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Warming effects on morphological and physiological performances of four subtropical montane tree species Authors Authors and affiliations / Yiyong Li in Annals of Forest Science [en ligne], Vol 77 n° 1 (March 2020)
Titre : Warming effects on morphological and physiological performances of four subtropical montane tree species Authors Authors and affiliations Type de document : Article/Communication Auteurs : Yiyong Li, Auteur ; Yue Xu, Auteur ; Ting Wu, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : 11 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] changement climatique
[Termes descripteurs IGN] croissance végétale
[Termes descripteurs IGN] diagnostic foliaire
[Termes descripteurs IGN] effet thermique
[Termes descripteurs IGN] forêt tropicale
[Termes descripteurs IGN] hauteur des arbres
[Termes descripteurs IGN] montagne
[Termes descripteurs IGN] morphologie
[Termes descripteurs IGN] photosynthèse
[Termes descripteurs IGN] stress hydrique
[Vedettes matières IGN] Végétation et changement climatiqueRésumé : (auteur) Key message: In a downward transplantation experiment, warming stimulated growth and photosynthesis of Schima superba Gardn. et Champ., Syzygium rehderianum Merr. et Perry and Itea chinensis Hook. et Arn. via increased stomatal conductance. Warming had no effect on growth of Machilus breviflora (Benth.) Hemsl., indicating species-specific differences in response to warming. Context: Climate change has been shown to shift species composition and community structure in subtropical forests. Thus, understanding the species-specific responses of growth and physiological processes to warming is essential. Aims:
To investigate how climate warming affects growth, morphological and physiological performance of co-occurring tree species when they are growing at different altitudes. Methods: Soils and 1-year-old seedlings of four subtropical co-occurring tree species (Schima superba Gardn. et Champ., Syzygium rehderianum Merr. et Perry, Itea chinensis Hook. et Arn. and Machilus breviflora (Benth.) Hemsl.) were transplanted to three altitudes (600 m, 300 m and 30 m a.s.l.), inducing an effective warming of 1.0 °C and 1.5 °C. Growth, morphological, and physiological performances of these seedlings were monitored. Results: When exposed to warmer conditions, aboveground growth of the four species except M. breviflora was strongly promoted, accompanied by increased light-saturated photosynthetic rate and stomatal conductance. Warming also significantly increased concentrations of non-structural carbohydrates in leaves of S. rehderianum and M. breviflora, stems of S. superba and S. rehderianum, and roots of I. chinensis. However, we did not detect any effect of warming on stomatal length and stomatal density. Conclusion:
Our results provide evidence that climate warming could have species-specific impacts on co-occurring tree species, which might subsequently shift species composition and forest structure.Numéro de notice : A2020-037 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s13595-019-0910-3 date de publication en ligne : 10/01/2020 En ligne : https://doi.org/10.1007/s13595-019-0910-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94491
in Annals of Forest Science [en ligne] > Vol 77 n° 1 (March 2020) . - 11 p.[article]
Titre : Simulation and analysis of photogrammetric UAV image blocks - Influence of camera calibration error Type de document : Article/Communication Auteurs : Yilin Zhou, Auteur ; Ewelina Rupnik Année de publication : 2020 Projets : 1-Pas de projet / Article en page(s) : n° 22 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique
[Termes descripteurs IGN] bloc d'images
[Termes descripteurs IGN] compensation par faisceaux
[Termes descripteurs IGN] effet thermique
[Termes descripteurs IGN] étalonnage de chambre métrique
[Termes descripteurs IGN] image de drone
[Termes descripteurs IGN] obturateur
[Termes descripteurs IGN] prise de vue aérienneRésumé : (auteur) Unmanned aerial vehicles (UAV) are increasingly used for topographic mapping. The camera calibration for UAV image blocks can be performed a priori or during the bundle block adjustment (self-calibration). For an area of interest with flat scene and corridor configuration, the focal length of camera is highly correlated with the height of the camera. Furthermore, systematic errors of camera calibration accumulate on the longer dimension and cause deformation. Therefore, special precautions must be taken when estimating camera calibration parameters. In order to better investigate the impact of camera calibration errors, a synthetic, error-free aerial image block is generated to simulate several issues of interest. Firstly, the erroneous focal length in the case of camera pre-calibration is studied. Nadir images are not able to prevent camera poses from drifting to compensate for the erroneous focal length, whereas the inclusion of oblique images brings significant improvement. Secondly, the case where the focal length varies gradually (e.g., when the camera subject to temperature changes) is investigated. The neglect of this phenomenon can substantially degrade the 3D measurement accuracy. Different flight configurations and flight orders are analyzed, the combination of oblique and nadir images shows better performance. At last, the rolling shutter effect is investigated. The influence of camera rotational motion on the final accuracy is negligible compared to that of the translational motion. The acquisition configurations investigated are not able to mitigate the degradation introduced by the rolling shutter effect. Other solutions such as correcting image measurements or including camera motion parameters in the bundle block adjustment should be exploited. Numéro de notice : A2020-415 Affiliation des auteurs : LaSTIG (2020- ) Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3390/rs12010022 date de publication en ligne : 19/12/2019 En ligne : https://doi.org/10.3390/rs12010022 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95503
