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The real potential of current passive satellite data to map aboveground biomass in tropical forests / Nidhi Jha in Remote sensing in ecology and conservation, vol 7 n° 3 (September 2021)  

Public [article]  inRemote sensing in ecology and conservation > vol 7 n° 3 (September 2021) . - pp 504 - 520 Titre : The real potential of current passive satellite data to map aboveground biomass in tropical forests Type de document : Article/Communication Auteurs : Nidhi Jha, Auteur ; Nitin Kumar Tripathi, Auteur ; Nicolas Barbier, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : pp 504 - 520 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] analyse comparative [Termes IGN] biomasse aérienne [Termes IGN] forêt tropicale [Termes IGN] image Landsat-8 [Termes IGN] image Sentinel-MSI [Termes IGN] image Worldview [Termes IGN] Thaïlande Résumé : (auteur) Forest biomass estimation at large scale is challenging and generally entails large uncertainty in tropical regions. With their wall-to-wall coverage ability, passive remote sensing signals are frequently used to extrapolate field estimates of forest aboveground biomass (AGB). However, studies often use limited reference data and/or flawed validation schemes and thus report unreliable extrapolation error estimates. Here, we compared the ability of three medium- to high-resolution passive satellite sensors, Landsat-8 (L8), Sentinel-2B (S2) and Worldview-3 (WV3), to map AGB in a forest landscape of Thailand. We used a large airborne LiDAR-derived AGB dataset as a reference to train and validate a random forest algorithm and conducted robust error assessments and variable selection using spatialized cross-validations. Our results indicate that the selected predictors strongly varied among the three sensors and between analyses restricted to low (≤200 Mg ha−1) and high (>200 Mg ha−1) AGB areas. WV3 and S2 data outperformed L8 data to extrapolate AGB (RMSE of 68 and 72 against 84 Mg ha−1, respectively) due to the inclusion of the red-edge band and, probably, to their higher spatial and spectral resolution. Sensitivity to large AGB values was higher for WV3 than for S2 and L8 with saturation point of 247 Mg ha−1 against 204 and 192 Mg ha−1. AGB values above these saturation points remained poorly predictable, especially for L8, indicating that several tropical forest AGB maps should be interpreted with extreme caution. However, predicted gradients of lower AGB values (≤200 Mg ha−1), i.e., in early forest successional stages, were fairly consistent among sensors (r > 0.70), even if the mean absolute difference between estimates was large when AGB predictions were extrapolated out of the calibration area at regional level (34%). We finally showed that calibrating the model only within the sensitivity AGB domain (e.g., Numéro de notice : A2021-731 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.1002/rse2.203 En ligne : https://doi.org/10.1002/rse2.203 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98676 [article]

Modelling 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)  

Public [article]  inGeocarto international > vol 29 n° 7 - 8 (November - December 2014) . - pp 842 - 859 Titre : Modelling electrical conductivity of soil from backscattering coefficient of microwave remotely sensed data using artificial neural network Type de document : Article/Communication Auteurs : Walaiporn Phonphan, Auteur ; Nitin Kumar Tripathi, Auteur ; Taravudh Tipdecho, Auteur ; et al., Auteur Année de publication : 2014 Article en page(s) : pp 842 - 859 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] image ALOS-PALSAR [Termes IGN] micro-onde [Termes IGN] rétrodiffusion [Termes IGN] salinité Résumé : (Auteur) Soil salinity is one of the main agricultural problems which expand to larger areas. Soil scientists categorize salinity level by electrical conductivity (EC) measurement. However, field measurements of EC require extensive time, cost and experiences. Remote sensing is one suitable option to investigate and collect spatial data in larger areas. Many researches estimated soil moisture through microwave, but there are fewer studies which mentioned about direct relationship between EC and backscattering coefficient (BC). Thus, this study aims to propose the estimation of EC directly from BC of microwave. The relationship between EC obtained from field survey and BC from microwave is non-linear, artificial neural network (ANN) is one technique proposed in this study to figure out EC and BC relationship. ANN uses multilayer of interconnected processing resulting in EC value with high accuracy which is acceptable. For this reason, ANN model can be successfully utilized as an effective tool for EC estimation from microwave. Numéro de notice : A2014-469 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/10106049.2013.868040 En ligne : https://doi.org/10.1080/10106049.2013.868040 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=74046 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
059-2014041	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Coastal and marine ecological changes and fish cage culture development in Phu Quoc, Vietnam (2001 to 2011) / Diep Thi Hong Nguyen in Geocarto international, vol 29 n° 5 - 6 (August - October 2014)  

