X-ray Computed Tomography (CT) is a well known diagnostic technique. However, it could be very complex if one wants to use it in fields other than medicine. When CT is applied to large objects, as in cultural heritage, several thousand digital images have to be elaborated, operation that takes a long time. As it is not possible to leave the measurement stage near a monument or in a museum for a long time, it is necessary to develop fast image reconstruction software to allow the experimenters to “look inside” the objects quickly in order to repeat the measurements, if necessary, in a more suitable condition before dismantling the equipment. The X-Ray Imaging Group (University of Bologna) has developed several systems for CT of large objects and, recently, a software, for fast image elaboration, that operates on a network of computers. For illustrating the power of our computing system, this presentation will discuss the CT (done in 2008) of a large Japanese wooden statue (over 200cm of height) of the XIII century, located at the royal palace “La Venaria Reale” (Turin). To investigate the entire statue volume, up to 36 scans were necessary and for each of them 720 radiographs were acquired. To reconstruct all the slices of the complete volume of the object (120 GB) it took 20 days of computing on a good standard PC. The parallelization work was done using the Microsoft (Redmond) HPC cluster and thereafter on a new, transportable, 32 cores cluster at the INFN of Bologna. The HPC environment has proven to be dramatically powerful and easy to use allowing to have the results very quickly. A superlinear speedup of 75 was reached with a 32 cores cluster (the speed up factor, 75, is higher than the number of cores, 32).

SUPERLINEAR SPEEDUP IN PARALLEL 3D COMPUTED TOMOGRAPHY APPLIED TO LARGE OBJECTS IN CULTURAL HERITAGE

BRANCACCIO, ROSA;BETTUZZI, MATTEO;CASALI, FRANCO;MORIGI, MARIA PIA;LEVI, GIUSEPPE;
2011

Abstract

X-ray Computed Tomography (CT) is a well known diagnostic technique. However, it could be very complex if one wants to use it in fields other than medicine. When CT is applied to large objects, as in cultural heritage, several thousand digital images have to be elaborated, operation that takes a long time. As it is not possible to leave the measurement stage near a monument or in a museum for a long time, it is necessary to develop fast image reconstruction software to allow the experimenters to “look inside” the objects quickly in order to repeat the measurements, if necessary, in a more suitable condition before dismantling the equipment. The X-Ray Imaging Group (University of Bologna) has developed several systems for CT of large objects and, recently, a software, for fast image elaboration, that operates on a network of computers. For illustrating the power of our computing system, this presentation will discuss the CT (done in 2008) of a large Japanese wooden statue (over 200cm of height) of the XIII century, located at the royal palace “La Venaria Reale” (Turin). To investigate the entire statue volume, up to 36 scans were necessary and for each of them 720 radiographs were acquired. To reconstruct all the slices of the complete volume of the object (120 GB) it took 20 days of computing on a good standard PC. The parallelization work was done using the Microsoft (Redmond) HPC cluster and thereafter on a new, transportable, 32 cores cluster at the INFN of Bologna. The HPC environment has proven to be dramatically powerful and easy to use allowing to have the results very quickly. A superlinear speedup of 75 was reached with a 32 cores cluster (the speed up factor, 75, is higher than the number of cores, 32).
ART'11 10th International conference on non destructive investigations and microanalysis for the diagnostics and conserservation of cultural and environmental heritage.
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Rosa Brancaccio; Matteo Bettuzzi; Franco Casali; Maria Pia Morigi; Giuseppe Levi; Alessandro Gallo; Giovanni Marchetti; Daniel Schneberk
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11585/108441
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