Rene Chenier - Academia.edu (original) (raw)

Papers by Rene Chenier

Research paper thumbnail of Satellite derived bathymetry for Arctic charting: a review of sensors and techniques for operational implementation within the Canadian Hydrographic Service

Canada’s coastline presents challenges for navigational charting. Within Arctic regions, in situ ... more Canada’s coastline presents challenges for navigational charting. Within Arctic regions, in situ surveying presents risks to surveyors, is time consuming and costly. To better meet its mandate, the Canadian Hydrographic Service (CHS) has been investigating the potential of remote sensing to compliment traditional charting techniques. This paper focuses on an evaluation of sensors and techniques for operational Satellite Derived Bathymetry (SDB) implementation. Analysis focused on Cambridge Bay, Nunavut using Pléiades, SPOT, WorldView and PlanetScope imagery. Multiple SDB techniques were applied to evaluate their agreement with in-situ bathymetric measurements: • An empirical logarithm band ratio approach. • A multiple band modeling technique. • A multi-dimensional Look-Up-Table approach. Through this analysis, CHS attempted to answer critical questions for operational SDB implementation: • Do specific optical sensors offer advantages for SDB? • Are there advantages/disadvantages with the application of SDB techniques within the examined environment? • Can multiple SDB techniques improve CHS’s understanding of the confidence it can place in remotely sensed bathymetry estimates? Early results have achieved overall root mean square errors of 0.56 to 0.99 m relative to in situ survey depths for all sensors and techniques. These similarities suggest that CHS can be confident in the accuracies observed from various SDB approaches. Results do not indicate significant advantages or disadvantages of particular optical sensors, suggesting other factors contain greater importance for SDB image selection (e.g. sea floor visibility). While this analysis provides excellent information for operational empirical SDB implementation within Arctic environments, further work is required within other Canadian coastal regions to support national SDB application.

Research paper thumbnail of CHS priority planning tool - A GIS to prioritize data gaps

International Hydrographic Review, Nov 1, 2022

Research paper thumbnail of Photogrammetric Bathymetry for the Canadian Arctic

Marine Geodesy, Nov 22, 2019

This study proposes and demonstrates a through-water photogrammetry approach for Satellite Derive... more This study proposes and demonstrates a through-water photogrammetry approach for Satellite Derived Bathymetry (SDB), which may be used to map nearshore bathymetry in the Canadian Arctic. A four step process is used: First, a standard photogrammetric extraction is performed on 2 m resolution WorldView stereo imagery, then apparent depths are calculated by referencing submerged points to the extracted elevation of the water level seen in the image. Due to the effects of refraction, these apparent depths are underestimates, and a refraction correction factor is applied to convert to actual depths. Finally, tidal stage at the time of image acquisition is used to bring depths to chart datum. A post processing step may be applied to remove erroneous depths caused by water surface objects such as boats, debris, or large waves. This was demonstrated in six study areas across Nunavut, Canada to test its robustness under a variety of environmental conditions, including different seafloor types, and under varying sea states. The six study sites were (with vertical accuracy given in Root Mean Square Error/and vertical bias, both in meters): eastern Coral Harbour (1.18/0.03), western Coral Harbour (0.78/-0.32), Cambridge Bay (1.16/0.08), Queen Maud Gulf (0.97/0.13), Arviat (1.02/0.13), and Frobisher Bay, where bathymetry extraction largely failed due to unfavourable sea surface conditions. These findings show that the proposed method has similar or better vertical accuracy as currently established SDB approaches; however, it has several benefits over the established methods which make it better suited for the Arctic. Namely, not requiring the precise atmospheric correction necessary for physics-based models, which is difficult at high latitudes; as well as being able to function in heterogeneous seafloor environments and not needing in-situ calibration data like the empirical spectral ratio approach, better suiting it to remote Arctic waters which often lack existing bathymetric survey data. First and foremost, I would like to thank Dr. Anders Knudby for giving me the opportunity to complete my Master's degree under his excellent guidance. Anders has always been extremely supportive of my academic efforts, and has been an invaluable help during my Master's program, as well as before, when I worked for him during my undergrad at Simon Fraser University. For that, I will be forever grateful.

Research paper thumbnail of 3D Mapping with High Resolution Images

High-resolution images, EROS-A1, IKONOS and QuickBird-2 from 2 m to 0.6 m pixel spacing respectiv... more High-resolution images, EROS-A1, IKONOS and QuickBird-2 from 2 m to 0.6 m pixel spacing respectively, are geometrically processed with a 3D parametric model developed at the Canada Centre for Remote Sensing. A positioning accuracy of one pixel for the ortho-images can be obtained if 7-10 ground control points (GCPs) used in the 3D parametric model computation are better than 1-pixel accurate (cartographic and image coordinates) and if the digital terrain model (DTM) used in the ortho-rectification process is more accurate than 5-m. When the GCPs are less accurate (around 3-5 m) 20 are necessary to avoid the error propagation through the 3D parametric model. Furthermore, a DTM is extracted from stereo IKONOS images using automatic image matching. A general accuracy of 6.5 m (68% level of confidence) when compared to an airborne lidar DTM (0.5 m accurate) is obtained but is correlated with the land covers. However, the accuracy on bare soils improves to 1.5 m (68% level of confidence). Since the surface heights are included in DTM, the surface and the height of buildings can be extracted from the stereo IKONOS DTM. Different methods are proposed, which should used an expert system to integrate a priori information on the buildings in the different processing steps.

Research paper thumbnail of 3-D Radargrammetric Modeling of RADARSAT-2 Ultrafine Mode: Preliminary Results of the Geometric Calibration$^{\ast}$

IEEE Geoscience and Remote Sensing Letters, Jul 1, 2009

The geometry and the accuracy of the 3-D cartographic localization of RADARSAT-2 images are being... more The geometry and the accuracy of the 3-D cartographic localization of RADARSAT-2 images are being evaluated as part of the Canadian Space Agency's Science and Operational Applications Research program. In a first step, the Toutin's 3-D physical model, previously developed for RADARSAT-1, was adapted to RADARSAT-2 sensor and applied to two ultrafine mode images (U2 and U25) acquired over an area in Beauport, Quebec. Both the 3-D modeling computed with only 12 ground control points and its geometric localization were evaluated with different check data: 1) independent check points; 2) the two quasi-epipolar images; 3) the two orthoimages; and 4) 1-m accurate orthophotos. All four results and validations are in agreement and confirm that the 3-D geometric localization and restitution accuracy are 1 m in planimetry and 2 m in elevation. The checked data error being included in these evaluations and the relative error computed from the quasi-epipolar comparison provided a high level of confidence that the precision of Toutin's 3-D radargrammetric model is better than 0.25 m.

