Fractal modeling using free form techniques

IFS models have become a powerful tool for the construction of fractal sets. They offer a straightforward way to generate complex, self-similar figures as attractors. However, they present the fundamental disadvantage of providing little control over the global form of the attractor. In contrast, free form techniques give a high control over smooth man-made objects with the use of a set of control points. In this paper, we present a new approach of fractal modeling which is based on IFS theory. We shall use free form techniques to give a practical and efficient way to build controlled fractal attractors. The resulting effect consists on the ability to deform a fractal shape interactively into the desired shape, in the same way as parametric forms (Bézier, splines).     

Generating extraterrestrial terrain

In recent years, generating both realistic and fanciful terrain has roused substantial interest among computer graphics specialists, motion picture and special-effects artists, geologists, and even mathematicians. Most fractal terrain models have been based on Fourier filtering, midpoint displacement, Poisson faulting, and successive random additions. Techniques such as these, while often creating convincing fractal forgeries of natural mountain terrain, do not always account for the fact that mountains are not statistically self-similar or identical from top to bottom. Nor do many prior methods naturally account for the beautiful ridges, craters, streaks, and various other features often associated with extraterrestrial terrain. The simple, flexible approach I present creates aesthetic extraterrestrial terrain with rich structures of varying asymmetry     

基于VTK分形理论的研究

分形理论是一种新兴的几何学,在多种学科中都有着广泛的应用.可视化图形工具包是一个功能强大的可视化和图形图像处理类库.运用VTK流水线进行图形以及三维渲染可使现阶段的分形理论研究可视化,实现分形图形的逼真模拟.在分析分形理论基本算法的基础上,借助VTK设计二维和三维分形图形绘制的渲染流水线,提供生成分形图形和三维分形实体的一种新方法,并以典型的分形集合(曼德尔伯特集)为例,显示渲染效果.     

Oracular Functioning and Architecture of Five Ancient Apollo Temples Through Archaeoastronomy: Novel Approach and Interpretation

Five temples of Apollo on Mainland Greece and Ancient Ionia (Asia Minor), namely Delphi, Didyma, Hierapolis, Delos and Rhodes, have been examined regarding their functioning through astronomical orientation. Recent research has shown that the rise, setting, orbit and observation of certain constellations in the celestial sphere, as well as the solar stands, can be directly related to the architecture of the temple, i.e. construction, orientation, and keeping a calendar of the most important Apollonian oracular temple at Delphi. Here this lunar-solar-stellar configuration has been applied to other significant temples of Apollo. It is shown that at Didyma, Hierapolis and Delphi, the celestial pattern, as well as the landscape, local geology and architecture are similar, but different in temples without oracular function (Delos and Rhodes). Measurements were carried out by in situ readings and by Google Map tools.     

中国古建的三维设计方法研究

中国古建是我国的珍贵文化遗产,保护与研究古建是现时代的重要任务。利用三维设计再现古建筑的形态,是目前解读与研究古建的重要方法。中国古建绝大多数采用木结构,先制作构件,再进行组装;因此,利用三维设计来表现古建,是一个值得研究的课题。本文应用MAYA的建模技术对中国古建进行三维设计提出了较为可行的方法,从＂MAYA＂的三维技术手段对古建的设计研究的影响以及建构方法和实例建模（塔、殿、桥、坊）等方面进行了较好的研究。     

A Monte Carlo Approach for ɛ Placement in Fractal-Dimension Calculations for Waveform Graphs

Many diverse and complicated objects of nature and math possess the quality of self-similarity, and algorithms which produce self-similar shapes provide a way for computer graphics to represent natural structures. For a variety of studies in signal processing and shape-characterization, it is useful to compare the structures of many different "objects". Unfortunately, large amounts of computer time are needed as prerequisite for rigorous self-similarity characterization and comparison. The present paper describes a fast computer technique for the characterization of self-similar shapes and signals based upon Monte Carlo methods. The algorithm is specifically designed for digitized input (e.g. pictures, acoustic waveforms, analytic functions) where the self-similarity is not obvious from visual inspection of just a few sample magnifications. A speech waveform graph is used as an example, and additional graphics are included as a visual aid for conceptualizing the Monte Carlo process when applied to speech waveforms.     

