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The effect of broadleaf canopies on survey-grade horizontal GPS-GLONASS measurements / Thomas H. Meyer in Surveying and land information systems, vol 62 n° 4 (01/12/2002)
[article]
Titre : The effect of broadleaf canopies on survey-grade horizontal GPS-GLONASS measurements Type de document : Article/Communication Auteurs : Thomas H. Meyer, Auteur ; J.E. Bean, Auteur ; C.R. Ferguson, Auteur ; J.M. Naismith, Auteur Année de publication : 2002 Article en page(s) : pp 215 - 224 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] diffusion du rayonnement
[Termes IGN] feuille (végétation)
[Termes IGN] instrumentation Trimble
[Termes IGN] ligne de base
[Termes IGN] positionnement par GLONASS
[Termes IGN] positionnement par GPS
[Termes IGN] récepteur GPS
[Termes IGN] récepteur mixte
[Termes IGN] seuillage
[Termes IGN] signal GLONASS
[Termes IGN] signal GPSRésumé : (Auteur) A study was conducted to empirically determine the degradation of survey-grade GPS horizontal position measurements due to the effects of broadleaf forest canopies. The measurements were taken using GPS/GLONASS-capable receivers measuring C/A and P-codes, and carrier phase. Fourteen survey markers were chosen in central Connecticut to serve as reference makers for study. These markers had varying degrees of sky obstruction due to overhanging tree canopies. Sky obstruction was measured by photographing the sky with a 35 mm reflex camera fitted with a hemispherical lens. The negative was scanned and the image mapped using an equal-area projection to remove the distortion caused by the lens. The resulting digital image was thresholded to produce a black-and-white image in which a count of the black pixels is a measure of sky-area obstruction. The locations of the markers were determined independently before the study. During the study, each marker was occupied for four 20-minutes sessions over the period of one week in mid-july 1999. The locations of the study markers produced relatively long baselines, as compared with similar studies. We compared the accuracy of GPS-only vs. GPS&GLONASS as a function of sky obstruction. Based on our results, GLONASS observations did not improve of degrade the accuracy of the position measurements. There is a loss of 2 mm of accuracy per percent of sky obstruction for both GPS only and GPS&GLONASS. Numéro de notice : A2002-360 Affiliation des auteurs : non IGN Thématique : FORET/POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22271
in Surveying and land information systems > vol 62 n° 4 (01/12/2002) . - pp 215 - 224[article]Leaf morphological differentiation between Quercus robur and Quercus petraea is stable across western European mixed oak stands / Antoine Kremer in Annals of Forest Science, vol 59 n° 7 (novembre 2002)
[article]
Titre : Leaf morphological differentiation between Quercus robur and Quercus petraea is stable across western European mixed oak stands Type de document : Article/Communication Auteurs : Antoine Kremer, Auteur ; Jean-Luc Dupouey, Auteur ; J. Douglas Deans, Auteur ; Joan Cottrell, Auteur ; Ulrike Csaikl, Auteur ; Reiner Finkeldey, Auteur ; Santiago Espinel, Auteur ; et al., Auteur Année de publication : 2002 Article en page(s) : pp 777 - 787 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation
[Termes IGN] Europe occidentale
[Termes IGN] feuille (végétation)
[Termes IGN] peuplement forestier
[Termes IGN] Quercus pedunculata
[Termes IGN] Quercus sessiliflora
[Termes IGN] taxinomieMots-clés libres : morphology leaf Quercus robur Quercus petraea taxonomy Résumé : (auteur) Leaf morphology was assessed in nine mixed oak stands (Quercus petraea and Q. robur) located in eight European countries. Exhaustive sampling was used in an area of each stand where the two species coexisted in approximately equal proportions (about 170 trees/species/ stand). Fourteen leaf characters were assessed on each of 5 to10 leaves collected from the upper part of each tree. Three multivariate statistical techniques (CDA, canonical discriminant analysis; PCA, principal component analysis; MCA, multiple correspondence analysis) were used in two different ways: first on the total set of leaves over all stands (global analysis) and second, separately within each stand (local analysis). There was a general agreement of the results among the statistical methods used and between the analyses conducted (global and local). The first synthetic variable derived by each multivariate analysis exhibited a clear and sharp bimodal distribution, with overlapping in the central part. The two modes were interpreted as the two species, and