Identification of Violin Reduction via Contour Lines Classification

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dc.contributor.authorBeghin, Philémonen_US
dc.contributor.authorCeulemans, Anne-Emmanuelleen_US
dc.contributor.authorGlineur, Françoisen_US
dc.contributor.editorCampana, Stefanoen_US
dc.contributor.editorFerdani, Danieleen_US
dc.contributor.editorGraf, Holgeren_US
dc.contributor.editorGuidi, Gabrieleen_US
dc.contributor.editorHegarty, Zackaryen_US
dc.contributor.editorPescarin, Sofiaen_US
dc.contributor.editorRemondino, Fabioen_US
dc.date.accessioned2025-09-05T20:25:38Z
dc.date.available2025-09-05T20:25:38Z
dc.date.issued2025
dc.description.abstractThe first violins date back to the end of the 16th century in Italy. For around 200 years, these instruments have spread throughout Europe and luthiers of various royal courts, eager to experiment with new techniques, created a highly diverse family of instruments. In an attempt to normalise violins for European orchestras and conservatories, size standards were imposed around 1750. Instruments that fell between two standards were then reduced to a smaller size by luthiers. These reductions have an impact on several characteristics of violins, in particular on the contour lines, i.e. lines of constant altitude as measured from a reference plane between the violin plates, which look more like a 'U' for non reduced instruments and a 'V' for reduced ones. Those differences between (un)reduced violins have been observed empirically but to our knowledge no quantitative study has been carried out on the subject. In this paper, we aim at developing a tool for classifying violin contour lines in order to distinguish reduced instruments from non reduced instruments. We study a corpus of 25 instruments whose 3D geometric meshes have been acquired via photogrammetry. For each instrument, we sample contour lines at 10-20 levels, regularly spaced every millimetre. Each contour line is fitted with a parabola-like curve (with an equation of the type $y = \alpha |x|^\beta$) depending on two parameters, describing how open ($\beta$) and how vertically stretched ($\alpha$) the curve is. We compute additional features from those parameters, using regressions and counting how many values fall under some threshold. We also deal with outliers and non equal numbers of levels, and eventually obtain a numerical profile for each instrument. We then applied different learning techniques on those profiles to determine whether instruments can be classified solely according to their geometry. We find that distinguishing between reduced and non reduced instruments is feasible to some degree, taking into account that a whole spectrum of more or less transformed violins exists, for which it is more difficult to quantify the reduction. We also find the opening parameter $\beta$ to be the most predictive.en_US
dc.description.sectionheadersAnalysing and Documenting the Creation Process, Evolution and Context
dc.description.seriesinformationDigital Heritage
dc.identifier.doi10.2312/dh.20253083
dc.identifier.isbn978-3-03868-277-6
dc.identifier.pages10 pages
dc.identifier.urihttps://doi.org/10.2312/dh.20253083
dc.identifier.urihttps://diglib.eg.org/handle/10.2312/dh20253083
dc.publisherThe Eurographics Associationen_US
dc.rightsAttribution 4.0 International License
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.titleIdentification of Violin Reduction via Contour Lines Classificationen_US
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