Research paper thumbnail of 3D Models for High Resolution Images: Examples with Quickbird, IKONOS, and EROS

EROS, IKONOS and Quickbird are the three civilian satellites, which presently provide panchromati... more EROS, IKONOS and Quickbird are the three civilian satellites, which presently provide panchromatic images with the highest spatial resolution: 2-m, 1-m and 0.6-m, respectively. They also have off-nadir viewing up-to-60º in any azimuth depending on the sensor, which enables stereo images (along and across track) to be acquired. However, the image acquisition system produces different geometric distortions, which need to be accurately corrected. The paper reviews the image distortions and the different 3D models (non-parametric and parametric) for the geometric processing with their applicability to high-resolution images depending on the type of images and their pre-processing level. Results are then presented with stereo images for the three sensors using different 3D models. In general, the 3D parametric models achieve more consistent results. RÉSUMÉ : EROS, IKONOS et Quickbird sont les trois satellites civils, qui fournissent des images panchromatiques avec la meilleure résolution spatiale : 2 m, 1 m et 0,6 m, respectivement. Ils peuvent aussi dépointer jusqu'à 60° dans tous les azimuts pour acquérir des images stéréoscopiques (dans le sens de l'orbite ou perpendiculairement). Par contre, le système d'acquisition des images crée différentes distorsions géométriques, qui doivent être corrigées avec précision. L'article présente les distorsions géométriques et les différents modèles 3D (non-paramétrique et paramétrique) pour le traitement géométrique, ainsi que leur applicabilité aux images de haute résolution suivant le type d'images et leur niveau de prétraitement. Des résultats sont alors donnés avec des images stéréoscopiques des trois capteurs avec les différents modèles 3D. En général, les modèles paramétriques 3D donnent des résultats plus cohérents.

Research paper thumbnail of 3D Geometric Modeling of Radarsat-2 Ultra-Fine Mode Using Differential GPS Data

ESASP, Apr 1, 2009

The geometry and the accuracy of the three-dimensional (3-D) cartographic localization of RADARSA... more The geometry and the accuracy of the three-dimensional (3-D) cartographic localization of RADARSAT-2 images are being evaluated as part of the Canadian Space Agency's Science and Operational Applications Research program. In a first step, the Toutin's 3-D physical model, previously developed for Radarsat-1, was adapted to Radarsat-2 sensor and applied to two ultra-fine mode images (U2 and U25) acquired over a hilly area in Beauport, Quebec. Both the 3-D modeling computed with only 8 ground control points and its geometric localization were evaluated with different check data: (1) independent check points; (2) the two quasi-epipolar images; (3) the two ortho-images; and (4) 1-m accurate ortho-photos. All four results and validations are in agreement and confirm that the 3-D geometric localization and restitution accuracy is better than 1.5 m in planimetry and elevation. In addition the relative error computed from the comparison of the quasi-epipolar images provided a high level of confidence that the precision of Toutin's 3-D radargrammetric model is better than 0.25 m. I. INTRODUCTION This paper will investigate the adaptation of Toutin's 3-D radargrammetric model, previously developed at the Canada Centre for Remote Sensing for Radarsat-1 single, stereo or block images [1]-[3] and its application to highresolution Radarsat-2 modes. The paper will then addresses the processing of an ultra-fine mode (3-m resolution) stereo-pair and validate: (a) the precision of the modeling computed with ground control points (GCPs); (b) the accuracy of the two-dimensional (2-D) positioning accuracy of the ortho-images; (c) the accuracy of the 3-D positioning of extracted points.

Research paper thumbnail of Satellite derived photogrammetric bathymetry

Isprs Journal of Photogrammetry and Remote Sensing, Aug 1, 2018

Satellite Derived Bathymetry (SDB) is being adopted as a cheaper and more spatially extensive met... more Satellite Derived Bathymetry (SDB) is being adopted as a cheaper and more spatially extensive method for bathymetric mapping than traditional acoustic surveys, with research being conducted by the Canadian Hydrographic Service under a Government Related Initiatives Program (GRIP) of the Canadian Space Agency. Established SDB methods involve either an empirical approach, where a regression between known depths and various colour indexes is developed; or a physics-based Radiative Transfer Model (RTM) approach, where light interactions through the water column are simulated. Both methods have achieved vertical accuracies of around 1 m. However, the empirical approach is limited to areas with existing in-situ depth data, and has limited applicability in heterogeneous benthic environments, while the physics-based approach requires precise atmospheric correction. This paper proposes a through-water photogrammetric approach which avoids these limitations, in heterogeneous seafloor environments, by using feature extraction and image geometry rather than spectral radiance to estimate bathymetry. The method is demonstrated in Coral Harbour, Nunavut, Canada using a WorldView-2 stereo pair. A standard photogrammetric extraction was performed on the stereo pair, including a blunder removal and noise reduction. Apparent depths were then calculated by referencing underwater points to the extracted elevation of the waterline. Actual in-image depths were calculated from apparent depths by applying a correction factor to account for the effects of refraction at the air-water boundary. A tidal reduction brought depths to local chart datum, allowing for validation with Canadian Hydrographic Service survey data showing a mean error of 0.031 m and an RMSE of 1.178 m. The method has a similar accuracy to the two established SDB methods, allowing for its use for bathymetric mapping in circumstances where the established methods are not applicable due to their inherent limitations.

