Centre de documentation
scientifique

Dépouillements

A comparison of fuzzy vs. augmented-ISODATA classification algorithms for cloud-shadow discrimination from Landsat images / A.M. Melesse in Photogrammetric Engineering & Remote Sensing, PERS, vol 68 n° 9 (September 2002)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 68 n° 9 (September 2002) . - pp 905 - 911 Titre : A comparison of fuzzy vs. augmented-ISODATA classification algorithms for cloud-shadow discrimination from Landsat images Type de document : Article/Communication Auteurs : A.M. Melesse, Auteur ; J.D. Jordan, Auteur Année de publication : 2002 Article en page(s) : pp 905 - 911 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] analyse comparative [Termes IGN] bande visible [Termes IGN] classification dirigée [Termes IGN] classification floue [Termes IGN] classification ISODATA [Termes IGN] image Landsat-TM [Termes IGN] nuage [Termes IGN] ombre Résumé : (Auteur) Satellite images are the most important source of landcover data over a large range of temporal and spatial scales. However, the complete realization of satellite imagery as a source of landcover information is limited by the presence of contaminants such as cloud and associated shadows in the image. These contaminants are not adequately handled with conventional image classification techniques such as the unsupervised maximumlikelihood technique. This study comprises a comparison of two classification algorithms, the fuzzy technique and an augmented form of the Iterative SelfOrganizing Data Analysis (ISODATA) technique, which were used to discriminate lowaltitude clouds and their shadows on a Landsat Thematic Mapper (TM) image of the Econlockhatchee River basin (Econ), in central Florida. Preliminary conventional unsupervised maxim umlikelihood classification of the image resulted in clouds being mixed with builtups and shadows being mixed with water bodies. Regions containing these two kinds of mixed categories were first masked, then fuzzy and augmented ISODATA classifications were performed on them. The ISODATA classification algorithm was run on the TM visible/shortwave bands and augmented with scatter diagrams of surface temperature versus several vegetation indices; the fuzzy algorithm was run on TM bands 1 through 5 and band 7. An accuracy assessment of the techniques was carried out using 40 randomly selected points within the image. Results of the classifications showed that both algorithms successfully discriminated clouds from other bright features, and shadows from other dark features, with an overall accuracy of greater than 80 percent. Numéro de notice : A2002-182 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : sans En ligne : https://www.asprs.org/wp-content/uploads/pers/2002journal/september/2002_sep_905 [...] Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22097 [article]

Techniques for mapping suburban sprawl / J. Epstein in Photogrammetric Engineering & Remote Sensing, PERS, vol 68 n° 9 (September 2002)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 68 n° 9 (September 2002) . - pp 913 - 918 Titre : Techniques for mapping suburban sprawl Type de document : Article/Communication Auteurs : J. Epstein, Auteur ; K. Payne, Auteur ; E. Kramer, Auteur Année de publication : 2002 Article en page(s) : pp 913 - 918 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] cartographie urbaine [Termes IGN] classification non dirigée [Termes IGN] image Landsat [Termes IGN] urbanisation Résumé : (Auteur) The pervasive problems generated by urban sprawl have prompted us to examine methods for delineating the extent of suburban land cover in Georgia. This paper assesses the advantages and disadvantages of two different methods of mapping suburban neighborhoods: traditional unsupervised classification of Landsat 5 TM data and a newly devised procedure for editing and buffering road coverages. We conclude that, while the amount of time required to edit and buffer road coverages is significantly higher than that for traditional remote sensing techniques, the improved thematic accuracy, spatial contiguity, and potential future uses of the resulting dataset justifies its use in a statewide mapping program. Numéro de notice : A2002-183 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : sans En ligne : https://www.asprs.org/wp-content/uploads/pers/2002journal/september/2002_sep_913 [...] Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22098 [article]

