Continuous LOD Model of Coniferous Foliage

Interactive and realistic rendering of forest is a challenge due to a huge amount of tiny geometric detail. We present an approach to construct continuous level of detail (LOD) models for coniferous foliage geometry. The models are defined with multi-resolution cylinders and semi-transparent lines. When a coniferous leaf is wider than one pixel on the image space, cylinder is used to represent it; otherwise, line will be used. And Line transparency is applied to show the sub-pixel detail of foliage needles. In addition, lines are further merged to a new line when they are too thin on the image space, so that the number of lines will be decreased when they are farther from the viewer. All steps of simplification are recorded in preprocessing. During rendering, appropriate approximation models will be established for different viewpoints automatically on the fly, and the transition from high resolution to a lower one is continuous. Compared with other foliage simplification methods, our approach can produce more realistic results for close views, and can get higher compression ratio for distant coniferous foliage.