Geodesy and Geomatics Engineering Technical Reports

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Continuous GPS monitoring of crustal deformation with the Western Canada Deformation Array
Continuous GPS monitoring of crustal deformation with the Western Canada Deformation Array
The objective of this thesis is to conduct research on high-precision. Continuous GPS monitoring of crustal deformation in the northern Cascadia subduction zone, which is located in southwestern British Columbia and known to be one of the most seismically active regions in North America. Although conventional geodetic measurements were made in the past showing a consistent deformation pattern in the region, these measurements have relatively large uncertainties. In contrast, GPS, as a modern geodetic techniques, provides the best means for deformation monitoring: higher accuracy, lower cost, more efficient, and near-real time. The Western Canada Deformation Array (WCDA) is a GPS network designed to monitor the crustal deformation with high precision. It has been in operation since its establishment in the summer of 1992 and is still under development. The daily data collected from the WCDA stations have been reduced using the CGPS22 software package and the precise orbits generated by Natural Resources Canada (NRCan) or the International GPS Service for Geodynamics (IGS). A specific estimation strategy has been designed and different measurement models have been tested in order to achieve high accuracies. Based on the estimation strategy, 811 days of daily solutions spanning from September 1992 to April 1995 have been obtained and analyzed in particular. Problems associated with hardware and errors due to scattering effects have been detected and identified from the results. The scattering effects at stations DRAO, ALBH and WILL caused offsets in the vertical component and the east component of the baselines (Latter for the ALBH-DRAO only) in the solutions. Meanwhile, the east component of the baseline ALBH-DRAO also suffered an apparent annual variation due possible to the same scattering effects. All these offsets and variation display a systematic dependence on the choice of elevation or cutoff angle. Small annual variations were found in the north component of most, if not all, of the WCDA baselines and these variations were analyzed with great emphasis. Five tests were carried out in order to identify the source of these annual variations. From the results of these tests, some factors, such as tidal effects and tropospheric mismodelling, can probably be discounted. A test on the GPS satellite antenna offsets reveals a similarity in features between the annual variations and an error caused by an uncalibrated GPS antenna offset along the satellite local x-axis. This leads to a suspicion that a systematic error at a few cm level in the precise orbit/EOP data is the cause of the annual variations, though further efforts are required to verify this claim. The precision assessment for the WCDA solutions shows long-term repeatabilities of2 to 5 mm in horizontal components and 6 to 9 mm in vertical components for baseline lengths ranging from 302 to 627 km. Linear rates in each of the baseline components have been estimated by the Least Squares Spectral Analysis algorithm, along with offsets and periodic constituents. In general, these linear rates show a deformation pattern consistent with that obtained from previous conventional measurements. However, a high resolution on crustal deformation signals and a better separation of GPS measurement errors from the deformation signals would require a longer set of solutions and more effort on error handling.
Coupling of repetitive multibeam surveys and hydrodynamic modelling to understand bedform migration and delta evolution
Coupling of repetitive multibeam surveys and hydrodynamic modelling to understand bedform migration and delta evolution
This study addresses channelized delta top sediment transport on the Squamish estuary in Howe Sound, British Columbia. The mechanism of bedform migration and delta evolution is affected by the manner in which the available sediment flux from the feeder fluvial system is distributed. The present study is complementary to a parallel project looking at the sediment migrating on the delta slope as landslides or turbidity currents. The termination of the Squamish River consists of a single channel that flows between flanking intertidal sand bars and over a mouth bar at the lip of the delta. The delta front is growing rapidly with about 1 million m[superscript 3] of sediment being input from the river system annually. There is a 3 to 5 m tidal range that strongly modulates the flow in the channel and over the adjacent intertidal sand banks. In 2011, the delta top channel was surveyed every 3 to 4 day at high water, over a period of 4 months during which the river discharge waxed and waned and the tides ranged from springs to neaps. In 2012 and again in 2013, the channel was surveyed daily over a week while the tides increased from neaps to springs. In order to understand the sediment transport mechanism in this estuary, this research parameterized the short wavelength bedform morphology and the long wavelength channel shape on the delta top, extracted the shape of the delta lip, and used volumetric characterization of the sediment on the delta top and the delta lip vicinity. A three dimensional hydrodynamic model was also built to predict the flow within the river, the delta top, and adjacent fjord over the complete tidal cycle so that the bed shear stress associated with tide modulation and river discharge could be quantified. This research shows that the short wavelength bedform characteristics and long wavelength channel shape are primarily a result of the low water period when the offdelta flows are strongest. The flow fields of the research area are dominated by the tidal modulation. However the river surge also plays a role during the high flow regime. Good correlation was demonstrated between flow conditions (parameterized by the Froude number) and all of: the bedform roughness, the bedform mobility, the 1D bedform roughness spectra and the off-delta sediment flux. These relationships indicate that a single snapshot of the riverbed morphology could potentially be used to estimate sediment transport conditions.
