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Effects of forest environment and survey protocol on GPS accuracy / Christian Piedallu in Photogrammetric Engineering & Remote Sensing, PERS, vol 71 n° 9 (September 2005)
[article]
Titre : Effects of forest environment and survey protocol on GPS accuracy Type de document : Article/Communication Auteurs : Christian Piedallu, Auteur ; Jean-Claude Gégout, Auteur Année de publication : 2005 Article en page(s) : pp 1070 - 1078 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] acquisition de données
[Termes IGN] affaiblissement géométrique de la précision
[Termes IGN] analyse comparative
[Termes IGN] antenne GPS
[Termes IGN] correction différentielle
[Termes IGN] couvert forestier
[Termes IGN] feuillu
[Termes IGN] forêt
[Termes IGN] GPS en mode différentiel
[Termes IGN] instrumentation Trimble
[Termes IGN] positionnement par GPS
[Termes IGN] précision de localisation
[Termes IGN] récepteur GPS
[Termes IGN] ressources naturelles
[Termes IGN] saisonRésumé : (Auteur) The aim of the study is to test GPS equipment receivers commonly used for natural resource management, and to quantify recording rate and positioning quality under different conditions, the objective being to assist GPS users in their choices. Four factors were evaluated: (a) the type of receiver: three ranges of GPS equipment were compared; (b) forest cover effects (three covers were tested: open cover, coppice and deciduous high forest); (c) the effects of GPS survey components: the number of recordings (between 1 and 300), the Position Dilution of Precision (PDOP) thresholding (between 4 and 50), the time interval between recordings (between 1 and 15 seconds), and the differential correction effect; and (d) the season (winter and summer). A GPS survey was carried out and a database of 140,000 readings was established, from which a large number of random rover files were extracted for each combination of factors. It appears the only factor not to be significant is the seasonal effect. The type of equipment used and the forest cover effect both modify positioning accuracy by a factor of 2 or 3, as does the use of differential correction for Trimble receivers in open cover. Increasing the number of recordings and the time interval between recordings, and decreasing the PDOP threshold, improve precision, with a different effect according to the GPS receiver and the forest cover. The effect is generally more pronounced under high forest cover. The combined effects of GPS survey components produce significant changes in accuracy at the expense of the time spent in acquiring data. Numéro de notice : A2005-390 Affiliation des auteurs : non IGN Thématique : FORET/POSITIONNEMENT Nature : Article DOI : 10.14358/PERS.71.9.1071 En ligne : https://doi.org/10.14358/PERS.71.9.1071 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27526
in Photogrammetric Engineering & Remote Sensing, PERS > vol 71 n° 9 (September 2005) . - pp 1070 - 1078[article]Separating surface emissivity and temperature using two-channel spectral indices and emissivity composites and comparison with a vegetation fraction method / P. Dash in Remote sensing of environment, vol 96 n° 1 (15/05/2005)
[article]
Titre : Separating surface emissivity and temperature using two-channel spectral indices and emissivity composites and comparison with a vegetation fraction method Type de document : Article/Communication Auteurs : P. Dash, Auteur ; F. Göttsche, Auteur ; et al., Auteur Année de publication : 2005 Article en page(s) : pp 1 - 17 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image
[Termes IGN] analyse comparative
[Termes IGN] correction atmosphérique
[Termes IGN] données de terrain
[Termes IGN] données météorologiques
[Termes IGN] éclairement énergétique
[Termes IGN] emissivité
[Termes IGN] erreur
[Termes IGN] image NOAA-AVHRR
[Termes IGN] Normalized Difference Vegetation Index
[Termes IGN] radiance
[Termes IGN] rayonnement infrarouge thermique
[Termes IGN] saison
[Termes IGN] simulation de surface
[Termes IGN] température au sol
[Termes IGN] thermal infrared multispectral scannerRésumé : (Auteur) The temperature-independent thermal infrared spectral indices (TISI) method is employed for the separation of land surface temperature (LST) and emissivity from surface radiances (atmospherically corrected satellite data). The daytime reflected solar irradiance and the surface emission at ~3.8 um have comparable magnitudes. Using surface radiances and a combination of day-night 2-channel TISI ratios, the ~3.8 um reflectivity is derived. For implementing the TISI method, coefficients for NOAA 9-16 AVHRR channels are obtained. A numerical analysis with simulated surface radiances shows that for most surface types (showing nearly Lambertian behavior) the achievable accuracy is ~0.005 for emissivity (AVHRR channel-5) and ~1.5 K for LST. Data from the European Centre for Medium-Range Weather Forecasts (ECMWF) is used for calculation of atmospheric attenuation. Comparisons are made over a part of central Europe on two différent dates (seasons). Clouds pose a major problem to surface observations; hence, monthly emissivity composites are derived. Additionally, using TISI-based monthly composites of emissivities, a normalized difference vegetation index (NDVI)-based method is tuned to the particular study area and the results are intercompared. Once the coefficients are known, the NDVI method is easily implemented but holds well only for