Jérôme Théau

Jérôme Théau
Université de Sherbrooke | UdeS · Department of Applied Geomatics

PhD

About

63
Publications
19,172
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1,015
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Publications

Publications (63)
Chapter
This chapter is an overview of change detection techniques applied to Earth observation. Section 7.1 gives a short definition of change detection followed by the historical background of this process (Sect. 7.2). Methods of change detection are described in Sect. 7.3, and are illustrated using an analysis of wildlife habitat (Sect. 7.4). Typical ap...
Chapter
Full-text available
Principles and functioning of thermal imaging Acquisition process with TIR UAV TIR images (pre-)processing Analyzing TIR images acquired by UAV Challenges and limits
Chapter
The book serves as a handbook and guideline for the application of UAV-based remote sensing. Data acquisition, processing and interpretation was explained in-depth, and was correlated by a variety of practical examples and case studies. Open Access book available at: https://www.wbg-wissenverbindet.de/shop/42282/uavs-for-the-environmental-sciences
Article
Full-text available
Survey and monitoring of wildlife populations are among the key elements in nature conservation. The use of unmanned aerial vehicles and light aircrafts as aerial image acquisition systems is growing, as they are cheaper alternatives to traditional census methods. However, the manual localization and identification of species within imagery can be...
Article
One of the main challenges of outdoor pig production systems is their potential environmental impact due to direct deposition of pigs’ excreta on the land that can lead to nitrate leaching. However, plants can recycle nutrients, and a sufficient vegetation cover can mitigate adverse environmental impacts of outdoor pigs. The aim of this study was t...
Article
Full-text available
Grasslands are among the most widespread ecosystems on Earth and among the most degraded. Their characterization and monitoring are generally based on field measurements, which are incomplete spatially and temporally. The recent advent of unmanned aerial vehicles (UAV) provides data at unprecedented spatial and temporal resolutions. This study aims...
Article
Full-text available
The combination of unmanned aerial vehicles (UAV) with deep learning models has the capacity to replace manned aircrafts for wildlife surveys. However, the scarcity of animals in the wild often leads to highly unbalanced, large datasets for which even a good detection method can return a large amount of false detections. Our objectives in this pape...
Article
Full-text available
Flavescence dorée (FD) is a grapevine disease caused by phytoplasmas and transmitted by leafhoppers that has been spreading in European vineyards despite significant efforts to control it. In this study, we aim to develop a model for the automatic detection of FD-like symptoms (which encompass other grapevine yellows symptoms). The concept is to de...
Article
Agricultural intensification causes habitat modification, sometimes leading to habitat loss and subsequent loss of connectivity. Remaining species in these agriculture-dominated landscapes often use hedgerows, such as windbreaks or riparian strips, as movement corridors or even as habitats. However, the understanding of the use of these hedgerows b...
Technical Report
Full-text available
La présente revue de littérature couvre les définitions générales des écosystèmes riverains et des bandes riveraines des points de vue légal et écologique dans un objectif de suivi des écosystèmes riverains. Les fonctions écologiques liées à la biodiversité et celles qui influencent directement les ressources en eau seront également abordées. Les i...
Article
Full-text available
Crop scouting is essential to manage crops such as potatoes and detect stresses. In fact, conventional approaches require a lot of time and staff. The rise of unmanned aerial vehicle (UAV) imagery offers interesting perspectives in this area. However, the development of interpreted and generalizable cartographic products that can be used directly b...
Article
In order to control severe soil erosion, large-scale ecological restoration programs (ERPs) were undertaken, which greatly increased vegetation cover in the Chinese Loess Plateau. Although this has generated positive impacts on soil erosion reduction, the conflicts between water supply and the ERPs in the Loess Plateau remain debatable. The impacts...
Technical Report
Full-text available
Cette recherche avait comme objectif de dresser le portrait écologique, social et économique des initiatives agroenvironnementales mises en place en milieu agricole depuis les dernières années au Québec. En plus de mettre en lumière ces initiatives, ce projet visait à étudier leur efficacité sur le déplacement de la faune et l’adhésion des producte...
Article
We examined the use of ecosystem service (ES) approaches at the landscape scale to assess two major ecological restoration programs (ERPs) in China. We found 68 papers highlighting four aspects: (1) most papers considered only one ES, and all ES categories were not covered equally; (2) regional-scale and short-term assessments dominated the reviewe...
Conference Paper
Full-text available
Since the early 2010’s, great progress has been made in image classification through deep learning and convolutional neural networks (CNNs). This allows us to consider the development of automatic high-precision scouting tools for agricultural use. The objective of this project is the automatic identification of grapevine downy mildew –Plasmopara v...
Article
Full-text available
Deep learning techniques, and in particular Convolutional Neural Networks (CNNs), have led to significant progress in image processing. Since 2016, many applications for the automatic identification of crop diseases have been developed. These applications could serve as a basis for the development of expertise assistance or automatic screening tool...
