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Today's mobile artificial agents, such as mobile robots, are based on an object-oriented paradigm. They partition their environment into various objects and act in relation to individual properties of these objects. Such perception and acting is insufficient for goal-directed behavior in dynamic environments, which requires action-relevant information in the form of affordances. Affordances describe action possibilities with respect to a specific agent. In this paper, we propose a functional model for affordance-based agents. This model integrates an adjusted version of the HIPE theory of function and an extended theory of affordances. We demonstrate the applicability of the functional model by relating it to two different cases of mobile robot interaction and outline an affordance-oriented robot architecture. [ABSTRACT FROM AUTHOR]

Following a similar method to that of Mark and Egenhofer (1994), a questionnaire-based experiment tested for possible effects of scale, context and spatial relation type on the acceptability of spatial prepositions. The results suggest that the previous assumption of scale invariance in spatial language is incorrect. The physical world as experienced by humans, and described by human language, is not a fractal: scale appears to change its very physical nature, and hence the meaning of its spatial relations. The experiment demonstrated how scale influences preposition use, and how different preposit-ions appeared to evoke different levels of acceptability in themselves. Context, in terms of object type (solid or liquid), interacted with these factors to demonstrate specific constraints upon spatial language use. The results are discussed in terms of figure-ground relations, as well as the role of human experience and the classification of the world into 'objects' in different ways at different scales. Since this was a preliminary and artificially-constrained experiment, the need for further research is emphasized. [ABSTRACT FROM AUTHOR]

Similarity measurement is currently being established as a method to explore content on the Semantic Web. Semantically annotated content requires formal concept specifications. Such concepts are dynamic and their semantics can change depending on the current context. The influence of context on similarity measurement is beyond dispute and reflected in recent similarity theories. However, the systematics of this influence has not been investigated so far. Intuitively, the results of similarity measurements should change depending on the impact of the current context. Particularly, such change should converge to 0 with a decreasing impact of the respective contexts. To hold up to this assertion, a quantification of the impact of context on similarity measurements is required. In this paper, we use a combination of the SIM-DL theory, which measures similarity between concepts represented using description logic, and a context model distinguishing between internal and external context to quantify this impact. The behavior of similarity measurements within an ontology specifying geospatial feature types is observed under varying contexts. The results are discussed with respect to the corresponding impact values. [ABSTRACT FROM AUTHOR]

Geographic information is based on observations or measurements. The Open Geospatial Consortium (OGC) has developed an implementation specification for observations and measurements (O&M). It specifies precisely how to encode information. Yet, the O&M conceptual model does not specify precisely which real-world entities are denoted by the specified information objects. We provide formal semantics for the central O&M terms by aligning them to the foundational ontology DOLCE. The alignment to a foundational ontology restricts the possible interpretations of the central elements in the O&M model and establishes explicit relations between categories of real world entities and classes of information objects. These relations are essential for assessing semantic interoperability between geospatial information sources. [ABSTRACT FROM AUTHOR]

Recent advances in Internet technologies, coupled with wide adoption of the web services paradigm and interoperability standards, makes the World Wide Web a popular vehicle for geo-spatial information distribution and online geo-processing. Web GIS is rapidly evolving and adapting to advances in Internet technologies. Web GISes are predominantly designed under a "thin-client / fat-server" paradigm. This approach has several disadvantages. For example, as the number of users increases, the load on the server increases and system performance decreases. Recently the focus has been shifted towards client-side Web GISes, which are heavy-duty, stand-alone systems. We take an opposing approach and present a load balancing client/server Web-based spatial analysis system, UMN-MapServer, and evaluate its performance in a regional natural resource mapping and analysis (NRAMS) application which utilizes biweekly AVHRR imagery and several other raster and vector geo-spatial datasets. We also evaluate alternative approaches and assess the pros and cons of our design and implementation. UMN-MapServer also implements several open standards, such as, WMS, WCS, GML and WFS. In this paper, we also describe in detail the WMS, WCS,and GML extensions from the interoperability point of view, and discuss issues related to adoption of such standards. Keywords: WebGIS, WMS, WMT, GML, WFS, Load-balancing Architecture. [ABSTRACT FROM AUTHOR]

