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A posteriori bias correction of three models used for environmental reporting / Bogdan M. Strimbu in Forestry, an international journal of forest research, vol 91 n° 1 (January 2018)  

Public [article]  inForestry, an international journal of forest research > vol 91 n° 1 (January 2018) . - pp 49 - 62 Titre : A posteriori bias correction of three models used for environmental reporting Type de document : Article/Communication Auteurs : Bogdan M. Strimbu, Auteur ; Alexandru Amarioarei, Auteur ; John Paul McTague, Auteur ; Mihaela M. Paun, Auteur Année de publication : 2018 Article en page(s) : pp 49 - 62 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Statistiques [Termes descripteurs IGN] correction [Termes descripteurs IGN] erreur systématique [Termes descripteurs IGN] Louisiane (Etats-Unis) [Termes descripteurs IGN] modèle mathématique [Termes descripteurs IGN] Oregon (Etats-Unis) [Termes descripteurs IGN] Pinus ponderosa [Termes descripteurs IGN] pseudotsuga menziesii [Termes descripteurs IGN] résidu [Termes descripteurs IGN] Roumanie [Termes descripteurs IGN] Texas (Etats-Unis) Résumé : (Auteur) A plethora of forest models were developed by transforming the dependent variable, which introduces bias if appropriate corrections are not applied when back-transformed. Many recognized models are still biased and the original data sets are no longer available, which suggests ad hoc bias corrections. The present research presents a procedure for bias correction in the absence of needed information from summary statistics. Additionally, we developed a realistic correction of the square root transformation based on a truncated normal distribution. The transformations considered in this study are the logarithm, the square root and arcsine square root. Using simulated data we found that uncorrected back-transformation created biases by as much as 100 percent. The generated data revealed that depending on available information, that bias can still be present after correction. In addition to generated data we corrected the site index of Douglas-fir and ponderosa pine in Oregon USA, tree volume of 27 species from Romania, stand merchantable volume for longleaf pine in Louisiana and East Texas USA, and canopy fuel weight in Washington USA. Using only the available information, the unbiased back-transformed estimates can change from ≤1 percent (i.e. the site index and canopy fuel weight) to ≥⅓ (tree and stand volume). Numéro de notice : A2018-631 Thématique : FORET/MATHEMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1093/forestry/cpx032 date de publication en ligne : 10/08/2017 En ligne : https://doi.org/10.1093/forestry/cpx032 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93217 [article]

Bumps and bruises in the digital skins of cities: unevenly distributed user-generated content across US urban areas / Colin Robertson in Cartography and Geographic Information Science, Vol 43 n° 4 (September 2016)  

Public [article]  inCartography and Geographic Information Science > Vol 43 n° 4 (September 2016) . - pp 283 - 300 Titre : Bumps and bruises in the digital skins of cities: unevenly distributed user-generated content across US urban areas Type de document : Article/Communication Auteurs : Colin Robertson, Auteur ; Robert Feick, Auteur Année de publication : 2016 Article en page(s) : pp 283 - 300 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique web [Termes descripteurs IGN] analyse de données [Termes descripteurs IGN] Dallas (Texas) [Termes descripteurs IGN] données descriptives [Termes descripteurs IGN] données localisées des bénévoles [Termes descripteurs IGN] données socio-économiques [Termes descripteurs IGN] géoétiquetage [Termes descripteurs IGN] image 2D [Termes descripteurs IGN] Nouvelle-Orléans (Louisiane) [Termes descripteurs IGN] qualité des données [Termes descripteurs IGN] représentation des données [Termes descripteurs IGN] representativité [Termes descripteurs IGN] Seattle (Washington) Résumé : (Auteur) As momentum and interest build to leverage new forms of user-generated content that contains geographical information, classical issues of data quality remain significant research challenges. In this article, we explore issues of representativeness for one form of user-generated content, geotagged photographs in US urban centers. Generalized linear models were developed to associate photograph distribution with underlying socioeconomic descriptors at the city-scale, and examine intra-city variation in relation to income inequality. We conclude our analyses with a detailed examination of Dallas, Seattle, and New Orleans. Our findings add to the growing volume of evidence outlining uneven representativeness in user-generated data, and our approach contributes to the stock of methods available to investigate geographic variations in representativeness. In addition to city-scale variables relating to distribution of user-generated content, variability remains at localized scales that demand an individual and contextual understanding of their form and nature. The findings demonstrate that careful analysis of representativeness at both macro and micro scales can simultaneously provide important insights into the processes giving rise to user-generated data sets and potentially shed light on their embedded biases and suitability as inputs to analysis. Numéro de notice : A2016-415 Thématique : GEOMATIQUE Nature : Article DOI : https://doi.org/10.1080/15230406.2015.1088801 En ligne : https://doi.org/10.1080/15230406.2015.1088801 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81309 [article]