Public [article]  inGeocarto international > vol 29 n° 5 - 6 (August - October 2014) . - pp 486-506 Titre : Coastal and marine ecological changes and fish cage culture development in Phu Quoc, Vietnam (2001 to 2011) Type de document : Article/Communication Auteurs : Diep Thi Hong Nguyen, Auteur ; Nitin Kumar Tripathi, Auteur ; Wenresti G. Gallardo, Auteur ; et al., Auteur Année de publication : 2014 Article en page(s) : pp 486-506 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image mixte [Termes IGN] classification orientée objet [Termes IGN] détection de changement [Termes IGN] eaux côtières [Termes IGN] herbier marin [Termes IGN] image ALOS-AVNIR2 [Termes IGN] image Landsat-TM [Termes IGN] image Theos [Termes IGN] milieu marin [Termes IGN] qualité des eaux [Termes IGN] Viet Nam Résumé : (auteur) This study employed image enhancement for LANDSAT TM and ALOS imagery to monitor the changing status of coastal resources from 2001 to 2011, object-based classification of high-resolution THEOS imagery to extract fish cage culture sites and interpolation methods to determine marine environmental quality in 2011 in the northern part of Phu Quoc Island. There were five classes in the study site: natural forest, Melaleuca forest, agriculture, peat and built-up areas. Agricultural land and Melaleuca forest changing into built-up areas constituted approximately 51.13% of the total area changing. The benthic seagrass habitat increased dramatically from 2001 to the end of 2010. Besides, marine culture has been concerned to cage culture which is one of the sources directly affecting aquatic life and water quality in coastal environment. Cage culture locations were detected using high-resolution imagery as THEOS data for image fusion and Object-based Image Analysis methods. Water quality criteria including nitrogen, phosphorus and chlorophyll-a concentrations were determined by interpolation method, and the spatial distribution of these parameters showed a concentration in the study area in the range from 0.17 to 0.49 mg/L, 0.012 to 0.073 mg/L and 0.26 to 1.046 μg/L, respectively. Numéro de notice : A2014-408 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/10106049.2013.798358 En ligne : http://www.tandfonline.com/doi/full/10.1080/10106049.2013.798358 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=73945 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
059-2014031	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Effective graphic features for multivariate symbol mapping / Vasan Choengsa-Ard in Cartographic journal (the), vol 50 n° 1 (February 2013)  

Public [article]  inCartographic journal (the) > vol 50 n° 1 (February 2013) . - pp 66 - 81 Titre : Effective graphic features for multivariate symbol mapping Type de document : Article/Communication Auteurs : Vasan Choengsa-Ard, Auteur ; Nitin Kumar Tripathi, Auteur ; Paul Janecek, Auteur Année de publication : 2013 Article en page(s) : pp 66 - 81 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Rédaction cartographique [Termes IGN] données spatiotemporelles [Termes IGN] données statistiques [Termes IGN] prototype [Termes IGN] sémiologie graphique [Termes IGN] signe conventionnel [Termes IGN] symbole graphique [Termes IGN] vision Résumé : (Auteur) Various patterns of cartographic multivariate symbols (MSs) have been developed to work efficiently with objective symbol mapping. One such MS pattern is composed of a graph that uses spatial data to represent statistical data. A preliminary study revealed major problems with users’ perceptions and understanding of the symbol. These problems present obstacles to the presentation objectives. We are therefore interested in studying the human factors that contribute to the visual perception of graph symbols. We predict that the graph symbols currently in use are too complex for viewers to fully understand what they are intended to represent. This research aims to study the mechanisms and behaviours of human visual perception that are necessary to understand cartography MSs and to determine a more effective prototype symbol that presents and conveys information to viewers more efficiently. The prototype design is based on a basic cartographic symbol and includes the characteristics and properties of the original patterns of graph symbols via a study of their pros and cons. Graphic structures and properties were modified to create a more effective symbol. Numéro de notice : A2013-190 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1179/1743277412Y.0000000025 En ligne : https://doi.org/10.1179/1743277412Y.0000000025 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32328 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
030-2013011	RAB	Revue	Centre de documentation	En réserve L003	Disponible