Real-time rendering of large-scale tree scene

High-quality, realistic visualization of vegetation and tree model is always a long-standing goal of complex virtual natural scene. Rendering a photo-realistic forest scene in real time has an important significance in simulating the growing tree. In this paper, we present a method of 3D tree modeling and a hybrid rendering algorithm of large-scale forest scene based-on open scene graph (OSG). The three-dimensional forest scene can be rendered according to the data of reality forest stand which are stored in the XML file. A 3D tree model is described with growth characteristics, which is composed of tree trunk, tree branch and leaves. In the modeling, we can simulate different age´s trees by using different layers of tree ages branch. An OSG scene graph structure is used to organize and optimize the complicated virtual scene. In order to achieve the interactive frame rates, a view-dependent LOD model selection algorithm and a GPU-based billboard image rendering technology are adopted, which can balance the GPU and CPU´s operating burden by using the vertex and index shader buffer. Finally, the technique is proved to be effective in large-size forest scene´s real-time rendering.