数理统计特征的快速图像分形压缩算法研究

图像自相似是图像分形研究中一个重要的研究方向,尤其是对自相似图像子块的特征提取量化问题尤为引人关注。在分形图像编码发展的过程中,图像自相似特征的提取和量化得到了广泛的研究和应用。通过对图像数理统计特征的研究,提出了一种对图像子块进行分类的方法,使拥有相似特征的图像子块能够划分到更小的区域范围内,改进了分形图像压缩算法。经过分析和实验证明,该方法在不影响重建图像质量的前提下,提高了分形编码的速度,较大程度地减少了计算量。     

基于分形的自然景物描述方法比较研究

对自然景物进行描述一直是计算机图形学中的一个挑战性问题.研究了基于分形的3种描述自然景物方法,即递归法、L-系统法和IFS法,3种方法得到了令人满意的实验结果.模拟效果与具体景物的性质有关,景物越复杂,就具有更多的精细结构,自相似越强,则模拟效果越好.逼真度越高.其中IFS法适合具有较多细节结构的景物,L-系统法适合生长规律具有较强的拓扑性的景物,递归法适合具有严格自相似的景物.     

使用C++ Builder编程演示曼德布罗分形图

分形几何方法在计算机图形学和模拟仿真学的研究中具有重要的应用,而曼德布罗分形图是分形几何中的一个经典实例.阐述了如何使用C Builder编程实现曼德布罗分形图的多级放大与缩小演示,只要将其中分形迭代的算法进行改变,此方法可以对其他的分形图进行多级放大与缩小演示.     

基于MATLAB的Koch分形图生成算法研究

分形理论作为一门新兴的数学分支,对传统几何学的一个延伸,具有十分广泛的应用前景。用计算机绘制分形图的算法理论及程序设计已成为一个独立的研究方向,使用计算机绘制分形图形提供了一种高效的分形图生成方法,有力的促进了分形科学的发展,同时分形图案应用于实际带来了巨大的经济利益,并促进了其他学科的进一步发展。在详细介绍了绘制Koch分形图的计算机算法的基础上给出了使用MATLAB语言编写的计算机算法的实现过程。对其他分形图的绘制也有一定的参考作用。     

寺庙园林景观研究——以福建省寺庙园林为例

从福建省寺庙园林景观的意义,福建寺庙园林的特点,阐释寺庙园林的人文景观价值和历史价值,针对如何保护福建寺庙园林进行总结并提出新的建议,从而指导保护寺庙园林景观的实践工作。     

无损分形整形器模型及其性能分析研究

在自相似网络入口处利用分形整形器对输入业务流进行监控是实现自相似网络QoS保障和避免拥塞的必要手段。基于网络演算建立了无损分形整形器的数学模型,进而给出了无损分形整形器的性能模型,分析并讨论了无损分形整形器的引入对自相似网络性能的影响。     

基于牛顿迭代算法的分形艺术图形设计

分形艺术图形是分形艺术最主要的表现形式之一,分形艺术图形的生成需要借助计算机,并通过数学模型和程序才能完成。文中主要利用牛顿迭代算法、特效处理算法和着色算法生成分形艺术图形,其中牛顿迭代算法是核心算法,为创作分形艺术图形提供素材;着色算法也是不可缺少的,为仓Ⅱ作分形艺术图形提供调色板,决定了生成的分形艺术图形的精美程度;特效处理算法是可选的,对分形艺术图形进行二次加工,也在一定程度上决定了分形艺术图形的精美程度。笔者利用Visual C＋＋6．0开发工具编制了一个分形艺术图形生成软件,生成了大量绚丽多彩的分形艺术图形,这说明该算法是有效的。     

What is a Simulation Model?

