Design and Development of a Web Based Application for Location Based, Semantic Search and Retrieval

Search, discovery, and prioritizing important places and facilities is a vital requirement of users in urban environments. Over the past twenty years, web mapping applications have been continuously improving to better proffer location based services to users. A considerable part of users’ search in web mapping application can be addressed by simple distance-based spatial search. However, there are cases where, in order to properly address user requirements, web mapping applications need to consider not only simple spatial criteria but also spatial relationships. Additionally, current web is moving towards machine readable and machine understandable contents through semantic web. Semantic web provides standards and technologies for machines to be capable of understanding documents on the web. Meanwhile, the amount of spatial data that is published on the web is rapidly growing. These data are faced with problems such as diversity, heterogeneity, incompleteness, and therefor are not well prepared for retrieval and utilization. Description of spatial data using semantic web concepts is a solution to most of the mentioned problems. Currently, different standardization organizations in geospatial community are working on development of required standards for semantic spatial data. GeoSPARQL, a semantic query language, is a standard developed to query and retrieve semantically described spatial information over the web. In order to enable citizens to search and recommend urban facilities, this study developed a web mapping application. In this application, GIS and semantic web technologies are integrated to enhance the performance of the system. Search and discovery based on simple geometric relations, topological relationships, spatial operators, semantic relations and descriptive characteristics of features are implemented in the system. The system implements semantic web technologies, ontology, Open World Assumption and spatio-semantic query language. GeoSPARQL ontology is used to define a RDF/OWL vocabulary for representing spatial objects and querying topological and non-topological relations. QallMe ontology is used to define concepts related to the tourism industry including urban facilities. In this system, interests and needs of citizens are considered as well. There are two executive routines in the system, including data entry and query handling. In the data preparation phase, spatial characteristics and attribute information of urban service centers from various sources are gathered and converted to a semantic representation based on the application ontologies. This semantic representation is saved in Parliament triple store. Having the data prepared in the triple store, a user can access the system through a web based user interface and search for required facilities or places within the city. The query is transformed to GeoSPARQL Select queries afterward and executed on the triple store. The responses are presented to the user on a map, developed by Google Maps APIs. In order to demonstrate the feasibility of the developed application, two usage scenarios are thoroughly implemented and described. The implementation results in spatial software comparing the developed application show the general adequacy of the system. Additionally, diversity, heterogeneity and incompleteness problems of spatial information on the web have decreased to a significant extent. The developed system helps citizens to find urban facilities accurately and efficiently.