Rock Santerre
Université Laval, Geomatic Sciences, Faculty Member
- Rock Santerre is a full professor of Geodesy and GPS in the Department of Geomatics Sciences and a member of the Cent... moreRock Santerre is a full professor of Geodesy and GPS in the Department of Geomatics Sciences and a member of the Center for Research in Geomatics at Laval University, Quebec City, Canada. He obtained his Ph.D. in Surveying Engineering (GPS) from the University of New Brunswick (Fredericton, Canada) in 1989. His research activities are mainly related to high-precision GPS for static and kinematic positioning.edit
GNSS coordinate time series data for permanent reference stations often suffer from random, or even continuous, missing data. Missing data interpolation is necessary due to the fact that some data processing methods require evenly spaced... more
GNSS coordinate time series data for permanent reference stations often suffer from random, or even continuous, missing data. Missing data interpolation is necessary due to the fact that some data processing methods require evenly spaced data. Traditional missing data interpolation methods usually use single point time series, without considering spatial correlations between points. We present a MATLAB software for dynamic spatiotemporal interpolation of GNSS missing data based on the Kriged Kalman Filter model. With the graphical user interface, users can load source GNSS data, set parameters, view the interpolated series and save the final results. The SCIGN GPS data indicate that the software is an effective tool for GNSS coordinate time series missing data interpolation.
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On compare les precisions de deux azimuts geodesiques et on clarifie la signification des azimuts calcules en appliquant la latitude et la longitude tiree d'une carte, aux observations sur plusieurs etoiles en precisant le role de la... more
On compare les precisions de deux azimuts geodesiques et on clarifie la signification des azimuts calcules en appliquant la latitude et la longitude tiree d'une carte, aux observations sur plusieurs etoiles en precisant le role de la longitude geodesique attribuee a une premiere station Black lors de l'etablissement d'un controle d'orientation
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Many different research projects on geomatics data acquisition and processing are being carried out in the Department of Geomatics Sciences at Laval University. The projects have undergone a great ...
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Time series analysis is an important part of geodetic and geodynamic studies, especially when continuous GPS observations are used to explore areas with a low rate of deformation. In this domain, having precise and robust tools for... more
Time series analysis is an important part of geodetic and geodynamic studies, especially when continuous GPS observations are used to explore areas with a low rate of deformation. In this domain, having precise and robust tools for processing and analyzing position time series is a prerequisite. To meet this requirement, a new software package called GPS Interactive Time Series Analysis was developed using the MATLAB language. Along with calculating basic statistics and quality parameters such as mean and variance, the software is capable of importing and visualizing different time series formats, determining and removing jumps and outliers, interpolating data, and producing numerical and publication quality graphical outputs. Furthermore, bivariate statistical analysis (such as correlation coefficients, curvilinear and nonlinear regression), residual analysis, and spectral analysis (such as auto-spectrum, Lomb-Scargle spectrum, evolutionary power spectrum, and wavelet power spectru...
Based on a hundred years of experience in geomatics education at Laval University, certain futitre directions for instruction emerge. This paper considers the content of geomatics courses and the methods of delivery. The content of... more
Based on a hundred years of experience in geomatics education at Laval University, certain futitre directions for instruction emerge. This paper considers the content of geomatics courses and the methods of delivery. The content of courses must adjust to the convergence of technologies as, for example, when methods of location become embed~ ded in more and more (smaller and smaller) ubiq~ uitous devices. A central concept in instructional design is the "half~ life" of the mate rial taught. Of equal importance is the societal context of the use of geomatics technology. At the same time, the methods of instruction are changing due to the same pressures of technological change. A main conclusion is that teaching requires substantial geospatial infrastructural investments.
