Abstract. Navigation services communicate optimal routes to users by providing sequences of instructions for these routes. Each single instruction guides the wayfinder from one decision point to the next. The instructions are based on geometric data from the street network, which is typically the only dataset available. This paper addresses the question of enriching such wayfinding instructions with local landmarks. We propose measures to formally specify the landmark saliency of a feature. Values for these measures are subject to hypothesis tests in order to define and extract landmarks from datasets. The extracted landmarks are then integrated in the wayfinding instructions. A concrete example from the city of Vienna demonstrates the applicability and usefulness of the method. 1

The integration of information of different kinds, such as spatial and alphanumeric at different levels of detail, is a challenge. While a solution is not reached, it is widely recognized that the need to integrate information is so pressing that it does not matter if detail is lost, as long as integration is achieved. This paper shows the potential for information retrieval at different levels of granularity inside the framework of information systems based on ontologies. Ontologies are theories that use a specific vocabulary to describe entities, classes, properties and functions related to a certain view of the world. The use of an ontology, translated into an active information system component, leads to Ontology-Driven Information Systems and, in the specific case of GIS, leads to what we call Ontology-Driven Geographic Information Systems.

. In multi-resolution data handling, a less detailed structure is often derived from a more detailed one by amalgamating elements which are indistinguishable at the lower level of detail. This gathering together of indistinguishable elements is called a granulation of the more detailed structure. When handling spatial data at several levels of detail the granulation of graphs is an important topic. The importance of graphs arises from their widespread use in modelling networks, and also from the use of dual graphs of spatial partitions. This paper demonstrates that there are several quite different kinds of granulation for graphs. Four kinds are described in detail, and situations where some of these may arise in spatial information systems are indicated. One particular kind of granulation leads to a new formulation of the boundary-sensitive approach to qualitative location developed by Bittner and Stell. Vague graphs and their connection with granulation are also discusse...

…for its continued progress in building a culture of regional cooperation and decision-making to increase the quality of life of member nations, The development of a Regional Spatial Data Infrastructure (Regional SDI) is much more challenging than the development of a National SDI initiative within a nation. This is mainly because of the voluntary nature of cooperation at a multi-national level and participation in a Regional SDI initiative. As a result, despite considerable interest and activities, the development of an effective and comprehensive Asia-Pacific Regional Spatial Data Infrastructure (APSDI) is hampered by a lack of support from member nations which results in this initiative remaining only an innovative concept. Based on this situation, the aim of this research is to design an improved conceptual model for Regional SDI and an implementation strategy. It is proposed that this problem can be partly addressed by increasing the level of awareness about the nature and value of SDIs; improving the SDI conceptual model to better meet the needs of nations; and by identifying key factors that facilitate development by better understanding the

Qualitative formalisms, suited to express qualitative temporal or spatial relationships between entities, have gained wide acceptance as a useful way of abstracting from the real world. The question remains how to describe spatio temporal concepts, such as the interaction between disconnected moving objects, adequately within a qualitative calculus and more specifically how to use this in geographical information systems. In this paper, the Basic Qualitative Trajectory Calculus (QTCB) for representing and reasoning about moving objects is presented. QTCB enables comparisons between positions of objects at different time points to be made. The calculus is based on few primitives (i.e., distance and speed constraints), making it elegant and theoretically simple. To clarify the way in which trajectories are represented within QTCB, specific cases of movements (e.g. circular movement) are presented. To illustrate the naturalness of QTC, a “predator-prey” example is studied.

Abstract. Wayfinding in road networks is a hierarchical process. It involves a sequence of tasks, starting with route planning, continuing with the extraction of wayfinding instructions, and leading to the actual driving. From one task level to the next, the relevant road network becomes more detailed. How does the wayfinding process change? Building on a previous, informal hierarchical highway navigation model and on graph granulation theory, we are working toward a theory of granularity transformations for wayfinding processes. The paper shows the first results: a formal ontology of wayfinding at the planning level and an informal model of granularity mappings.

Formal specifications are difficult to read.Executable specifications allow to see the behavior of the specified objects and help the domain specialist to detect errors quickly. We present here a method which allows to write axiomatic specifications which can be executed and discuss the limitations in expressive power imposed by the restriction to constructive axioms and how it can be circumvented. The method results from practical efforts to formalize the meaning of object types for Geographic Information Systems. If such data are shared betweenorganisations, differences in the semantics become apparent and formal methods for their definition become necessary. Most formal methods are based on first order languages. Software engineering often uses algebraic methods, but tools practically used for data exchange standard definitions are restricted to signatures and do not capture the behavior of the operations. We present here an algebraic approach using a functional programming language...

Abstract: This paper introduces a practical approach to constructing a hybrid 3D metrical–topological model of a university campus or other extended urban region from labeled 2D floor plan geometry. An exhaustive classification of adjacency types is provided for a typical

The tool we use influences the product. This paper demonstrates that higher order functions are a necessary tool for research in the GIS area, because higher order functions permit to separate the treatment of attribute data from the organisation of processing in data structures. Higher order functions are functions which have functions as arguments. A function to traverse a data structure can thus have as an argument a function to perform specific operations with the attribute data stored. This is crucial in the GIS arena, where complex spatial data structures are necessary. Higher order functions were tacitly assumed for Tomlin's Map Algebra. The lack of higher order functions in the design stage of GIS and in the implementation is currently most felt for visualization, where the problems of the interaction between the generic computer graphics solutions and the particulars of the application area preclude advanced solutions, which combine the best results from both worlds. Similar ...

Abstract. Map Algebra is a collection of functions for handling continuous spatial data, which allows modeling of different problems and getting new information from the existing data. There is an established set of map algebra functions in the GIS literature, originally proposed by Dana Tomlin. However, the question whether his proposal is complete is still an open problem in GIScience. This paper describes the design of a map algebra that generalizes Tomlin’s map algebra by incorporating topological and directional spatial predicates. Our proposal enables operations that are not directly expressible by Tomlin’s proposal. One of the important results of our paper is to show that Tomlin’s Map Algebra can be defined as an application of topological predicates to coverages. This paper points to a convergence between these two approaches and shows that it is possible to develop a foundational theory for GIScience where topological predicates are the heart of both object-based algebras and field-based algebras. 1.