A differential volume rendering method with second-order difference for time-varying volume data

[[abstract]]© 2003 Elsevier - The differential volume rendering method is a ray casting based method for time-varying volume data. In the differential volume rendering method, the changed voxels between consecutive time steps are extracted to form differential files in advance. When the dataset is to be rendered, changed voxels are projected onto the image plane to determine the positions of changed pixels. Only the changed pixels, instead of all pixels on the image, are updated by casting new rays in each time step. The main overhead of the differential volume rendering method is the determination of changed pixels. In this paper, we propose a two-level differential volume rendering method, in which the determination of changed pixels is accelerated by the aid of the second-order difference. Since changed voxels in two consecutive differential files may partially overlap in the space, the projection computation spent on the overlapped area is redundant. We use this property to extract the difference of changed voxels between consecutive differential files to form the second-order difference. Based on the second-order difference, the changed pixels can be determined more efficiently. The experimental results show that the proposed method outperforms the comparative methods for all test datasets in most cases. In addition, the rendering time can be predicted once the data files are loaded in each time step.[[department]]資訊工程學