The Study Of Virtual Plant In Campus Based On Fractal Geometry

The study on realistic Rendering of Plants is always an important topic in the field of virtual reality and computer simulation. It is also a difficult problem because of variety of plants species, plentiful external morphology, and complex growth process. In the view of fractal, plants mostly have self-similar fractal characteristics. It bears very simple rules behind the irregular features of natural Scene. Realistic and complex natural scenes can be generated by the combination of fractal theory and virtual reality technology. Tree is a representative plant in natural, and because characteristics of tree morphology have strong self-similarity, it can reflect the fractal characteristics better. At present, in the virtual city, virtual buildings or virtual campus, the plant model is generally based on the representation of the image-based representations method, so the granularity is very rough compared with other objects. Taking trees as object, interactive simulation system of three-dimensional forms based on virtual campus is developed. It uses visual simulation tool MultiGen Creator to establish the campus’s model, and Use real-time three-dimensional visual simulation software named MultiGen Vega to integrate different building models in virtual campus, by which Observer can be roaming in the virtual campus; Mathematical model of three-dimensional trees is established by using Iterated Function System, combined with the OpenGL API; Multigen, Vega, VC++platfonn and OpenGL are combined effectively. Simulated trees are added to the virtual campus through The OpenGL API function called by Vega API callback function. Finally, the simulating effect of external morphology, physiological ecological processes, and meteorological landscape interaction of trees are displayed intuitively as the manner of three-dimensional visualization.The Modeling approach based on IFS has the following characteristics:(1) It has modular structure and is flexible. Various components of the trees, including Overall model of the trees, branches model, branch element model and leaves model, can be adjusted which ensures the realism of the trees in the external morphology.(2) It has a strong interaction. The physiological and ecological processes of the trees and the meteorological landscape (cloud, rain, snow, fog, light, etc.) are simulated Interactive. By means of simulation of meteorological landscape, the complex phenomenon like as climate change and proliferation of trees can be reproduced within a very short time.(3) It has a certain degree of versatility. Though determining the IFS code, different morphology of three-dimensional trees can be constructed. The mathematical model of three-dimensional trees constructed in this paper not only get a good visual effect in virtual campus, also can be applied in other virtual scene.