the overlapping region was interpreted as an area where the within-species variations were superimposed. There was no discontinuity in the distribution or no visible evidence of a third mode which would have indicated the existence of a third population composed of trees with intermediate morphologies. Based on petiole length and number of intercalary veins, an “easy to use” discriminant function applicable to a major part of the natural distribution of the species was constructed. Validation on an independent set of trees provided a 98% rate of correct identification. The results were interpreted in the light of earlier reports about extensive hybridization occurring in mixed oak stands. Maternal effects on morphological characters, as well as a lower frequency or fitness of hybrids in comparison with parent species could explain the maintenance of two modes, which might be composed of either pure species or pure species and introgressed forms. Numéro de notice : A2002-055 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1051/forest:2002065 En ligne : http://dx.doi.org/10.1051/forest:2002065 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81013
in Annals of Forest Science > vol 59 n° 7 (novembre 2002) . - pp 777 - 787[article]Documents numériques
en open access
Leaf morphological differentiationAdobe Acrobat PDF Improvement of an oak canopy model extracted from digital photogrammetry / P. Gong in Photogrammetric Engineering & Remote Sensing, PERS, vol 68 n° 9 (September 2002)
[article]
Titre : Improvement of an oak canopy model extracted from digital photogrammetry Type de document : Article/Communication Auteurs : P. Gong, Auteur ; X. Mei, Auteur ; S. Biging, Auteur ; Z. Zhang, Auteur Année de publication : 2002 Article en page(s) : pp 919 - 924 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image
[Termes IGN] couvert forestier
[Termes IGN] extraction du sursol
[Termes IGN] feuille (végétation)
[Termes IGN] interpolation
[Termes IGN] modèle numérique de surface
[Termes IGN] photogrammétrie numérique
[Termes IGN] Quercus (genre)
[Termes IGN] surveillance forestièreRésumé : (Auteur) Digital surface models (DSMs) automatically derived with digital photogrammetric systems are useful in land surface change monitoring, including forest growth monitoring. However, they cannot be applied directly to forest canopy change analysis with high accuracy due to the inevitable deficiencies in existing commercial digital photogrammetry packages. In a hardwood rangeland monitoring study, we found that the oak tree and woodland canopy boundaries were not well determined using several digital photogrammetry packages available to us. There was a noticeable discrepancy between the true crown closure and that determined by subtracting the DSM and the corresponding DEM that excludes tree heights. In this paper, we present a correction method for improvement at the erroneous canopy boundary locations in the DSM using shadow and boundary information extracted from imagery. The method is designed for correcting errors for broadleaf tree canopies. Aerial photographs taken over oak woodland hills were tested. Using manual photogrammetric measurements as the reference, we found that most of the points (88.3 percent) on the canopy boundaries were displaced by greater than 1 meter with a conventional digital photogrammetric package. After the proposed algorithms were applied, greater than 98.6 percent of the points on canopy boundaries were found to be within 1 meter of their reference positions. 78.4 percent of the reference points had greater than 2 meters elevation errors with the conventional package while greater than 85.6 percent of those points were found to be within 2 meters of the reference after the proposed algorithms were applied. Numéro de notice : A2002-184 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : sans En ligne : https://www.asprs.org/wp-content/uploads/pers/2002journal/september/2002_sep_919 [...] Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22099
in Photogrammetric Engineering & Remote Sensing, PERS > vol 68 n° 9 (September 2002) . - pp 919 - 924[article]Réflectances foliaires et acclimatation à un déficit hydrique / P. Beaumont (1995)
Titre : Réflectances foliaires et acclimatation à un déficit hydrique : cas des feuilles de tournesol Type de document : Thèse/HDR Auteurs : P. Beaumont, Auteur Editeur : Toulouse : Université de Toulouse 3 Paul Sabatier Année de publication : 1995 Importance : 129 p. Format : 21 x 30 cm Note générale : Bibliographie