in Remote sensing > vol 12 n° 1 (January 2020) . - n° 22[article]
Titre : Simulation and analysis of photogrammetric UAV image blocks: influence of camera calibration error Type de document : Article/Communication Auteurs : Yilin Zhou, Auteur ; Ewelina Rupnik Congrès : ISPRS Geospatial Week 2019 (10 - 14 juin 2019; Enschede, Pays-Bas), Commanditaire Année de publication : 2019 Projets : 1-Pas de projet / Article en page(s) : pp 195 - 200 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes descripteurs IGN] bloc d'images
[Termes descripteurs IGN] compensation par faisceaux
[Termes descripteurs IGN] effet thermique
[Termes descripteurs IGN] erreur systématique
[Termes descripteurs IGN] estimation de pose
[Termes descripteurs IGN] étalonnage de chambre métrique
[Termes descripteurs IGN] étalonnage en vol
[Termes descripteurs IGN] image aérienne oblique
[Termes descripteurs IGN] image de drone
[Termes descripteurs IGN] longueur focale
[Termes descripteurs IGN] photogrammétrie aérienne
[Termes descripteurs IGN] point d'appui
[Termes descripteurs IGN] point de liaison (imagerie)Résumé : (auteur) Unmanned aerial vehicles (UAV) are increasingly used for topographic mapping. The camera calibration for UAV image blocks can be performed a priori or during the bundle block adjustment (self-calibration). For an area of interest with flat, corridor configuration, the focal length of camera is highly correlated with the height of camera. Furthermore, systematic errors of camera calibration accumulate on the longer dimension and cause deformation. Therefore, special precautions must be taken when estimating camera calibration parameters. In this paper, a simulated, error-free aerial image block is generated. error is then added on camera calibration and given as initial solution to bundle block adjustment. Depending on the nature of the error and the investigation purpose, camera calibration parameters are either fixed or re-estimated during the bundle block adjustment. The objective is to investigate how certain errors in the camera calibration impact the accuracy of 3D measurement without the influence of other errors. All experiments are carried out with Fraser camera calibration model being employed. When adopting a proper flight configuration, an error on focal length for the initial camera calibration can be corrected almost entirely during bundle block adjustment. For the case where an erroneous focal length is given for pre-calibration and not re-estimated, the presence of oblique images limits the drift on camera height hence gives better camera pose estimation. Other than that, the error on focal length when neglecting its variation during the acquisition (e.g., due to camera temperature increase) is also investigated; a bowl effect is observed when one focal length is given in camera pre-calibration to the whole image block. At last, a local error is added in image space to simulate camera flaws; this type of error is more difficult to be corrected with the Fraser camera model and the accuracy of 3D measurement degrades substantially. Numéro de notice : A2019-591 Affiliation des auteurs : LaSTIG (2020- ) Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/isprs-annals-IV-2-W5-195-2019 date de publication en ligne : 29/05/2019 En ligne : https://doi.org/10.5194/isprs-annals-IV-2-W5-195-2019 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94551
in ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences > IV-2/W5 (May 2019) . - pp 195 - 200[article]
Titre : Improvement of photogrammetric accuracy by modeling and correcting the thermal effect on camera calibration Type de document : Article/Communication Auteurs : Mehdi Daakir, Auteur ; Yilin Zhou, Auteur ; Marc Pierrot-Deseilligny Année de publication : 2019 Projets : 1-Pas de projet / Article en page(s) : pp 142 - 156 Note générale : Bibliographie
voir préprint dans HAL https://hal.archives-ouvertes.fr/hal-01987463Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes descripteurs IGN] CamLight
[Termes descripteurs IGN] déformation d'image
[Termes descripteurs IGN] détecteur CMOS
[Termes descripteurs IGN] effet thermique
[Termes descripteurs IGN] étalonnage de capteur (imagerie)
[Termes descripteurs IGN] image de drone
[Termes descripteurs IGN] modèle géométrique de prise de vue
