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Detection of areas associated with flood and erosion caused by a heavy rainfall using multitemporal Landsat TM data / A.S. Dhakal in Photogrammetric Engineering & Remote Sensing, PERS, vol 68 n° 3 (March 2002)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 68 n° 3 (March 2002) . - pp 233 - 239 Titre : Detection of areas associated with flood and erosion caused by a heavy rainfall using multitemporal Landsat TM data Type de document : Article/Communication Auteurs : A.S. Dhakal, Auteur ; T. Amada, Auteur ; M. Aniya, Auteur ; R.R. Sharma, Auteur Année de publication : 2002 Article en page(s) : pp 233 - 239 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] analyse en composantes principales [Termes IGN] analyse spectrale [Termes IGN] bande spectrale [Termes IGN] bande visible [Termes IGN] bassin hydrographique [Termes IGN] données multitemporelles [Termes IGN] érosion hydrique [Termes IGN] image Landsat-TM [Termes IGN] inondation [Termes IGN] Népal Résumé : (Auteur) The potential of multi-temporal Landsat Thematic Mapper (TM) data was examined for its use in detecting areas affected by flood and erosion from a heavy rainfall. The study area is the Kulekhani watershed (124 km') located in the central region of Nepal. Four change-detection techniques were compared for their effectiveness including (1) Spectral Image Differencing (SID), (2) Tasseled Cap Brightness Image Differencing (TCBID), (3) Principal Component Analysis (PCA), and (4) Spectral Change Vector Analysis (SCVA). SID was performed on four raw bands (bands 1, 2, 3, and 7), and altogether seven new images (change images) were produced. Visible bands were effective in detecting affected areas. SCVA (using bands 1, 2, and 3) was found to be most accurate for detecting areas affected by flood and erosion followed by SID (band 2), PCA (using bands 1, 2, and 3), SID (band 1), and SID (band 3). The change image produced from SCVA showed overall and Khat accuracies of 88.3 percent and 75.4 percent, respectively. The analysis of spatial agreement conducted among the seven change images, produced from different techniques, varied from 89 percent to 98 percent. The change image produced from SCVA showed high spatial agreements with change images produced from PCA, SID (band 3), and SID (band 2). SGVA and SID (band 3) showed the spatial agreement of 88.1 percent and 98.7 percent in the change and no-change categories, respectively. Numéro de notice : A2002-028 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : sans En ligne : https://www.asprs.org/wp-content/uploads/pers/2002journal/march/2002_mar_233-239 [...] Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=21945 [article]

Use of contour-based DEM for deriving and mapping topographic attributes / H. Mizukoshi in Photogrammetric Engineering & Remote Sensing, PERS, vol 68 n° 1 (January 2002)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 68 n° 1 (January 2002) . - pp 83 - 93 Titre : Use of contour-based DEM for deriving and mapping topographic attributes Type de document : Article/Communication Auteurs : H. Mizukoshi, Auteur ; M. Aniya, Auteur Année de publication : 2002 Article en page(s) : pp 83 - 93 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] analyse d'image numérique [Termes IGN] détection de contours [Termes IGN] gradient de pente [Termes IGN] modèle hydrographique [Termes IGN] modèle numérique de surface [Termes IGN] modèle numérique de terrain [Termes IGN] profil topographique Résumé : (Auteur) Algorithms using contour-based DEMs to calculate slope gradient and aspect, and to classify and map slope profile and plan forms, were developed, which we call C-BATM (Contour-Based Automatic Terrain Mapping). These are important topographic attributes for various analyses and terrain-related hazard mapping. As a first step, a fall line, the line of the maximum gradients or a flow path, was generated from all data points of all contours. Then, using the fall line segment (between adjacent contours), slope gradient and aspect were calculated. The change in, slope gradients in three consecutives contours are the basis for classifying slope profile from into concave, planar and convex. Slope plan form was classified from the contour crenulation, using a point of inflection by examining the directional change of contour segments (line between two consecutive data points). In the process of classifying slope morphologies, the profile and plans curvatures were also calculated and recorded. Test results of these methods in mountainous areas indicate the advantage of using contour-based DEMs over the use of the grid-based DEM or TIN. These methods have a potential of much wider applications to terrain analyses and hydrological modeling. Numéro de notice : A2002-011 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : sans En ligne : https://www.asprs.org/wp-content/uploads/pers/2002journal/january/2002_jan_83-93 [...] Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=21928 [article]