Geodesy and Geomatics Engineering Technical Reports

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Estimation of sounding uncertainty from measurments of water mass variability
Estimation of sounding uncertainty from measurments of water mass variability
Analysis techniques are proposed that allow for estimation of potential sounding uncertainty due to water mass variability based solely on high temporal and/or spatial resolution observations of either sound speed or oceanographic measurements of temperature and salinity. The techniques do not require sounding data, thus analyses can be tailored to match any survey system; this allows for pre-analysis campaigns to optimize survey instrumentation, sound speed profiling locations/rates and survey line spacing such that a desired sounding accuracy can be maintained. In addition to this, the output of the methods can provide a higher fidelity estimation of sounding uncertainty due to water mass variability as compared to existing uncertainty models in common use. The analysis techniques are used to assess an extensive oceanographic data set collected in the Canadian Arctic Archipelago (CAA) in an effort to provide water mass sampling guidelines for current and future seabed mapping efforts in the CAA. In particular, the problem of mapping while in transit is investigated with oceanographic climatological grids of temperature and salinity being examined as a potential source of sound speed information when underway sampling of the water column is not possible.
Estimation of variance-covariance components for geodetic observations and implications on deformation trend analysis
Estimation of variance-covariance components for geodetic observations and implications on deformation trend analysis
The statistical methods for the estimation of the variance-covariance components for unbalanced data are reviewed in this thesis. Computational aspects of the presented methods are compared and their applicability to geodetic data is discussed. Prior information about the unknown variance components is introduced within the framework of the Generalized Maximum Likelihood (GML) methodology. The inverted gamma prior is used to introduce prior information about the variance components, and the noninformative prior is used when no prior information is available. The Fisher scoring method is applied to the resulting posterior probability density functions and the estimating equations are derived. Prior information is also introduced by means of the weighted constraints on the unknown variance-covariance components in the dispersion-mean model. The estimating equations of the dispersion-mean model with weighted constraints are derived, and conditions for equivalence between the dispersion-means model with weighted constraints and the GML estimation are formulated. The effect of neglecting the errors of the estimated variance-covariance components. In the least squares adjustment, on the covariance matrix of the estimated location parameters is discussed. The influence of different aspects of the estimation of variance components on the results pf spatial deformation trend analysis is investigated, based on practical examples. These include the amount of prior information, the choice of the method of estimation, and the choice of the error model. An efficient numerical algorithm for detecting influential observations, in terms of their influence on the results of variance components estimation, is developed and tested on geodetic survey data. All numerical procedures and algorithms developed in the thesis are demonstrated on practical examples.
Evaluation of mathematical models for gyrocompass behaviour:
Evaluation of mathematical models for gyrocompass behaviour:
Heading information is a fundamental parameter in ship’s navigation. Traditionally a gyrocompass is used as the primary sensors to provide heading reference on board ship. However, gyrocompass indicated headings are subject to a number of errors, which are functions of the ship’s motion and of the latitude of operation. The objective of this thesis is to investigate the gyrocompass behavior, study its deviations under different conditions of operation and develop suitable algorithms for the software compensation of these deviations. To meet this objective, mathematical models describing the gyrocompass behaviour are developed using different dynamic considerations. In particular, the gyrocompass equations of motion and their solutions are developed for the cases of a stationary, uniformly moving, and maneuvering ship. A general discrete-time model as well as a special model to represent a maneuvering ship are developed. Specific attention is drawn to the problem of high latitude behaviour of the gyrocompass. Simulation studies of the gyrocompass dynamic response are carried out using the mathematical models developed in this study. The simulation results indicate that transient errors of 1° are expected at latitudes of 30°, while errors in excess of 10° are likely to occur at latitudes of 70°. These errors may degrade considerable not only the gyrocompass performance, but also the performance of a multi-sensor integrated navigation system (e.g. introducing as much as 0.5 nautical miles error in a satellite fix), or they may introduce an error of as much as 2 mgals in real-time Eötvös correction calculations in precise sea gravimetry. An open-loop software compensation procedure of gyrocompass errors is proposed as an alternative to manual mechanical compensation traditionally used, to improve the gyroscope performance. The algorithm developed in this thesis is a function of the gyrocompass design parameters and of the particular dynamics of the ship’s motion. Finally, recommendations for future work include sea-trials of the developed software compensation algorithm, extension of the mathematical models to incorporate random disturbing forces, and evaluation of the dynamic response of modern marine gyrocompasses, such as, the Sperry MK 37 Gyrocompass Equipment.
