An Ontology Integrating the Open Standards of City Models and Internet of Things for Smart-City Applications

Smart city applications integrate the human, physical, and digital systems in a built environment with Internet of Things (IoT) resources, city models, and domain models. However, existing methods for the integration are suitable for individual applications and lack interoperability among application modules. This study analyzed existing integration strategies and developed an ontology for integrating the data modeling standards of the Open Geospatial Consortium (OGC) CityGML, IndoorGML, and SensorThings API. To cope with the broad definition of 'things' in the IoT, the proposed ontology supports multiple views of things, including the a-building-as-a-thing, a-room-as-a-thing, an-opening-as-a-thing, and a-device-as-a-thing views. Thus, the proposed ontology relates information from these three standards and supports semantic queries. We demonstrated the proposed solution in smart home, smart security, smart health care, and fire evacuation systems. Overall, the proposed solution can facilitate the integration of standard-based IoT resources and city models to support smart city applications.