vegetated areas. The error of the NDVI-based emissivities (with respect to the TISI results) ranges between -0.038 and 0.032, but for vegetated areas the peak of the error-histogram is at ~0.002. The algorithm for retrieving emissivity via TISI was validated with synthetic data. Due to the different spatial scales of satellite and surface measurements and the lack of homogeneous areas, which are representative for low-resolution pixels and ground measurements, ground-validation is a daunting task. However, for operational products ground-truth validation is necessary. Therefore, also an approach to identify suitable validation sites for meteorological satellite products in Europe is described. Numéro de notice : A2005-209 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2004.12.023 En ligne : https://doi.org/10.1016/j.rse.2004.12.023 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27346
in Remote sensing of environment > vol 96 n° 1 (15/05/2005) . - pp 1 - 17[article]DTM generation from Ikonos in-track stereo images using a 3D physical model / Thierry Toutin in Photogrammetric Engineering & Remote Sensing, PERS, vol 70 n° 6 (June 2004)
[article]
Titre : DTM generation from Ikonos in-track stereo images using a 3D physical model Type de document : Article/Communication Auteurs : Thierry Toutin , Auteur Année de publication : 2004 Article en page(s) : pp 695 - 702 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique
[Termes IGN] analyse comparative
[Termes IGN] appariement d'images
[Termes IGN] azimut
[Termes IGN] compensation par faisceaux
[Termes IGN] données lidar
[Termes IGN] données multitemporelles
[Termes IGN] erreur systématique
[Termes IGN] image à résolution métrique
[Termes IGN] image Ikonos
[Termes IGN] modèle géométrique de prise de vue
[Termes IGN] modèle numérique de surface
[Termes IGN] modèle numérique de terrain
[Termes IGN] pente
[Termes IGN] point d'appui
[Termes IGN] saison
[Termes IGN] utilisation du sol
[Termes IGN] végétationRésumé : (Auteur) A digital elevation model (DEM) extracted from Ikonos in-track stereo images using a 3D physical model developed at the Canada Centre for Remote Sensing, Natural Resources Canada was evaluated. First, the stereo photogrammetric bundle adjustment was set up with about ten accurate ground control points. The DEM was then generated using an area-based multiscale image matching method and 3D semiautomatic editing tools and then compared to lidar elevation data with a 0.2-m accuracy. Because the DEM is, in fact, a digital terrain surface model where the height of land cover (trees, houses) is included, the accuracy varies depending on land cover types. Using 3D visual classification of the stereo Ikonos images, different classes (forests, residential, bare soil, lakes) were generated to take into account the height of the surface (natural and human-made) in the accuracy evaluation. An elevation linear error with 68 percent confidence level (LE68) of 1.5 m was obtained for bare surfaces while an LE68 of 6.4 m was achieved over the full area. Five-meter contour lines could thus be derived, compliant with the highest topographic standard. Better results could thus be expected when using stereo-images acquired in the summertime. On the other hand, an LE68 of 2.5 m to 6.6 m was obtained depending on the land-cover type and its surface height. For residential areas, the surface height did not affect the errors very much (2.5-m LE68) when compared to bare surface results because one- and two-story houses were sparse in the test area. Because the images were unfortunately acquired in wintertime and the lidar data in summertime, elevation errors (LE68 and bias) also depended on the type of forest (deciduous, coniferous, mixed, sparse). An evaluation based on terrain slope and azimuth showed that the DEM error was linearly correlated with slope and that elevations on sun-facing slopes were 1-m more accurate than elevations on slopes facing away from the sun. Numéro de notice : A2004-204 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.70.6.695 En ligne : http://dx.doi.org/10.14358/PERS.70.6.695 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26731
in Photogrammetric Engineering & Remote Sensing, PERS > vol 70 n° 6 (June 2004) . - pp 695 - 702[article]Hyperspectral monitoring of physiological parameters of wheat during a vegetation period using AVIS data / N. Oppelt in International Journal of Remote Sensing IJRS, vol 25 n° 1 (January 2004)
[article]
Titre : Hyperspectral monitoring of physiological parameters of wheat during a vegetation period using AVIS data Type de document : Article/Communication Auteurs : N. Oppelt, Auteur ; W. Mauser, Auteur Année de publication : 2004 Article en page(s) : pp 145 - 159 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] analyse de données
[Termes IGN] analyse diachronique
[Termes IGN] Bavière (Allemagne)
[Termes IGN] blé (céréale)
[Termes IGN] classificateur paramétrique
[Termes IGN] hétérogénéité sémantique
[Termes IGN] image AVIRIS
[Termes IGN] image hyperspectrale
[Termes IGN] indice de végétation
[Termes IGN] Normalized Difference Vegetation Index
[Termes IGN] réflectance végétale
[Termes IGN] saison
[Termes IGN] surveillance agricole