There are many situations in GIScience where it would be useful to be able to assign a region to characterize the space occupied by a set of points. Such a region should represent the location or configuration of the points as an aggregate, abstracting away from the individual points themselves. In this paper, we call such a region a ‘footprint' for the points. We investigate and compare a number of methods for producing such footprints, with respect to nine general criteria. The discussion identifies a number of potential choices and avenues for further research. Finally, we contrast the related research already conducted in this area, highlighting differences between these existing constructs and our ‘footprints'. [ABSTRACT FROM AUTHOR]

Several representations have been created to store topological information in normal spatial databases. However, not that much work has been done to store such relationships for spatiotemporal data. This paper extends the representation of moving objects from [7] so that it can also store and enforce some of the topological relationships between the objects. This is done in a fashion similar to the Node-Arc-Area model for normal spatial databases. One use of such a rep resentation is storing a changing spatial partition. [ABSTRACT FROM AUTHOR]

It is difficult to generate raster Digital Elevation Models (DEMs) from terrain mass point data sets too large to fit into memory, such as those obtained by LIDAR. We describe prototype tools for streaming DEM generation that use memory and disk I/O very efficiently. From 500 million bare-earth LIDAR double precision points (11.2 GB) our tool can, in just over an hour on a standard laptop with two hard drives, produce a 50,394 × 30,500 raster DEM with 20 foot post spacing in 16 bit binary BIL format (3 GB), using less than 100 MB of main memory and less than 300 MB of temporary disk space. [ABSTRACT FROM AUTHOR]

In an earlier paper we introduced Anchoring, a new approach for handling indeterminate location in a spatial information system. Here we develop it further, showing how Anchoring can be made to work in real systems. In particular, we specify a new kind of locational component for a spatial data model. We then show how that component can be implemented into an object-relational database with extensions conforming to the OpenGIS Consortium's Simple Feature Model. We argue that Anchoring, in contrast to other formalisms for handling indeterminate location, is better suited to the needs of a spatial data provider who, in supplying data to different organisations, needs to be authoritative, and thus does not want to compromise data quality by representing indeterminate data with unwarranted precision. Anchoring, in providing new ways to describe spatiality, allows that we state only what we know for certain. [ABSTRACT FROM AUTHOR]

Points are dimensionless geometric elements often employed by geographic information systems to model a range of real-world objects such as people and vehicles. Many analytical tools have been developed for finding and validating certain patterns of static points such as clustering. In this paper, we present our preliminary efforts to develop statistical methods for analyzing patterns of moving points whose locations are tracked at equal intervals of time. Focus is placed on simple descriptive statistics—rather than more sophisticated inferential statistics—useful for detecting a tendency of two or more points to move in some coordinated fashion. A major implication of this paper is that statistical analysis complements spatial data query and modeling with respect to dynamics of sets of point-like objects in a way that potentially interrelated subsets are screened. [ABSTRACT FROM AUTHOR]

Querying heterogeneous spatial databases involves not only characterizing and comparing the information content of several databases, but also navigating or accessing the data sets with the query answer. This work proposes a formalism that relates the information content of data sets by three basic types of correspondence relations: data equivalence, difference of data omission, and difference of data commission. These correspondence relations define the information space over which a navigation process is carried out. Based on a complete or an incomplete information space, this work proposes strategies that optimize the retrieval process of information coming from different databases. The results of this study show the advantages of defining the information space to select and access databases. In particular, strategies that estimate the information contribution of data sets based on correspondence relations outperform a strategy that considers a random list or a list of data sets sorted by size. [ABSTRACT FROM AUTHOR]