Research paper thumbnail of Nearshore Bathymetry Estimation Using Synthetic Aperture Radar (SAR) Imagery

Canadian Journal of Remote Sensing

Abstract A method to estimate nearshore bathymetry using SAR imagery is presented in this paper. ... more Abstract A method to estimate nearshore bathymetry using SAR imagery is presented in this paper. A Fast-Fourier Transform (FFT) and Wavelet hybrid method is proposed to analyze the wave spectra and calculate the wavelength of the long swell waves from SAR acquisitions. The water depth can be retrieved using the linear dispersion relation for shallow water, which requires wavelength and wave period as input parameters. The retrieved bathymetric method are validated with the SAR image over Western Africa and Haida Gwaii. The retrieved results are compared with the ground truth data and have an over 0.9 correlation coefficient. It is found that this method is more feasible to the swell waves with larger significant wave height.

Research paper thumbnail of The impact of sensors for satellite derived bathymetry within the Canadian Arctic

Geomatica, 2020

Canada’s coastline presents challenges for charting. Within Arctic regions, in situ surveying pre... more Canada’s coastline presents challenges for charting. Within Arctic regions, in situ surveying presents risks to surveyors, is time consuming and costly. To better meet its mandate, the Canadian Hydrographic Service (CHS) has been investigating the potential of remote sensing to complement traditional charting techniques. Much of this work has focused on evaluating the effectiveness of empirical satellite derived bathymetry (SDB) techniques within the Canadian context. With greater knowledge of applying SDB techniques within Canadian waters, CHS is now interested in understanding how characteristics of optical sensors can impact SDB results. For example, how does the availability of different optical bands improve or hinder SDB estimates? What is the impact of spatial resolution on SDB accuracy? Do commercial satellites offer advantages over freely available data? Through application of a multiple band modelling technique to WorldView-2, Pléiades, PlanetScope, SPOT, Sentinel-2, and L...

Research paper thumbnail of Investigating the Use of Sentinel-1 for Improved Mapping of Small Peatland Water Bodies: Towards Wildfire Susceptibility Monitoring in Canada’s Boreal Forest

Hydrology

Peatlands provide vital ecosystem and carbon services, and Canada is home to a significant peatla... more Peatlands provide vital ecosystem and carbon services, and Canada is home to a significant peatland carbon stock. Global climate warming trends are expected to lead to increased carbon release from peatlands, as a consequence of drought and wildfire. Monitoring hydrologic regimes is a key in understanding the impacts of warming, including monitoring changes in small and temporally variable water bodies in peatlands. Global surface water mapping has been implemented, but the spatial and temporal scales of the resulting data products prevent the effective monitoring of peatland water bodies, which are small and prone to rapid hydrologic changes. One hurdle in the quest to improve remote-sensing-derived global surface water map quality is the omission of small and temporally variable water bodies. This research investigated the reasons for small peatland water body omission as a preparatory step for surface water mapping, using Sentinel-1 SAR data and image classification methods. It w...

Research paper thumbnail of Mapping Intertidal Changes Using Polarimetry and Interferometry Techniques

World Academy of Science, Engineering and Technology, International Journal of Geological and Environmental Engineering, Jul 29, 2019

Research paper thumbnail of Investigation of C-Band SAR Polarimetry for Mapping a High-Tidal Coastal Environment in Northern Canada

Remote Sensing, 2020

Synthetic Aperture Radar (SAR) has been used in characterizing intertidal zones along northern Ca... more Synthetic Aperture Radar (SAR) has been used in characterizing intertidal zones along northern Canadian coastlines. RADARSAT-2, with its full polarimetric information, has been considered for monitoring these vulnerable ecosystems and helping enhance the navigational safety of these waters. The RADARSAT Constellation Mission (RCM) will ensure data continuity with three identical SAR satellites orbiting together, providing superior revisit capabilities. The three satellites are equipped with multiple configurations, including single-polarization (HH, HV, VV), conventional (HH-HV, VV-VH, and HH-VV), hybrid (i.e., compact) dual polarization, and fully polarimetric (FP) modes. This study investigates the potential of the compact polarimetric (CP) mode for mapping an intertidal zone located at Tasiujaq village on the southwest shore of Ungava Bay, Quebec. Simulated RCM data were generated using FP RADARSAT-2 images collected over the study site in 2016. Commonly used tools for CP analysi...

Research paper thumbnail of Earth Observation and Artificial Intelligence for Improving Safety to Navigation in Canada Low-Impact Shipping Corridors

ISPRS International Journal of Geo-Information, 2020

In 2014, through the World-Class Tanker Safety System (WCTSS) initiative, the Government of Canad... more In 2014, through the World-Class Tanker Safety System (WCTSS) initiative, the Government of Canada launched the Northern Marine Transportation Corridors (NMTC) concept. The corridors were created as a strategic framework to guide Federal investments in marine transportation in the Arctic. With new government investment, under the Oceans Protection Plan (OPP), the corridors initiative, known as the Northern Low-Impact Shipping Corridors, will continue to be developed. Since 2016, the Canadian Hydrographic Service (CHS) has been using the corridors as a key layer in a geographic information system (GIS) model known as the CHS Priority Planning Tool (CPPT). The CPPT helps CHS prioritize its survey and charting efforts in Canada’s key traffic areas. Even with these latest efforts, important gaps in the surveys still need to be filled in order to cover the Canadian waterways. To help further develop the safety to navigation and improve survey mission planning, CHS has also been exploring...

Research paper thumbnail of CHS Priority Planning Tool (CPPT)—A GIS Model for Defining Hydrographic Survey and Charting Priorities

ISPRS International Journal of Geo-Information, 2018

This paper presents a geographic information system (GIS) model that the Canadian Hydrographic Se... more This paper presents a geographic information system (GIS) model that the Canadian Hydrographic Service (CHS) developed to prioritize hydrographic survey and charting at a national scale. Canada has the largest coastline in the world; determining its survey and charting priorities at a national scale is a challenging task, requiring sufficient data to provide national coverage. In order to achieve this task and manage the geospatial layers, CHS has developed a GIS-based model, the CHS Priority Planning Tool (CPPT). Geospatial information of navigational significance (e.g., traffic patterns, water depth, and infrastructure) have been compiled into a GIS model to identify where CHS's hydrographic survey and charting priorities exist. Probability risk modelling, such as a risk of grounding and collision model, as well as a drift model, are included in the CPPT to ensure that CHS has proper mitigation measures in "high-risk" areas. Other environmental factors such as ice and wind speed are also included to help define national priorities for CHS. The CPPT is operational and is currently being used to define and prioritize CHS's survey and charting requirements nationally for multiple years. A GIS web tool has been developed to facilitate accessibility for all Department of Fisheries and Oceans employees and to aid in decision making regarding CHS's national priorities.