Article
Wetlands are affected by climate and anthropogenic changes, which influence the ecosystem services (ES) they provide. This study presents a spatially explicit quantification of wetland ESs. The study site is the Yamaska river watershed located in Quebec, Canada. The proposed approach includes four main steps: (1) statistical selection of function i...
Article
Full-text available
Unmanned aerial vehicles (UAVs) have become popular platforms for collecting various types of geospatial data for various mapping, monitoring and modelling applications. With the advancement of imaging and computing technologies, a vast variety of photogrammetric, computer-vision and, nowadays, end-to-end learning workflows are introduced to produc...
Research Proposal
Full-text available
Conception et cartographie d'un indice de suivi de l'état des écosystèmes riverains applicable à l'échelle du Québec méridional Mise en contexte et problématique - Certaines directions du ministère de l'Environnement et de la Lutte contre les changements climatiques du Québec (MELCC) ont pour mandat d'effectuer un suivi et une surveillance de l'é...
Article
Full-text available
One of the most active areas of research in photogrammetry and computer vision is dense three-dimensional (3D) reconstruction of the environment via high-density image matching. This research interest is mainly driven by the growing popularity of unconventional imaging solutions such as images captured from unmanned aerial vehicles. With such data,...
Article
Full-text available
Over the last few years, several of the world’s national park networks have implemented ecological integrity monitoring programs. These programs are based on a series of indicators to detect changes in ecosystem integrity. There are many scientific and logistical challenges in developing these programs due to limits in both our knowledge of ecosyst...
Data
Error matrix describing classification results of ecosystems for the Frontenac National Park. (DOCX)
Data
Ecosystem mapping of the Frontenac National Park. (DOCX)
Data
Data source and characteristics. (DOCX)
Data
Conceptual model of freshwater ecosystem (adapted from Parks Canada, 2005). (DOCX)
Article
Full-text available
In this paper, a robust technique based on a genetic algorithm is proposed for estimating two-view epipolar-geometry of uncalibrated perspective stereo images from putative correspondences containing a high percentage of outliers. The advantages of this technique are three-fold: (i) replacing random search with evolutionary search applying new stra...
Article
Full-text available
Dense stereo matching is one of the fundamental and active areas of photogrammetry. The increasing image resolution of digital cameras as well as the growing interest in unconventional imaging, e.g. unmanned aerial imagery, has exposed stereo image pairs to serious occlusion, noise and matching ambiguity. This has also resulted in an increase in th...
Article
Full-text available
Dense stereo matching is one of the fundamental and active areas of photogrammetry. The increasing image resolution of digital cameras as well as the growing interest in unconventional imaging, e.g. unmanned aerial imagery, has exposed stereo image pairs to serious occlusion, noise and matching ambiguity. This has also resulted in an increase in th...
Article
Wildlife management is based on various measurements representative of the health of populations and their habitats. Some agencies are focusing on animal surveys to manage species such as white-tailed deer (Odocoileus virginianus). Current survey methods are faced with the challenge of reduced operating costs as well as estimating and correcting de...
Article
Full-text available
The specific requirements of UAV-photogrammetry necessitate particular solutions for system development, which have mostly been ignored or not assessed adequately in recent studies. Accordingly, this paper presents the methodological and experimental aspects of correctly implementing a UAV-photogrammetry system. The hardware of the system consists...
Conference Paper
Full-text available
Along with the advancement of unmanned aerial vehicles (UAVs), improvement of high-resolution cameras and development of vision-based mapping techniques, unmanned aerial imagery has become a matter of remarkable interest among researchers and industries. These images have the potential to provide data with unprecedented spatial and temporal resolut...
Conference Paper
Full-text available
Wildlife aerial surveys require time and significant resources. Multispecies detection could reduce costs to a single census for species that coexist spatially. Traditional methods are demanding for observers in terms of concentration and are not adapted to multispecies censuses. The processing of multispectral aerial imagery acquired from an unman...
Conference Paper
Full-text available
La maîtrise professionnelle en sciences géographiques de l'Université de Sherbrooke est offerte de façon simultanée par le biais de visioconférences entre le campus principal de Sherbrooke et le campus éloigné de Longueuil depuis 2010. Ce programme vise notamment à développer des compétences au niveau de l'analyse du territoire dans ses dimensions...
Article
Abstract Ecological networks (EN) are designed to maintain biodiversity and ecological processes by protecting habitats and their linkages. By considering the functional role of the landscape, EN can support the integration of ecological sustainability with human activities. Although all EN share the same general objectives, there are many differen...
Conference Paper
Full-text available
In this paper, we propose a robust technique using genetic algorithm for detecting inliers and estimating accurate motion parameters from putative correspondences containing any percentage of outliers. The proposed technique aims to increase computational efficiency and modelling accuracy in comparison with the state-of-the-art via the following co...
