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Fig. 6. Effect of image resolution on image properties analyzed with simulated media. (A) The mean breadth of the mapped particles, divided by the analytically determined breadth of the spheres, becomes positive for resolutions with voxel sizes smaller than 23 to 25% of the mean particle radius (arrows). The large symbols indicate the voxel size of the measurements with X-rays from tubes (black) or thermal neutrons (gray), respectively. For the tomography of the glass beads using neutron transmission technique, the voxel size was 16.7% of the mean particle radius and this requirement was fulfilled. (B) The Euler-Poincaré characteristic (EPC) of the solid phase divided by the number of particles. For high resolutions, the spheres in the image become separated and a positive EPC results. The resolutions of the tomography did not fulfill this condition.