Large amounts of cheap and easily deployable wireless sensors enable area-wide monitoring of both urban environments and inhospitable terrain. Due to the random deployment of these sensor nodes, one of the key issues is their position determination. Noisy distance measurements and the highly limited resources of every sensor node, due to tiny hardware and small battery capacity, demand the development of robust, energy aware, and precise localization algorithms. We believe this can be achieved by appropriately distributing the complex localization task between all participating nodes. Therefore, we use a linearization tool to linearize the arising non-linear system of equations into a linear form that can be solved by a distributed least squares method. It is shown in this paper that we can save with this new approach more than 47% of computation cost whilst maintaining a low network traffic. Additionally, we describe memory optimizations to process the complex matrix operations with only a few kilobyte of memory on the sensor node. [ABSTRACT FROM AUTHOR]

This paper explores the spatial aspects of GIS-based multi-criteria evaluation. We provide a systematic account of geographically defined decision criteria based on three classes of spatial relations: location, proximity, and direction. We also discuss whether the evaluation score of a decision alternative should be directly influenced by neighbouring scores and outline a methodology for distance-based adjustment of evaluation scores. A home buyer case study is employed to demonstrate how spatial criteria can be included in a spatial decision support system and to investigate the effect of geographically adjusting the evaluation scores of decision alternatives. The case study demonstrates how spatial criteria can be presented to decision-makers and their effects be observed in the decision outcome. Further, the spatial adjustment of evaluation scores using the performance of neighbouring properties smoothes the distribution of scores across the study area and allows decision-makers to consider a location's environment. Keywords: Multi-Criteria Evaluation, Residential Real-Estate Choice, Spatial Decision Support Systems, Spatial Relations. [ABSTRACT FROM AUTHOR]

Urban multi-criteria optimized route guidance by considering unspecified site satisfaction, an extended type of urban multi-objective optimized route selection, called as both NP-Hard problems and one of the branches of multi-criteria shortest path problems (MSPP). It is not only suggests a route based on route guidance principles and optimized due to routing criteria but also passes through all unspecified site(s) such as gas stations, banks determined by drivers. By proposing a novel approach on the bases of route guidance navigation system principles, virus theory (viral infection and local/site infection) and by GIS and GA utilization, this paper is come up to rate of search improvement in urban multi-criteria optimized route guidance by considering unspecified site satisfaction on real network with multiple dependent criteria. Tests of route selection for a part of north-west of Tehran traffic network are conducted and the results show the efficiency of the algorithm and support our analyses. Keywords: GIS, Network analysis, Multi-criteria shortest path problem, Multi objective Genetic algorithm. [ABSTRACT FROM AUTHOR]

Complex systems theory and Cellular Automata (CA) are widely used in geospatial modeling. However, existing models have been limited by challenges such as handling of multiple datasets, parameter definition and the calibration procedures in the modeling process. Bayesian network (BN) formalisms provide an alternative method to address the drawbacks of these existing models. This study proposes a hybrid model that integrates BNs, CA and Geographic Information Systems (GIS) to model land use change. The transition rules of the CA model are generated from a graphical formalism where the key land use drivers are represented by nodes and the dependencies between them are expressed by conditional probabilities extracted from historical spatial datasets. The results indicate that the proposed model is able to realistically simulate and forecast spatio-temporal process of land use change. Further, it forms the basis for new synergies in CA model design that can lead to improved model outcomes. [ABSTRACT FROM AUTHOR]

