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A synergic automatic clustering technique (syneract) for multispectral image analysis / K.Y. Huang 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 33 - 40 Titre : A synergic automatic clustering technique (syneract) for multispectral image analysis Type de document : Article/Communication Auteurs : K.Y. Huang, Auteur Année de publication : 2002 Article en page(s) : pp 33 - 40 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] analyse d'image numérique [Termes IGN] analyse de groupement [Termes IGN] classification dirigée [Termes IGN] classification ISODATA [Termes IGN] classification non dirigée [Termes IGN] image multibande Résumé : (Auteur) The Iterative Self-Organizing Data Analysis Technique (ISODATA) has been widely used in unsupervised and supervised classification. However, ISODATA suffers from several limitations. The user often spends much analyst time on specifying input parameters by trial and error, particularly initial cluster centers. Of more importance, an inapropriate choice of initial clusters may cause poor classification results. ISODATA is computationally intensive because of its iterative process . This study aimed to develop a synergistic automatic clustering technique (SYNERACT) that combined the hierachical descending and ISODATA clustering procedures to avoid those limitations. The two methods were compared using multispectral digitized video images. An inappropriate choice of initial seeds for SODATA was shown to reduce accuracies significantly. In contrast, SYNERACT was capable of determining the suitable locations for the initial clusters automatically from the data, therby avoiding those limitations. Owing to this capability, SYNERACT was not so heavily dependent on the iterative process as was ISODATA, and thus was much faster than ISODATA. SYNERACT also matched ISODATA in accuracy. Accordingly, SYNERACT could serve as an alternative to ISODATA for multispectral image analysis. Numéro de notice : A2002-008 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_33-40 [...] Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=21925 [article]

Fuzzy objects: their changes and uncertainties / T. Cheng 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 41 - 49 Titre : Fuzzy objects: their changes and uncertainties Type de document : Article/Communication Auteurs : T. Cheng, Auteur Année de publication : 2002 Article en page(s) : pp 41 - 49 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] analyse d'image numérique [Termes IGN] incertitude des données [Termes IGN] objet flou Résumé : (Auteur) Although most geographical entities represented as objects in a GIS have crisp boubaries, in relity they have indeterminate boundaries and fuzzy spatial extent. This is due to the fact that they are distributed continuously in space and time. Futhermore, measurement procedures generally produce data with a limited accuracy , which lead to the uncertain description of geographical entities. Because of these facts, uncertainties exist in the crisp object description of geographical entities. When temporal information is applied to analyze their change, these uncertainties will influence the final results of mapping. Therefor, the effects of the uncertainties on monitiring geographical entities should be studied, in order to provide accurate information to decision makers. This paper discusses the indeterminate nature of geographic entities and its effects on change detection when they are monitored through time. The concept of fuzzy objects and fuzzy change detection are applied to describe heterogeneous objects or objects with indeterminate boundaries. Several measures for fuzzy change detection are presented to evaluate the change processes of the objects. A pratical example of the dynamics of sediments along the Dutch coast is elaborated to demontrate the approach and the concepts proposed. Numéro de notice : A2002-009 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : sans En ligne : https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ve [...] Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=21926 [article]

Scale and texture in digital image classification / J.S. Ferro 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 51 - 63 Titre : Scale and texture in digital image classification Type de document : Article/Communication Auteurs : J.S. Ferro, Auteur ; T.A. Warner, Auteur Année de publication : 2002 Article en page(s) : pp 51 - 63 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] accentuation de contours [Termes IGN] analyse d'image numérique [Termes IGN] classification dirigée [Termes IGN] classification multidimensionnelle [Termes IGN] classification non dirigée [Termes IGN] classification par maximum de vraisemblance [Termes IGN] image ADAR [Termes IGN] image multibande [Termes IGN] incertitude des données [Termes IGN] qualité d'image [Termes IGN] superposition d'images Résumé : (Auteur) Classification errors using texture are most likely associated with class edges, but investigators often avoid edges when evaluating textures for classification. The large window needed to produce a stable texture measure produce large edge effects. Small windows minimize edge effects, but often do not provide stable texture measures. Simulated data experiments showed that class separability increased when texture was used in addition to spectral information. Texture separability improved with larger windows. This improvement was over estimated when pixels were chosen away from class edges. Airborne Data Acquisition and Registration (ADAR) data showed that separability of class interiors improved with the addition of texture, but that, for the whole class, separability fell. Maximum-likelihood classification of the ADAR data demonstrated the effect of edges and multiple scales in reducing the accuracy of classification incorporating texture. Numéro de notice : A2002-010 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_51-63 [...] Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=21927 [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]