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The spatial and temporal variability of ice forces near dam faces have been studied over three winter seasons. This paper introduces the project and explores some of the preliminary results acquired to date. Field measurements included... more
The spatial and temporal variability of ice forces near dam faces have been studied over three winter seasons. This paper introduces the project and explores some of the preliminary results acquired to date. Field measurements included ice deformations rates calculated using a robotic total station and image analyses. In-ice stresses were determined using in-situ stress gauges places at various locations and depths. Ice pressures against the wall were measured directly at four elevations and at up to 11 locations. While ice displacement measurements followed a fairly regular pattern associated with thermal events and water level fluctuations, in-ice stresses behaved in a spatial-temporal chaotic manner – sometimes in phase with ice displacement and sometimes not. Measured pressures against wall face showed correlations with temperature changes and water level fluctuations but were also fairly chaotic. This article presents some reflections on the nature of the observed spatial-tempo...
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Dans le but d’eliminer les points d’appui servant a orienter un couple stereoscopique provenant de cameras numeriques, une methode consistant a les jumeler a des theodolites et a des recepteurs GPS...
Missing values in data series is a common problem in many research and applications. Most of existing interpolation methods are based on spatial or temporal interpolation, without considering the spatiotemporal correlation of observation... more
Missing values in data series is a common problem in many research and applications. Most of existing interpolation methods are based on spatial or temporal interpolation, without considering the spatiotemporal correlation of observation data, resulting in poor interpolation effect. In this paper, a Modified Spatiotemporal Mixed-Effects (MSTME) model for interpolation of spatiotemporal data series is proposed. Experiments with simulated data and real SCIGN data are performed to assess the validity of the proposed model in comparison with Kriged Kalman Filter (KKF) model and Spatiotemporal Mixed-Effects (STME) model. The average improvements of simulated data and SCIGN data for observed stations are around 46% and 19% over the KKF model and 62% and 21% over the STME model, and those for unobserved stations are around 23% and 34% over the KKF model and 41% and 16% over the STME model, respectively, indicating that the proposed MSTME model can achieve better accuracy for interpolating ...
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The geographically and temporally weighted regression (GTWR) model is a dynamic model which considers the spatiotemporal correlation and the spatiotemporal nonstationarity. Taking into account these advantages, we proposed a... more
The geographically and temporally weighted regression (GTWR) model is a dynamic model which considers the spatiotemporal correlation and the spatiotemporal nonstationarity. Taking into account these advantages, we proposed a spatiotemporal deformation modelling method based on GTWR. In order to further improve the modelling accuracy and efficiency and considering the application characteristics of deformation modelling, the inverse window transformation method is used to search the optimal fitting window width and furthermore the local linear estimation method is used in the fitting coefficient function. Moreover, a comprehensive model for the statistical tests method is proposed in GTWR. The results of a dam deformation modelling application show that the GTWR model can establish a unified spatiotemporal model which can represent the whole deformation trend of the dam and furthermore can predict the deformation of any point in time and space, with stronger flexibility and applicabi...
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The spatio-temporal random effect (STRE) model, a type of spatio-temporal Kalman filter model, can be used for the fusion of the Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) data to... more
The spatio-temporal random effect (STRE) model, a type of spatio-temporal Kalman filter model, can be used for the fusion of the Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) data to generate high spatio-temporal resolution deformation series, assuming that the land deformation is spatially homogeneous in the monitoring area. However, when there are multiple deformation sources in the monitoring area, complex spatial heterogeneity will appear. To improve the fusion accuracy, we propose an enhanced STRE fusion method (eSTRE) by taking spatial heterogeneity into consideration. This new method integrates the spatial heterogeneity constraints in the STRE model by constructing extra-constrained spatial bases for the heterogeneous area. The effectiveness of this method is verified by using simulated data and real land surface deformation data. The results show that eSTRE can reduce the root mean square (RMS) of InSAR interpolation results b...
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The integration of multi-constellation Global Navigation Satellite System (GNSS) measurements can effectively improve the accuracy and reliability of navigation and positioning solutions, while the Inter-System Bias (ISB) is a key issue... more
The integration of multi-constellation Global Navigation Satellite System (GNSS) measurements can effectively improve the accuracy and reliability of navigation and positioning solutions, while the Inter-System Bias (ISB) is a key issue for compatibility. The ISB is traditionally estimated as an unknown parameter along with three-dimensional position coordinates and a receiver clock offset with respect to Global Positioning System (GPS) time. ISB estimation of this sort will sacrifice a satellite observation for each integrated GNSS system. These sacrificed observations could be vital in situations of limited satellite visibility. In this study, an enhanced multi-GNSS navigation algorithm is developed to avoid sacrificing observations under poor visibility conditions. The main idea of this algorithm is to employ a moving average filter to smooth the ISBs estimated at previous epochs. The filtered value is utilised as a priori information at the current epoch. Experimental tests were...