Directed line segments are fundamental geometric elements used to model through their spatial relations such concepts as divergence, confluence, and interference. A new model is developed that captures spatial relations between pairs of directed line segments through the intersections of the segments' heads, bodies, and tails. This head-body-tail intersection identifies 68 classes of topological relations between two directed line segments highlighting two equal-sized subsets of corresponding relations that differ only by their empty and non-empty body-body intersections. The relations' con-ceptual neighborhood graph takes the shape of a torus inside a torus, one for each subset. Another 12 classes of topological relation classes are distinguished if the segments' exteriors are considered as well, lining up such that their conceptual neighborhood graph forms another torus that contains the other two tori. These conceptual neighborhoods as well as the relations' composition table enable spatial inferences and similarity assessments in a consistent and reasoned manner. [ABSTRACT FROM AUTHOR]

The query for retrieving the rank of all neighbors of a moving object at any given time, a continuous rank query, is an important case of continuous nearest neighbor (CNN) queries. An application for ranking queries is given by an ambulance driver who needs to keep track of the closest hospitals at all times. We present a set of incremental algorithms that facilitate efficient rank updates for some or all neighbors of a moving query point. The proposed algorithms allow us not only to maintain the exact rank of all n neighbors at any given time but also to track the rank of a subset of all neighbors. We show that updates for these continuous rank queries can be performed in linear time for arbitrary polygonal curves in two dimensions and in logarithmic time for movements along a fixed direction. Instead of using Voronoi diagrams, our algorithms are based on small subsets of all bisectors between neighbors. We prove that it is sufficient to keep track of only n-1 bisectors for all n neighbors. The algorithms for maintaining the rank only require minimal incremental updates on the bisector sets. [ABSTRACT FROM AUTHOR]

We are aiming for semantic representations of route descriptions for dialogues between a driver and the Bremen intelligent wheelchair Spatial Cognition Rolland, integrating qualitative orientation calculi with RouteGraphs. Relative orientations, and the algebraic properties of the inverse and full complement operations, are the basis for specifying properties of orientations between directed edges between locations. 8 orientations at the entry and the exit of an edge are then used to define the relations of variants of the Double-Cross Calculus with 8 and 12 orientations, resp. With an additional predicate "at" a location, we then define all 15 relations. Edges are related to route segments with orientation functions at entries and exits. The inherent origin orientation at a place is then used to solve the place integration problem when joining individual routes into Route Graphs. Finally, some abstract predicates for route descriptions such as "via", "pass by", etc., are defined in terms of these calculi. [ABSTRACT FROM AUTHOR]

The paper will introduce into the subject of recognition of typical patterns in road networks. Especially we will describe the search for ring structures and its implementation in detail. Applications to detect these patterns and to use them for eliciting additional implicit knowledge in vector data are shown. We will familiarise the reader with different methods and approaches for the automatic detection of those patterns in vector data. The retrieval of implicit information in vector data can be very helpful for many tasks, ranging from generalisation of maps to the spatial analysis and enrichment of GIS data to make it searchable by search engines. [ABSTRACT FROM AUTHOR]

Acquisition and semantic annotation of data are fundamental tasks within the domain of cultural heritage. With the increasing amount of available data and ad hoc cross linking between their providers and users (e.g. through web services), data integration and knowledge refinement becomes even more important. To integrate information from several sources it has to be guaranteed that objects of discourse (which may be artifacts, events, persons, places or periods) refer to the same real world phenomena within all involved data sources. Local (database) identifiers however only disambiguate internal data, but fail in establishing connections to/between external data, while global identifiers can only partially solve this problem. Software assistants should support users in establishing such connections by delivering identity assumptions, i.e. by estimating whether examined data actually concerns the same real word phenomenon. This paper points out how similarity measures can act as groundwork for such assistants by introducing a similarity-based identity assumption assistant for historical places to support scholars in establishing links between distributed historical knowledge. [ABSTRACT FROM AUTHOR]

In this paper we present an approach to providing landmark-based routes using a shortest-path algorithm. We start from the assumption, that at one junction there can be several landmarks to choose among, in order to find an optimal description of a route. The landmark selection used for describing the route is optimized taking the quality measures for the landmarks into account. Therefore, it is necessary to define quality measures. In the paper different types of quality measures are introduced and their integration in the route graph, as well as in a routing algorithm is presented. The usability of the approach is demonstrated using test data. [ABSTRACT FROM AUTHOR]