Thèse en vue de l'obtention du doctorat de l'université Paul Sabatier, spécialité écophysiologie végétale et télédétectionLangues : Français (fre) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] feuille (végétation)
[Termes IGN] optique
[Termes IGN] réflectance spectrale
[Termes IGN] réflectance végétale
[Termes IGN] stress hydrique
[Termes IGN] tournesol
[Termes IGN] variable biophysique (végétation)Index. décimale : THESE Thèses et HDR Numéro de notice : 23389 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Thèse française Note de thèse : Thèse de doctorat : écophysiologie végétale et télédétection : Toulouse 3 : 1995 Organisme de stage : Labortoire d'Ecophysiologie Végétale, Centre d'Etudes Spatiales de la Biosphère CESBIO nature-HAL : Thèse DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=45316 Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 23389-01 THESE Livre Centre de documentation Thèses Disponible Utilisation de la stéréovision pour estimer des paramètres de structure d'un couvert végétal / Nikolay Ivanov in Bulletin [Société Française de Photogrammétrie et Télédétection], n° 131 (Juillet 1993)
[article]
Titre : Utilisation de la stéréovision pour estimer des paramètres de structure d'un couvert végétal Type de document : Article/Communication Auteurs : Nikolay Ivanov, Auteur ; Paul Boissard, Auteur ; Michel Chapron, Auteur ; Pierre Valery, Auteur Année de publication : 1993 Article en page(s) : pp 24 - 33 Note générale : bibliographie Langues : Français (fre) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] couple stéréoscopique
[Termes IGN] couvert végétal
[Termes IGN] estimation des paramètres
[Termes IGN] feuille (végétation)
[Termes IGN] maquette numérique
[Termes IGN] restitutionRésumé : (auteur) Une méthode de reconstruction d'un couvert végétal en trois dimensions est présentée. Elle est basée sur la "stéréovision" qui est une technique utilisée depuis longtemps en photogrammétrie, mais aussi en robotique pour localiser des objets dans l'espace à partir de deux images acquises par des caméras situées en deux points de vue différents. Cette méthode a été appliquée à des plantes artificielles en laboratoire ainsi qu'à des plants de maïs au champ. Elle a permis de reconstruire la géométrie 3D des plantes. Le résultat est une maquette réaliste tridimensionnelle limitée à la partie commune aux deux images. Cette maquette permet de mesurer des paramètres de structure du couvert tels que la position, l'orientation et la surface des feuilles. Ces paramètres difficiles à acquérir dans les conditions du terrain, sont des données d'entrée pour les modèles d'échange radiatifs ou pour simuler la pénétration et l'interaction du rayonnement incident avec la végétation. Numéro de notice : A1993-043 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89159
in Bulletin [Société Française de Photogrammétrie et Télédétection] > n° 131 (Juillet 1993) . - pp 24 - 33[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 018-93031 RAB Revue Centre de documentation En réserve L003 Disponible Remote sensing of forest resources / J.A. Howard (1991)PermalinkThematic Mapper detection of changes in the leaf area of closed canopy pine plantations in central Massachusetts / S.R. Herwitz in Remote sensing of environment, vol 30 n° 2 (November 1989)PermalinkDetection of changes in leaf water content using near and middle-infrared reflectances / E.R. Hunt in Remote sensing of environment, vol 30 n° 1 (01/10/1989)PermalinkBidirectional scattering of light from tree leaves / T.W. Brakke in Remote sensing of environment, vol 29 n° 2 (01/08/1989)PermalinkThe influence of leaf orientation and the specular component of leaf reflectance on the canopy bidirectional reflectance / Jeff Ross in Remote sensing of environment, vol 27 n° 3 (01/03/1989)PermalinkSeasonal visible, near-infrared and mid-infrared spectra of rice canopies in relation to LAI and above-ground dry phytomass / M. Shibayama in Remote sensing of environment, vol 27 n° 2 (01/02/1989)PermalinkA new technique to measure the spectral properties of conifer needles / C.S.T. Daughtry in Remote sensing of environment, vol 27 n° 1 (01/01/1989)PermalinkPrediction of leaf chemistry by the use of visible and near infrared reflectance spectroscopy / D.H. Card in Remote sensing of environment, vol 26 n° 2 (01/11/1988)PermalinkRelationship between discoloration and histological changes in leaves of trees affected by forest decline / E. Hoque in Remote sensing of environment, vol 26 n° 2 (01/11/1988)PermalinkThermal infrared (2.5 micrometers to 13.5 micrometers) directional hemispherical reflectance of leaves / J.W. Salisbury in Photogrammetric Engineering & Remote Sensing, PERS, vol 54 n° 9 (september 1988)Permalink