Some early violins have been reduced during their history to fit imposed morphological standards, while more recent ones have been built directly to these standards. We propose an objective photogrammetric approach to differentiate between a reduced and an unreduced instrument, whereby a three-dimensional mesh is studied geometrically by examining 2D slices. Our contribution is twofold. First, we validate the quality of the photogrammetric mesh through a comparison with reference images obtained by medical imaging, and conclude that a sub-millimetre accuracy is achieved. Then, we show how quantitative and qualitative features such as contour lines, channel of minima and a measure of asymmetry between the upper and lower surfaces of a violin can be automatically extracted from the validated photogrammetric meshes, allowing to successfully highlight differences between instruments.

翻译：一些早期小提琴在历史进程中曾被改小以符合强加的外形标准，而较晚近的小提琴则直接按这些标准制造。我们提出一种客观的摄影测量方法，通过研究三维网格，以2D切片进行几何分析，来区分被改小和未经改小的乐器。我们的贡献有两方面：首先，通过与医学影像获取的参考图像进行对比，验证了摄影测量网格的质量，并得出结论——该方法可达到亚毫米级精度；其次，我们展示了如何从经验证的摄影测量网格中自动提取定量与定性特征，如等高线、最小谷值通道以及小提琴上下表面不对称性度量，从而成功凸显乐器间的差异。