Evaluation of strategies for estimating residual neutral-atmosphere propagation delay in high precision Global Positioning System data analysis
Evaluation of strategies for estimating residual neutral-atmosphere propagation delay in high precision Global Positioning System data analysis
The research described in this thesis compares and evaluates techniques for the estimation of residual neutral-atmosphere propagation delay of Global Positioning System (GPS) measurements in high precision geodetic relation positioning applications. Three techniques were analysed: (1) a conventional weighted least squares adjustment, (2) a sequential weighted least squares adjustment, and (3) Kalman filtering. The University of New Brunswick Differential Positioning Program (DIPOP) package was extensively modified to estimate residual neutral-atmosphere delay parameters for the three techniques under investigation. A data set of five baselines of regional length, 50 to 700 KM, was analysed with the new DIPOP software. Ten days of data were analysed to determine the sensitivity of baseline component estimates to a priori constraints, and to provide an estimate of the precision and accuracy of the three techniques. Short-term repeatability of estimated baseline components were compared with the International Earth Rotation Service (IERS) Terrestrial Research Frame of 1993 (ITRF93). Particular attention was given to the vertical component of the baselines, since the vertical component of a GPS geodetic baseline is up to three times more sensitive to residual neutral-atmospheric delay than the horizontal components. Mapping the repeatability of the estimated baseline components against a priori constraints showed that baseline component estimates are significantly sensitive to the initial constraints place on the estimated residual delay parameters. The three techniques are capable of estimating geodetic parameters at approximately the same level of accuracy and precision. The sequential weighted least squares approach was found to be equivalent to the Kalman filtering approach for estimating residual delays when the random walk model was used to characterise the delay variability. However, the equivalence breaks down when a stochastic process with time correlated states is used in the sequential weighted least squares technique. The precision analysis revealed: (1) baseline component estimates are significantly sensitive to the a priori constraints placed on the estimated delay parameters; (2) the three techniques are capable of operating at the same level of precision; (3) empirical determination (sensitivity testing) of the stochastic process coefficients and constraints for the least squares residual delay parameters is necessary due to a lack of correlation between optimal residual delay parameter coefficients and baseline vector components; (4) precision for the conventional weighted least squares case ranged in magnitude from 5.6 mm to 13.0 mm in the height component, and 2.4 mm to 9.5 mm in the length component; (5) precision for the Kalman filter Gauss-Markov case ranged in magnitude from 5.8 mm to 9.8 mm in the height component, and 2.4 mm to 9.0 mm in the length component; and (6) precision for the Kalman filter random walk case ranged in magnitude from 5.9 mm to 10.1 mm in the height component, and 2.4 mm to 9.6 mm in the length component. The accuracy assessment revealed: (1) the three techniques are capable of estimating baseline components at approximately the same level of accuracy; (2) two of the five estimated baseline vectors agree well (within a factor of 2 times their short term repeatability) in terms of height and length with the ITRF93 coordinates; (3) three of the five baseline vectors showed large height discrepancies (of the order of 4 to 9 cm); however, they agree well in the length component estimates.
Evaluation of the CARIS hydrographic production database in the production of paper charts, END and AML
Evaluation of the CARIS hydrographic production database in the production of paper charts, END and AML
CARIS Hydrographic Production Database (HPD) is a representative example of a new generation of software systems designed for the production of nautical cartographic products. Conceptually, it is based on a system of applications implemented over a Spatial Database and Management System (SDBMS), where each feature just needs to be stored once, and using the single data set is able to produce the range of cartographic products created in a typical Hydrographic Office (HO). The characteristics of CARIS HPD have created great interest in several HOs, including the Portuguese, related to the possibility of significantly increasing the efficiency of its cartographic production. However, as CARIS HPD is a new product, with several functionalities that are still in development, it needs to be evaluated as to whether it can really meet the general requirements of a HO. Those requirements include cartographic data management, data updating and the production of paper charts, Electronic Navigational Charts (ENCs) and Additional Military Layers (AML). To execute such an evaluation, the general requirements have been identified. A sample database was created and populated with data from three Portuguese ENCs cells. With these data an ENC and a paper chart were produced. Additionally the production of AML products was attempted. All the processes implicated in the data loading, management, preparation and the production of ENCs, paper chart and AML products were analyzed. During the evaluation sixty two requirements were identified, CARIS HPD being fully compliant with forty of them. In addition forty-six issues were identified and thirty seven recommendations were produced. In conclusion, CARIS HPD is a system capable of positively answering the HOs’ expectations, especially in data storage, management and preparation, and in the production of ENC products. Three issues do not allow the production of a paper chart completely compliant with the International Hydrographic Organization (IHO) specifications, but due to the simplicity of those issues, the system should be compliant in the very near future.
Evaluation of the plumb line curvature effect on the deflection of the vertical
Evaluation of the plumb line curvature effect on the deflection of the vertical
The curvature of the plumb line should be considered to find the undistorted geodetic networks without the plumb line curvature effect and to determine the astrogeodetic geoid as well as for other purposes. A few approaches have been developed to estimate the curvature effect. In most of the methods, the need for sufficient gravity data, the knowledge of the density distribution, and other data make the estimation of the plumb line curvature effect a difficult task. Without knowing the density distribution inside the earth, the curvature effect can be determined for the user of Vening Meinesz’s and Molodenskij’s formulae together. However, the procedure is laborious and time-consuming, and the integrations should be extended over the whole earth. This thesis investigates the utilization of the combination of the Stokes’s and Molodenskij’s approaches to determine the curvature effect of the plumb line. In other word, the determination of the curvature effect of the plumb line is based on combining Vening Meinesz’s and Molodenskij’s formulae. In this approach, the integrations will not be extended over the whole earth but a 25x25 minutes rectangular area. A determination of the plumb line curvature effect has been attempted at six stations in New Brunswick. The results show that this approach has been successfully used and can give a higher accuracy. The estimation of the curvature effect of the plumb line is no longer a difficult job.