Research paper thumbnail of Charting Dynamic Areas in the Mackenzie River with RADARSAT-2, Simulated RADARSAT Constellation Mission and Optical Remote Sensing Data

Remote Sensing, 2019

Mariners navigating within Canadian waters rely on Canadian Hydrographic Service (CHS) navigation... more Mariners navigating within Canadian waters rely on Canadian Hydrographic Service (CHS) navigational charts to safely reach their destinations. To fulfil this need, CHS charts must accurately reflect the current state of Canadian coastal regions. While many coastal regions are stable, others are dynamic and require frequent updates. In order to ensure that important and potentially dangerous changes are reflected in CHS products, the organization, in partnership with the Canadian Space Agency, is exploring coastal change detection through satellite remote sensing (SRS). In this work, CHS examined a hybrid shoreline extraction approach which uses both Synthetic Aperture Radar (SAR) and optical data. The approach was applied for a section of the Mackenzie River, one of Canada’s most dynamic river systems. The approach used RADARSAT-2 imagery as its primary information source, due to its high positioning accuracy (5 m horizontal accuracy) and ability to allow for low and high water line...

Research paper thumbnail of Consideration of Level of Confidence within Multi-Approach Satellite-Derived Bathymetry

ISPRS International Journal of Geo-Information, 2019

The Canadian Hydrographic Service (CHS) publishes nautical charts covering all Canadian waters. T... more The Canadian Hydrographic Service (CHS) publishes nautical charts covering all Canadian waters. Through projects with the Canadian Space Agency, CHS has been investigating remote sensing techniques to support hydrographic applications. One challenge CHS has encountered relates to quantifying its confidence in remote sensing products. This is particularly challenging with Satellite-Derived Bathymetry (SDB) where minimal in situ data may be present for validation. This paper proposes a level of confidence approach where a minimum number of SDB techniques are required to agree within a defined level to allow SDB estimates to be retained. The approach was applied to a Canadian Arctic site, incorporating four techniques: empirical, classification and photogrammetric (automatic and manual). Based on International Hydrographic Organization (IHO) guidelines, each individual approach provided results meeting the CATegory of Zones Of Confidence (CATZOC) level C requirement. By applying the le...

Research paper thumbnail of Satellite-Derived Bathymetry for Improving Canadian Hydrographic Service Charts

ISPRS International Journal of Geo-Information, 2018

Approximately 1000 Canadian Hydrographic Service (CHS) charts cover Canada’s oceans and navigable... more Approximately 1000 Canadian Hydrographic Service (CHS) charts cover Canada’s oceans and navigable waters. Many charts use information collected with techniques that predate the more advanced technologies available to Hydrographic Offices (HOs) today. Furthermore, gaps in survey data, particularly in the Canadian Arctic where only 6% of waters are surveyed to modern standards, are also problematic. Through a Canadian Space Agency (CSA) Government Related Initiatives Program (GRIP) project, CHS is exploring remote sensing techniques to assist with the improvement of Canadian navigational charts. Projects exploring optical/Synthetic Aperture Radar (SAR) shoreline extraction and change detection, as well as optical Satellite-Derived Bathymetry (SDB), are currently underway. This paper focuses on SDB extracted from high-resolution optical imagery, highlighting current results as well as the challenges and opportunities CHS will encounter when implementing SDB within its operational chart...

Research paper thumbnail of Northern marine transportation corridors: Creation and analysis of northern marine traffic routes in Canadian waters

Transactions in GIS, 2017

The concept of the Northern Marine Transportation Corridors (NMTC) initiative was developed under... more The concept of the Northern Marine Transportation Corridors (NMTC) initiative was developed under the Government of Canada World-Class Tanker Safety System Initiative (WCTSS). The NMTC is an interdepartmental Arctic initiative within the Department of Fisheries and Oceans Canada (DFO), through the Canadian Coast Guard (CCG) and the Canadian Hydrographic Service (CHS), in collaboration with Transport Canada (TC). The NMTC initiative was developed to strengthen the safety of marine navigation in the Arctic, and to offer an efficient planning guide for present and future Arctic investments. Transportation corridors identified through this initiative will provide the Government of Canada the framework needed to better prioritize and deliver on its programs and services, including: nautical charts and products; aids to navigation; icebreaking services; and marine safety regulations. The corridors were generated and analyzed with a Geographic Information System (GIS) using two main data sources: the Automated Identification System (AIS) and CHS's nautical charts and publications. The geographic extent of the NMTC is defined as the Northern Canada Vessel Traffic Service Zone (NORDREG Zone) and the Mackenzie River. With close to 4 million km 2 of water in the Arctic and 162,000 km of coastline, surveying the Arctic to modern standards represents an enormous challenge to CHS. By adopting a corridor-based approach, CHS and other government programs can prioritize their efforts on 12% of the Canadian Arctic waters. CHS currently has 32% of the NMTC adequately surveyed, with an additional 3% surveyed to modern standards.

Research paper thumbnail of Bathymetric Photogrammetry to Update CHS Charts: Comparing Conventional 3D Manual and Automatic Approaches

ISPRS International Journal of Geo-Information, 2018

The Canadian Hydrographic Service (CHS) supports safe navigation within Canadian waters through a... more The Canadian Hydrographic Service (CHS) supports safe navigation within Canadian waters through approximately 1000 navigational charts as well as hundreds of publications. One of the greatest challenges faced by the CHS is removing gaps in bathymetric survey data, particularly in the Canadian Arctic where only 6% of navigational water is surveyed to modern standards. Therefore, the CHS has initiated a research project to explore remote sensing methods to improve Canadian navigational charts. The major components of this project explore satellite derived bathymetry (SDB), coastline change detection and coastline extraction. This paper focuses on the potential of two stereo satellite techniques for deriving SDB: (i) automatic digital elevation model (DEM) extraction using a semi-global matching method, and (ii) 3D manual delineation of depth contours using visual stereoscopic interpretation. Analysis focused on quantitative assessment which compared estimated depths from both automati...

