A real-time visualization method for large 3-D vegetation scenes
大规模三维植被场景实时可视化方法

This paper addresses an approach for dynamic and continuous multi-resolution visualization of large forests.Firstly,the approach uses the L-systems to generate 3D tree models,which are composed of two kinds of geometric elements: branches and leaves.The plants are simplified respectively to multi-resolution models of branches and foliage by our method.Secondly,the approach quantifies the resolution of LOD models by the length of branches and the quantity of foliage.The branch length for the branch LOD model and the leaf quantity for the foliage LOD model are obtained by the decay factor.Taking the values as the criterion,we extract LOD models from the multi-resolution models of branches and foliage in real time.Finally,we render the forest scene.This paper presents a continuous LOD rendering for forest landscape,and the main originalities of our method are summarized as follows.(1) To improve the efficiency for extracting the continuous LOD models,the multi-resolution chains and the binary tree structures are established respectively for the branches and the crowns,both of which consist of the preliminary models of the tree.(2) Our method for generating crown LOD models here shows that,they can implement large forest scene real-time visualization.(3) This paper makes new criteria for the LOD models,which use the decay factor to act on the original branch length and the original leaf quantity.In this way,the levels for displaying trunk and branches are calculated.This method is applicable to all kinds of plants with strong universality and practicability.So how to simplify crowns of such kind of trees is another important research subject.In future work,we should combine geometry-based and image-based simplification methods to further speed up visualization of large plant scenes.