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Mapping dead forest cover using a deep convolutional neural network and digital aerial photography / Jean-Daniel Sylvain in ISPRS Journal of photogrammetry and remote sensing, vol 156 (October 2019)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 156 (October 2019) . - pp 14 - 26 Titre : Mapping dead forest cover using a deep convolutional neural network and digital aerial photography Type de document : Article/Communication Auteurs : Jean-Daniel Sylvain, Auteur ; Guillaume Drolet, Auteur ; Nicolas Brown, Auteur Année de publication : 2019 Article en page(s) : pp 14 - 26 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes descripteurs IGN] apprentissage profond [Termes descripteurs IGN] arbre mort [Termes descripteurs IGN] base de données forestières [Termes descripteurs IGN] classification par réseau neuronal convolutif [Termes descripteurs IGN] couvert forestier [Termes descripteurs IGN] feuillu [Termes descripteurs IGN] forêt boréale [Termes descripteurs IGN] image aérienne [Termes descripteurs IGN] orthoimage [Termes descripteurs IGN] peuplement mélangé [Termes descripteurs IGN] pinophyta [Termes descripteurs IGN] Québec (Canada) [Termes descripteurs IGN] santé des forêts Résumé : (Auteur) Tree mortality is an important forest ecosystem variable having uses in many applications such as forest health assessment, modelling stand dynamics and productivity, or planning wood harvesting operations. Because tree mortality is a spatially and temporally erratic process, rates and spatial patterns of tree mortality are difficult to estimate with traditional inventory methods. Remote sensing imagery has the potential to detect tree mortality at spatial scales required for accurately characterizing this process (e.g., landscape, region). Many efforts have been made in this sense, mostly using pixel- or object-based methods. In this study, we explored the potential of deep Convolutional Neural Networks (CNNs) to detect and map tree health status and functional type over entire regions. To do this, we built a database of around 290,000 photo-interpreted trees that served to extract and label image windows from 20 cm-resolution digital aerial images, for use in CNN training and evaluation. In this process, we also evaluated the effect of window size and spectral channel selection on classification accuracy, and we assessed if multiple realizations of a CNN, generated using different weight initializations, can be aggregated to provide more robust predictions. Finally, we extended our model with 5 additional classes to account for the diversity of landcovers found in our study area. When predicting tree health status only (live or dead), we obtained test accuracies of up to 94%, and up to 86% when predicting functional type only (broadleaf or needleleaf). Channel selection had a limited impact on overall classification accuracy, while window size increased the ability of the CNNs to predict plant functional type. The aggregation of multiple realizations of a CNN allowed us to avoid the selection of suboptimal models and help to remove much of the speckle effect when predicting on new aerial images. Test accuracies of plant functional type and health status were not affected in the extended model and were all above 95% for the 5 extra classes. Our results demonstrate the robustness of the CNN for between-scene variations in aerial photography and also suggest that this approach can be applied at operational level to map tree mortality across extensive territories. Numéro de notice : A2019-316 Thématique : FORET/IMAGERIE Nature : Article DOI : 10.1016/j.isprsjprs.2019.07.010 date de publication en ligne : 02/08/2019 En ligne : https://doi.org/10.1016/j.isprsjprs.2019.07.010 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93353 [article]

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Wood quality of black spruce and balsam fir trees defoliated by spruce budworm: A case study in the boreal forest of Quebec, Canada / Carlos Paixao in Forest ecology and management, vol 437 (1 April 2019)  

