Infrastructure Engineering - Theses
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ItemAnalysis of the positional accuracy of linear features.( 2006-09)Although the positional accuracy of spatial data has long been of fundamental importance in GIS, it is still largely unknown for linear features. This is compromising the ability of GIS practitioners to undertake accurate geographic analysis and hindering GIS in fulfilling its potential as a credible and reliable tool. As early as 1987 the US National Center for Geographic Information and Analysis identified accuracy as one of the key elements of successful GIS implementation. Yet two decades later, while there is a large body of geodetic literature addressing the positional accuracy of point features, there is little research addressing the positional accuracy of linear features, and still no accepted accuracy model for linear features. It has not helped that national map and data accuracy standards continue to define accuracy only in terms of “well-defined points”. This research aims to address these shortcomings by exploring the effect on linear feature positional accuracy of feature type, complexity, segment length, vertex proximity and e-scale, that is, the scale of the paper map from which the data were originally captured or to which they are customised for output. The research begins with a review of the development of map and data accuracy standards, and a review of existing research into the positional accuracy of linear features. A geographically sensible error model for linear features using point matching is then developed and a case study undertaken. Features of five types, at five e-scales, are selected from commonly used, well-regarded Australian topographic datasets, and tailored for use in the case study. Wavelet techniques are used to classify the case study features into sections based on their complexity. Then, using the error model, half a million offsets and summary statistics are generated that shed light on the relationships between positional accuracy and e-scale, feature type, complexity, segment length, and vertex proximity. Finally, auto-regressive time series modelling and moving block bootstrap analysis are used to correct the summary statistics for correlation. The main findings are as follows. First, metadata for the tested datasets significantly underestimates the positional accuracy of the data. Second, positional accuracy varies with e-scale but not, as might be expected, in a linear fashion. Third, positional accuracy varies with feature type, but not as the rules of generalisation suggest. Fourth, complex features lose accuracy faster than less complex features as e-scale is reduced. Fifth, the more complex a real-world feature, the worse its positional accuracy when mapped. Finally, accuracy mid-segment is greater than accuracy end-segment.
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ItemSpatial cadastral information systems: the maintenance of digital cadastral maps( 2001-05)The management of a cadastral system's digital spatial data has promptedconsiderable research, generally with a focus limited to the organisationmaintaining the cadastral map. The approach of viewing the maintenanceof cadastral maps as a system encompassing the entire cadastral industryhas not been comprehensively studied and documented. This approach isseen as essential to transform cadastral mapping from its currentorganisation specific isolation, into a form that is truly interoperable withthe processing of spatial cadastral information in a digital environment.This dissertation documents a research program that is essentially adefinition and an analysis and design of spatial cadastral systems withparticular emphasis on the Australian State of Victoria. The researchsubstantiates the existence of a spatial cadastral system within the overallcadastral system. A review is presented of the analysis of a number ofinternational, western spatial cadastral systems, and establishes theboundary of the spatial cadastral system. An investigation of systemmethodologies used in cadastral research and information systemsconcludes the applicability of the Zachman Framework to structure anddocument the more comprehensive analysis of spatial cadastral systems.This analysis is undertaken for the spatial cadastral systems of theAustralian State of Victoria.The impacting developments, such as enabling technology, coupled withuser requirements and issues relating to existing spatial cadastralsystems, provides the basis for the presentation of a range of solutionalternatives to manage the spatial data associated with the maintenanceof the multipurpose cadastral map in a digital and Internet enabledenvironment.
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ItemThe effective implementation of GIS in local government using diffusion theory( 2001-06)Geographical Information Systems (GIS) are proving difficult to both define and effectively implement in Victorian Local Government. Current innovation diffusion theory, and emerging GIS and IS implementation theory are used to develop a framework for the implementation of either a new GIS, or for improving a currently ineffective GIS. The thesis describes a method of practically redefining GIS in the Local Government environment and then applying diffusion principles during the implementation of GIS. The first area of new investigation in the thesis is the approach to defining the GIS requirements of Local Government. In this thesis, GIS in Local Government is defined by starting with the business requirements and then letting them define the high level technical and functional requirements. This obtains a different answer from the traditional approach of assuming that current generic high level technical and functional definitions of GIS are correct, and that implementation is a selection and fine tuning process. The new approach is based mainly on the “productional perspective”; developed in recent theoretical GIS diffusion studies. The major difference is that GIS implementation in Local Government does not necessarily include the requirement for the design and construction of a specific GIS database. The GIS simply consists of graphical maps that spatially index and read existing non spatial databases within the Local Government IS environment. (For complete abstract open document)
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ItemGIS applied to administrative boundary design( 2003)The fragmentation of administrative boundaries is a serious problem in the analysis of social, environmental and economic data. This research focuses on the development of a coordinated approach to the design of administrative boundaries that endeavours to support accurate decision making. Around the world, administrative boundaries have been structured in an uncoordinated manner, limiting data exchange and integration between organisations. The solution proposed in this research adopts the hierarchical reorganisation of administrative boundaries to enhance data integration and data exchange within the spatial data infrastructure (SDI) framework.The SDI is an initiative intended to facilitate access to complete and consistent data sets. One of the most fundamental problems restricting the objectives of the SDI is the fragmentation of data between non-coterminous boundary systems. The majority of administrative boundaries have been constructed by individual agencies to meet individual needs. Examples of the proliferation of different boundary systems include postcodes, census-collector districts, health districts and police districts. Due to the lack of coordination between boundary systems, current technologies for analysing spatial data, such as geographic information systems (GIS), are not reaching their full potential. A review of the current literature reveals that, until now, little has been done to solve this problem.The prototype developed within this research provides a new mechanism for the design of administrative boundaries. The prototype incorporates two algorithms. These are based on HSR theory and administrative-agency constraints and are implemented within the GIS environment. Such an approach is an example of the potential that is available when we link spatial information theory with the SDI framework and disciplinary knowledge.
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ItemDecision-making under spatial uncertainty( 2005)Errors are inherent to all spatial datasets and give rise to a level of uncertainty in the final product of a geographic information system (GIS). There is growing recognition that the uncertainty associated with spatial information should be represented to users in a comprehensive and unambiguous way. However, the effects on decision-making of such representations have not been thoroughly investigated. Studies from the psychological literature indicate decision-making biases when information is uncertain. This study explores the effects of representing spatial uncertainty, through an examination of how decision-making may be affected by the introduction of thematic uncertainty and an investigation of the effects of different representations of positional uncertainty on decision-making. Two case studies are presented. The first of these considers the effects on decision-making of including thematic uncertainty information within the context of an airport siting decision task. An extremely significant tendency to select a zone for which the thematic classification is known to be of high certainty was observed. The reluctance to select a zone for which the thematic classification is of low certainty was strong enough to sometimes lead to decision-making that can only be described as irrational. The second case study investigates how decision-making may be affected by different representations of positional uncertainty within the context of maritime navigation. The same uncertainty information was presented to participants using four different display methods. Significant differences in their decisions were observed. Strong preferences for certain display methods were also exhibited, with some representations being ranked significantly higher than others. The findings from these preliminary studies demonstrate that the inclusion of uncertainty information does influence decision-making but does not necessarily lead to better decisions. A bias against information of low certainty was observed, sometimes leading to the making of irrational decisions. In addition, the form of uncertainty representation itself may affect decision-making. Further research into the effects on decision-making of representing spatial uncertainty is needed before it can be assumed that the inclusion of such information will lead to more informed decisions being made.