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Color correction of texture images for true photorealistic visualization / Y. Song in ISPRS Journal of photogrammetry and remote sensing, vol 65 n° 3 (May - June 2010)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 65 n° 3 (May - June 2010) . - pp 308 - 315 Titre : Color correction of texture images for true photorealistic visualization Type de document : Article/Communication Auteurs : Y. Song, Auteur ; J. Shan, Auteur Année de publication : 2010 Article en page(s) : pp 308 - 315 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] correction radiométrique [Termes IGN] réalité virtuelle [Termes IGN] texturage [Termes IGN] texture d'image [Termes IGN] visualisation de données Résumé : (Auteur) Photorealistic visualization combines 3-D geometric models with their texture images to render the virtual world. This paper points out that the texture images should be radiometrically corrected to achieve a true realistic appearance. Such a correction should include not only the color adjustment among images of the same object, but also the shade variation caused by the illumination change. The objective of this study is to correct the input texture images such that their shade varies when being rendered under different illumination directions. To achieve this goal we first apply the specular-to-diffuse mechanism based on the dichromatic reflection model to remove the specular component from the texture image. The resultant diffusion-only image then undergoes a shade correction to produce a normalized shade-free texture image. In the final step, shades under any illumination are produced to achieve a true photorealistic effect. Presented in the paper are the principles and methods for such corrections, along with a performance evaluation based on the graphic and numerical results for roof texture images. Numéro de notice : A2010-180 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2010.01.003 En ligne : https://doi.org/10.1016/j.isprsjprs.2010.01.003 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30375 [article]

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An adaptive approach to topographic feature extraction from Digital Terrain Models / Y. Song in Photogrammetric Engineering & Remote Sensing, PERS, vol 75 n° 3 (March 2009)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 75 n° 3 (March 2009) . - pp 281 - 290 Titre : An adaptive approach to topographic feature extraction from Digital Terrain Models Type de document : Article/Communication Auteurs : Y. Song, Auteur ; J. Shan, Auteur Année de publication : 2009 Article en page(s) : pp 281 - 290 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] Antarctique [Termes IGN] carte des pentes [Termes IGN] extraction automatique [Termes IGN] extraction de traits caractéristiques [Termes IGN] modèle numérique de terrain [Termes IGN] seuillage Résumé : (Auteur) This study presents an adaptive solution to topographic feature extraction from digital terrain model. First, a slope map is produced by the proposed slope estimator that combines the well-known D8 and finite difference methods. In the second step, the Laplacian of Gaussian (LOG) operator with multiple thresholds is applied to the resultant slope map to determine edge pixels that have local maximum curvature and maximum connectivity. The third step adopts the original and robust marching square algorithms to trace the topographic features. Modification is made to selectively introduce shoulder points according to the local topographic complexity. In comparison to the existing algorithms, the performance of the proposed adaptive marching square algorithm is evaluated in terms of precision and resolution of the extracted features. Digital terrain models over three locations in Antarctica are used for this study. It is shown overall reducing 75 percent of the shoulder points from the robust algorithm will cause 24 percent precision drop in the adaptive method. Copyright ASPRS Numéro de notice : A2009-038 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.75.3.281 En ligne : https://doi.org/10.14358/PERS.75.3.281 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29668 [article]