Opacity volume based halo generation for enhancing depth perception

Halos are usually used to enhance depth perception and display spatial relationships in illustrative visualization. In this paper, we present a simple and effective method to create volumetric halo illustration. In the pre-processing stage, we generate a view-independent halo intensity volume, which contains all potential halos around the boundaries of features, based on the opacity volume on graphic hardware. During halo rendering, the halo intensity volume is used to extract halos only around the contours of structures for the current viewpoint. The performance of our approach is significantly faster than previous halo illustration methods, which perform both halo generation and rendering during volume rendering. Experimental results demonstrate volumetric halo effects and the efficiency of the proposed approach.