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A graph-based segmentation algorithm for tree crown extraction using airborne LiDAR data / Victor F. Strimbu in ISPRS Journal of photogrammetry and remote sensing, vol 104 (June 2015)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 104 (June 2015) . - pp 30 - 43 Titre : A graph-based segmentation algorithm for tree crown extraction using airborne LiDAR data Type de document : Article/Communication Auteurs : Victor F. Strimbu, Auteur ; Bogdan M. Strimbu, Auteur Année de publication : 2015 Article en page(s) : pp 30 - 43 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes descripteurs IGN] données localisées 3D [Termes descripteurs IGN] extraction de la végétation [Termes descripteurs IGN] graphe [Termes descripteurs IGN] houppier [Termes descripteurs IGN] Louisiane (Etats-Unis) [Termes descripteurs IGN] segmentation [Termes descripteurs IGN] structure hiérarchique de données Résumé : (auteur) This work proposes a segmentation method that isolates individual tree crowns using airborne LiDAR data. The proposed approach captures the topological structure of the forest in hierarchical data structures, quantifies topological relationships of tree crown components in a weighted graph, and finally partitions the graph to separate individual tree crowns. This novel bottom-up segmentation strategy is based on several quantifiable cohesion criteria that act as a measure of belief on weather two crown components belong to the same tree. An added flexibility is provided by a set of weights that balance the contribution of each criterion, thus effectively allowing the algorithm to adjust to different forest structures. The LiDAR data used for testing was acquired in Louisiana, inside the Clear Creek Wildlife management area with a RIEGL LMS-Q680i airborne laser scanner. Three 1 ha forest areas of different conditions and increasing complexity were segmented and assessed in terms of an accuracy index (AI) accounting for both omission and commission. The three areas were segmented under optimum parameterization with an AI of 98.98%, 92.25% and 74.75% respectively, revealing the excellent potential of the algorithm. When segmentation parameters are optimized locally using plot references the AI drops to 98.23%, 89.24%, and 68.04% on average with plot sizes of 1000 m2 and 97.68%, 87.78% and 61.1% on average with plot sizes of 500 m2. More than introducing a segmentation algorithm, this paper proposes a powerful framework featuring flexibility to support a series of segmentation methods including some of those recurring in the tree segmentation literature. The segmentation method may extend its applications to any data of topological nature or data that has a topological equivalent. Numéro de notice : A2015-699 Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern En ligne : http://www.sciencedirect.com/science/article/pii/S0924271615000544 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78335 [article]

Quantifying urban land cover change between 2001 and 2006 in the Gulf of Mexico region / G. Xian in Geocarto international, vol 27 n° 6 (October 2012)  