Extending ECDIS content
Extending ECDIS content
Some of the world’s major shipping lanes run through ice-infested waters. To safely navigate these areas, mariners rely on daily ice charts produced by national governmental agencies. Most ice charts are designed to be displayed primarily on paper. Many vessels now possess Electronic Chart and Display Information Systems (ECDIS) on board that allows mariners to view Electronic Navigational Charts (ENC). Current ENC specifications allow for only one very limited description of ice conditions. New international standards specifying how detailed ice information is to be displayed in ECDIS could come into effect in 2007. The Canadian Ice Service (CIS) produces daily paper charts to assist mariners navigate Canadian ice-infested waters. The CIS produced the charts using computer imaging and mapping software. While the electronic versions of the charts do contain detailed ice information, the format of the data must be altered in order to be able to be used with existing ENCs. Using Arc Macro Language (AML) scripting, a prototype tool was created that converts daily ice charts from an ArcInfo format file into supplemental layers (Marine Information Objects) that could be used with official ENC data. An investigation was then performed to determine which is better: to use the developed tool to create electronic ice charts or to alter the CIS chart production process so that an Ice Information MIO, not a paper chart, is the primary product. It was found that the developed tool automatically creates an electronic ice chart in at most five minutes, well below the one-hour processing time originally sought by the CIS. Since using the tool requires no changes to the current chart production system, using the tool to create Ice Information MIOs is far more economical than altering the existing ice chart production process.
Extending land management approaches to coastal and oceans management
Extending land management approaches to coastal and oceans management
Canada’s approach to coastal and oceans management consists of a complex, multilayered system of laws, policies, organizations, and strategies. It is a fragmented approach to resource management and results in redundant efforts, inefficiency, ineffectiveness, and lack of coordination among agencies. One of the challenges encountered by Canada’s approach is to use, share, and manage information resources effectively. In particular, there is a need to provide complete and integrated inventories of information to mitigate conflicts among the growing ocean users, as well as to reduce administrative, jurisdictional and regulatory complexities. However, there is no comprehensive strategy to deal with the fractured and incomplete sets of data that are the legacy of the complex administrative and legal structures. Managing that information better should be the foundation for better decision-making regarding coastal and oceans resources. To address this challenge, this research provides a systems view of marine management with a focus on the role of the information on rights, responsibilities, and restraints in marine space, i.e. the tenure information. Marine management consists of several processes including, administration of marine activities, uses and interests; which depend on management of tenure information. This research investigates the role of tenure information and its management in implementing the Marine Protected Area (MPA) program by the Department of Fisheries and Oceans, Canada. Stakeholders in MPA establishment (e.g., government planners, environmental interest groups, coastal communities, and individual owners) often only have a vague understanding of the complexity of rights that may exist. Better management of this tenure information can therefore improve stakeholder participation. In this research, a framework for managing tenure information management for Canadian MPAs is designed. This framework is developed from a primary MPA case study - the Musquash Estuary in New Brunswick, and then is tested in a comparative analysis with additional case studies. The major conclusion of the research is that a framework should be based on three tenure information management activities: (1) determining tenure information requirements; (2) determining tenure information use; and (3) understanding the role of tenure information management groups. These activities facilitate the description of tenure information categories, their characteristics, their management, and their role in MPA establishment. Recommendations on the broader application of this framework in marine space management are also proposed.
Extracting sonar relative beam patterns for multi-sector multibeam sonar
Extracting sonar relative beam patterns for multi-sector multibeam sonar
The use of multibeam acoustic backscatter data for bottom characterization is currently being attempted by many researchers to aid geological, biological, and engineering projects. Ideally the absolute bottom backscatter strength would be measured, but in reality the reported data are overprinted by system-related geometric and radiometric effects. In real time, manufacturer-applied gain only partly reduces these effects. Existing post-processing algorithms undertake improved but still imperfect corrections to better account for these residual artifacts. The geometric effects include changing range, grazing angle and insonified area across the swath, whereas the radiometric effects include the angular variation in the transmitted energy and the receiver sensitivity. Recent developments in motion stabilization that involves multiple sectors, which are used to achieve higher and more equal sounding density, have added significantly more radiometric complications to the backscatter imagery. Before the backscatter data can be used for classification, either in the form of a mosaic or in the form of backscatter strength angular response curves, these remaining artifacts in the data have to be properly minimized. The residual artifacts reflect the fact that existing empirical beam pattern corrections imperfectly account for geometry and radiometry, and do not adequately distinguish between grazing and sonar relative angle. This research develops a new method of reducing the backscatter data by explicitly differentiating between seafloor angular response and radiometric artifacts. The new method further differentiates between along-track and across-track radiometric beam patterns. The developed method does not require any prior knowledge of seafloor characteristics. It is capable of propagating standard deviation from the backscatter data to the extracted radiometric beam pattern. This enables the user to access the reliability of extracted radiometric beam patterns.

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