Article
Full-text available
Climate change will cause major changes in ecosystems. Therefore, it is crucial that climate change policy consider the value of all services that are provided by watershed ecosystems. For this purpose, geospatial data and economic analysis are combined to determine a monetary value for wetland ecosystem goods and services (EGSs) in the watersheds...
Article
Full-text available
Afin de bien répondre à la mission des parcs nationaux du Québec, les gestionnaires de la Sépaq devaient être en mesure de suivre l'évolution du niveau d'intégrité écologique des parcs. Mis en place en 2003, le Programme de suivi de l'intégrité écologique (PSIE) a été l’option retenue pour répondre à ce besoin (Sépaq, 2011). Lors des dernières anné...
Article
Full-text available
Unmanned aerial vehicles have become popular platforms for remote-sensing applications, particularly when spaceborne technology, manned airborne techniques, and in situ methods are not as efficient for various reasons. These reasons include the temporal and spatial data resolutions, accessibility over time and space, cost efficiency, and operationa...
Article
Ecological networks are designed to maintain biodiversity and ecological processes by protecting habitats and their connectivity. Several approaches can be used to define the components of these networks at each stage of their design. These choices are a major source of uncertainty that influence the spatial configuration of the networks obtained,...
Chapter
This chapter is an overview of change detection techniques applied to Earth observation. Section 7.1 gives a short definition of change detection followed by an historical background of this process (Sect. 7.2). Methods of change detection are described in Sect. 7.3 and are illustrated using an analysis of wildlife habitat (Sect. 7.4). Typical appl...
Article
Full-text available
Snowshoe hare (Lepus americanus) behavior has been analyzed over a1-year period to understand the influence of climatic factors. Six animals were observed with a video camera in a 1350-m2 outdoor enclosure located in a wood stand andequipped with a computerized weather station. Temperature (°C), relative humidity (%), windspeed (km/h), and barometr...
Article
Full-text available
Multi-sensor comparisons are sometimes used due to limited image avail-ability and temporal coverage by a single sensor. However, multi-sensor comparabil-ity is not well documented. Factors affecting direct comparability such as atmospheric conditions, landscape heterogeneity, landscape changes, and sensor characteristics are difficult to quantify....
Article
Full-text available
Habitat studies are essential in order to understand the dynamics of migratory caribou herds and to better define management strategies. In this paper, multi-date Landsat images are used to map lichen in the summer range of the George River Caribou Herd (GRCH), Québec-Labrador (Canada), over the period from 1976 to 1998. Multi-Spectral Scanner scen...
Article
Many factors influence classification accuracy and a typical error budget includes uncertainty arising from the 1) selection of processing algorithms, 2) selection of training sites, 3) quality of orthorectification, and 4) atmospheric effects. With the development of high spatial resolution imagery, the impact of errors in geographic coregistratio...
Article
Full-text available
Studies of caribou herds in northern regions are important to better understand population dynamics and define wildlife management strategies. Lichen is a primary food source for caribou and is a good indicator of caribou herd activity because of its sensitivity to overgrazing and overtrampling, its widespread distribution over northern areas, and...
Article
Full-text available
The summer range of the George River caribou herd (GRCH) of northern Quebec-Labrador has been affected by various levels of grazing and trampling during the last century. A demographic explosion of (he herd during this period has caused severe local degradation of the vegetation cover and lichen mats. The slow recovery dynamics of habitats in this...
Conference Paper
We present a new approach for the detection and mapping of lichen in a heterogeneous habitat of northern Quebec using Landsat imagery. Results from the enhancement-classification method (ECM) and from spectral mixture analysis (SMA) were compared and evaluated for their potential to be applied over large territories. ECM is based on guided unsuperv...
Article
Full-text available
Snowshoe Hare (Lepus americanus) activity was observed during a one-year period to analyze the effect of environmental factors on activity at a seasonal and daily scale. The activity of six animals was recorded by video camera in a 1350 m2 outdoor enclosure located in a wood stand and equipped with a computerized weather station. Temperature, relat...
Article
Snowshoe Hare (Lepus americanus) activity was observed during a one-year period to analyze the effect of environmental factors on activity at a seasonal and daily scale. The activity of six animals was recorded by video camera in a 1350 m(2) outdoor enclosure located in a wood stand and equipped with a computerized weather station. Temperature, rel...
Article
Snowshoe hare (Lepus americanus) behavior has been analyzed over a 1-year period to understand the influence of climatic factors. Six animals were observed with a video camera in a 1350-m(2) outdoor enclosure located in a wood stand and equipped with a computerized weather station. Temperature (degrees C), relative humidity (%), wind speed (km/h),...

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Projects (3)
Project
Monitor vegetation stress in vineyards using visible-IR imagery.
Project
Explore new image processing techniques to detect and count large mammal populations in restricted environments.