In this paper, a qualitative shape representation is described for the purpose of characterising linear geographical and artificial objects. In particular, we focus on the curve progression telling us how objects spread across the landscape. For instance, sinuosities of rivers provide important information about imperilled locations in the case of flood waters. However, precise geometrical descriptions are overdetermined and frequently difficult or sometimes impossible to obtain. By contrast, we introduce a concept which allows curves to be classified on the basis of a qualitative representation that defines properties of linear objects, which derive from how segments of objects are located relative to other segments, arriving at conclusions such as how twisty a curve is. Especially, the new method can be applied if only coarse information is available and even then if objects are given incompletely. [ABSTRACT FROM AUTHOR]

Voronoi diagrams are widely used to represent geographical distributions of information, but they are not readily stacked in a hierarchical fashion. We propose a simple mechanism whereby each index Voronoi cell contains the generators of several Voronoi cells in the next lower level. This allows various processes of indexing, paging, visualization and generalization to be performed on various types of data. While one-level Voronoi indexes have been used before, and hierarchies of the dual Delaunay triangulation have been used for fast point location, we believe that this is the first time that the advantages of their integration have been demonstrated. [ABSTRACT FROM AUTHOR]

A GIS coordinator for a U.S. city complains about data sharing metadata with a single word: "headaches." He underscores the function of metadata in supporting the process of finding a collective understanding of what the data can be reliably used for. In John Searle's philosophical work on social reality, this coordinator articulates the struggle to create and maintain the status functions and collective intentionality required for successful data sharing. Each technical solution to data sharing can fail to ensure that the meaning of the shared data is understood. Data sharing must move one rung higher and become information sharing, which requires the collective recognition of status functions and the creation of collective intentionality. Integral to successful information sharing is the creation of an environment of trust that ensures that function recognition occurs. In this paper I examine cases that highlight trust as a measure of status function recognition. [ABSTRACT FROM AUTHOR]

Landmarks support the structuring of environmental information into cognitive conceptual units, they have the potential to identify uniquely pertinent intersections for route following, and they disambiguate spatial situations at complex intersections. Not using them in automatically generated route directions is a violation of cognitive ergonomics. While we have made great progress on the one hand in characterizing and on the other hand in mining potential landmarks, viable data structures that incorporate their cognitive conceptual functions in route directions are poorly developed. The present article closes this gap by providing a representation based on the OpenLS standard that allows for capturing the semantics of landmarks. In this data structure, the cognitive conceptual essence of a landmark is represented allowing for generating route directions automatically and imbuing street network data with cognitively meaningful elements. [ABSTRACT FROM AUTHOR]

Mesh-based terrain representations provide accurate descriptions of a terrain, but fail in capturing its morphological structure. The morphology of a terrain is defined by its critical points and by the critical lines joining them, which form a so-called surface network. Because of the large size of current terrain data sets, a multi-resolution representation of the terrain morphology is crucial. Here, we address the problem of representing the morphology of a terrain at different resolutions. The basis of the multi-resolution terrain model, that we call a Multi-resolution Surface Network (MSN), is a generalization operator on a surface network, which produces a simplified representation incrementally. An MSN is combined with a multi-resolution mesh-based terrain model, which encompasses the terrain morphology at different resolutions. We show how variable-resolution representations can be extracted from an MSN, and we present also an implementation of an MSN in a compact encoding data structure. [ABSTRACT FROM AUTHOR]

