From Bone Fragment to Sound - Virtual Reconstruction of a 15th Century Bone Flute

Niko Plath1, Sebastian Kirsch2, Jost Leonhardt Fischer3

1 Department of Media Technology, Hamburg University of Applied Sciences, Germany
2 Musée de la musique, Cité de la musique – Philharmonie de Paris, France
3 Institute of Systematic Musicology, University of Hamburg, Germany

Bone Flute

  • Vulture bone, dated 15th century
  • Provenance: Swiss Alps
  • On display: Musikinstrumentensammlung Willisau
  • Inner diameter of bone cylinder: 10 mm
  • The block is not preserved -> Not playable!
Fig.1: X-ray image of a modern recorder
Fig.2: Cross section of the bone flute

How could it have sounded?

Small print:
Without making any modifications to the original object!

Industrial X-ray Computed Tomography (CT)

  • 780 single X-ray images recorded from different angles
  • Spatial resolution: 100µm
  • CT leads to a set of 2D graphics representing X-ray attenuation coefficients via grey values.
  • Stacking 2D cross sections yields a 3D representation of the measurement volume.

Post-processing: Classification, Segmentation, and Cleaning

  • Distinguish and extract sub-structures with homogeneous properties from a heterogeneous object.
  • Each voxel is allocated to exactly one of the defined sub-volumes.
  • Watertight re-meshing: Poisson surface reconstruction (PSR).
  • Possible failures: Duplicate faces and vertices, non-manifold edges, self intersecting faces, zero area faces

Computer Aided Design (CAD) Modeling

Provided that it was playable at all, how should the block be shaped so that the flute produces a sound?

Computer Aided Design (CAD) Modeling

Provided that it was playable at all, how should the block be shaped so that the flute produces a sound?

Computer Aided Design (CAD) Modeling

Provided that it was playable at all, how should the block be shaped so that the flute produces a sound?

Computer Aided Design (CAD) Modeling

Provided that it was playable at all, how should the block be shaped so that the flute produces a sound?

Fluid Dynamic Simulation of the Blowing Process

  • Numerical simulations solving the compressible Navier-Stokes equations with suitable boundary and initial conditions.
  • Implementation: Open source C++ toolbox OpenFOAM.
  • Transfer flute geometry into pseudo 2D calculation grid, calculate the parameter space of geometry variations of the windway angle.
  • Numerical data is sampled inside the flute cylinder
  • Find the most stable sound production.

Print and Play!

Scale

Conclusion

  • Physical modeling of functional objects allows systematic iterations under strict ceteris paribus conditions.
  • The approach is non-invasive
    -> the original object is preserved.
  • Pre-processing measured 3D data for physical modeling is still fiddly!
  • Restorers perspective: it's easy to loose scale in virtual environment.
    => Combine virtual and real hands-on approaches.

Thank you!

Find this presentation: www.culturalheritage.digital/boneflute
Contact: niko.plath@culturalheritage.digital