  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.
