Geodesy and Geomatics Engineering Technical Reports

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A supervised approach for the estimation of parameters of multiresolution segmentation and its feature extraction from VHR imagery
A supervised approach for the estimation of parameters of multiresolution segmentation and its feature extraction from VHR imagery
With the advent of very high spatial resolution (VHR) satellite, spatial details within the image scene have increased considerably. This led to the development of object-based image analysis (OBIA) for the analysis of VHR satellite images. Image segmentation is the fundamental step for OBIA. However, a large number of techniques exist for RS image segmentation. To identify the best ones for VHR imagery, a comprehensive literature review on image segmentation is performed. Based on that review, it is found that multiresolution segmentation, as implemented in the commercial software eCognitionTM, is the most widely-used technique and has been successfully applied for a wide variety of VHR images. However, multiresolution segmentation suffers from the parameter estimation problem. Therefore, this study proposes a solution to the problem of the parameter estimation for improving its efficiency in VHR image segmentation. The solution aims to identify the optimal parameters, which correspond to effective segmentation. The solution to the parameter estimation is drawn from the equations related to the merging of any two adjacent objects in multiresolution segmentation. The solution utilizes spectral, shape, size, and neighbourhood relationships for a supervised solution. In order to justify the results of the solution, a global segmentation accuracy evaluation technique is also proposed. The solution performs excellently with the VHR images of different sensors, scenes, and land cover classes. In order to justify the applicability of solution to a real life problem, a building detection application based on multiresolution segmentation from the estimated parameters, is carried out. The accuracy of the building detection is found nearly to be eighty percent. Finally, it can be concluded that the proposed solution is fast, easy to implement, and effective for the intended applications.
A systems engineering approach to designing an ocean and coastal information management strategy
A systems engineering approach to designing an ocean and coastal information management strategy
With the enactment of the Oceans Act [1996], Canada made a commitment towards the sustainable development of its ocean and coastal resources. This new approach is based on the principles of collaborative and integrated management. The implementation of modern ocean management objectives must take place in an environment surrounded by a complex legal and institutional framework, changing economic priorities, escalating resource use conflicts, and increasing pressure to address problems at the ecosystem level. An examination of major legislative and policy directions, technological and conceptual background, and information management initiatives contributed to the formulation of a set of information requirements. A review of the existing information services in support of the ocean and coastal stakeholder community revealed a sporadic, disconnected collection of regional and sectoral initiatives without capacity for interaction while often duplicating efforts and expenses. These results are in conflict with an all-inclusive, systematically organized information framework that would better position the stakeholder community to address present and future challenges. Based on the principles of systems engineering, this research provides a conceptual design for an ocean and coastal information management strategy. The proposed design is iterative, and is built on a high level assessment of information requirements.
A web-based 3D visualization prototype system for high-resolution satellite colour stereo images
A web-based 3D visualization prototype system for high-resolution satellite colour stereo images
This thesis presents a Web-based 3D Visualization Prototype System (W3VPS) for high-resolution satellite stereo images. The W3VPS automatically generates 3D colour images using stereoscopic techniques for Web-based applications; it uses IKONOS images as source data, but is capable of using any other form of high-resolution satellite stereo images. The W3VPS uses a well-established 2D affine orientation model for automatic re-sampling of epipolar images and then forms 3D anaglyph images. The W3VPS does not require rigorous orientation parameters, DTMs, or GCPs as inputs for 3D generation. A new image-matching algorithm is developed for the automatic matching of correspondences. It modifies Zhang’s [1995] SM method and introduces a new algorithm for eliminating outliers that is based on the regression diagnostic approach. This matching algorithm successfully and efficiently finds a set of correspondences and eliminates the majority of reported correspondence outliers. For refinement of the 3D effect, a new method is developed based on the Quadtree technique. Finally, a one-tier Web client/server architecture is implemented for 3D Web visualization and provides ready access and exchange of files and full functionality to a dispersed user community. Research results demonstrate the possibility of visualizing a natural environment in colour 3D using high-resolution satellite images and presenting this on the Web through a fast, cost-effective system. Further, the successful implementation of the W3VPS shows that the integration of photogrammetric principles with Web technologies is available for further development of Web-based satellite stereo image applications.
