GCH 2022 - Eurographics Workshop on Graphics and Cultural Heritage

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https://diglib.eg.org/handle/10.2312/2633215

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Browsing GCH 2022 - Eurographics Workshop on Graphics and Cultural Heritage by Author "Eisemann, Elmar"

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    A New Baseline for Feature Description on Multimodal Imaging of Paintings
    (The Eurographics Association, 2022) Toorn, Jules van der; Wiersma, Ruben; Vandivere, Abbie; Marroquim, Ricardo; Eisemann, Elmar; Ponchio, Federico; Pintus, Ruggero
    Multimodal imaging is used by conservators and scientists to study the composition of paintings. To aid the combined analysis of these digitisations, such images must first be aligned. Rather than proposing a new domain-specific descriptor, we explore and evaluate how existing feature descriptors from related fields can improve the performance of feature-based painting digitisation registration. We benchmark these descriptors on pixel-precise, manually aligned digitisations of ''Girl with a Pearl Earring'' by Johannes Vermeer (c. 1665, Mauritshuis) and of ''18th-Century Portrait of a Woman''. As a baseline we compare against the well-established classical SIFT descriptor. We consider two recent descriptors: the handcrafted multimodal MFD descriptor, and the learned unimodal SuperPoint descriptor. Experiments show that SuperPoint starkly increases description matching accuracy by 40% for modalities with little modality-specific artefacts. Further, performing craquelure segmentation and using the MFD descriptor results in significant description matching accuracy improvements for modalities with many modalityspecific artefacts.
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    Semi-Automatic Perspective Lines from Paintings
    (The Eurographics Association, 2022) Coudert-Osmont, Yoann; Eisemann, Elmar; Marroquim, Ricardo; Ponchio, Federico; Pintus, Ruggero
    Perspective cues play an important role in painting analysis as it may unveil important characteristics about the painter's techniques and creation process. Nevertheless, extracting perspective lines and their corresponding vanishing points is usually a laborious manual task. Moreover, small variations in the lines may lead to large variations in the vanishing points. In this work, we propose a semi-automatic method to extract perspective lines from paintings in order to mitigate the human variability factor and reduce the workload.
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    Visual Analysis of RIS Data for Endmember Selection
    (The Eurographics Association, 2022) Popa, Andra; Gabrieli, Francesca; Kroes, Thomas; Krekeler, Anna; Alfeld, Matthias; Lelieveldt, Boudewijn; Eisemann, Elmar; Höllt, Thomas; Ponchio, Federico; Pintus, Ruggero
    Reflectance Imaging Spectroscopy (RIS) is a hyperspectral imaging technique used for investigating the molecular composition of materials. It can help identify pigments used in a painting, which are relevant information for art conservation and history. For every scanned pixel, a reflectance spectrum is obtained and domain experts look for pure representative spectra, called endmembers, which could indicate the presence of particular pigments. However, the identification of endmembers can be a lengthy process, which requires domain experts to manually select pixels and visually inspect multiple spectra in order to find accurate endmembers that belong to the historical context of an investigated painting. We propose an integrated interactive visual-analysis workflow, that combines dimensionality reduction and linked visualizations to identify and inspect endmembers. Here, we present initial results, obtained in collaboration with domain experts.