Research paper thumbnail of Satellite derived bathymetry for Arctic charting: a review of sensors and techniques for operational implementation within the Canadian Hydrographic Service

Canada’s coastline presents challenges for navigational charting. Within Arctic regions, in situ ... more Canada’s coastline presents challenges for navigational charting. Within Arctic regions, in situ surveying presents risks to surveyors, is time consuming and costly. To better meet its mandate, the Canadian Hydrographic Service (CHS) has been investigating the potential of remote sensing to compliment traditional charting techniques. This paper focuses on an evaluation of sensors and techniques for operational Satellite Derived Bathymetry (SDB) implementation. Analysis focused on Cambridge Bay, Nunavut using Pléiades, SPOT, WorldView and PlanetScope imagery. Multiple SDB techniques were applied to evaluate their agreement with in-situ bathymetric measurements: • An empirical logarithm band ratio approach. • A multiple band modeling technique. • A multi-dimensional Look-Up-Table approach. Through this analysis, CHS attempted to answer critical questions for operational SDB implementation: • Do specific optical sensors offer advantages for SDB? • Are there advantages/disadvantages with the application of SDB techniques within the examined environment? • Can multiple SDB techniques improve CHS’s understanding of the confidence it can place in remotely sensed bathymetry estimates? Early results have achieved overall root mean square errors of 0.56 to 0.99 m relative to in situ survey depths for all sensors and techniques. These similarities suggest that CHS can be confident in the accuracies observed from various SDB approaches. Results do not indicate significant advantages or disadvantages of particular optical sensors, suggesting other factors contain greater importance for SDB image selection (e.g. sea floor visibility). While this analysis provides excellent information for operational empirical SDB implementation within Arctic environments, further work is required within other Canadian coastal regions to support national SDB application.

Research paper thumbnail of CHS priority planning tool - A GIS to prioritize data gaps

International Hydrographic Review, Nov 1, 2022

Research paper thumbnail of Photogrammetric Bathymetry for the Canadian Arctic

Marine Geodesy, Nov 22, 2019

This study proposes and demonstrates a through-water photogrammetry approach for Satellite Derive... more This study proposes and demonstrates a through-water photogrammetry approach for Satellite Derived Bathymetry (SDB), which may be used to map nearshore bathymetry in the Canadian Arctic. A four step process is used: First, a standard photogrammetric extraction is performed on 2 m resolution WorldView stereo imagery, then apparent depths are calculated by referencing submerged points to the extracted elevation of the water level seen in the image. Due to the effects of refraction, these apparent depths are underestimates, and a refraction correction factor is applied to convert to actual depths. Finally, tidal stage at the time of image acquisition is used to bring depths to chart datum. A post processing step may be applied to remove erroneous depths caused by water surface objects such as boats, debris, or large waves. This was demonstrated in six study areas across Nunavut, Canada to test its robustness under a variety of environmental conditions, including different seafloor types, and under varying sea states. The six study sites were (with vertical accuracy given in Root Mean Square Error/and vertical bias, both in meters): eastern Coral Harbour (1.18/0.03), western Coral Harbour (0.78/-0.32), Cambridge Bay (1.16/0.08), Queen Maud Gulf (0.97/0.13), Arviat (1.02/0.13), and Frobisher Bay, where bathymetry extraction largely failed due to unfavourable sea surface conditions. These findings show that the proposed method has similar or better vertical accuracy as currently established SDB approaches; however, it has several benefits over the established methods which make it better suited for the Arctic. Namely, not requiring the precise atmospheric correction necessary for physics-based models, which is difficult at high latitudes; as well as being able to function in heterogeneous seafloor environments and not needing in-situ calibration data like the empirical spectral ratio approach, better suiting it to remote Arctic waters which often lack existing bathymetric survey data. First and foremost, I would like to thank Dr. Anders Knudby for giving me the opportunity to complete my Master's degree under his excellent guidance. Anders has always been extremely supportive of my academic efforts, and has been an invaluable help during my Master's program, as well as before, when I worked for him during my undergrad at Simon Fraser University. For that, I will be forever grateful.

Research paper thumbnail of 3D Mapping with High Resolution Images

High-resolution images, EROS-A1, IKONOS and QuickBird-2 from 2 m to 0.6 m pixel spacing respectiv... more High-resolution images, EROS-A1, IKONOS and QuickBird-2 from 2 m to 0.6 m pixel spacing respectively, are geometrically processed with a 3D parametric model developed at the Canada Centre for Remote Sensing. A positioning accuracy of one pixel for the ortho-images can be obtained if 7-10 ground control points (GCPs) used in the 3D parametric model computation are better than 1-pixel accurate (cartographic and image coordinates) and if the digital terrain model (DTM) used in the ortho-rectification process is more accurate than 5-m. When the GCPs are less accurate (around 3-5 m) 20 are necessary to avoid the error propagation through the 3D parametric model. Furthermore, a DTM is extracted from stereo IKONOS images using automatic image matching. A general accuracy of 6.5 m (68% level of confidence) when compared to an airborne lidar DTM (0.5 m accurate) is obtained but is correlated with the land covers. However, the accuracy on bare soils improves to 1.5 m (68% level of confidence). Since the surface heights are included in DTM, the surface and the height of buildings can be extracted from the stereo IKONOS DTM. Different methods are proposed, which should used an expert system to integrate a priori information on the buildings in the different processing steps.

Research paper thumbnail of 3-D Radargrammetric Modeling of RADARSAT-2 Ultrafine Mode: Preliminary Results of the Geometric Calibration$^{\ast}$

IEEE Geoscience and Remote Sensing Letters, Jul 1, 2009

The geometry and the accuracy of the 3-D cartographic localization of RADARSAT-2 images are being... more The geometry and the accuracy of the 3-D cartographic localization of RADARSAT-2 images are being evaluated as part of the Canadian Space Agency's Science and Operational Applications Research program. In a first step, the Toutin's 3-D physical model, previously developed for RADARSAT-1, was adapted to RADARSAT-2 sensor and applied to two ultrafine mode images (U2 and U25) acquired over an area in Beauport, Quebec. Both the 3-D modeling computed with only 12 ground control points and its geometric localization were evaluated with different check data: 1) independent check points; 2) the two quasi-epipolar images; 3) the two orthoimages; and 4) 1-m accurate orthophotos. All four results and validations are in agreement and confirm that the 3-D geometric localization and restitution accuracy are 1 m in planimetry and 2 m in elevation. The checked data error being included in these evaluations and the relative error computed from the quasi-epipolar comparison provided a high level of confidence that the precision of Toutin's 3-D radargrammetric model is better than 0.25 m.

