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Towards an enhanced understanding of airborne LiDAR measurements of forest vegetation / Aarne Hovi (2015)
Titre : Towards an enhanced understanding of airborne LiDAR measurements of forest vegetation Type de document : Thèse/HDR Auteurs : Aarne Hovi, Auteur Editeur : Vantaa [Finlande] : Finnish Society of Forest Science Année de publication : 2015 Collection : Dissertationes forestales, ISSN 1795-7389 num. 200 Format : 21 x 30 cm ISBN/ISSN/EAN : 978-951-651-489-8 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] analyse de sensibilité
[Termes IGN] composition d'un peuplement forestier
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] espèce végétale
[Termes IGN] forme d'onde
[Termes IGN] identification automatique
[Termes IGN] photogrammétrie terrestre
[Termes IGN] signal laserRésumé : (auteur) This thesis presents basic research on how airborne LiDAR measurements of forest vegetation are influenced by the interplay of the geometric-optical properties of vegetation, sensor function and acquisition settings. Within the work, examining the potential of waveform (WF) recording sensors was of particular interest.
Study I focused upon discrete return LiDAR measurements of understory trees. It showed that transmission losses influenced the intensity of observations and echo triggering probabilities, and also skewed the distribution of echoes towards those triggered by highly reflective or dense targets. The intensity data were of low value for species identification, but the abundance of understory trees could be predicted based on echo height distributions.
In study II, a method of close-range terrestrial photogrammetry was developed. Images were shown as being useful for visualizations and even the geometric quality control of LiDAR data. The strength of backscattering was shown to correlate with the projected area extracted from the images.
In study III, a LiDAR simulation model was developed and validated against real measurements. The model was able to be used for sensitivity analyses to illustrate how plant structure or different pulse properties influence the WF data. Both simulated and real data showed that WF data were able to capture small-scale variations in the structural and optical properties of juvenile forest vegetation.
Study IV illustrated the potential of WF data in the species classification of larger trees. The WF features that separated tree species were also dependent on other variables such as tree size and phenology. Inherent between-tree differences in structure were quantified and the effects of pulse density on the features were examined.
Overall, the thesis provides basic findings on how LiDAR pulses interact with forest vegetation, and serves to link theory with real observations. The results contribute to an improved understanding of LiDAR measurements and their limitations, and thus provide support for further improvements in both data interpretation methods and specific sensor design.Numéro de notice : 14979 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Thèse étrangère Note de thèse : PhD : Forest sciences : University of Helsinki : 2015 En ligne : http://www.metla.fi/dissertationes/df200.htm Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78367 Validity and behaviour of tropospheric gradients estimated by GPS in Corsica / Laurent Morel in Advances in space research, vol 55 n° 1 ([01/01/2015])
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Titre : Validity and behaviour of tropospheric gradients estimated by GPS in Corsica Type de document : Article/Communication Auteurs : Laurent Morel, Auteur ; Eric Pottiaux, Auteur ; Frédéric Durand, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 135 - 149 Langues : Anglais (eng) Descripteur : [Termes IGN] Corse
[Termes IGN] GAMIT
[Termes IGN] GIPSY-OASIS
[Termes IGN] gradient de troposphère
[Termes IGN] retard troposphérique
[Vedettes matières IGN] Traitement de données GNSSRésumé : (auteur) Estimation of tropospheric gradients in GNSS data processing is a well-known technique to improve positioning (e.g. Bar-Sever et al., 1998; Chen and Herring, 1997). More recently, several authors also focused on the estimation of such parameters for meteorological studies and demonstrated their potential benefits (e.g. Champollion et al., 2004). Today, they are routinely estimated by several global and regional GNSS analysis centres but they are still not yet used for operational meteorology.
This paper discusses the physical meaning of tropospheric gradients estimated from GPS observations recorded in 2011 by 13 permanent stations located in Corsica Island (a French Island in the western part of Italy). Corsica Island is a particularly interesting location for such study as it presents a significant environmental contrast between the continent and the sea, as well as a steep topography.
Therefore, we estimated Zenith Total Delay (ZTD) and tropospheric gradients using two software: GAMIT/GLOBK (GAMIT version 10.5) and GIPSY-OASIS II version 6.1. Our results are then compared to radiosonde observations and to the IGS final troposphere products. For all stations we found a good agreement between the ZWD estimated by the two software (the mean of the ZWD differences is 1 mm with a standard deviation of 6 mm) but the tropospheric gradients are in less good agreement (the mean of the gradient differences is 0.1 mm with a standard deviation of 0.7 mm), despite the differences in the processing strategy (double-differences for GAMIT/GLOBK versus zero-difference for GIPSY-OASIS).
