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Multispectral RTI Analysis of Heterogeneous Artworks

Andrea Giachetti, Irina Ciortan, Claudia Daffara, Ruggero Pintus, and Enrico Gobbetti

October 2017

Abstract

We propose a novel multi-spectral reflectance transformation imaging (MS-RTI) framework for the acquisition and direct analysis of the reflectance behavior of heterogeneous artworks. Starting from free-form acquisitions, we compute per-pixel calibrated multi-spectral appearance profiles, which associate a reflectance value to each sampled light direction and frequency. Visualization, relighting, and feature extraction is performed directly on appearance profile data, applying scattered data interpolation based on Radial Basis Functions to estimate per-pixel reflectance from novel lighting directions. We demonstrate how the proposed solution can convey more insights on the object materials and geometric details compared to classical multi-light methods that rely on low-frequency analytical model fitting eventually mixed with a separate handling of high-frequency components, hence requiring constraining priors on material behavior. The flexibility of our approach is illustrated on two heterogeneous case studies, a painting and a dark shiny metallic sculpture, that showcase feature extraction, visualization, and analysis of high-frequency properties of artworks using multi-light, multi-spectral (Visible, UV and IR) acquisitions.

Reference and download information

Andrea Giachetti, Irina Ciortan, Claudia Daffara, Ruggero Pintus, and Enrico Gobbetti. Multispectral RTI Analysis of Heterogeneous Artworks. In The 14th Eurographics Worhshop on Graphics and Cultural Heritage, October 2017. To appear.

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Bibtex citation record

@InProceedings{Giachetti:2017:MRA,
    author = {Andrea Giachetti and Irina Ciortan and Claudia Daffara and Ruggero Pintus and Enrico Gobbetti},
    title = {Multispectral RTI Analysis of Heterogeneous Artworks},
    booktitle = {The 14th Eurographics Worhshop on Graphics and Cultural Heritage},
    month = {October},
    year = {2017},
    abstract = { We propose a novel multi-spectral reflectance transformation imaging (MS-RTI) framework for the acquisition and direct analysis of the reflectance behavior of heterogeneous artworks. Starting from free-form acquisitions, we compute per-pixel calibrated multi-spectral appearance profiles, which associate a reflectance value to each sampled light direction and frequency. Visualization, relighting, and feature extraction is performed directly on appearance profile data, applying scattered data interpolation based on Radial Basis Functions to estimate per-pixel reflectance from novel lighting directions. We demonstrate how the proposed solution can convey more insights on the object materials and geometric details compared to classical multi-light methods that rely on low-frequency analytical model fitting eventually mixed with a separate handling of high-frequency components, hence requiring constraining priors on material behavior. The flexibility of our approach is illustrated on two heterogeneous case studies, a painting and a dark shiny metallic sculpture, that showcase feature extraction, visualization, and analysis of high-frequency properties of artworks using multi-light, multi-spectral (Visible, UV and IR) acquisitions. },
    note = {To appear},
    url = {http://vic.crs4.it/vic/cgi-bin/bib-page.cgi?id='Giachetti:2017:MRA'},
}