Introduction

Various location-based indoor applications, such as indoor navigation, indoor car parking and indoor emergency response, are increasingly involved in daily lives and the management of public buildings. These applications need information on indoor features (such as floors, rooms, doors and windows) and their spatial associations to describe the environment inside a building. Accordingly, many application systems and related standards have been developed in recent years.

OGC CityGML 3.0^[⁴^] is designed as a universal information model that defines object types and attributes which are useful for a broad range of applications. For the building model, CityGML focuses on the semantic definitions of buildings and their parts (e.g. walls, roofs, dormers, doors, windows, etc.) and the representation of the relations between those features. However, CityGML does not specify strict rules as to which semantic objects have to be included in a specific Level of Detail (LoD) model.^[⁷^] Although the CityGML model can be extended by the Application Domain Extension (ADE) mechanism by adding new object types or new properties for specific applications, it is possible to specify different ADEs for different information communities. Every ADE may add their specific properties to the same CityGML feature type as they can all belong to the same substitution group.^[⁶^] These CityGML feature types can also have the problem of semantic heterogeneity in sharing and intergrading datasets.

OGC IndoorGML 1.1^[⁴^] defines the representation and exchange of indoor navigation network models. It aims to establish a common schema for indoor navigation applications by modelling the topology and semantics of indoor spaces, which are needed for the components of navigation networks.^[²^] An IndoorGML document contains external links to referenced objects specified in other data sets such as CityGML and IFC (Industry Foundation Classes), where the objects in the external data set include geometric information.^[²^]

The Industry Foundation Classes (IFC) (ISO 16739‑1), an open international standard for Building Information Model (BIM) data, provide detailed 3D geometries and rich semantics to describe architectural components and engineering constructions of buildings. IFC aims to cover the whole project lifecycle, i.e. the "plan", "design", "construct", "operate" and "maintain" phases of buildings with more than 600 classes in different categories. However, IFCs contain too much architectural information and are too complex to be used in their current format for indoor emergency situations.^[¹¹^] It is not necessary to use all these classes for a specific application such as indoor navigation.^[⁹^] However, some information on the architectural components and engineering constructions of buildings defined in IFC can be extracted to describe the attributes of indoor features used in location-based indoor applications to describe indoor spatial environments to help people to implement their works or plans efficiently.

ISO/TS 19166 provides a conceptual framework for mapping BIM to Geographic Information Systems (GIS) with three mapping mechanisms, Perspective Definition (B2GPD), Element Mapping (B2GEM) and LOD Mapping (B2GLM). It focuses on the definition of BIM to GIS conceptual mapping requirements and framework without a bi-directional mapping method and the definition of physical schema. It cannot be used directly to guide which indoor features are to be extracted from BIM to describe indoor environments for location-based indoor applications. Different information communities can set different rules for the mapping from BIM to GIS and then produce GIS databases with different indoor features for the same building. This would make the sharing and integration of databases difficult.

OGC Indoor Mapping Data Format (IMDF)^[⁵^] provides a generalized, yet comprehensive model for any indoor location, providing a basis for orientation, navigation and discovery (19-089r1). IMDF mainly focuses on the contents of individual indoor features related to navigation issues and does not define a general structure of these indoor elements to cover the relationship between indoor spaces or features.

Therefore, a relatively independent and concise indoor feature model is needed for describing the required features of an indoor spatial environment for location-based indoor applications such as indoor navigation, indoor addressing, indoor car parking and indoor emergency response. This model could provide a common reference to guide the collection and organization of indoor spatial information, and serve as the foundation of a conceptual model for data mapping and sharing among various application systems.

This document defines such an indoor feature model by following the rules of application schema defined in ISO 19109. A dataset compliant with this document can serve as the common basic database in various location-based (LBS) indoor applications and facilitate data sharing and integrating among different platforms or applications. This document can be beneficial in reducing the overlapping efforts in the production of the basic database of buildings, and it can also be useful in the transfer of indoor-application platforms or systems with little adjustments from one building to another building based on the common basic database. The intention is for various stakeholders (including indoor data producers and users of location-based indoor application systems) to have a unified understanding of these features for the unambiguous retrieval of information.

Based on this document, a series of profiles can be specified for various location-based indoor applications for example, a profile for indoor navigation or way-finding by linking with a geometric and topological relationship specified in IndoorGML, or a profile for a fire emergency by adding the features related to firefighting emergency utilities.

This document provides two informative annexes to present the class-level referenced relationship between the Indoor Feature Model and BuildingModel of CityGML 3.0, IFC of ISO 16739‑1 and IndoorGML.

BS EN ISO 19164:2024

Geographic information. Indoor feature model

Current

Published:

31 Aug 2024