T-Shell Rendering and Manipulation

摘要

Previously shell rendering was shown to be an ultra fast method of rendering digital surfaces represented as sets of voxels. The purpose of this work is to describe a new extension to the shell rendering method that creates a new representation of surfaces called t-shells using triangulated surface elements. The great speed of the shell rendering technique is made available to rendering triangulated surfaces through the use of data structures that describe the shell and through algorithms that traverse this information to produce the two-dimensional projection of the three-dimensional data. In traditional shell rendering, each shell element (a voxel) is represented by a triple comprised of the offset of the voxel from the start of the row, the neighborhood code of the voxel, and the surface normal. We modify this data structure by replacing the neighborhood code with a code that indicates the Marching Cubes configuration of polygons (1 of 256 possible triangulated configurations) within that area (rather than the rasterization of a single, uniform shell element as was originally done). We present the general t-shell algorithm as well as the results of the two implementations as applied to input data which consist of different objects from various parts of the body and various modalities with a variety of surface sizes and shapes. We present some sample renditions as well as the results of liming experiments which demonstrate that the t-shell rendering is not only much faster than hardware-based rendering but is also capable of handling scenes that are much larger than those the hardware is capable of rendering while producing renditions of comparable quality.