Research paper thumbnail of 3D Models for High Resolution Images: Examples with Quickbird, IKONOS, and EROS

EROS, IKONOS and Quickbird are the three civilian satellites, which presently provide panchromati... more EROS, IKONOS and Quickbird are the three civilian satellites, which presently provide panchromatic images with the highest spatial resolution: 2-m, 1-m and 0.6-m, respectively. They also have off-nadir viewing up-to-60º in any azimuth depending on the sensor, which enables stereo images (along and across track) to be acquired. However, the image acquisition system produces different geometric distortions, which need to be accurately corrected. The paper reviews the image distortions and the different 3D models (non-parametric and parametric) for the geometric processing with their applicability to high-resolution images depending on the type of images and their pre-processing level. Results are then presented with stereo images for the three sensors using different 3D models. In general, the 3D parametric models achieve more consistent results. RÉSUMÉ : EROS, IKONOS et Quickbird sont les trois satellites civils, qui fournissent des images panchromatiques avec la meilleure résolution spatiale : 2 m, 1 m et 0,6 m, respectivement. Ils peuvent aussi dépointer jusqu'à 60° dans tous les azimuts pour acquérir des images stéréoscopiques (dans le sens de l'orbite ou perpendiculairement). Par contre, le système d'acquisition des images crée différentes distorsions géométriques, qui doivent être corrigées avec précision. L'article présente les distorsions géométriques et les différents modèles 3D (non-paramétrique et paramétrique) pour le traitement géométrique, ainsi que leur applicabilité aux images de haute résolution suivant le type d'images et leur niveau de prétraitement. Des résultats sont alors donnés avec des images stéréoscopiques des trois capteurs avec les différents modèles 3D. En général, les modèles paramétriques 3D donnent des résultats plus cohérents.

Research paper thumbnail of 3D Geometric Modeling of Radarsat-2 Ultra-Fine Mode Using Differential GPS Data

ESASP, Apr 1, 2009

The geometry and the accuracy of the three-dimensional (3-D) cartographic localization of RADARSA... more The geometry and the accuracy of the three-dimensional (3-D) cartographic localization of RADARSAT-2 images are being evaluated as part of the Canadian Space Agency's Science and Operational Applications Research program. In a first step, the Toutin's 3-D physical model, previously developed for Radarsat-1, was adapted to Radarsat-2 sensor and applied to two ultra-fine mode images (U2 and U25) acquired over a hilly area in Beauport, Quebec. Both the 3-D modeling computed with only 8 ground control points and its geometric localization were evaluated with different check data: (1) independent check points; (2) the two quasi-epipolar images; (3) the two ortho-images; and (4) 1-m accurate ortho-photos. All four results and validations are in agreement and confirm that the 3-D geometric localization and restitution accuracy is better than 1.5 m in planimetry and elevation. In addition the relative error computed from the comparison of the quasi-epipolar images provided a high level of confidence that the precision of Toutin's 3-D radargrammetric model is better than 0.25 m. I. INTRODUCTION This paper will investigate the adaptation of Toutin's 3-D radargrammetric model, previously developed at the Canada Centre for Remote Sensing for Radarsat-1 single, stereo or block images [1]-[3] and its application to highresolution Radarsat-2 modes. The paper will then addresses the processing of an ultra-fine mode (3-m resolution) stereo-pair and validate: (a) the precision of the modeling computed with ground control points (GCPs); (b) the accuracy of the two-dimensional (2-D) positioning accuracy of the ortho-images; (c) the accuracy of the 3-D positioning of extracted points.

Research paper thumbnail of Satellite derived photogrammetric bathymetry

Isprs Journal of Photogrammetry and Remote Sensing, Aug 1, 2018

Satellite Derived Bathymetry (SDB) is being adopted as a cheaper and more spatially extensive met... more Satellite Derived Bathymetry (SDB) is being adopted as a cheaper and more spatially extensive method for bathymetric mapping than traditional acoustic surveys, with research being conducted by the Canadian Hydrographic Service under a Government Related Initiatives Program (GRIP) of the Canadian Space Agency. Established SDB methods involve either an empirical approach, where a regression between known depths and various colour indexes is developed; or a physics-based Radiative Transfer Model (RTM) approach, where light interactions through the water column are simulated. Both methods have achieved vertical accuracies of around 1 m. However, the empirical approach is limited to areas with existing in-situ depth data, and has limited applicability in heterogeneous benthic environments, while the physics-based approach requires precise atmospheric correction. This paper proposes a through-water photogrammetric approach which avoids these limitations, in heterogeneous seafloor environments, by using feature extraction and image geometry rather than spectral radiance to estimate bathymetry. The method is demonstrated in Coral Harbour, Nunavut, Canada using a WorldView-2 stereo pair. A standard photogrammetric extraction was performed on the stereo pair, including a blunder removal and noise reduction. Apparent depths were then calculated by referencing underwater points to the extracted elevation of the waterline. Actual in-image depths were calculated from apparent depths by applying a correction factor to account for the effects of refraction at the air-water boundary. A tidal reduction brought depths to local chart datum, allowing for validation with Canadian Hydrographic Service survey data showing a mean error of 0.031 m and an RMSE of 1.178 m. The method has a similar accuracy to the two established SDB methods, allowing for its use for bathymetric mapping in circumstances where the established methods are not applicable due to their inherent limitations.

