Abstract. This paper presents a graph-based spatial model which can serve as a reference for guiding pedestrians inside buildings. We describe a systematic approach to construct the model from geometric data. In excess of the well-known topological relations, the model accounts for two important aspects of pedestrian navigation: firstly, visibility within spatial areas and, secondly, generating route descriptions. An algorithm is proposed which partitions spatial regions according to visibility criteria. It can handle simple polygons as encountered in floor plans. The model is structured hierarchically -each of its elements corresponds to a certain domain concept ('room', 'door', 'floor' etc.) and can be annotated with meta information. This is useful for applications in which such information have to be evaluated.

Abstract. In this article we propose a hybrid spatial model for indoor environments. The model consists of hierarchically structured graphs with typed edges and nodes. The model is hybrid in the sense that nodes and edges can be labelled with qualitative as well as quantitative information. The graphs support wayfinding and, in addition, provide helpful information for generating human-oriented descriptions of an indoor (and outdoor) path.

In this paper we propose to apply hierarchical graphs to indoor navigation. The intended purpose is to guide humans in large public buildings and assist them in wayfinding. We start by formally defining hierarchical graphs and explaining the particular benefits of this approach. In the main part, we suggest an algorithm to automatically construct such a multi-level hierarchy from floor plans. The algorithm is guided by the idea to exploit domain-specific characteristics of indoor environments. Besides this, two particular problems are addressed: first, how to incorporate three-dimensional elements in the hierarchy, and second, the need for extending the hierarchy at complex geometrical regions with implicit decision points. An extended version of this paper is also available [1].