Abstract
The level of detail (LoD) concept in CityGML (City Geography Markup Language), which indicates how closely the model mirrors its real-world counterpart, has been accepted and applied widely in various applications, including the 3D modeling of buildings. However, with an increasing number of human activities occurring in the indoor environment, the standardized LoD definition appears to be insufficient because of its narrow classifications for interior features, which can be presented only in LoD4. In view of this drawback, an extended indoor LoD (ILoD) specification is proposed, particularly for indoor spaces, allowing the existing LoD to become a more precise outdoor LoD (OLoD) by exploiting the advantages of two other international standards: Industry foundation classes (IFC) and IndoorGML. In this paper, the interior space is divided into distinct systems of three semantic aspects (structure, connectivity, and volume); the approach can be considered the guiding ideology to define the detailed indoor levels following a concrete theoretical realization based on extending the UML diagram of CityGML’s building model. Moreover, a continuous and seamless full LoD (FLoD) set obtained by combining various OLoDs and ILoDs is subsequently listed to realize the full specification for 3D building models. Furthermore, to demonstrate the proposed specification and prove the applicability of the building model at different LoDs, a practical experiment is conducted.
Highlights
Since the first geographic information system (GIS) was developed in the 1960s [1], such systems have been widely adopted and popularized in numerous fields, such as heritage preservation, location selection, land management, energy monitoring, and traffic navigation [2,3,4,5,6,7]
The research studies have typically focused on outdoor modeling, with the rapid development of computer-network and mobile-telephone technologies, indoor modeling has rapidly gained more interests from researchers and developers worldwide
Certain common technologies and concepts of outdoor modeling can be used for the interior, e.g., the level of detail (LoD), which can be traced back to October 1976, when James H
Summary
Since the first geographic information system (GIS) was developed in the 1960s [1], such systems have been widely adopted and popularized in numerous fields, such as heritage preservation, location selection, land management, energy monitoring, and traffic navigation [2,3,4,5,6,7]. LoD3 denotes the most detailed architectural exterior shell, potentially including openings (doors and windows) Interior structures, such as rooms, furniture, or installations, are appended into LoD4 with the same outer appearances as those of the LoD3 models. We propose an improved full LoD specification for building models combining indoor and outdoor scenes to meet the requirements of various applications. To achieve this goal, we first strip the LoD4 from the original LoD definition in CityGML and propose an indoor LoD concept for the interiors of 3D building models based on the application domain extension (ADE) mechanism [19].
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