Public [article]  inForest ecology and management > vol 437 (1 April 2019) . - pp 201-210 Titre : Wood quality of black spruce and balsam fir trees defoliated by spruce budworm: A case study in the boreal forest of Quebec, Canada Type de document : Article/Communication Auteurs : Carlos Paixao, Auteur ; Cornelia Krause, Auteur ; Hubert Morin, Auteur ; Alexis Achim, Auteur Année de publication : 2019 Article en page(s) : pp 201-210 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] Abies balsamea [Termes descripteurs IGN] biomasse forestière [Termes descripteurs IGN] bois sur pied [Termes descripteurs IGN] croissance végétale [Termes descripteurs IGN] défoliation [Termes descripteurs IGN] densité du bois [Termes descripteurs IGN] diamètre des arbres [Termes descripteurs IGN] données dendrométriques [Termes descripteurs IGN] forêt boréale [Termes descripteurs IGN] insecte nuisible [Termes descripteurs IGN] picea mariana [Termes descripteurs IGN] qualité du bois [Termes descripteurs IGN] Québec (Canada) [Termes descripteurs IGN] télédétection aérienne Résumé : (auteur) Spruce budworm (SBW – Choristoneura fumiferana Clem.) is one of the most damaging defoliating insects in the coniferous forests of eastern North America. In Canada, the widely distributed balsam fir (Abies balsamea L. (Mill)) and black spruce (Picea mariana B.S.P. (Mill)) are its most important hosts. Defoliation by SBW reduces growth in the host trees and can lead to host mortality. Although SBW impacts on growth are well documented, much less is known about changes in wood properties resulting from defoliation. To address this knowledge gap, we sampled 36 SBW-infested stands located in the boreal forest of Quebec (Canada) to determine whether defoliation modifies the wood quality of affected trees. The selected stands had been subjected to one to four years of SBW defoliation. For both species, we assessed ring growth, wood density, and the anatomical characteristics of stem wood formed during the outbreak years. We determined that rings formed during the SBW outbreak had a significant and progressive loss of biomass production with a longer duration of defoliation. SBW significantly reduced latewood density in the second and third year of defoliation for black spruce and the third and fourth year for balsam fir. Average ring density was reduced only in black spruce and only after four years of defoliation. The observed changes in growth and density were associated with changes in anatomical features. While the cellular characteristics of the earlywood remained fairly constant, significant reductions occurred in latewood cell-wall thickness after three years of defoliation. Our study shows that not only do SBW outbreaks reduce annual radial growth, but the cellular characteristics in latewood cells are also modified momentarily. Thus, SBW outbreaks affect wood density and quality in both black spruce and balsam fir. Numéro de notice : A2019-484 Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.foreco.2019.01.032 date de publication en ligne : 01/02/2019 En ligne : https://doi.org/10.1016/j.foreco.2019.01.032 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93661 [article]

Towards operational marker-free registration of terrestrial lidar data in forests / Jean-François Tremblay in ISPRS Journal of photogrammetry and remote sensing, vol 146 (December 2018)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 146 (December 2018) . - pp 430 - 435 Titre : Towards operational marker-free registration of terrestrial lidar data in forests Type de document : Article/Communication Auteurs : Jean-François Tremblay, Auteur ; Martin Béland, Auteur Année de publication : 2018 Article en page(s) : pp 430 - 435 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes descripteurs IGN] analyse comparative [Termes descripteurs IGN] canopée [Termes descripteurs IGN] cible réfléchissante [Termes descripteurs IGN] données lidar [Termes descripteurs IGN] données localisées 3D [Termes descripteurs IGN] Etats-Unis [Termes descripteurs IGN] forêt [Termes descripteurs IGN] inventaire forestier (techniques et méthodes) [Termes descripteurs IGN] matrice de covariance [Termes descripteurs IGN] modèle numérique de terrain [Termes descripteurs IGN] Québec (Canada) Résumé : (auteur) Terrestrial laser scanning (TLS) often makes use of multiple scans in forests to allow for a complete view of a given area. Combining measurements from multiple locations requires accurate co-registration of the scans to a common reference coordinate system, which currently relies on markers, an often cumbersome process in forests. Existing algorithms for achieving marker-free registration of TLS scans in forests promise to significantly decrease field work time, but are not yet operational and their results have not been validated against traditional methods. Here we present a new implementation of an existing approach which runs in parallel mode and is able to process TLS data acquired over large forest areas. To validate our algorithm, point cloud registration matrices (translation and rotation) derived from our algorithm were compared to those obtained using reflective markers in multiple forest types. The results show that our approach can be used operationally in forests with relatively clear understory, and it provides accuracy similar to that obtained from using reflective markers. Furthermore, we identified factors that can lead to this approach falling short of providing acceptable results in terms of accuracy. Numéro de notice : A2018-542 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2018.10.011 date de publication en ligne : 02/11/2018 En ligne : https://doi.org/10.1016/j.isprsjprs.2018.10.011 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91566 [article]

