3D reconstruction of images of soil samples: A sequential removal technique

A mechanical tomography system aiming at achieving 3D reconstruction and analysis of the soil structure is described in this paper. Undisturbed soil samples are impregnated with a polyester or epoxy resin after a dehydration treatment. A fluorescent dye is added in the resin. The hardened soil blocks are ground under a high precision (1?m) surface-grinding machine and 2D images of serial sections are acquired using a digital photo scanner (3600?2700 pixels). The information on the 2D sections is rearranged on a SGI Indigo 2 graphic workstation in order to reconstruct a 3D image of the soil block. Reconstruction is made using 2D sections spaced by the same amount of the pixel size allowing a reliable 3D representation of the soil with an isotropic grid of voxels. Analysis on porosity, pore size distribution, connectivity etc. can than be performed using algorithms of mathematical morphology. Discussion on the results on a trial experiment demonstrates that the system offers an useful instrument to obtain information on 3D organisation of the soil structure.