Public [article]  inGeocarto international > vol 27 n° 6 (October 2012) . - pp 479 - 497 Titre : Quantifying urban land cover change between 2001 and 2006 in the Gulf of Mexico region Type de document : Article/Communication Auteurs : G. Xian, Auteur ; Collin Homer, Auteur ; B. Bunde, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 479 - 497 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes descripteurs IGN] Alabama (Etats-Unis) [Termes descripteurs IGN] analyse diachronique [Termes descripteurs IGN] Floride (Etats-Unis) [Termes descripteurs IGN] Géorgie (Etats-Unis) [Termes descripteurs IGN] image Landsat [Termes descripteurs IGN] littoral [Termes descripteurs IGN] Louisiane (Etats-Unis) [Termes descripteurs IGN] Mexique (golfe du) [Termes descripteurs IGN] Mississippi (Etats-Unis) [Termes descripteurs IGN] occupation du sol [Termes descripteurs IGN] surface imperméable [Termes descripteurs IGN] Texas (Etats-Unis) [Termes descripteurs IGN] urbanisation Résumé : (Auteur) We estimated urbanization rates (2001-2006) in the Gulf of Mexico region using the National Land Cover Database (NLCD) 2001 and 2006 impervious surface products. An improved method was used to update the NLCD impervious surface product in 2006 and associated land cover transition between 2001 and 2006. Our estimation reveals that impervious surface increased 416 km2 with a growth rate of 5.8% between 2001 and 2006. Approximately 1110.1 km2 of non-urban lands were converted into urban land, resulting in a 3.2% increase in the region. Hay/pasture, woody wetland, and evergreen forest represented the three most common land cover classes that transitioned to urban. Among these land cover transitions, more than 50% of the urbanization occurred within 50 km of the coast. Our analysis shows that the close-to-coast land cover transition trend, especially within 10 km off the coast, potentially imposes substantial long-term impacts on regional landscape and ecological conditions. Numéro de notice : A2012-510 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/10106049.2011.652675 date de publication en ligne : 01/02/2012 En ligne : https://doi.org/10.1080/10106049.2011.652675 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31956 [article]

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St-Charles Parish and GNSS signal shadow issues: Satellite shadow reduction technology / K. Corbley in Geoinformatics, vol 15 n° 4 (01/06/2012)

Public [article]  inGeoinformatics > vol 15 n° 4 (01/06/2012) . - pp 24 - 25 Titre : St-Charles Parish and GNSS signal shadow issues: Satellite shadow reduction technology Type de document : Article/Communication Auteurs : K. Corbley, Auteur Année de publication : 2012 Article en page(s) : pp 24 - 25 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] Louisiane (Etats-Unis) [Termes descripteurs IGN] mise à jour cartographique [Termes descripteurs IGN] ombre [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] précision du positionnement [Termes descripteurs IGN] système d'information géographique Résumé : (Auteur) In an effort to improve the accuracy of its GIS maps, St. Charles Parish, La. purchased its own GNSS equipment. The parish Waterworks Department experienced outstanding result when mapping water infrastructure features-except when working beneath the parish's towering oak trees, which deflected or blocked GNSS satellite signals. After upgrading mapping GNSS handleds, they saw an immediate improvement in productivity and accuracy. Numéro de notice : A2012-228 Thématique : POSITIONNEMENT Nature : Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31674 [article]

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Mapping and interpreting the human geography of New Orleans, Louisiana, USA / R. Campanella in Le monde des cartes, n° 204 (juin 2010)

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Detection of roadway sign condition changes using multi-scale sign image matching (M-SIM) / Y.J. Tsai in Photogrammetric Engineering & Remote Sensing, PERS, vol 76 n° 4 (April 2010)  

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Louisiana wetland water level monitoring using retracked Topex-Poseidon altimetry / H. Lee in Marine geodesy, vol 32 n° 3 (July - September 2009)

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Remote sensing applications for sustainable watershed management and food security / G. Rochon (14/05/2001)

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Les îles, du mythe à la réalité / Monique Pelletier (2001)

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Landsat TM versus MSS data for forest type identification / D.L. Evans in Geocarto international, vol 5 n° 3 (September - November 1990)

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Description and measurement of Landsat TM images using fractals / N. Siu-Ngan Lam in Photogrammetric Engineering & Remote Sensing, PERS, vol 56 n° 2 (february 1990)

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Georeferencing airborne imagery over new deltas in Louisiana / D. Rickman in Photogrammetric Engineering & Remote Sensing, PERS, vol 55 n° 8 (august 1989)

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Modeling future trends in wetland loss and brown shrimp production in Louisiana using Thematic Mapper imagery / J.A. Browder in Remote sensing of environment, vol 28 n° 1 (April - June 1989)

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