Research Of Tree Modeling And Simulation Technology Base On L-system

Trees as a common scenario model have been widely used in the simulation of natural scenes. How to draw a realistic tree which has high drawing efficiency in large-scale scene has become a hot and difficult topic in computer graphics. The approach based on L-system is a common method for modeling trees. It is a form of the fractal method, belongs to the category of computer graphics. Trees can be created conveniently by setting the initial string and turtle diagram cleverly. In recent years, many researchers have done a lot of researches in the simulation of trees by using L-system method. However, existing methods exists a lot of^shortcomings. Such as lack of interactivity, generated trees with rigid shapes, single structure, and have a poor render speed in the large-scale scene.In order to use the convenience of L-system, draw a realistic and high efficiency tree, this paper improve the existing methods in the following aspects:1. This paper uses a lot of parameters to control the detail of branches. Such as branch length, radius, angle etc. Users can use the scroll bar to change the parameters to implement the "fine-tuning" of the tree morphology. Using this method to create a realistic tree conveniently.2. In order to obtain diversity of trees, this paper use triple-random algorithm.(1) The probability factor of production is set to make the same initial string can generate a variety of rewriting strings after rewriting operations to show the same kind of trees in a variety of styles;(2)Choose the rewriting string randomly in the multiple rewriting string which stored in the memory in the drawing stage. Use this method to show the variety of trees in a variety of styles;(3)Choose the parameters which describes branching morphology randomly in the threshold range, ensure that even if the method (2) selected the same rewriting string can still generate a diversity of trees. 3. To ensure the efficiency of L-system approach, made the following measures.(1)Change the drawing process of traditional L-system, when user modifier the parameters which control the detail of branches, stop doing the unnecessary string rewrite operation;(2) use three structures stored fractal calculation results, if the user did not modify the parameters, stop doing unnecessary calculation in each frame refresh;(3)proposes a slice reduction algorithm based on recursive depth, without losing detail of trees, greatly reducing the number of rectangular slices need in drawing the scene, combined with the LOD method to further improve the L system trees rendering efficiency in large-scale scene.Finally, introduce the implement of Easy Tree. Compare the improved algorithm and traditional algorithm in this system. Comparison showed that the application of the algorithm can draw diversity and realistic trees, and the rendering speed has been significantly improved in large-scale scene.