Access and privacy of distributed land related information
Access and privacy of distributed land related information
As information technology evolves and the perception of the value of information changes, the legal solutions designed to provide checks and balances for qualities such as information access and privacy are struggling to stay abreast of social and technological developments. The ease with which vast arrays of information may be accessed in a distributed computing environment was not foreseen by the authors of much of the legislation and policy in place today. The issues of information access and privacy can not be discussed in isolation. Satellite factors such as information ownership, distribution, pricing, liability and security all have an impact and must be taken into account. Consideration of these issues must play a part in policy formulation. After studying existing and proposed legislation, principles and policies, components have been isolated which should find a place in any policy that deals with access and privacy for land related information in a distributed environment. The guidelines formulated are generic in nature and do not address jurisdiction dependent idiosyncrasies. In addition to the policy components, a development strategy is proposed. The main thrusts of the strategy are that the policy should attempt to be: media independent; applicable to all sectors of society, especially when dealing with the issue of privacy; encouraging of a proactive approach to information dissemination; and, aware that privacy is a vital quality that must be considered in coincidence with all access decisions. The combination of the components and the development strategy provides a framework that will prevent discontinuities and inconsistencies in the application of the policy. The suggestions made should prove useful in the development of access and privacy policies for land information in a distributed information environment that are appropriate, effective and applicable both now and in the future.
Advanced health information sharing with web-based GIS
Advanced health information sharing with web-based GIS
Web-based GIS is increasingly utilized in health organizations to share and visualize georeferenced health data through the Web. In the development of a public information and disease surveillance network, issues of data publishing and user access are important concerns. The handling of data heterogeneity, lack of available data and tools, and methods of health information representation constitute continuing challenges. The purpose of this research is to address these three problems and provide new solutions for health information sharing. Regarding data heterogeneity, a geospatial-enabled RuleML method has been designed for semantic disease information queries. Geospatial and non-spatial components of health data are represented through an ontology-based approach. The support for spatial representation in the proposed method enables the discovery of spatial relations in a semantic system. This research proposed an improved system, based on ontologies and rules, addressing both non-spatial and geospatial semantics for the querying of respiratory disease information. Furthermore, a new architecture based on open standards and Web Services was designed to provide better solutions in health information sharing with Web-based GIS. This architecture overcomes the weakness of a closely coupled design, allows interoperable data access, and enables dynamic data integration from different providers for decision making. This architecture has demonstrated its effectiveness in an infectious disease information mapping application across international borders. In addition to demonstrating health information sharing, this research provided an initial approach to designing and implementing Web Processing Services that allow online sharing of health data processing functionalities. For the dissemination of health information, a health information representation model has been designed to facilitate users’ understanding in using health information. This model covers health information representation in the semantic, geometric, and graphic dimensions with the purpose of minimizing user misunderstanding. The platform-independent XML format was utilized in the implementation of this model, and maps can be generated from this XML format for visualization and analysis.
Advanced mission planning tool for real-time kinematic (RTK) GPS surveying
Advanced mission planning tool for real-time kinematic (RTK) GPS surveying
Conventional mission planning in GPS surveying involves locating a site with minimal obstructions and determining satellite availability at the location to be surveyed. Tools used in the planning process usually include topographic maps and satellite availability software. In recent years, with the advent of Real Time Kinematic (RTK) GPS surveying, it is possible to obtain centimeter-level accuracy while in the field. Applications for RTK GPS surveying include, but are not limited to: construction layout, land survey, photogrammetric survey control, and GIS updating. One of the key factors in the RTK GPS technique is the data link between the reference station and rover. Without this link RTK GPS results are not attainable in the field. For this reason mission planning in RTK GPS surveying takes on another level of complexity: not only does the reference station have to visible to the satellites, but it must also be visible to the rover. However, available mission planning tools do not provide a means to predict the data link coverage of the reference station. The purpose of this investigation is to determine the best wave propagation model or models to be used in an RTK GPS survey mission planning tool. This study will present current wave propagation models being used by communications planning software and then use these models to predict data link coverage. The performance of these models was evaluated through field testing of two RTK GPS systems. This investigation concludes that there are three wave propagation models that could be used to accurately predict data link coverage by using only digital terrain information. The implementation of these models relies on available documentation and potential source code. In researching this project, it was evident the availability of documentation varies between models. Based on performance criteria and implementation considerations, two models are recommended to be implemented into a mission planning tool for RTK GPS surveying: Parabolic Equation and TIREM.
