Research On Tree Model Based On Three-dimensional Geometric Modeling Method

Virtual nature scenes is a challenging topic in computer graphics. As a very important part of natural scenery, the algorithm research on modeling of trees has attracted much attention. Trees have complex structure and various kinds, which are difficult to create, storage and render.According to different applications, the trees growth stimulantion technology can be divided into tow classes: applied in agroforestry and the another class is applied in other field. The two classes are different on principle of modeling and the standard of results' realistic requirements. The first should be faithful to physiological principle strictly, the latter is based on realistic image synthesis to represent natural scene.The research of this paper belongs to the second kind. After analyzed and studied on some algorithms about how to create and render tree models, a improved algorithm which is based on Three-dimensional geometric modeling method proposed. This algorithm divides the structure of tree into three levels and constructs the level model using trees' self-similar characteristic. Then, we can adjust the deflexed angles to level model, which is influenced by lighting and gravitation. Using the trees represented algorithm to control the new branches' creating. Adding the parameters to control side-branches, it solves the FCFP(First coming First Prosessing) problem in trees. Finally, using the theory of LOD, Multi-complex tree models are used to express trees in different view distances. It improves the effect of rendering.It presents a demo system to verify this algorithm. Experimental result show that tree model rendered by the improved algorithm can reflect tree's space combination, and reflect the characteristic of phototaxis ,geotropism and FCFP. The algorithm improves the realistic of trees.