用FBM方法生成自然对象真实感图形的研究

【作者】 秦忠宝；

【导师】 高满屯；

【作者基本信息】 西北工业大学 ， 机械设计与理论， 2001， 硕士

【摘要】 生成几何对象的真实感图形是计算机图形学的重要内容。对于自然对象，由于其所具有的不规则性，无法用传统的欧几里德方法写出其准确的方程，因而在几何造型过程中，通常只能采用近似逼近的方法。分形几何则另辟蹊径，它从自然对象所固有不规则性入手，在不规则中寻找其“规则”的一面，突破了传统方法的局限，从而为自然对象的真实感显示提供了全新的思路和方法。 分形布朗运动FBM是分形几何的重要内容，利用它可以构建出极具分形特性的三维几何模型，这种几何模型可以用来生成多种不同的自然对象，如山脉、云彩等的真实感图形。中点偏移法是生成分形布朗运动的重要方法，它所采用的递归和迭代的实现模式，也是计算机最长于完成的。VC++6.0提供了一个功能完备、操作简便的程序开发平台，而OpenGL作为一个功能强大，易于移植的三维应用程序接口（3D API），则成为实现自然对象数据模型可视化的必备工具。 本论文给出了一种用中点偏移法生成山脉、云彩等自然对象的三维几何模型的完整方法，并在VC++6.0开发环境下，借助于OpenGL对其实现了可视化，生成了具有真实感的山脉和云彩图形。更多还原

【Abstract】 It is an important part of the computer graphics to build graphics for a three-dimension geometric object. Because of its scrambling, it is impossible to build an exactly equation for a natural object by the traditional Euclidean method. Thus, we have to use some approximate methods in the geometrical modeling. On the other hand, fractal geometry opens a new way for this field, which describes the natural object with its scrambling and searches for the rules within the scrambling. Outdoing the Euclidean method, fractal geometry has given us some new ideas and measures to build the graphic for a three- dimension natural object. The Fractal Brown Motion (FBM) is an important content of the fractal geometry. Using the FBM method, we can develop many three- dimension geometrical models with fractal characteristics, such as mountains, clouds and so on. The mid-point displacement method is an important method in the FBM. The iterative and recursive patterns that mid-point displacement method adopts are what computers are good at. VC++6.O offers us a workspace with self-contained functions and many convenient operations, based on which programs can be developed. In addition, OpenGL has become an essential tool to made a data model of the natural object to be visual, because there are 3D API with strong functions and good transplant. This paper has offered a whole process to build the geometric models for natural objects like mountains, clouds by the mid-pointdisplacement method, and to made the models be visual throughusing OpenGL on VC++6.0. At the end of the paper, we gain thegraphics of three-dimension mountains and three-dimension clouds.更多还原