Advances in gravity based height systems
Advances in gravity based height systems
In order to have physical meaning, a height system must have some relation to the Earth’s gravity field. Of the height systems that do, orthometric heights match best with our intuitive understanding of height. The orthometric height of a point is the distance travelled along a plumbline from that point to the geoid, and can be arrived at either directly from leveling and gravity observations or indirectly by converting geodetic heights to orthometric heights using a geoid model. This dissertation investigates recent advances in orthometric height determination, to find out whether orthometric height determinations can meet modern centimetre-level accuracy requirements. Persistent barriers to improving orthometric height accuracy have been the impossibility of fully modeling topographical density effects, the lack of suitable numerical methods, and the lack of sufficient data. The problem is addressed in six articles. The first two deal with direct calculation of orthometric heights, providing a practical implementation of a rigorous theory of orthometric heights able to deliver sub-centimetre accuracy in most cases, and showing that numerical errors in this process can be kept below the one centimetre level. The next two articles address the problem of the unknown density distribution in geoid determination, describing a framework for including the full three-dimensional effect of topographical density, and demonstrating that existing laterally-varying density models can provide sub-centimetre results in most areas. Vertical density variations neglected in such models are only expected to reduce accuracy to a few centimetres in mountainous areas. The fifth article demonstrates a new method for downward continuation of gravity anomalies, one of the largest numerical barriers to accurate geoid determination. The final article evaluates satellite altimetry as a source of gravity data over lakes, finding it promising but in need of further refinement. The ultimate conclusion is that the physically meaningful system of orthometric heights can be now realized to about a centimetre in most areas, given suitable data, although in some especially challenging areas (e.g. mountain ranges) errors of several centimetres must be accepted.
An analysis of a worldwide status for monitoring and analysis of dam deformation
An analysis of a worldwide status for monitoring and analysis of dam deformation
The primary role of dam deformation surveys is to examine regularly the conditions of the dam and its overall safety. The state of monitoring programs has been a growing concern by many countries and professional groups at the national and international levels. Canada is no exception. Canada’s dams are generally characterized as having poorly designed monitoring systems and inadequate instrumentation. Today, this is no longer considered justifiable. This research is one of a series of steps in an attempt to rectify this situation. It was initiated as the initial stepping stone to a formalized set of proposed guidelines form which monitoring specifications can be written for each individual dam. The work is based on a collection of material from questionnaire forwarded to 79 member organizations of the International Commission of Large Dams (ICOLD) and from available literature on the monitoring and analysis of dam deformation (mainly ICOLD Bulletins, and reports of the International Federation of Surveyors (FIG) Study Group on Deformation Measurements). One of the major conclusion of the survey is that Surveying Engineers have had very little involvement in dam deformation. One of the reason suggested is that Survey Engineers may not be promoting or educating themselves adequately in the field of dam deformation. Consequently, this lead to the subsequent objective: to take the initiative to attempt to improve this situation by providing junior Surveying Engineers with example of the major types of large dams (h >15m) and the basic principles on their behaviour, and the methods used to monitor and analyze their deformations. Some of the other key issues that have resulted from this research include: (1) there is obvious lack of communication and/or understanding amongst profession in the field of deformation, (2) the realization of the proposed monitoring guidelines is largely dependent on having a legislation in place to enforce monitoring of all large dams, (3) Canada is the single leading country in the development of a global integration technique which utilizes both geodetic and geotechnical observables into a simultaneous deformation analysis, and (4) the successful implementation of new developments in the field of deformation measurements supports the need to continue on using both geodetic and geotechnical means in modelling dam deformation. In support of the monitoring guidelines this research recommends the need for further studies to determine the frequency and accuracy requirement of the observables, and the minimum number and type of instruments that must be included in all the major types of large dams.
An assessment of empirical models for the prediction of the transionospheric propagation delay of radio signals
An assessment of empirical models for the prediction of the transionospheric propagation delay of radio signals
The objective of this thesis research was to test several empirical models of the ionosphere to see which, if any, might be a better predictor of the ionosphere's total electron content (TEC) (and therefore ionospheric delays) than the GPS single-frequency Broadcast model. A total of four models were tested, namely: (1) The Bent Model; (2) The Ionospheric Conductivity and Electron Density (ICEED) profile model; (3) The 1986 International Reference Ionosphere (IR186); and (4) The GPS single-frequency Broadcast model. Each model was adapted to enable multiple epoch/location predictions of TEC. Model testing was broken down into two distinct stages: (1) The first three models were tested against a 48 station months of Faraday rotation measurements of TEC, from a total of five North American sites and one European site, recorded during three different levels of solar activity from the previous cycle; and (2) All four models were then compared with ionospheric delays recovered from dual-frequency GPS data recorded at two Canadian stations during a period disturbed ionospheric behaviour in February 1991. Comparisons with the Faraday rotation data revealed that the Bent and IR186 models were the best. Comparisons with the GPS data showed that the Broadcast and IR186 models to be the best - the Broadcast model was able to account for approximately 70 to 90% of the daytime ionospheric delay and 60 to 70% of the night-time delay. Based upon the findings of this research some strategies for further related work are suggested.

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