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Landsat sub-pixel analysis in mapping impact of climatic variability on prairie pothole changes / B. Zhang in Transactions in GIS, vol 13 n° 2 (April 2009)  

Public [article]  inTransactions in GIS > vol 13 n° 2 (April 2009) . - pp 179 - 195 Titre : Landsat sub-pixel analysis in mapping impact of climatic variability on prairie pothole changes Type de document : Article/Communication Auteurs : B. Zhang, Auteur ; F. Schwartz, Auteur ; D. Tong, Auteur Année de publication : 2009 Article en page(s) : pp 179 - 195 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] analyse infrapixellaire [Termes IGN] cartographie thématique [Termes IGN] changement climatique [Termes IGN] classification ascendante hiérarchique [Termes IGN] classification par arbre de décision [Termes IGN] classification pixellaire [Termes IGN] Dakota du Sud (Etats-Unis) [Termes IGN] détection de changement [Termes IGN] image Landsat [Termes IGN] lac [Termes IGN] sécheresse [Termes IGN] système d'information géographique [Termes IGN] variation saisonnière [Termes IGN] zone humide Résumé : (Auteur) The Prairie Pothole Region in the United States contains millions of seasonal, semi-permanent, or permanent lakes and wetlands that typically range in size from 0.1 to 10 ha. These lakes and wetlands are vulnerable to climate change, especially in our study area in South Dakota, in which a period of deluge following a sharp drought considerably expanded the areal extent of prairie pothole lakes during the last decade of the twentieth century. Preliminary estimates of lake areas, determined using LANDSAT 5 and 7 images, had appreciable errors especially for the smallest of these lakes. This article describes a new sub-pixel approach integrated with a CART (Classification and Regression Tree) model using a GIS (Geographical Information System) to quantify mixed water pixels along lake boundaries to improve area estimations for pothole lakes. Errors in estimated area were typically 10% or less for lakes greater than 1 ha in size. An analysis of lakes in our study area demonstrates how lake area changed with the transition from drought to deluge. Small lakes exhibited a distinct seasonal variation in contrast to large lakes that tended to follow precipitation trends more broadly. The total water area of lakes is consistent with broad variation in rainfall. Numéro de notice : A2009-541 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/j.1467-9671.2009.01149.x En ligne : https://doi.org/10.1111/j.1467-9671.2009.01149.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30170 [article]

The effects of quality control on decreasing error propagation in the LandScan USA population distribution model: a case study of Philadelphia County / L. Patterson in Transactions in GIS, vol 13 n° 2 (April 2009)  

Public [article]  inTransactions in GIS > vol 13 n° 2 (April 2009) . - pp 215 - 228 Titre : The effects of quality control on decreasing error propagation in the LandScan USA population distribution model: a case study of Philadelphia County Type de document : Article/Communication Auteurs : L. Patterson, Auteur ; M. Urban, Auteur ; A. Myers, Auteur ; et al., Auteur Année de publication : 2009 Article en page(s) : pp 215 - 228 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] contrôle qualité [Termes IGN] démographie [Termes IGN] détection de changement [Termes IGN] géostatistique [Termes IGN] image à moyenne résolution [Termes IGN] Philadelphie [Termes IGN] propagation d'erreur [Termes IGN] répartition géographique Résumé : (Auteur) LandScan USA is a 90 m population distribution model that is used for a variety of applications, including emergency management. Models should have a measure of accuracy; however, the accuracy of population distribution models is difficult to determine due to the inclusion of multiple input datasets and the lack of quantifiable, observable (validated) data to confirm model output. Validated data enables quantification of: (1) overall model accuracy and (2) changes in model output at different levels of quality control. This article examines the effect of quality control for two national school datasets incorporated as input in LandScan USA for Philadelphia County, Pennsylvania; which had a local, validated school dataset available. The effect of each stage of quality control efforts utilized throughout the LandScan USA process were assessed to determine what level of quality control was required to have a statistically significant change of the model's population distribution. The typical level of quality control for LandScan USA resulted in 36% of schools being moved to the correct location and 20% of missing student enrollments were found, compared to 87% and 98% respectively for the validated dataset. The costs of increasing quality control resulted in a six-fold increase in labor time; however, the additional quality control did not produce statistically significant improvements in the LandScan USA model. Thus, typical quality control efforts for schools in LandScan USA produced a population distribution similar to the validated level of quality control, and can be applied with confidence for policy, planning, and emergency situations. Copyright Blackwell Publishing Numéro de notice : A2009-542 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/j.1467-9671.2009.01148.x En ligne : https://doi.org/10.1111/j.1467-9671.2009.01148.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30171 [article]