A comparison of 2D vs. 3D thresholding of X-ray CT imagery

Non-destructive soil constituent analysis has advanced from resin impregnation of intact samples to the utilization of non-destructive imaging devices (i.e., CT scanners) for 3D composition. A difficulty of CT scanning is the finite resolution of such devices and the resulting non-definitive boundaries. Isolation of voxels that contain a single constituent (i.e., low variance voxels) allows for improved segregation of 3D data by histogram thresholding. The results from proposed 2D and 3D low variance voxel segmentation techniques were compared to establish whether or not 3D consideration should be used when analyzing CT and intact soil columns. It was determined that 2D processing in single orientation and as a multiplicative orthogonal process produced dissimilar results to 3D processed data. The authors encourage further exploration of 3D investigation in soil science, particularly related to soil composition and arrangement.