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Influence of resolution in irrigated area mapping and area estimations / N. Velpuri in Photogrammetric Engineering & Remote Sensing, PERS, vol 75 n° 12 (December 2009)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 75 n° 12 (December 2009) . - pp 1383 - 1395 Titre : Influence of resolution in irrigated area mapping and area estimations Type de document : Article/Communication Auteurs : N. Velpuri, Auteur ; Prasad S. Thenkabail, Auteur ; M. Gumma, Auteur ; et al., Auteur Année de publication : 2009 Article en page(s) : pp 1383 - 1395 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] carte agricole [Termes IGN] classification dirigée [Termes IGN] cultures irriguées [Termes IGN] image Landsat-ETM+ [Termes IGN] image multitemporelle [Termes IGN] image NOAA-AVHRR [Termes IGN] image Terra-MODIS [Termes IGN] Inde [Termes IGN] irrigation [Termes IGN] limite de résolution géométrique [Termes IGN] parcelle agricole [Termes IGN] précision de la classification Résumé : (Auteur) The overarching goal of this paper was to determine how irrigated areas change with resolution (or scale) of imagery. Specific objectives investigated were to (a) map irrigated areas using four distinct spatial resolutions (or scales), (b) determine how irrigated areas change with resolutions, and (c) establish the causes of differences in resolution-based irrigated areas. The study was conducted in the very large Krishna River basin (India), which has a high degree of formal contiguous, and informal fragmented irrigated areas. The irrigated areas were mapped using satellite sensor data at four distinct resolutions: (a) NOAA AVHRR Pathfinder 10,000 m, (b) Terra MODIS 500 m, (c) Terra MODIS 250 m, and (d) Landsat ETM+ 30 m. The proportion of irrigated areas relative to Landsat 30 m derived irrigated areas (9.36 million hectares for the Krishna basin) were (a) 95 percent using MODIS 250 m, (b) 93 percent using MODIS 500 m, and (c) 86 percent using AVHRR 10,000 m. In this study, it was found that the precise location of the irrigated areas were better established using finer spatial resolution data. A strong relationship (R2 = 0.74 to 0.95) was observed between irrigated areas determined using various resolutions. This study proved the hypotheses that “the finer the spatial resolution of the sensor used, greater was the irrigated area derived,” since at finer spatial resolutions, fragmented areas are detected better. Accuracies and errors were established consistently for three classes (surface water irrigated, ground water/conjunctive use irrigated, and nonirrigated) across the four resolutions mentioned above. The results showed that the Landsat data provided significantly higher overall accuracies (84 percent) when compared to MODIS 500 m (77 percent), MODIS 250 m (79 percent), and AVHRR 10,000 m (63 percent). Copyright ASPRS Numéro de notice : A2009-500 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.75.12.1383 En ligne : https://doi.org/10.14358/PERS.75.12.1383 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30129 [article]

A simplified analytical model for a-priori Lidar pointpositioning error estimation and a review of Lidar error source / Mihaela Triglav Cekada in Photogrammetric Engineering & Remote Sensing, PERS, vol 75 n° 12 (December 2009)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 75 n° 12 (December 2009) . - pp 1425 - 1439 Titre : A simplified analytical model for a-priori Lidar pointpositioning error estimation and a review of Lidar error source Type de document : Article/Communication Auteurs : Mihaela Triglav Cekada, Auteur ; F. Crosilla, Auteur ; Mojca Kosmatin-Fras, Auteur Année de publication : 2009 Article en page(s) : pp 1425 - 1439 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] données lidar [Termes IGN] erreur de positionnement [Termes IGN] erreur systématique [Termes IGN] modèle d'erreur [Termes IGN] qualité des données [Termes IGN] source d'erreur Résumé : (Auteur) Although various rigorous lidar error models already exist and examples of a-posteriori studies of lidar data accuracies verified with field-work can be found in the literature, a simple measure to define a-priori error sizes is not available. In this paper, the lidar error contributions are described in detail: the basic systematic error sources, the flight-mission-related error sources, and the target-characteristic-related error sources. A review of the different error-source sizes is drawn from the literature in order to define the boundary conditions for each error size. Schenk’s geolocation equation is used as a basis for deriving a simplified error model. This model enables a quick calculation and gives a-priori plausible values for the average and maximum error size, independent of the scan and heading angles as well as being independent of any specific lidar system’s characteristics. Additionally, some notes are provided for assistance when ordering lidar data, to enable easier a-posteriori quality control. Copyright ASPRS Numéro de notice : A2009-501 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.75.12.1425 En ligne : https://doi.org/10.14358/PERS.75.12.1425 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30130 [article]