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Parametric bootstrap estimators for hybrid inference in forest inventories / Mathieu Fortin in Forestry, an international journal of forest research, vol 91 n° 3 (July 2018)  

Public [article]  inForestry, an international journal of forest research > vol 91 n° 3 (July 2018) . - pp 354 - 365 Titre : Parametric bootstrap estimators for hybrid inference in forest inventories Type de document : Article/Communication Auteurs : Mathieu Fortin, Auteur ; Ruben Manso, Auteur ; Robert Schneider, Auteur Année de publication : 2018 Article en page(s) : pp 354 - 365 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] Bootstrap (statistique) [Termes descripteurs IGN] complexité [Termes descripteurs IGN] erreur systématique [Termes descripteurs IGN] inférence statistique [Termes descripteurs IGN] inventaire forestier (techniques et méthodes) [Termes descripteurs IGN] inventaire forestier étranger (données) [Termes descripteurs IGN] modèle stochastique [Termes descripteurs IGN] Québec (Canada) [Termes descripteurs IGN] variance [Vedettes matières IGN] Inventaire forestier Résumé : (Auteur) In forestry, the variable of interest is not always directly available from forest inventories. Consequently, practitioners have to rely on models to obtain predictions of this variable of interest. This context leads to hybrid inference, which is based on both the probability design and the model. Unfortunately, the current analytical hybrid estimators for the variance of the point estimator are mainly based on linear or nonlinear models and their use is limited when the model reaches a high level of complexity. An alternative consists of using a variance estimator based on resampling methods (Rubin, D. B. (1987). Multiple imputation for nonresponse surveys. John Wiley & Sons, Hoboken, New Jersey, USA). However, it turns out that a parametric bootstrap (BS) estimator of the variance can be biased in contexts of hybrid inference. In this study, we designed and tested a corrected BS estimator for the variance of the point estimator, which can easily be implemented as long as all of the stochastic components of the model can be properly simulated. Like previous estimators, this corrected variance estimator also makes it possible to distinguish the contribution of the sampling and the model to the variance of the point estimator. The results of three simulation studies of increasing complexity showed no evidence of bias for this corrected variance estimator, which clearly outperformed the BS variance estimator used in previous studies. Since the implementation of this corrected variance estimator is not much more complicated, we recommend its use in contexts of hybrid inference based on complex models. Numéro de notice : A2018-637 Thématique : FORET/MATHEMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1093/forestry/cpx048 date de publication en ligne : 22/11/2017 En ligne : https://doi.org/10.1093/forestry/cpx048 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93246 [article]

Post-1980 shifts in the sensitivity of boreal tree growth to North Atlantic Ocean dynamics and seasonal climate / Clémentine Ols in Global and Planetary Change, vol 165 (June 2018)  