We also observe that gradient amplitudes are correlated with the seasonal behaviour of the humidity. Like ZWD estimates, they are larger in summer than in winter. Their directions are stable over the time but not correlated with the IWV anomaly observed by ERA-Interim. Tropospheric gradients observed at many sites always point to inland throughout the year. These preferred directions are almost opposite to the largest slope of the local topography as derived from the world Digital Elevation Model ASTER GDEM v2. These first results give a physical meaning to gradients but the origin of such directions need further investigations.Numéro de notice : A2015-297 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2014.10.004 En ligne : https://doi.org/10.1016/j.asr.2014.10.004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76458
in Advances in space research > vol 55 n° 1 [01/01/2015] . - pp 135 - 149[article]Evaluating tree detection and segmentation routines on very high resolution UAV LiDAR data / Luke Wallace in IEEE Transactions on geoscience and remote sensing, vol 52 n° 12 (December 2014)
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Titre : Evaluating tree detection and segmentation routines on very high resolution UAV LiDAR data Type de document : Article/Communication Auteurs : Luke Wallace, Auteur ; Arko Lucieer, Auteur ; Christopher S. Watson, Auteur Année de publication : 2014 Article en page(s) : pp 7619 - 7628 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] arbre (flore)
[Termes IGN] canopée
[Termes IGN] contour
[Termes IGN] détection de cible
[Termes IGN] données lidar
[Termes IGN] drone
[Termes IGN] Eucalyptus globulus
[Termes IGN] hauteur des arbres
[Termes IGN] image à très haute résolution
[Termes IGN] implémentation (informatique)
[Termes IGN] prise de vue aérienne
[Termes IGN] semis de pointsRésumé : (Auteur) Light detection and Ranging (LiDAR) is becoming an increasingly used tool to support decision-making processes within forest operations. Area-based methods that derive information on the condition of a forest based on the distribution of points within the canopy have been proven to produce reliable and consistent results. Individual tree-based methods, however, are not yet used operationally in the industry. This is due to problems in detecting and delineating individual trees under varying forest conditions resulting in an underestimation of the stem count and biases toward larger trees. The aim of this paper is to use high-resolution LiDAR data captured from a small multirotor unmanned aerial vehicle platform to determine the influence of the detection algorithm and point density on the accuracy of tree detection and delineation. The study was conducted in a four-year-old Eucalyptus globulus stand representing an important stage of growth for forest management decision-making process. Five different tree detection routines were implemented, which delineate trees directly from the point cloud, voxel space, and the canopy height model (CHM). The results suggest that both algorithm and point density are important considerations in the accuracy of the detection and delineation of individual trees. The best performing method that utilized both the CHM and the original point cloud was able to correctly detect 98% of the trees in the study area. Increases in point density (from 5 to 50 points/m2) lead to significant improvements (of up to 8%) in the rate of omission for algorithms that made use of the high density of the data. Numéro de notice : A2014-640 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2014.2315649 En ligne : https://doi.org/10.1109/TGRS.2014.2315649 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75077
in IEEE Transactions on geoscience and remote sensing > vol 52 n° 12 (December 2014) . - pp 7619 - 7628[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 065-2014121 RAB Revue Centre de documentation En réserve L003 Disponible High resolution imagery collection for post-disaster studies utilizing unmanned aircraft systems (UAS) / Stuart M. Adams in Photogrammetric Engineering & Remote Sensing, PERS, vol 80 n° 12 (December 2014)
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Titre : High resolution imagery collection for post-disaster studies utilizing unmanned aircraft systems (UAS) Type de document : Article/Communication Auteurs : Stuart M. Adams, Auteur ; Marc L. Levitan, Auteur ; Carol J. Friedland, Auteur Année de publication : 2014 Article en page(s) : pp 1161 - 1168 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] Alabama (Etats-Unis)
[Termes IGN] catastrophe naturelle
[Termes IGN] drone
[Termes IGN] image à haute résolution
[Termes IGN] photographie aérienne
[Termes IGN] prise de vue aérienne