Critical evaluation of stereophotogrammetric methodology with emphasis on close-range applications
Critical evaluation of stereophotogrammetric methodology with emphasis on close-range applications
This dissertation represents a critical evaluation of the photogrammetric methodology in terms of the functional model, stochastic mode, numerical processing scheme, and operational system. This study then focuses on close-range applications. For the functional model, the relationship between algebraic and physical form of the perspective transformation model is fully explored, and applications are provided for both the single photo case and multi-photo one. Different functional models are studied comparatively. As an extension of the basic functional models, the conventional approach with additional parameters is investigated from both function and numerical perspectives, and other trend removal approaches are also evaluated. Finally, the recovery ability of “calibration” parameters in the conventional approach with additional parameters is studied with experiments. Concerning the stochastic model and the numerical processing scheme, a weighted constraint model, and a parametric model with additional observations are compared with a combined model. The utilization of a variance-covariance-component-estimation technique (MINQUE) for covariance matrix estimation is evaluated. The application of Box-Jenkin’s time series analysis technique, along with a general data processing scheme in the numerical realm are outlined. Photogrammetry has been applied at close-range under different forms. A conceptualized model is developed in order to bring these together within a generalized photogrammetric family. Rasterstereography, one if the methods utilizing structured light, is found to be attractive in today’s environment. An experiment with film-based raterstereography is described. The feasibility of measuring image coordinates with an enlarger-digitizer approach is fully explored, and finally, the utilization of a home video camcorder for image acquisition.
De-correlation of tropospheric error and height component on GNSS using combined zenith-dependent parameter
De-correlation of tropospheric error and height component on GNSS using combined zenith-dependent parameter
For high precision GNSS positioning, the troposphere is one of the most problematic error sources. Typically, the effect is minimal due to the spatio-temporal correlation when the baseline length is short enough in the relative positioning scenario. When a strong tropospheric anomaly effect is present, the problem can be much more complicated and the resultant positioning solution is typically no longer precise even for a baseline of a few kilometres in length. As the troposphere delay and height estimates are almost linearly correlated above a 20° elevation angle, the problem exists of how to de-correlate these two parameters to avoid such ill-conditioned cases. To obtain reliable height estimates, and avoid ill-conditioned cases, a new method is proposed in this dissertation: these two common zenith dependent parameters are combined into a single parameter plus weighting parameters. Once the parameters are combined and corresponding weighting parameters are determined, the vertical component can be retrieved. The feasibility of the methodology is investigated in a kinematic situation. To determine the weighting coefficient in this case, the residuals in a least-square estimator are analyzed. As the residuals can be decomposed into two different realms, either troposphere or ionosphere, the magnitude of the residual contribution of the troposphere for each satellite pair in the double difference can be determined. This value is further used to determine the weighting parameters. Through this new method, the common zenith-dependent parameters are found to be de-correlated. A number of data sets are processed and the results are analyzed, especially during severe inhomogeneous tropospheric conditions and under humid environments. In summary, in a kinematic scenario, the achievement is shown to be up to 20% (4 cm to 3 cm rms) with processed data. Compared to the conventional approach, the degradation of the vertical component during an anomalous weather period is almost eliminated in kinematic scenarios, which is the main goal of the research described in this dissertation. This means that this new approach is resistant to an anomalous tropospheric event.
Demarcation and registration of indigenous land in Brazil
Demarcation and registration of indigenous land in Brazil
11 years after the demarcation deadline mandated by Brazil’s 1988 promulgated constitution, over 45% of indigenous territories have still not been demarcated. To explore how the demarcation process continues to be physically obstructed the current framework under which indigenous territories are demarcated and registered, and the conflicting interests that impede this process will be explored. Later, to illustrate the magnitude of this problem, a historical overview of the government’s prioritisation of indigenous issues will also be examined. In sum, this report will explore why Brazil’s demarcation delay has persisted, despite the fact that indigenous people desperately require secure land tenure to protect their unique lifestyles.
