Computer simulation of the natural scenery is an important topic in the computer graphics . The natural scenery is difficult to be described using traditional methods because its randomness and irregularity. After fractal being established, as a new interdisciplinary subject, it was took seriously by the misalignment academic circle. Fractal has provided the new concept and the method for the hunting of the objective law and the inner link of complex things in the nature. In simulation of the natural scenery specially the plant simulation, the fractal has unfolded its unique superiority, becoming one focus of era researchers.The plant simulation using the fractal technology in fact is to produce plant graph using fractal characteristic of its own structure. Presently, there is a lot of methods of plant simulation ,such as Iterated Function System (IFS), the L- system, Diffusion Limited Aggregation (DLA) the Particle System and so on. This article made the focus on Iteration Function System , this method may analyze and construct a large kind of artificial or natural objects with similar structure. and it is one very effective method in the scientific research to simplify things.In the beginning this article introduce the basic principle, the important concept and two algorithms of production fractal with IFS: Determinism iterative algorithm and the stochastic iterative algorithm, to make the foundation for the following plant simulation using the IFS. This article mainly has the following two aspects:Two Dimension IFS plant modeling. In this part, mainly aims at getting of the two- Dimension IFS codes and the shadow-making technology. Firstly analyzes existing methods to get two- Dimension IFS codes, such as the traditional spelling method, the three-point method and the triangle method. Then proposed the rectangular frame method and obtains the effect chart which certain kind of plant's IFS code and corresponds. The rectangular frame method is draws spells pastes in the original map , in the schematic drawing using the rectangular frame to restrain then to take spots with the original map and each copy. This method make certain improvement on taking spots and selecting spells pastes; Then, analyze the existing two- Dimension IFS plant simulation the shadow-making technology, and make further improvements, by the linear substitution to the picture element, eliminated the phenomenon of tree's shadow deviation tree body's.Three Dimension IFS plant modeling. First elaborate the foundation of the 3D-IFS plant modeling, analyze and summarize the predecessor's research results, then propose 3D-IFS code definite algorithm aims at separately gathers the axis branching and the single axle branching trees. Moreover, after 3D IFS modeling , through the definition of the coloration variable and the coloration function, present one kind of tree coloration method based on the 3-D IFS. This method definite basic colors of various part of trees according to different affine transformations, then definite difference color value according to various parameters'role and influence in the 3D-IFS modeling.last synthesizes determination tree body various part of colors .This method not only can show the different color of the tree body, eliminate the color block phenomenon, but also overall evaluat various parameters'influence to the trees color, describe carefully internal color difference of the tree body .Through programming on the computer, it proved that this method might strengthen the sense of level of the tree's color greatly. |