Classification for Volume Rendering of Industrial CT Based on Moment of Histogram

In the volume rendering, the classification step is used to determine voxel visibility and plays an important role. In this paper, a new classification algorithm, which is based on moment of histogram of volume data, is proposed for volume rendering. Firstly, the histogram of volume data is partitioned into different subsections by the number of object classes, which is developed through calculating the entropy of the histogram of volume data. Secondly, in each subsection a threshold is computed according to the moment of the histogram of volume data. Finally, the opacity of each voxel is assigned by a transfer function, which is split by these thresholds into subsection. Three schemes based on the moment of histogram of volume data are applied to determine the threshold and three corresponded results is compared. Examples from industrial CT dataset are presented. In the volume rendering results, industrial components are shown explicitly and can be successfully disassembled in the simulated by the computer.