Safeguarding location privacy is becoming a critical issue in location-based services and location-aware computing generally. Two drawbacks of many previous models of location privacy are: 1) the models only consider a person's location privacy protection, but not the invasion of location privacy by external agents; and 2) the models are static and do not consider the spatiotemporal aspects of movement. We argue that, to be complete, any model of location privacy needs to enable the analysis and identification of techniques both to protect and to invade an individual's location privacy over time. One way to protect an individual's location privacy is to minimize the information revealed about a person's location, termed obfuscation. This paper presents an explicitly spatiotemporal model of location privacy that models a third party's limited knowledge of a mobile individual's location. We identify two core strategies that a third party can use to refine its knowledge, so potentially invading that mobile individual's location privacy. A global refinement strategy uses the entire history of knowledge about an agent's location in a single step. A local refinement strategy iteratively constructs refined knowledge over time. We present a formal model of global and local refinement operators, and show how this formal model can be translated into a computational model in a simulation environment. [ABSTRACT FROM AUTHOR]

This paper presents a model for positional relations among bodies of arbitrary shape in three dimensions. It is based on an existing model for projective relations among regions in two dimensions. The motivation is to provide a formal qualitative spatial relations model for emerging 3D applications. Two sets of relations are defined: ternary projective relations based on the concept of collinearity between a primary object and two reference objects and quaternary projective relations based on the concept of coplanarity between a primary object and three reference objects. Four sets of JEPD relations are defined for points and bodies in R3. [ABSTRACT FROM AUTHOR]

The research presented in this paper introduces a graph-based and computational modelling approach that derives a social network and computes its emerging spatial and thematic properties from the semantics embedded in a series of Web pages. We apply several local and global graph-based operators, and complement them with thematic, spatial and similarity operators. This allows us to infer the degree of correlation between the different properties of the network. The approach is applied to the study of the GIS research communities as exemplified by the International COSIT and GIScience conferences. Keywords: graph analysis, semantic space, social networks, GIScience, web communities. [ABSTRACT FROM AUTHOR]

Determining the grade of semantic similarity between geospatial concepts is the basis for evaluating semantic interoperability of geographic information services and their users. Geometrical models, such as conceptual spaces, offer one way of representing geospatial concepts, which are modelled as n-dimensional regions. Previous approaches have suggested to measure semantic similarity between concepts based on their approximation by single points. This paper presents a way to measure semantic similarity between conceptual regions—leading to more accurate results. In addition, it allows for asymmetries by measuring directed similarities. Examples from the geospatial domain illustrate the similarity measure and demonstrate its plausibility. [ABSTRACT FROM AUTHOR]

Measuring semantic similarity among concepts is the core method for assessing the degree of semantic interoperability within and between ontologies. In this paper, we propose to extend current semantic similarity measures by accounting for the spatial relations between different geospatial concepts. Such integration of spatial relations, in particular topologic and metric relations, leads to an enhanced accuracy of semantic similarity measurements. For the formal treatment of similarity the theory of conceptual vector spaces—sets of quality dimensions with a geometric or topologic structure for one or more domains—is utilized. These spaces allow for the measurement of semantic distances between concepts. A case study from the geospatial domain using Ordnance Survey's MasterMap is used to demonstrate the usefulness and plausibility of the approach. [ABSTRACT FROM AUTHOR]

Wayfinding is a basic activity people do throughout their entire lives as they navigate from one place to another. In order to create different spaces in such a way that they facilitate people's wayfinding it is necessary to integrate principles of human spatial cognition into the design process. This paper presents a methodology to structure space based on experiental patterns, called image schemata. It integrates cognitive and engineering aspects in three steps: (1) interviewing people about their spatial experiences as they perform a wayfinding task in the application space, (2) extracting the image schemata from these interviews and formulating a sequence of subtasks, and (3) structuring the application space (i.e., the wayfinding task) with the extracted image schemata. We use wayfinding in airports as a case study to demonstrate the methodology. Our observations show that most often image schemata are correlated with other image schemata in the form of image-schematic blocks and rarely occur in isolation. Such image-schematic blocks serve as a knowledge-representation scheme for wayfinding tasks. [ABSTRACT FROM AUTHOR]