Improvement of an oak canopy model extracted from digital photogrammetry / P. Gong in Photogrammetric Engineering & Remote Sensing, PERS, vol 68 n° 9 (September 2002)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 68 n° 9 (September 2002) . - pp 919 - 924 Titre : Improvement of an oak canopy model extracted from digital photogrammetry Type de document : Article/Communication Auteurs : P. Gong, Auteur ; X. Mei, Auteur ; S. Biging, Auteur ; Z. Zhang, Auteur Année de publication : 2002 Article en page(s) : pp 919 - 924 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] couvert forestier [Termes IGN] extraction du sursol [Termes IGN] feuille (végétation) [Termes IGN] interpolation [Termes IGN] modèle numérique de surface [Termes IGN] photogrammétrie numérique [Termes IGN] Quercus (genre) [Termes IGN] surveillance forestière Résumé : (Auteur) Digital surface models (DSMs) automatically derived with digital photogrammetric systems are useful in land surface change monitoring, including forest growth monitoring. However, they cannot be applied directly to forest canopy change analysis with high accuracy due to the inevitable deficiencies in existing commercial digital photogrammetry packages. In a hardwood rangeland monitoring study, we found that the oak tree and woodland canopy boundaries were not well determined using several digital photogrammetry packages available to us. There was a noticeable discrepancy between the true crown closure and that determined by subtracting the DSM and the corresponding DEM that excludes tree heights. In this paper, we present a correction method for improvement at the erroneous canopy boundary locations in the DSM using shadow and boundary information extracted from imagery. The method is designed for correcting errors for broadleaf tree canopies. Aerial photographs taken over oak woodland hills were tested. Using manual photogrammetric measurements as the reference, we found that most of the points (88.3 percent) on the canopy boundaries were displaced by greater than 1 meter with a conventional digital photogrammetric package. After the proposed algorithms were applied, greater than 98.6 percent of the points on canopy boundaries were found to be within 1 meter of their reference positions. 78.4 percent of the reference points had greater than 2 meters elevation errors with the conventional package while greater than 85.6 percent of those points were found to be within 2 meters of the reference after the proposed algorithms were applied. Numéro de notice : A2002-184 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : sans En ligne : https://www.asprs.org/wp-content/uploads/pers/2002journal/september/2002_sep_919 [...] Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22099 [article]

Detecting and measuring individual trees using an airborne laser scanner / A. Persson in Photogrammetric Engineering & Remote Sensing, PERS, vol 68 n° 9 (September 2002)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 68 n° 9 (September 2002) . - pp 925 - 932 Titre : Detecting and measuring individual trees using an airborne laser scanner Type de document : Article/Communication Auteurs : A. Persson, Auteur ; Johan Holmgren, Auteur Année de publication : 2002 Article en page(s) : pp 925 - 932 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] arbre (flore) [Termes IGN] contour [Termes IGN] données lidar [Termes IGN] erreur moyenne quadratique [Termes IGN] forêt [Termes IGN] houppier [Termes IGN] télémétrie laser aéroporté [Termes IGN] tronc Résumé : (Auteur) High-resolution airborne laser scanner data offer the possibility to detect and measure individual trees. In this study, an algorithm which estimated position, height, and crown diameter of individual trees was validated with field measurements. Because all the trees in this study were measured on the ground with high accuracy, their positions could be linked with laser measurements, making validation on an individual tree basis possible. In total, 71 percent of the trees were correctly detected using laser scanner data. Because a large portion of the undetected trees had a small stem diameter, 91 percent of the total stem volume was detected. Height and crown diameter of detected trees could be estimated with a root-mean-square error (RMSE) of 0,63 m and 0,61 m, respectively. Stem diameter was estimated, using laser measured tree height and crown diameter, with an RMSE of 3,8 cm. Different laser beam diameters (0,26 to 3,68 m) were also tested, the smallest beam size showing a better detection rate in dense forest. However, estimates of tree height and crown diameter were not affected much by different beam size. Copyright ASPRS Numéro de notice : A2002-323 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : sans En ligne : https://www.asprs.org/wp-content/uploads/pers/2002journal/september/2002_sep_925 [...] Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22234 [article]