Public [article]  inGlobal and Planetary Change > vol 165 (June 2018) . - pp 1 - 12 Titre : Post-1980 shifts in the sensitivity of boreal tree growth to North Atlantic Ocean dynamics and seasonal climate Type de document : Article/Communication Auteurs : Clémentine Ols , Auteur ; Valérie Trouet, Auteur ; Martin P. Girardin, Auteur ; Annika Hofgaard, Auteur ; Yves Bergeron, Auteur ; Igor Drobyshev, Auteur Année de publication : 2018 Article en page(s) : pp 1 - 12 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] analyse de sensibilité [Termes descripteurs IGN] Atlantique Nord [Termes descripteurs IGN] cerne [Termes descripteurs IGN] circulation océanique [Termes descripteurs IGN] climat [Termes descripteurs IGN] croissance végétale [Termes descripteurs IGN] dendrochronologie [Termes descripteurs IGN] forêt boréale [Termes descripteurs IGN] inventaire forestier étranger (données) [Termes descripteurs IGN] océanographie dynamique [Termes descripteurs IGN] Picea abies [Termes descripteurs IGN] picea mariana [Termes descripteurs IGN] puits de carbone [Termes descripteurs IGN] Québec (Canada) [Termes descripteurs IGN] Suède [Vedettes matières IGN] Végétation et changement climatique Résumé : (auteur) The mid-20th century changes in North Atlantic Ocean dynamics, e.g. slow-down of the Atlantic meridional overturning thermohaline circulation (AMOC), have been considered as early signs of tipping points in the Earth climate system. We hypothesized that these changes have significantly altered boreal forest growth dynamics in northeastern North America (NA) and northern Europe (NE), two areas geographically adjacent to the North Atlantic Ocean. To test our hypothesis, we investigated tree growth responses to seasonal large-scale oceanic and atmospheric indices (the AMOC, North Atlantic Oscillation (NAO), and Arctic Oscillation (AO)) and climate (temperature and precipitation) from 1950 onwards, both at the regional and local levels. We developed a network of 6876 black spruce (NA) and 14437 Norway spruce (NE) tree-ring width series, extracted from forest inventory databases. Analyses revealed post-1980 shifts from insignificant to significant tree growth responses to summer oceanic and atmospheric dynamics both in NA (negative responses to NAO and AO indices) and NE (positive response to NAO and AMOC indices). The strength and sign of these responses varied, however, through space with stronger responses in western and central boreal Quebec and in central and northern boreal Sweden, and across scales with stronger responses at the regional level than at the local level. Emerging post-1980 associations with North Atlantic Ocean dynamics synchronized with stronger tree growth responses to local seasonal climate, particularly to winter temperatures. Our results suggest that ongoing and future anomalies in oceanic and atmospheric dynamics may impact forest growth and carbon sequestration to a greater extent than previously thought. Cross-scale differences in responses to North Atlantic Ocean dynamics highlight complex interplays in the effects of local climate and ocean-atmosphere dynamics on tree growth processes and advocate for the use of different spatial scales in climate-growth research to better understand factors controlling tree growth. Numéro de notice : A2018-662 Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.gloplacha.2018.03.006 date de publication en ligne : 18/03/2018 En ligne : https://doi.org/10.1016/j.gloplacha.2018.03.006 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93844 [article]

GPS coordinate time series measurements in Ontario and Quebec, Canada / Hadis Samadi Alinia in Journal of geodesy, vol 91 n° 6 (June 2017)  

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InSAR assessment of surface deformations in urban coastal terrains associated with groundwater dynamics / Jonathan C. L. Normand in IEEE Transactions on geoscience and remote sensing, vol 53 n° 12 (December 2015)

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Cahiers de géographie de Quebec : Toponymie (Bulletin de Cahiers de géographie du Québec) / L. Trottier

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Pertinence de l’utilisation du LiDAR terrestre pour l’acquisition de données 3D à des fins de représentations cadastrales (condominiums) / Marc Vasseur (2014) 

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Pratique professionnelle de l'arpentage et SIG au Québec / Francis Roy in Géomètre, n° 2107 (octobre 2013)

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Couplage de l'AMCD avec les SIG en appui au processus décisionnel d'analyse des projets de fermes éoliennes, L'approche DEMIT / Maria De Vazquez in Revue internationale de géomatique, vol 23 n° 1 (mars - mai 2013)

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Utilisation d'ArcGIS pour la production de livrables cartographiques dans le cadre d'un projet d'acquisition de connaissances sur les eaux souterraines / Jacques Gautier (2012)

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Accessibilité spatiale aux parcs urbains pour les enfants et injustice environnementale : Exploration du cas montréalais / P. Apparicio in Revue internationale de géomatique, vol 20 n° 3 (septembre - novembre 2010)

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A crustal deformation study of the Charlevoix seismic zone in Quebec / Marc Cocard in Geomatica, vol 64 n° 3 (September 2010)

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Géo-simulation des coûts généralisés de déplacement en transports privés et publics : automatisation du paramétrage spatio-temporel / N. Lachance-Bernard in Revue internationale de géomatique, vol 20 n° 1 (mars - mai 2010)

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