MUSICES - Musical Instrument Computed Tomography Examination Standard: The Final Report Featuring Methods for Optimization, Results of Measurements, Recommondations, Check-lists and Meta-Data Models

Abstract

Digitalization of irreplaceable objects of cultural and/or historical significance as field of research is gaining more and more importance recently. The Germanisches Nationalmuseum (GNM) in Nürnberg, Germany, and the Development Center for X-ray Technology (EZRT) of the Fraunhofer Institute for Integrated Circuits (IIS) in Fürth, Germany, were jointly working in the MUSICES project, addressing issues of 3-dimensional (3D) digitalization of historically important musical instruments. This project was funded by the German research association DFG (Deutsche Forschungsgemeinschaft) and ends in January 2018. The project partners developed examination standards that, independent of the deployed devices and operating staff, are set to deliver high-quality 3D volume data sets representing musical instruments. Plenty of representative examples carried out during the project ensure the applicability of the technical parameters. MUSICES has been dealing with testimonials of the manufacturing of musical instruments during the last five centuries. From 2015 to 2017, more than 100 historically remarkable objects in the collection of the GNM were digitized by means of fully 3D image acquisition with X-ray CT The CT measurements were performed at the EZRT site in Fürth, where X-ray systems with maximum radiation energies of between 60 and 9,000 keV are used for CT scanning and reconstruction, as well as means for multispectral material analysis and algorithms for the correction, visualization and evaluation of image data. Several methods were applied to optimize CT parameters via extended studies of simulated virtual data sets. In detail, the simulated data sets were based on a simplified virtual representation of the respective specimen. Its orientation with respect to the axis of rotation and in case of dual energy measurements the spectral quality of both partial data acquisition runs were varied computationally until the minimum Shannon entropy of the resulting reconstructed slices was achieved. Parameters identified in such a way beforehand were then applied for the real measurement. Based on the evaluation of all acquired 3D-images, standard procedures are proposed. The image data itself are made available to the broad public. Additionally, the final report published in 2018 provides various checklists for preparation, transport, positioning, best practice for measurement of various classes of instruments (wood/metal/mixed/other resp. size and shape), an elaborate data base structure description for long term archiving and methods for detailed image quality assessment.