Many philosophical accounts of scientific models fail to distinguish between a simulation model and other forms of models. This failure is unfortunate because there are important differences pertaining to their methodology and epistemology that favor their philosophical understanding. The core claim presented here is that simulation models are rich and complex units of analysis in their own right, that they depart from known forms of scientific models in significant ways, and that a proper understanding of the type of model simulations are fundamental for their philosophical assessment. I argue that simulation models can be distinguished from other forms of models by the many algorithmic structures, representation relations, and new semantic connections involved in their architecture. In this article, I reconstruct a general architecture for a simulation model, one that faithfully captures the complexities involved in most scientific research with computer simulations. Furthermore, I submit that a new methodology capable of conforming such architecture into a fully functional, computationally tractable computer simulation must be in place. I discuss this methodology—what I call recasting—and argue for its philosophical novelty. If these efforts are heading towards the right interpretation of simulation models, then one can show that computer simulations shed new light on the philosophy of science. To illustrate the potential of my interpretation of simulation models, I briefly discuss simulation-based explanations as a novel approach to questions about scientific explanation.

     

基于OpenGL的三维建模可视化软件开发

伴随着计算机图形学的发展,形成了可视化技术及其三维表现技术。可视化技术,即我们可以直接操作三维图形中的具有物体信息,与计算机直接交互;三维表现技术,即我们可以用它呈现出三维世界中的各种物体。目前在众多可视化工具中,表现突出的是SGI公司推出的OpenGL三维图形库,功能强大而且易于使用。本文是阐述如何用OpenGL进行三维建模,开发可视化软件。     

Portability of interactive graphics software

One solution to obtaining a portable graphics architecture is presented. By abstracting the functionality present in most 3-D graphics systems and augmenting it with advanced rendering features, a highly portable, efficient, and modern graphics architecture for interactive 3-D graphics applications (including modeling, animation, and scientific visualization) is obtained. Using appropriate object-oriented design procedures ensures the efficiency, maintainability, and portability of the architecture. The design and implementation of the graphics system used to achieve this high degree of portability are described     

Effective immunization of online networks: a self-similar selection approach

This paper proposes a self-similar selection method as an alternative to existing immunization strategies for online networks. Given the self-similar characteristics of online networks which are shown to have fractal and scale-free structure, we presume that the self-similar selection which is well developed in physics outperforms random or targeted vaccination based on incoming or outgoing connections. We examine the effectiveness of the proposed self-similar selection method with random vaccination and other different types of targeted vaccination strategies in terms of delaying the spread of computer virus over a scale-free computer network constructed using real-world World Wide Web data. Our computer simulation results indicate that the self-similar selection method is more effective in deterring virus propagation than the existing vaccination strategies. In addition, vaccination based on self-similar selection is practical since it does not require detailed information about network morphology at the individual node level, which is often not easy to observe. Our findings have significant implications for both policy makers and network security providers.     

A Unified, Object-Oriented Graphics System and Software Architecture for Visualising CAD/CAM Presentations

Most object-oriented graphics systems (OOGS) either support general purpose graphics capabilities (drawing editors, ray tracing, etc.), or have targeted specific areas of computer graphics, for example, interface building, animation, and visualisation. However, the key concept in CAD/CAM graphics systems is that of presentations—pictures that convey information about products or parts of products. CAD/CAM graphics systems that create and manipulate presentations have specific graphical requirements that have not been addressed by existing OOGS. These requirements include the support of CAD/CAM concepts such as drawings, views and view-specific graphics, and layers, and the ability to allow external geometric modelers to be linked into the presentation. We describe an object-oriented presentation architecture that allows the application to describe the structure of the CAD/CAM presentation. This architecture provides a unified interface to drawings, views, layers and entities, and allows linkage to models created with an external geometric modeler, while isolating applications from details of the underlying traditional graphics rendering systems. It is our hope that this architecture provide the foundation for the architecture of next generation OOGS. We also present an implementation of this architecture and compare it to other OOGS.