Research paper thumbnail of Nearshore Bathymetry Estimation Using Synthetic Aperture Radar (SAR) Imagery

Canadian Journal of Remote Sensing

Abstract A method to estimate nearshore bathymetry using SAR imagery is presented in this paper. ... more Abstract A method to estimate nearshore bathymetry using SAR imagery is presented in this paper. A Fast-Fourier Transform (FFT) and Wavelet hybrid method is proposed to analyze the wave spectra and calculate the wavelength of the long swell waves from SAR acquisitions. The water depth can be retrieved using the linear dispersion relation for shallow water, which requires wavelength and wave period as input parameters. The retrieved bathymetric method are validated with the SAR image over Western Africa and Haida Gwaii. The retrieved results are compared with the ground truth data and have an over 0.9 correlation coefficient. It is found that this method is more feasible to the swell waves with larger significant wave height.

Research paper thumbnail of The impact of sensors for satellite derived bathymetry within the Canadian Arctic

Geomatica, 2020

Canada’s coastline presents challenges for charting. Within Arctic regions, in situ surveying pre... more Canada’s coastline presents challenges for charting. Within Arctic regions, in situ surveying presents risks to surveyors, is time consuming and costly. To better meet its mandate, the Canadian Hydrographic Service (CHS) has been investigating the potential of remote sensing to complement traditional charting techniques. Much of this work has focused on evaluating the effectiveness of empirical satellite derived bathymetry (SDB) techniques within the Canadian context. With greater knowledge of applying SDB techniques within Canadian waters, CHS is now interested in understanding how characteristics of optical sensors can impact SDB results. For example, how does the availability of different optical bands improve or hinder SDB estimates? What is the impact of spatial resolution on SDB accuracy? Do commercial satellites offer advantages over freely available data? Through application of a multiple band modelling technique to WorldView-2, Pléiades, PlanetScope, SPOT, Sentinel-2, and L...

Research paper thumbnail of Investigating the Use of Sentinel-1 for Improved Mapping of Small Peatland Water Bodies: Towards Wildfire Susceptibility Monitoring in Canada’s Boreal Forest

Hydrology

Peatlands provide vital ecosystem and carbon services, and Canada is home to a significant peatla... more Peatlands provide vital ecosystem and carbon services, and Canada is home to a significant peatland carbon stock. Global climate warming trends are expected to lead to increased carbon release from peatlands, as a consequence of drought and wildfire. Monitoring hydrologic regimes is a key in understanding the impacts of warming, including monitoring changes in small and temporally variable water bodies in peatlands. Global surface water mapping has been implemented, but the spatial and temporal scales of the resulting data products prevent the effective monitoring of peatland water bodies, which are small and prone to rapid hydrologic changes. One hurdle in the quest to improve remote-sensing-derived global surface water map quality is the omission of small and temporally variable water bodies. This research investigated the reasons for small peatland water body omission as a preparatory step for surface water mapping, using Sentinel-1 SAR data and image classification methods. It w...

Research paper thumbnail of Mapping Intertidal Changes Using Polarimetry and Interferometry Techniques

World Academy of Science, Engineering and Technology, International Journal of Geological and Environmental Engineering, Jul 29, 2019

Research paper thumbnail of Investigation of C-Band SAR Polarimetry for Mapping a High-Tidal Coastal Environment in Northern Canada

Remote Sensing, 2020

Synthetic Aperture Radar (SAR) has been used in characterizing intertidal zones along northern Ca... more Synthetic Aperture Radar (SAR) has been used in characterizing intertidal zones along northern Canadian coastlines. RADARSAT-2, with its full polarimetric information, has been considered for monitoring these vulnerable ecosystems and helping enhance the navigational safety of these waters. The RADARSAT Constellation Mission (RCM) will ensure data continuity with three identical SAR satellites orbiting together, providing superior revisit capabilities. The three satellites are equipped with multiple configurations, including single-polarization (HH, HV, VV), conventional (HH-HV, VV-VH, and HH-VV), hybrid (i.e., compact) dual polarization, and fully polarimetric (FP) modes. This study investigates the potential of the compact polarimetric (CP) mode for mapping an intertidal zone located at Tasiujaq village on the southwest shore of Ungava Bay, Quebec. Simulated RCM data were generated using FP RADARSAT-2 images collected over the study site in 2016. Commonly used tools for CP analysi...

Research paper thumbnail of Earth Observation and Artificial Intelligence for Improving Safety to Navigation in Canada Low-Impact Shipping Corridors

ISPRS International Journal of Geo-Information, 2020

In 2014, through the World-Class Tanker Safety System (WCTSS) initiative, the Government of Canad... more In 2014, through the World-Class Tanker Safety System (WCTSS) initiative, the Government of Canada launched the Northern Marine Transportation Corridors (NMTC) concept. The corridors were created as a strategic framework to guide Federal investments in marine transportation in the Arctic. With new government investment, under the Oceans Protection Plan (OPP), the corridors initiative, known as the Northern Low-Impact Shipping Corridors, will continue to be developed. Since 2016, the Canadian Hydrographic Service (CHS) has been using the corridors as a key layer in a geographic information system (GIS) model known as the CHS Priority Planning Tool (CPPT). The CPPT helps CHS prioritize its survey and charting efforts in Canada’s key traffic areas. Even with these latest efforts, important gaps in the surveys still need to be filled in order to cover the Canadian waterways. To help further develop the safety to navigation and improve survey mission planning, CHS has also been exploring...

Research paper thumbnail of CHS Priority Planning Tool (CPPT)—A GIS Model for Defining Hydrographic Survey and Charting Priorities

ISPRS International Journal of Geo-Information, 2018

This paper presents a geographic information system (GIS) model that the Canadian Hydrographic Se... more This paper presents a geographic information system (GIS) model that the Canadian Hydrographic Service (CHS) developed to prioritize hydrographic survey and charting at a national scale. Canada has the largest coastline in the world; determining its survey and charting priorities at a national scale is a challenging task, requiring sufficient data to provide national coverage. In order to achieve this task and manage the geospatial layers, CHS has developed a GIS-based model, the CHS Priority Planning Tool (CPPT). Geospatial information of navigational significance (e.g., traffic patterns, water depth, and infrastructure) have been compiled into a GIS model to identify where CHS's hydrographic survey and charting priorities exist. Probability risk modelling, such as a risk of grounding and collision model, as well as a drift model, are included in the CPPT to ensure that CHS has proper mitigation measures in "high-risk" areas. Other environmental factors such as ice and wind speed are also included to help define national priorities for CHS. The CPPT is operational and is currently being used to define and prioritize CHS's survey and charting requirements nationally for multiple years. A GIS web tool has been developed to facilitate accessibility for all Department of Fisheries and Oceans employees and to aid in decision making regarding CHS's national priorities.

