is the best proof. Open Data, or in this case more precisely – Open Government Data are the initiatives for sharing data with the society in such forms that it can be used freely and without restrictions. This means that data is published on open licenses and with the use of open standards. It enables potential users to create new services and products, for example useful applications or services based on published spatial data, which can provide a stimulus for economy and business. In the age of social media, it is also a way for data verification, which can improve its quality. But the essence of publishing Open Data is not only the use of open standards, but also providing data which can be not only human readable but also machine readable. This approach is based on and strictly connected with Semantic Web technologies and it is called Linked Data. Publishing open data by means of Linked Data has gained the name of Linked Open Data (LOD).
Publishing spatial data in LOD cloud involves meeting few requirements, known as the principles of creating Linked Open Data. Firstly, the data must be published on open license, ensuring that the data can be used without restrictions. Secondly, the data must be in structured representations. Thirdly, it must be published with the use of open standards, for example WKT instead of Shapefile. Moreover, it must be possible to represent the data with the use of RDF (Resource Description Framework) model and every entity within the data set must have a unique URI identifier. Last but not least, it is important to link newly published resources with the other by creating relations between them. Linked Open Data technologies consist of data representation model RDF, query language SPARQL, URI identifiers and ontology modeling languages OWL and RDFS. With the use of these technologies a new approach to spatial data representation, acquisition, integration and discovery emerges. Although the technologies connecting this approach with spatial data are still immature, the Linked Open Data enters the field of geomatics. The actions undertaken in many countries around the world prove that publishing and providing governmental spatial data as Open Data is crucial and is undoubtedly beneficial for the economy. However, there is a strong need to initiate this great change, especially in the way of thinking, which appears to be the biggest obstacle and difficulty.