Browsing by Author "Guennebaud, Gaël"

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    3D for Studying Reuse in 19th Century Cairo: the Case of Saint-Maurice Residence
    (The Eurographics Association, 2021) Baillet, Vincent; Mora, Pascal; Cou, Corentin; Tournon-Valiente, Sarah; Volait, Mercedes; Granier, Xavier; Pacanowski, Romain; Guennebaud, Gaël; Hulusic, Vedad and Chalmers, Alan
    3D restitution is now a well-known tool to validate hypotheses on historical buildings that do not exist anymore. The present project takes the method a step further in order to explore the art historical topic of ornament reuse in 19th century revival architecture, particularly in Cairo. The case study is the Saint-Maurice residence, built 1875-79, for which an extensive collection of documents in varied formats, and from multiple locations and disciplines, has been conducted. The paper presents some preliminary results on the 3D restitution, the remaining open questions and the challenges they raise.
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    One-to-Many Spectral Upsampling of Reflectances and Transmittances
    (The Eurographics Association and John Wiley & Sons Ltd., 2023) Belcour, Laurent; Barla, Pascal; Guennebaud, Gaël; Ritschel, Tobias; Weidlich, Andrea
    Spectral rendering is essential for the production of physically-plausible synthetic images, but requires to introduce several changes in the content generation pipeline. In particular, the authoring of spectral material properties (e.g., albedo maps, indices of refraction, transmittance coefficients) raises new problems. While a large panel of computer graphics methods exists to upsample a RGB color to a spectrum, they all provide a one-to-one mapping. This limits the ability to control interesting color changes such as the Usambara effect or metameric spectra. In this work, we introduce a one-to-many mapping in which we show how we can explore the set of all spectra reproducing a given input color. We apply this method to different colour changing effects such as vathochromism - the change of color with depth, and metamerism.