[Termes descripteurs IGN] photogrammétrie métrologiqueRésumé : (Auteur) This paper presents a new method for improving the geometric accuracy of photogrammetric reconstruction by modeling and correcting the thermal effect on camera image sensor. The objective is to verify that when the temperature of image sensor varies during the acquisition, image deformation induced by the temperature change is quantifiable, modelisable and correctable. A temperature sensor integrated in the camera enables the measurement of image sensor temperature at exposure. It is therefore natural and appropriate to take this effect into account and to finally model and correct it after a calibration step. Nowadays, in cartography applications performed with UAV, the frame rate of acquisitions is continuously increasing. A high frame rate over a long acquisition time can result in an important temperature increase of the image sensor and thus introduces image deformations. The correction of the above-mentioned effect can improve the measurement accuracy. We present three methods to calibrate the thermal effect and experiments on two datasets are carried out to verify the improvement in terms of the photogrammetric accuracy. Numéro de notice : A2019-072 Affiliation des auteurs : LaSTIG (2020- ) Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2018.12.012 date de publication en ligne : 04/01/2019 En ligne : https://doi.org/10.1016/j.isprsjprs.2018.12.012 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92159
in ISPRS Journal of photogrammetry and remote sensing > vol 148 (February 2019) . - pp 142 - 156[article]Réservation
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Titre : 100% automatic metrology with UAV photogrammetry and embedded GPS, and its application in dike monitoring Type de document : Thèse/HDR Auteurs : Yilin Zhou, Auteur ; Marc Pierrot-Deseilligny Editeur : Champs/Marne : Université Paris-Est Marne-la-Vallée UPEM Année de publication : 2019 Importance : 181 p. Format : 21 x 30 cm Note générale : bibliographie
Thèse de Doctorat de l'Université Paris-Est, Sciences et Technologies de l'Information GéographiqueLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes descripteurs IGN] angle nadiral
[Termes descripteurs IGN] digue
[Termes descripteurs IGN] données GNSS
[Termes descripteurs IGN] effet thermique
[Termes descripteurs IGN] étalonnage de chambre métrique
[Termes descripteurs IGN] image aérienne
[Termes descripteurs IGN] image aérienne oblique
[Termes descripteurs IGN] image de drone
[Termes descripteurs IGN] modélisation 3D
[Termes descripteurs IGN] obturateur
[Termes descripteurs IGN] photogrammétrie métrologique
[Termes descripteurs IGN] point d'appui
[Termes descripteurs IGN] réseau fluvialRésumé : (auteur) The development of unmanned aerial vehicle (UAV) platform makes it nowadays a valuable source of data for inspection, surveillance, mapping and 3D modeling issues. UAV photogrammetry opens various new applications in close-range aerial domain and introduces a low-cost alternative to classical manned vehicle photogrammetry. Corridor mapping, one of the fields with substantial importance for UAV photo-grarnmetry, is largely demanded in the surveillance and management of infrastructure assets — highways, railways, waterways and pipelines. Due to the special geometry of the scene, corridor mapping is one case that needs taking precautions. Errors accumu-late easily on the longer dimension of the scene and a bowl effect is often observed; the flatness of the scene introduces strong correlations between parameters to be determi-ned, these two factors together, make it more difficult to obtain high accuracy results in corridor configuration than in classical ones. This thesis is a research project initiated by the CNR, a river concessionary, which has the responsibility of the maintenance and surveillance of its hydraulic facilities, more particularly the dikes. The objective is to apply UAV photogrammetry, which is faster, cheaper and offers a 3D dense reconstruction of the scene, to the monitoring of dikes. While maintaining a high surveying accuracy, a reduced field work, i.e. the number of ground control points (GCPs) is expected. In the first place, simulations are carried out to gain an insight of several problems of corridor mapping that impact the final accuracy. Then, thorough investigations are conducted on three aspects that interest us the most. The first study focuses on the aerial acquisition geometry, discussions are given on the influence of oblique images, nadir images of different flight heights as well as the possibility of an in-flight camera calibration and its application on unfavourable acquisition geometry. The second study aims to improve the acquisition performance for high-end metric cameras. The image deformation introduced by camera temperature variation is investigated and modelled. A method for the correction of this thermal effect is proposed, its performance is eva-luated on both terrestrial and aerial datasets of corridor configuration. The last study interests in the rolling shutter effect for consumer-grade cameras, which is commonly seen in UAV platforms on the market. Two methods are presented to calibrate the camera readout time, a property that is often not given by camera manufacturers. A two-step method is proposed for the correction of rolling shutter effect, its performance is evaluated in both block and corridor configurations. Note de contenu : 1- Introduction en français
2- Introduction
3- State of the art
4- Simulation and analysis
5- Study of aerial acquisition geometry
6- Study of thermal effect
7- Study of rolling shutter effect
8- Conclusion and perspectiveNuméro de notice : 25522 Affiliation des auteurs : LaSTIG (2020- ) Thématique : IMAGERIE Nature : Thèse française Note de thèse : Thèse de Doctorat : Géophysique : Paris-Est : 2019 Organisme de stage : LaSTIG (IGN) nature-HAL : Thèse date de publication en ligne : 11/02/2020 En ligne : https://tel.archives-ouvertes.fr/tel-02474315v2/document Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94383 Réservation
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