Improvement on Direct Volume Rendering

Direct volume-rendering (DVR) is usually used in medical volume visualization, DVR images tend to be over-loaded with the content (blurred images). Thus, in many practical applications simpler techniques which do not rely on complex transfer functions are employed. For example, maximum intensity projection (MIP) which depicts the maximum value along each viewing ray. In this paper, we improve the illustrative context-preserving volume rendering based on visualization toolkit (VTK). In our method, it can simultaneously visualize interior and exterior structures while preserving clear shape cues. The main limitation of MIP is that it cannot adequately depict the spatial relationships of overlapping tissues. An approach has been proposed to eliminate this drawback: local maximum intensity projection (LMIP). LMIP is an extended version of MIP. LMIP selects the first local maximum value encountered that is larger than a pre-selected threshold value along an optical ray from the viewpoint in the viewing direction. In this paper we propose an improved local maximum intensity projection. An appropriate threshold and shading are computed in this improved method. We show that the improved method is a useful technology in volumetric dataset visualization.