Application of X-ray computed tomography in diagnostics and reverse engineering of bowed stringed musical instruments

This contribution summarizes several works on the application of industrial X-ray computed tomography to bowed stringed instruments, developed by Francesco Piasentini and TEC-Eurolab since 2014, in collaboration with the University of Padova. Some of these works were disseminated during the WoodMusICK FP1302 COST ACTION and elsewhere. This paper offers an in-depth analysis of practical aspects of CT scanning a violin with cone-beam industrial X-ray CT scanner. Examples of the effects of CT system settings are presented, including those related to X-ray tube voltage and current, detector binning and geometric magnification. Surface determination is a critical step in the dimensional analysis of CT volumes. For instance, surfaces determined using global or local thresholding algorithms can exhibit significant deviations, especially with multi-material instruments or materials showing strong variations in density, such as spruce. Investigations of CT metrology for violin tops allowed measurement uncertainties to be determined for a series of dimensions that are relevant for bowed stringed instruments.