Design and analysis of the vertical control for the Superconducting Super Collider Project in Texas
Design and analysis of the vertical control for the Superconducting Super Collider Project in Texas
The stringent accuracy requirements for the Superconducting Super Collider (SSC) have required a rigorous approach in designing and analyzing the vertical control required for the construction of the tunnel. All possible sources of errors are estimated to determine a realistic value for the achievable accuracy. This thesis deals with the design of the network and the dev elopement of standards, specification and procedures, unique to the SSC Project. All forms of vertical control were included in the standards, specifications and procedures, such as surface control (Primary Vertical Control Network), densification on the service areas where the shafts are located, elevation transfer techniques, and propagation of control in the tunnels. Geodetic effects that are deemed important in the Primary Vertical Control Network are analyzed to ensure the adjusted elevations are accurate and reliable. The use of a corrected weighting scheme is analyzed through the use of the Minimum Norma Quadratic Estimation (MINQE) and adjusted accordingly. Densification, elevation transfers, tunnel control and the initial tunnel breakthroughs are analyzed to be all within the tunneling requirements. The final tunnel elevations are calculated by the combined adjustment of all densification and shaft transfer surveys. The improvement of accuracy of the combined adjustment with that of the adjustment prior to breakthrough shows an increase of up to 2.8 mm at the 00 percent level of confidence. The determination of an appropriate geoidal model was performed using a combination of Global Positioning System (GPS) and levelling to acquire a micro-geoid for accurate final invert elevations. The geoid undulations were determined to an accuracy of 13 mm at the 99 percent level of confidence. Final estimated accuracy of 14 mm to 17 mm at the 99 percent level of confidence can be achieved for the invert elevations of the main tunnel.
Design and implementation of a GIS-enabled online discussion forum for participatory planning
Design and implementation of a GIS-enabled online discussion forum for participatory planning
Public participation is a process whose ultimate goal is to facilitate consensus building. To achieve this goal, there must be intensive communication and discussion among the participants who must have access to information about the matters being addressed. Recent efforts in Public Participation Geographic Information Systems (PPGIS), however, concentrate mainly on making GIS and other spatial decision-making tools available and accessible to the general public. Relatively little effort to date has been put into addressing the communication and discussion needs of participatory planning, such as facilitating the transparent exchange of ideas among the participants. Simply making such tools available and accessible cannot satisfy the communication needs during participation. In this thesis, a prototype has been designed and implemented to demonstrate that web-based GIS can be integrated with an online discussion forum to enhance communication during spatially-related discussions in participatory planning. Based on the evaluation criteria developed in this thesis, the prototype confirmed its ability to enhance communication as compared with selected major online PPGIS applications.
Design and implementation of a coastal collaborative GIS to support sea level rise and storm surge adaptation strategies
Design and implementation of a coastal collaborative GIS to support sea level rise and storm surge adaptation strategies
The ICURA C-Change is a collaboration of universities and eight communities in Canada and the Caribbean to develop adaptation strategies for the effects of sea level rise and storm surges. These vulnerable communities have topographic and sea level data, ranging from high to low precision for developing scientific scenarios of coastal threats. Scientific scenarios without precise data lead to gaps in quantifying the extent of threats in coastal communities, which is vital in developing adaptation strategies. This research develops an online Coastal Collaborative GIS (CCGIS) using local knowledge as input in threat mapping to supplement existing data. The CCGIS developed using the Zend Framework, OpenLayers and ExtJS provide both server-side and client-side programming to embed Google and Bing Maps as base layers to capture spatial input described with multimedia. The purpose was to develop a low cost, user-friendly system, which could be used in any community. Local knowledge acquired in a coastal community is digitized as point, line, and polygons representing a location, linear and area features respectively. Descriptions of spatial objects with rich attributes such as video, audio, pictures, and text captured in a local environment compliment the CCGIS spatial abstraction. A prototype review mechanism and a peer review process to maintain a degree of trust in contributors and their contributions was implemented. This research evaluated the developed CCGIS prototype based on user and system requirements. User tests indicated functional requirements were achieved with more improvements required in some areas.
Design and implementation of a spatially enabled panoramic virtual reality prototype
Design and implementation of a spatially enabled panoramic virtual reality prototype
Conventional approaches to adding virtual reality-based realism in a GIS environment involve the development of complicated 3-dimensional geometric models through the use of sophisticated computer hardware and software. While these approaches provide for some benefits with regard to increased user comprehension, they are often limited due to the complexity of their creation and inability to provide realistic visual cues for the user. This is especially significant in the development of interactive computer-based touring guides, where the uninitiated user must be able to quickly and efficiently interpret directions provided on a computer display. This research focuses on the integration of digital terrestrial photographs in a map-based environment acquired with a set of non-metric cameras mounted on a simple tripod system. A novel combination of stereo-photographic and image processing techniques are used to link 360-degree panoramic virtual environments to a dynamic map-based environment within a software and hardware prototype developed by the author. The linked panoramic and map interface allows for user query and interaction. Techniques and results are outlined for the creation of the system, including: acquisition, processing (data reduction), and visualization. Ease of use and low cost were primary considerations for the development of the prototype. Results suggest that an un-calibrated stereo and camera setup can provide appropriate accuracy for the purposes of GIS integration. Further, the successful implementation of the prototype provides proof of concept for an alternative approach for spatially enabled virtual reality and map integration.

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