Infrastructure Engineering - Research Publications
Permanent URI for this collection
Search Results
1 - 10 of 13
-
ItemAssessment of error in digital vector data using fractal geometry(Taylor & Francis, 2000)This paper presents a new method for assessment of error in digital vector geographic data, where the features represented can be modelled closely by fractal geometry. Using example hydrological data from Ordnance Survey of Great Britain maps at a range of scales, a resolution smaller than which the digital representation of the feature does not exhibit fractal characteristics can be calculated. It is proposed that this resolution reflects the minimum ground resolution of the map, which in turn can be related to the source map scale.
-
ItemSpatial data quality capture through inductive learning(Springer Verlag (Germany), 2000)The relatively weak uptake of spatial error handling capabilities by commercial GIS companies and users can in part be attributed to the relatively low availability and high costs of spatial data quality information. Based on the well established artificial intelligence technique of induction, this paper charts the development of an automated quality capture tool. By learning from example, the tool makes very efficient use of scarce spatial data quality information, so helping to minimise the cost and maximise availability of data quality. The example application of the tool to a telecommunications legacy data capture project indicates the practicality and potential value of the approach.
-
ItemA formal approach to imperfection in geographic information(Elsevier, 2001)Traditional computational models of geographic phenomena offer no room for imperfection. Underlying this tradition is the simplifying assumption that reality is certain, crisp, unambiguous, independent of context, and capable of quantitative representation. This paper reports on initial work which explicitly recognises that most geographic information is intrinsically imperfect. Based on an ontology of imperfection the paper explores a formal model of imperfect geographic information using multi-valued logic. The development of Java software able to assist with a geodemographic retail site assessment application is used to illustrate the utility of a formal approach.
-
ItemImprecise Navigation(SpringerLink, 2003)Conventional models of navigation commonly assume a navigation agent's location can be precisely determined. This paper examines the more general case, where an agent's actual location cannot be precisely determined. This paper develops a formal model of navigation under imprecision using a graph. Two key strategies for dealing with imprecision are identified and defined: contingency and refinement. A contingency strategy aims to find an instruction sequence that maximizes an agent's chances of reaching its destination. A refinement strategy aims to use knowledge gained as an agent moves through the network to disambiguate location. Examples of both strategies are empirically tested using a simulation with computerized navigation agents moving through a road network at different levels of locational imprecision. The results of the simulation indicate that both the strategies, contingency and refinement, applied individually can produce significant improvements in navigation performance under imprecision, at least at relatively fine granularities. Using both strategies in concert produced significant improvements in performance across all granularities.
-
ItemAn algebraic approach to automated information fusion(Taylor & Francis, 2005)This paper presents a new technique for information fusion. Unlike most previous work on information fusion, this paper explores the use of instance-level (extensional) information within the fusion process. This paper proposes an algorithm that can be used automatically to infer the schema-level structure necessary for information fusion from instance-level information. The approach is illustrated using the example of geospatial land cover data. The method is then extended to operate under uncertainty, such as in cases where the data is inaccurate or imprecise. The paper describes the implementation of the fusion method within a software prototype. Finally, the paper discusses several key topics for future research, including applications of this work to spatial data mining and the semantic web.
-
ItemComputational structure in three-valued nearness relations(Springer, 2001)The development of cognitively plausible models of humanspatial reasoning may ultimately result in computational systems thatare better equipped to meet human needs. This paper explores how humansubjects perceive the qualitative spatial relation nearness within anenvironmental space. Based on experimental data, a three-valued nearnessrelation is analysed in two stages. First, the results are analysedwith special reference to the existence of subsets of candidate landmarkplaces, from which nearness relations between other places may be partiallyinferred. Second, the desirable properties of such landmark setsare considered and some of their formal properties are presented. Theseproperties are then considered in the light of the data furnished by theexperiment. The paper concludes with a discussion of the signicance ofthe analyses and the scope for further work in this area.
-
Item"Simplest" paths: automated route selection for navigation(Springer, 2003)Numerous cognitive studies have indicated that the form andcomplexity of route instructions may be as important to human navigatorsas the overall length of route. Most automated navigation systemsrely on computing the solution to the shortest path problem, and not theproblem of finding the “simplest” path. This paper addresses the issueof finding the “simplest” paths through a network, in terms of the instructioncomplexity. We propose a “simplest” paths algorithm that hasquadratic computation time for a planar graph. An empirical study ofthe algorithm’s performance, based on an established cognitive model ofnavigation instruction complexity, revealed that the length of a simplestpath was on average only 16% longer than the length of the correspondingshortest path. In return for marginally longer routes, the simplest pathalgorithm seems to offer considerable advantages over shortest paths interms of their ease of description and execution. The conclusions indicateseveral areas for future research: in particular cognitive studies areneeded to verify these initial computational results. Potentially, the simplestpaths algorithm could be used to replace shortest paths algorithmsin any automated system for generating human navigation instructions,including in-car navigation systems, Internet driving direction servers,and other location-based services.
-
ItemInformation dissemination in mobile ad-hoc geosensor networks(SPRINGER-VERLAG BERLIN, 2004)
-
ItemA formal model of obfuscation and negotiation for location privacy(Springer, 2005)Obfuscation concerns the practice of deliberately degradingthe quality of information in some way, so as to protect the privacy ofthe individual to whom that information refers. In this paper, we arguethat obfuscation is an important technique for protecting an individual’slocation privacy within a pervasive computing environment. The papersets out a formal framework within which obfuscated location-based servicesare defined. This framework provides a computationally efficientmechanism for balancing an individual’s need for high-quality informationservices against that individual’s need for location privacy. Negotiationis used to ensure that a location-based service provider receivesonly the information it needs to know in order to provide a service ofsatisfactory quality. The results of this work have implications for numerousapplications of mobile and location-aware systems, as they providea new theoretical foundation for addressing the privacy concerns thatare acknowledged to be retarding the widespread acceptance and use oflocation-based services.
-
ItemSimulation of obfuscation and negotiation for location privacy(Springer, 2005)Current mobile computing systems can automatically sense and communicatedetailed data about a person’s location. Location privacy is an urgent researchissue because concerns about privacy are seen to be inhibiting the growthof mobile computing. This paper investigates a new technique for safeguardinglocation privacy, called obfuscation, which protects a person’s location privacy bydegrading the quality of information about that person’s location. Obfuscation isbased on spatial imperfection and offers an orthogonal approach to conventionaltechniques for safeguarding information about a person’s location. Imprecisionand inaccuracy are two types of imperfection that may be used to achieve obfuscation.A set of simulations are used to empirically evaluate different obfuscationstrategies based on imprecision and inaccuracy. The results show that obfuscationcan enable high quality of service in concert with high levels of privacy.