Geospatial Semantics

Geospatial Semantics Yingjie Hu GSDA Lab, Department of Geography, University of Tennessee, Knoxville, TN 37996, USA

Abstract Geospatial semantics is a broad field that involves a variety of research areas. The term semantics refers to the meaning of things, and is in contrast with the term syntactics. Accordingly, studies on geospatial semantics usually focus on understanding the meaning of geographic entities as well as their counterparts in the cognitive and digital world, such as cognitive geographic concepts and digital gazetteers. Geospatial semantics can also facilitate the design of geographic information systems (GIS) by enhancing the interoperability of distributed systems and developing more intelligent interfaces for user interactions. During the past years, a lot of research has been conducted, approaching geospatial semantics from different perspectives, using a variety of methods, and targeting different problems. Meanwhile, the arrival of big geo data, especially the large amount of unstructured text data on the Web, and the fast development of natural language processing methods enable new research directions in geospatial semantics. This chapter, therefore, provides a systematic review on the existing geospatial semantic research. Six major research areas are identified and discussed, including semantic interoperability, digital gazetteers, geographic information retrieval, geospatial Semantic Web, place semantics, and cognitive geographic concepts.
Keywords: geospatial semantics, semantic interoperability, ontology engineering, digital gazetteers, geographic information retrieval, geospatial Semantic Web, cognitive geographic concepts, qualitative reasoning, place semantics, natural language processing, text mining, spatial data infrastructures, location-based social networks

1. Introduction The term semantics refers to the meaning of expressions in a language, and is in contrast with the term syntactics. For example, the two expressions “I love GIS” and “I ❤ GIS” have clearly different syntactics; however, they have close, if not the same, semantics. Geospatial semantics adds the adjective geospatial in front of semantics, and this addition both restricts and extends the initial applicable area of semantics. On one hand, geospatial semantics focuses on the expressions that have a connection with geography rather than any general expressions; on the other hand, geospatial semantics enables studies on not only linguistic expressions but also the meaning of geographic places, geospatial data, and the GeoWeb.

Yingjie Hu (2017). Geospatial Semantics. In Bo Huang, Thomas J. Cova, and Ming-Hsiang Tsou et al. (Eds): Comprehensive Geographic Information Systems, Elsevier. Oxford, UK. http://dx.doi.org/10.1016/B978-0-12- 409548-9.09597-X 2    While geospatial semantics is a recognized subfield in GIScience (Agarwal, 2005; D. Mark, Egenhofer, Hirtle, & Smith, 2000), it also involves a variety of related research areas. Kuhn (2005) defines geospatial semantics as “understanding GIS contents, and capturing this understanding in formal theories.” This definition can be divided into two parts: understanding and formalization. The understanding part triggers the question: who is supposed to understand the GIS content, people or machines? When the answer is “people”, research in geospatial semantics involves human cognition of geographic concepts and spatial relations (Egenhofer & Mark, 1995; Golledge, 2002; B. Smith & Mark, 2001); whereas when the answer is “machines”, it can involve research on the semantic interoperability of distributed systems, digital gazetteers, and geographic information retrieval (Y. Bishr, 1998; F. T. Fonseca, Egenhofer, Agouris, & Câmara, 2002; Goodchild & Hill, 2008; Harvey, Kuhn, Pundt, Bishr, & Riedemann, 1999; C. B. Jones & Purves, 2008). The second part of the definition proposes to capture this understanding through formal theories. Ontologies, as formal specifications of concepts and relations, have been widely studied and applied in geospatial semantics (Couclelis, 2010; Frank, 2001; Pundt & Bishr, 2002; Visser, Stuckenschmidt, Schuster, & Vögele, 2002), and formal logics, such as first-order logic (Russell, Norvig, Canny, Malik, & Edwards, 2003) and description logics (Hitzler, Krotzsch, & Rudolph, 2009), are often employed to define the concepts and axioms in an ontology. While Kuhn’s definition includes these two parts, research in geospatial semantics is not required to have both– one study can focus on understanding, while another one examines formalization. Advances in computer and information technologies, especially the Web, have greatly facilitated geospatial semantic research. With the Semantic Web initially proposed by Berners-Lee, Hendler, and Lassila (2001), Egenhofer (2002) envisioned the Geospatial Semantic Web which is able to understand the semantic

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