[Termes IGN] zone humideRésumé : (Auteur) Information on the quantity and spatial distribution of canopy physiological and biochemical components is of importance for the study of nutrient cycles, productivity, vegetation stress and, more recently, in driving ecosystem models. In this context, remote sensing can play a unique and essential role because of its ability to acquire synoptic information at different time and space scales. This paper presents parts of a two-year field and laboratory study with the new airborne hyperspectral sensor, the Airborne Visible near Infrared Imaging Spectrometer (AVIS), over a test site in the Bavarian Alpine foothills, Germany (48' 8'N, 11°17' E ). The 80-band AVIS was developed at the Department for Earth and Environmental Sciences of the LudwigMaximiliansUniversity Munich and records the 550-1000 mn spectral range. Using this system, 18 hyperspectral datasets were collected between April and September of 1999 and 2000. Weekly measurements of several plant parameters (height, biomass, leaf chlorophyll content, leaf nitrogen content) were carried out during these time periods on three (1999) and six (2000) fields of winter wheat, whereby two different cultivars were investigated in 2000. After system correction and calibration, the hyperspectral data were atmospherically corrected and calibrated to reflectance. The resulting spectra were analysed for their chemical compounds. The statistical analysis was carried out using the Chlorophyll Absorption Integral (CAI) in comparison to established indices: Optimized Soil-Adjusted Vegetation Index (OSAVI) and hyperspectral Normalized Difference Vegetation Index (hNDVI). Both the chlorophyll and nitrogen content of the leaves showed good correlations with CAI on a field mean basis. These results as well as two-dimensional information on these parameters are presented to provide information about the spatial heterogeneity within a field. Numéro de notice : A2004-036 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/0143116031000115300 En ligne : https://doi.org/10.1080/0143116031000115300 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26564
in International Journal of Remote Sensing IJRS > vol 25 n° 1 (January 2004) . - pp 145 - 159[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 080-04011 RAB Revue Centre de documentation En réserve L003 Exclu du prêt Suivi de la croissance des cultures en zone hétérogène au moyen d'informations satellitaires, 1. Volume 1 / A. Fischer (1992)
Titre de série : Suivi de la croissance des cultures en zone hétérogène au moyen d'informations satellitaires, 1 Titre : Volume 1 : Complémentarité avec les modèles de croissance Type de document : Thèse/HDR Auteurs : A. Fischer, Auteur Editeur : Toulouse : Université de Toulouse 3 Paul Sabatier Année de publication : 1992 Importance : 338 p. Format : 21 x 30 cm Note générale : Bibliographie
Thèse présentée pour obtenir le titre de docteur discipline astrophysique, géophysique et techniques spatiales, spécialité télédétection spatialeLangues : Français (fre) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] Beauce
[Termes IGN] cultures
[Termes IGN] image NOAA-AVHRR
[Termes IGN] indice de végétation
[Termes IGN] modèle de Monteith
[Termes IGN] Normalized Difference Vegetation Index
[Termes IGN] saison
[Termes IGN] simulation SPOTIndex. décimale : THESE Thèses et HDR Résumé : (Auteur) La télédétection, par des mesures radiatives globales et répétées, permet d'avoir accès à la quantité d'énergie absorbée par la biosphère qui est un des facteurs prépondérants pour déterminer la production primaire et ainsi contrôler les échanges entre les couverts et l'atmosphère. La bonne connaissance de ces mécanismes sur les cultures fait que l'observation des régions agricoles tempérées est particulièrement intéressante. Le travail présenté propose une modélisation semi-empirique des variations temporelles d'un indice dérivé des mesures radiométriques obtenu sur les régions agricoles. Cette modélisation, utilisant une fonction double logistique, s'applique à la couverture homogène d'une parcelle agricole. A l'échelle régionale, l'association de différentes cultures constitue un milieu hétérogène dont l'évolution moyenne perçue par les satellites à faible résolution spatiale peut être décrite à l'aide de ce type de fonctions. Les simulations réalisées montrent qu'un couplage haute résolution spatiale - haute résolution temporelle permet de retrouver le comportement individuel des principaux types de couverts végétaux, avec notamment l'estimation des périodes de croissance et de décroissance, sur une région comme la Beauce. L'application de cette démarche à de véritables données satellitaires met en évidence le problème de l'information contenue dans le signal, qui est dépendante non seulement de l'état biologique du couvert, mais aussi des conditions directionnelles et atmosphériques de l'acquisition. Les limites dues au fait de contraindre l'évolution par une forme mathématique imposée sont aussi discutées. La conclusion décrit alors les perpectives concernant le couplage d'un modèle biophysique d'évolution du couvert avec un modèle de transfert directionnel et atmosphérique permettant l'assimilation des données spatiales afin de faire progresser la compréhension des mécanismes intervenant aux niveaux des échanges à l'interface biosphère-atmosphère. Numéro de notice : 45063 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse française Note de thèse : Thèse de doctorat : Astrophysique, géophysique et techniques spatiales. Télédétection spatiale : Toulouse 3 : 1992 nature-HAL : Thèse DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=45523 Réservation
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