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An indoor navigation standard must support multiple and different localization methods and infrastructures based on arbitrary indoor sensor technologies. Furthermore, the ad-hoc selection and combination of technolo-
gies used by the portable end-user device must be supported. This requires the abstraction from concrete sensor technologies in order to allow for their integrated representation in a common model.
5.1.2 Multiple and Different Modes of Locomotion
Geoinformation about the interior built environment is nowadays available through semantic 3D city and build- ing models, such as CityGML or IFC, which provide the geometry and the thematic differentiation of indoor
structures and areas. This thematic differentiation is already suitable for addressing, route descriptions, and route tracking homing, e.g. by room numbers. The derivation of navigable spaces and corresponding route networks,
however, requires further partitioning of the built indoor space according to the mode of locomotion, e.g. walk- ing, driving, and flying. Each mode of locomotion may lead to a specific and separate partitioning of indoor
topographic space into navigable and non-navigable areas. Thus, for different modes of locomotion the resulting navigable areas may be disjoint, overlapping or equal.
For example, the navigable space for persons using a wheel chair may not include areas and obstacles which are inaccessible by a wheel chair, such as stairs, steps or narrow passages. Since those areas may, however, be
accessible for pedestrians, the navigable and non-navigable spaces for different types of locomotion have to be modeled separately from each other. An indoor navigation standard must support multiple and different repre-
sentations of navigable spaces according to various modes of locomotion as well as the selection of the appropri- ate representation for the individual navigation context of a moving subject or object.
5.1.3 Logical Navigation Constraints
In addition to the mode of locomotion, the derivation of navigable route sections is also strongly affected by thematic or logical constraints and restrictions. For example, security zones or evacuation areas denote logical
spaces within buildings which influence the accessibility of indoor areas such as rooms or hallways. Navigation constraints may result from different criteria, e.g. topographicgeometric door widths, opening direction of
doors, etc., zonal security zones, fire detector areas, etc., or temporal access constraints opening hours, etc.. Although logical spaces may lead to a further partitioning of the navigable space denoted by the mode of loco-
motion, their spatial extent does not necessarily has to follow the physical built structure of the interior environ- ment. For example, a security zone may split a single room into accessible and non-accessible parts, and may
even affect outdoor areas around the building. Furthermore, navigation constraints can vary according to the individual context of navigation. For example, security staff members usually have access permission to interior
areas which are not accessible for other persons.
An indoor navigation standard has to support logical navigation constraints. They should be represented inde- pendently from the topographic interior space as changes of the interior built environment not necessarily have
an impact on their spatial extent. Finally, the context-dependent selection of navigation constraints must be supported.
5.1.4 Support for Dynamic Aspects
Logical spaces may describe temporal and dynamic phenomena, e.g. areas covered by fire detectors which temporally affect the navigable space in case of a fire emergency. An active fire detector indicates a fire incident
for its monitored area. This, however, may lead to two different navigation scenarios. The first is to navigate fire fighter forces to the fire spot, whereas the second aims as determining escape routes avoiding the dangerous area
in order to evacuate the building. As soon as the fire has been fought, the fire detector will become inactive again giving general access to its monitored area.
Such temporal restrictions in navigable space require a flexible model, especially if the temporal restriction causes ad-hoc changes of the navigation context. For example, the determination of escape routes for immediate
evacuation in case of a fire emergency may additionally require the deregulation of access restrictions due to security zones. The support of dynamic aspects and corresponding flexible models are essential requirements for
an indoor navigation standard.
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5.2 Modeling of Interior Spaces