[Termes IGN] tempêteRésumé : (auteur) This paper examines the use of unmanned aircraft systems (UAS) to capture imagery for use in post-disaster field studies at the neighborhood and individual building level. A discussion of post-disaster imagery collection including satellite, aerial, and ground-based platforms is first presented. Applications of UAS in recent disasters as described in the literature are then surveyed, and a case study investigating UAS capabilities for imagery collection following an EF-3 tornado in northern Alabama on 02 March 2012 is presented. Case study considerations include the multi-rotor unmanned aerial vehicle (UAVj equipment and ground station, onboard imagery devices, flight considerations and capabilities, and imagery aid metadata collection capabilities of the UAS. Sample post-tornado imagery of building damage is shown, demonstrating the order of magnitude improvement in imagery resolution compared to traditional post-disaster aerial photography. Numéro de notice : A2014-671 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.80.12.1161 En ligne : https://doi.org/10.14358/PERS.80.12.1161 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75130
in Photogrammetric Engineering & Remote Sensing, PERS > vol 80 n° 12 (December 2014) . - pp 1161 - 1168[article]Motion blur disturbs – the influence of motion-blurred images in photogrammetry / T. Sieberth in Photogrammetric record, vol 29 n° 148 (December 2014 - February 2015)
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Titre : Motion blur disturbs – the influence of motion-blurred images in photogrammetry Type de document : Article/Communication Auteurs : T. Sieberth, Auteur ; R. Wackrow, Auteur ; Jim H. Chandler, Auteur Année de publication : 2014 Article en page(s) : pp 434 – 453 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] étalonnage de capteur (imagerie)
[Termes IGN] flou
[Termes IGN] image à haute résolution
[Termes IGN] tâche claire
[Termes IGN] traitement d'imageRésumé : (Auteur) Unmanned aerial vehicles (UAVs) have become an interesting and active research topic for photogrammetry. Current research is based on images acquired by UAVs which have a high ground resolution and good spectral resolution due to low flight altitudes combined with a high-resolution camera. One of the main problems preventing full automation of data processing of UAV imagery is the unknown degradation effect of blur caused by camera movement during image acquisition. The purpose of this paper is to analyse the influence of blur on photogrammetric image processing. Images with precisely known motion blur were produced to determine the effect. It was found that even small blurs affect normal photogrammetric processes significantly. Although operator intervention might be time consuming, it can ensure that the results are still of acceptable accuracy. Numéro de notice : A2014-649 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/phor.12082 Date de publication en ligne : 16/12/2014 En ligne : https://doi.org/10.1111/phor.12082 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75095
in Photogrammetric record > vol 29 n° 148 (December 2014 - February 2015) . - pp 434 – 453[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 106-2014041 RAB Revue Centre de documentation En réserve L003 Disponible Multi-UAV surveillance over forested regions / Vengatesan Govindaraju in Photogrammetric Engineering & Remote Sensing, PERS, vol 80 n° 12 (December 2014)PermalinkOrthophotographie nocturne à haute résolution : la nuit, vue du ciel / Eva Frangiamone in Géomatique suisse, vol 112 n° 12 (décembre 2014)PermalinkPerceptually shaded slope maps for the visualization of digital surface models / Thomas J. Pingel in Cartographica, vol 49 n° 4 (Winter 2014)PermalinkRetrieval of spectral reflectance of high resolution multispectral imagery acquired with an autonomous unmanned aerial vehicle: AggieAir™ / Bushra Zaman in Photogrammetric Engineering & Remote Sensing, PERS, vol 80 n° 12 (December 2014)PermalinkAssessment of crop foliar nitrogen using a novel dual-wavelength laser system and implications for conducting laser-based plant physiology / Jan U.H. Eitel in ISPRS Journal of photogrammetry and remote sensing, vol 97 (November 2014)PermalinkChanging the light azimuth in shaded relief representation by clustering aspect / Fabio Veronesi in Cartographic journal (the), vol 51 n° 4 (November 2014)PermalinkComparison of individual and combined zenith tropospheric delay estimations during CONT08 campaign / Arnaud Pollet in Journal of geodesy, vol 88 n° 11 (November 2014)PermalinkEstimating leaf chlorophyll of barley at different growth stages using spectral indices to reduce soil background and canopy structure effects / Kiyun Yu in ISPRS Journal of photogrammetry and remote sensing, vol 97 (November 2014)PermalinkA fast volume-gradient-based band selection method for hyperspectral image / X. Geng in IEEE Transactions on geoscience and remote sensing, vol 52 n° 11 tome 1 (November 2014)PermalinkModelling electrical conductivity of soil from backscattering coefficient of microwave remotely sensed data using artificial neural network / Walaiporn Phonphan in Geocarto international, vol 29 n° 7 - 8 (November - December 2014)Permalink