Research paper thumbnail of Charting Dynamic Areas in the Mackenzie River with RADARSAT-2, Simulated RADARSAT Constellation Mission and Optical Remote Sensing Data

Remote Sensing, 2019

Mariners navigating within Canadian waters rely on Canadian Hydrographic Service (CHS) navigation... more Mariners navigating within Canadian waters rely on Canadian Hydrographic Service (CHS) navigational charts to safely reach their destinations. To fulfil this need, CHS charts must accurately reflect the current state of Canadian coastal regions. While many coastal regions are stable, others are dynamic and require frequent updates. In order to ensure that important and potentially dangerous changes are reflected in CHS products, the organization, in partnership with the Canadian Space Agency, is exploring coastal change detection through satellite remote sensing (SRS). In this work, CHS examined a hybrid shoreline extraction approach which uses both Synthetic Aperture Radar (SAR) and optical data. The approach was applied for a section of the Mackenzie River, one of Canada’s most dynamic river systems. The approach used RADARSAT-2 imagery as its primary information source, due to its high positioning accuracy (5 m horizontal accuracy) and ability to allow for low and high water line...

Research paper thumbnail of Consideration of Level of Confidence within Multi-Approach Satellite-Derived Bathymetry

ISPRS International Journal of Geo-Information, 2019

The Canadian Hydrographic Service (CHS) publishes nautical charts covering all Canadian waters. T... more The Canadian Hydrographic Service (CHS) publishes nautical charts covering all Canadian waters. Through projects with the Canadian Space Agency, CHS has been investigating remote sensing techniques to support hydrographic applications. One challenge CHS has encountered relates to quantifying its confidence in remote sensing products. This is particularly challenging with Satellite-Derived Bathymetry (SDB) where minimal in situ data may be present for validation. This paper proposes a level of confidence approach where a minimum number of SDB techniques are required to agree within a defined level to allow SDB estimates to be retained. The approach was applied to a Canadian Arctic site, incorporating four techniques: empirical, classification and photogrammetric (automatic and manual). Based on International Hydrographic Organization (IHO) guidelines, each individual approach provided results meeting the CATegory of Zones Of Confidence (CATZOC) level C requirement. By applying the le...

Research paper thumbnail of Satellite-Derived Bathymetry for Improving Canadian Hydrographic Service Charts

ISPRS International Journal of Geo-Information, 2018

Approximately 1000 Canadian Hydrographic Service (CHS) charts cover Canada’s oceans and navigable... more Approximately 1000 Canadian Hydrographic Service (CHS) charts cover Canada’s oceans and navigable waters. Many charts use information collected with techniques that predate the more advanced technologies available to Hydrographic Offices (HOs) today. Furthermore, gaps in survey data, particularly in the Canadian Arctic where only 6% of waters are surveyed to modern standards, are also problematic. Through a Canadian Space Agency (CSA) Government Related Initiatives Program (GRIP) project, CHS is exploring remote sensing techniques to assist with the improvement of Canadian navigational charts. Projects exploring optical/Synthetic Aperture Radar (SAR) shoreline extraction and change detection, as well as optical Satellite-Derived Bathymetry (SDB), are currently underway. This paper focuses on SDB extracted from high-resolution optical imagery, highlighting current results as well as the challenges and opportunities CHS will encounter when implementing SDB within its operational chart...

Research paper thumbnail of Northern marine transportation corridors: Creation and analysis of northern marine traffic routes in Canadian waters

Transactions in GIS, 2017

The concept of the Northern Marine Transportation Corridors (NMTC) initiative was developed under... more The concept of the Northern Marine Transportation Corridors (NMTC) initiative was developed under the Government of Canada World-Class Tanker Safety System Initiative (WCTSS). The NMTC is an interdepartmental Arctic initiative within the Department of Fisheries and Oceans Canada (DFO), through the Canadian Coast Guard (CCG) and the Canadian Hydrographic Service (CHS), in collaboration with Transport Canada (TC). The NMTC initiative was developed to strengthen the safety of marine navigation in the Arctic, and to offer an efficient planning guide for present and future Arctic investments. Transportation corridors identified through this initiative will provide the Government of Canada the framework needed to better prioritize and deliver on its programs and services, including: nautical charts and products; aids to navigation; icebreaking services; and marine safety regulations. The corridors were generated and analyzed with a Geographic Information System (GIS) using two main data sources: the Automated Identification System (AIS) and CHS's nautical charts and publications. The geographic extent of the NMTC is defined as the Northern Canada Vessel Traffic Service Zone (NORDREG Zone) and the Mackenzie River. With close to 4 million km 2 of water in the Arctic and 162,000 km of coastline, surveying the Arctic to modern standards represents an enormous challenge to CHS. By adopting a corridor-based approach, CHS and other government programs can prioritize their efforts on 12% of the Canadian Arctic waters. CHS currently has 32% of the NMTC adequately surveyed, with an additional 3% surveyed to modern standards.

Research paper thumbnail of Bathymetric Photogrammetry to Update CHS Charts: Comparing Conventional 3D Manual and Automatic Approaches

ISPRS International Journal of Geo-Information, 2018

The Canadian Hydrographic Service (CHS) supports safe navigation within Canadian waters through a... more The Canadian Hydrographic Service (CHS) supports safe navigation within Canadian waters through approximately 1000 navigational charts as well as hundreds of publications. One of the greatest challenges faced by the CHS is removing gaps in bathymetric survey data, particularly in the Canadian Arctic where only 6% of navigational water is surveyed to modern standards. Therefore, the CHS has initiated a research project to explore remote sensing methods to improve Canadian navigational charts. The major components of this project explore satellite derived bathymetry (SDB), coastline change detection and coastline extraction. This paper focuses on the potential of two stereo satellite techniques for deriving SDB: (i) automatic digital elevation model (DEM) extraction using a semi-global matching method, and (ii) 3D manual delineation of depth contours using visual stereoscopic interpretation. Analysis focused on quantitative assessment which compared estimated depths from both automati...