Algorithm And Application Research Of Object-order Volume Rendering

Volume visualization especially volume rendering has been the most important and rapid developed techniques in the visualization of three-dimensional data sets recent years. It has been widely used in three-dimensional medical reconstruction, computational dynamic fluid, post-processing of finite element computation, seismic and geological applications. Because object-order volume rendering methods have the advantages including simple voxel traverse, easy use of all kinds of speedup techniques, high parallel ability, and easy hardware implementation, at the same time these algorithms have the disadvantages such as computation inaccuracy and aliasings, object-order volume rendering is discussed in this paper. First, by studying the fundamental principle of object-order volume rendering especially the Splatting algorithm, we find the main reasons of the traditional Splatting inaccuracy and aliasings: the traditional Splatting algorithm pre-integrates the reconstruction kernel into two dimensional footprints table, which results in inevitable integration problem, overlay problem, so it is difficult to produce accurate rendering results. As an improvement, sheet-buffer method overcomes the overlapping problem, at the same time introduces popping artifacts into Splatting. In this paper, we present a new kind method which is based on view-buffer rather than sheet-buffer. By using a voxel traversal order which is parallel to the view-buffer, and a pre-integrated three dimensional lookup table, we solve the problems of classic splatting algorithm efficiently. The method we proposed can not only solve the popping problem in the rotation process, but also obtain high quality refined rendering.Second,based on the analyzing the advantages of all volume rendering methods, especially the essence of Splatting algorithm, a new object-order volume rendering algorithm is proposed in this paper. Firstly, the new algorithm constructs an efficient data structure, namely, a two-step look-up table, which is used for the three-dimensional reconstruction. Secondly, a novel slice-order traversal strategy is adopted for the projection. The resample operation in the proposed method is much coincidental to the sample theory, which makes the method much closer to the ideal rendring method. Because the new method is an object-order volume rendering, it inherites the advantages of the Splatting method, in addition, it can produce ray-casting like rendering quality. At the same time, the proposed method has high parallel ability---this provides us a firm basis for our future hardware-accelerated volume rendering architecture research.At last, a three-dimensional medical reconstruction system---VolGraph, which is developed by our research team, is dicussed...