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We analyzed the noise characteristics of 112 continuously operating GPS stations in eastern North America using the Spectral Analysis and the Maximum Likelihood Estimation (MLE) methods. Results of both methods show that the combination... more
We analyzed the noise characteristics of 112 continuously operating GPS stations in eastern North America using the Spectral Analysis and the Maximum Likelihood Estimation (MLE) methods. Results of both methods show that the combination ofwhite plus flicker noise is the best model for describing the stochastic part of the position time series. We explored this further using the MLE in the time domain by testing noise models of (a) powerlaw, (b)white, (c)white plus flicker, (d)white plus randomwalk, and (e) white plus flicker plus random-walk. The results show that amplitudes of all noise models are smallest in the north direction and largest in the vertical direction. While amplitudes of white noise model in (c–e) are almost equal across the study area, they are prevailed by the flicker and Random-walk noise for all directions. Assuming flicker noise model increases uncertainties of the estimated velocities by a factor of 5–38 compared to the white noise model.
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One of the CIDCO’s (The Interdisciplinary Center for the Development of Ocean Mapping) HydroBall® GNSS buoys has been specifically adapted to evaluate its potential for wave measurement at centimeter accuracy level. Multiple GNSS... more
One of the CIDCO’s (The Interdisciplinary Center for the Development of Ocean Mapping) HydroBall® GNSS buoys has been specifically adapted to evaluate its potential for wave measurement at centimeter accuracy level. Multiple GNSS processing strategies were tested, namely PPK (Post-Processed Kinematic), PPP (Precise Point Positioning), and TRP (Time Relative Positioning). Experiments were carried out in a hydraulic flume where waves of different amplitudes and periods were generated in a controlled environment. The wave heights obtained by the various GNSS solutions were compared with ultrasonic gauge measurements placed along the flume. The best results were obtained with the PPK and TRP solutions with root mean squared (RMS) values of 2 cm (on average). The main advantages of the TRP solution are that it does not require any reference station nearby (contrary to PPK) or precise ephemerides (required by PPP). A sinusoidal regression comparison of the wave height time series allowed ...
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This review paper summarises the recent, on-going, and future research activities in precise positioning at Laval University. The projects undertaken by the GPS and Geodesy Research Group are presented following three main research... more
This review paper summarises the recent, on-going, and future research activities in precise positioning at Laval University. The projects undertaken by the GPS and Geodesy Research Group are presented following three main research topics. The first one deals with the use of precise positioning for deformation monitoring of engineering structures. The study of ice forces on dams using a robotic total station and the improvement of GPS height determination using multiple GPS antennas linked to a single receiver with calibrated fiber optics are presented. A second topic of research is the crustal deformation of the Charlevoix seismic zone in Quebec. This study uses GPS and levelling techniques and involves an investigation of the temporal stability of the GPS permanent stations available in the surrounding area. Finally, research on single GPS receiver positioning techniques is presented, namely, Precise Point Positioning (PPP) and Time Relative Positioning (TRP).
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Eastern Canada is characterized by many intraplate earthquakes mostly concentrated along the Saint Lawrence River and Ottawa River valleys. After the rigid plate rotation of North America, the glacial isostatic adjustment (GIA) is by far... more
Eastern Canada is characterized by many intraplate earthquakes mostly concentrated along the Saint Lawrence River and Ottawa River valleys. After the rigid plate rotation of North America, the glacial isostatic adjustment (GIA) is by far the largest source of geophysical signal in eastern Canada. We estimate a set of Euler pole parameters for this area using a velocity field of 19 continuously operating GPS stations out of 112, and show that they are different from the overall rotation of the North American plate. This difference potentially reflects local stresses in this seismic region, and the difference in intraplate velocities between the two flanks of the Saint Lawrence River valley accumulate stress along the river.
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ABSTRACT