Application of a perspective cursor as a 3D locator device

The functionality of a 3D cursor is described. It can be used as a 3D locator device in such applications as interactive path planning (robotics), motion specification in 3D computer animation design, and wireframe modelling. With respect to the last of these applications, it is important that the cursor can be used either in constructive mode, as a set of three mutually orthogonal rulers, or in trace mode to copy a 2D perspective view of an object while reconstruction its 3D shape. As a special feature, the cursor may be equipped with a mirror of locations in scenes that are (partially) symmetric, but also allows 3D symmetric objects to be entered from 2D (perspective) views, while making use of symmetry as a clue for reconstructing z-coordinates.     

Improving bi-manual 3D input in CAD modelling by part rotation optimisation

Part modelling in a CAD environment requires a bi-manual 3D input interface to fully exploit its potentialities. In this research we provide extensive user tests on bi-manual modelling using different devices to control 3D model’s rotation. Our results suggest that a simple trackball device is effective when the user task is mostly limited to rotation control (i.e. when modelling parts in a CAD environment). In our tests, performances are even better than those achieved with a specifically designed device. Since the task of rotating a CAD part often shows the need of flipping the controlled object, we introduce a non linear transfer function which combines the precision of a zero order control mode with the ability to recognise fast movements. This new modality shows a significant improvement in the user’s performances and candidates itself for integration in next generation CAD interfaces.     

扩展的L系统与三维自然景物图形

介绍扩展的Ｌ－ｓｙｓｔｅｍ和它的三维图形系统,以及植物设计和显示。首先说明Ｌ－ｓｙｓｔｅｍ的定义,Ｌ－ｓｙｓｔｅｍ与植被和分形图形的生成;并简述Ｌ－ｓｔｙｓｔｅｍ的实现;然后是ＥＬＳＹＳ语言和程序设计;最后用树和小麦三维景物作为本Ｌ－ｓｙｓｔｅｍ三维图形系统的应用实例。     

中国古建筑蕴含的现代设计特征及三维CAD 方法研究

论文涉及中国古建筑梁架结构中蕴含的类似现代工业产品设计的理念与方 法,包括零件——装配体设计、模数化设计和系列化设计的理念与方法,论文还涉及利用三 维CAD 手段表达中国古建筑设计的研究。     

Low-cost hardware platform for developing realtime 3D graphics

BRAD3D, a low-cost hardware platform for the development of a realtime 3D graphics software is presented. The BRAD3D configuration is derived from a generalization of 3D image synthesis. Three basic processes have been identified: the geometric process, dealing with the measurements of the scene; the topologic process, extracting visible information from the polygonal structure; and the scan-conversion process, producing pixel values on a frame buffer. BRAD3D is implemented as a three-stage pipeline and accommodates depth-list and scan-line hidden-surface-removal algorithms. Each stage of the pipeline can be implemented using different hardware solutions. A microprocessor-based solution is presented as a general prototyping approach.     

Java 3D, 3D graphical environments and behaviour

A brief outline of the structure of the Java 3D API as a means of producing graphical environments is provided. We then go on to examine issues in the development of a behaviour rich scene, in particular the issues of scene animation and collisions between scene objects. The animation issue is examined first, where issues of timing and architecture are considered. The Java 3D requirements for, and view of, collision are discussed next from a general perspective, identifying several problems with the implementation. Four simple scenes using animation and collision detection are examined. In each case a number of difficulties have been identified, partly related to the responsiveness of the operating system in the case of animation, but particularly due to the view and implementation of the collision detection system provided. Collisions often involve modifications to the states of all objects involved in the collision and some of the issues this raises in the context of Java 3D's provision are examined and reported on. Finally, we finish with a summary of our findings and conclusions on the suitability of Java 3D for building environments. Copyright © 2002 John Wiley & Sons, Ltd.     

一个基于认知特性的数据可视化3D模型的研究

随着计算机系统中信息规模的增大,有限的屏幕尺寸已不能满足大信息量显示的需求。针对这个问题,提出了一种全新“不倒翁”模型。该3D数据可视化模型基于对计算机图形图像学、心理学和认知学理论的研究,创造性地利用了“鱼眼视图”的优势和人们的空间认知特点,具有很强的交互性和易用性,使得用户能在“小屏幕”上方便地进行“大信息”的浏览和检索。实验结果表明它起到了预期的效果。     

战场态势三维图形仿真系统的设计与实现

针对现代战场对态势仿真系统的要求,分析了系统的功能点、技术支持体系和系统架构,深入研究了军事概念模型分类、地形生成算法、轨迹平滑算法、数据存储算法等关键技术,设计了一个扩展性良好的系统架构,实现了一个战场态势三维图形仿真系统的原型系统.试验结果表明:原型系统仿真效果好,可以作为进一步开发的基础.     

多学时制图课程融入三维CAD 的教学探讨

针对机械类多学时传统制图教学中如何融入三维CAD 教学的问题,分析 了其融入的形式和特点,归纳了工程图表达中与投影相悖的表示法,提出分两步走的方法： 首先以传统制图内容与三维CAD 相互支撑的融合式教学,然后以三维CAD 为主线的独立 式教学相结合。在教学上,可通过Inventor 三维建模的实践,提高学生的工程图表达能力、 创新思维能力和构型能力,以适应现代设计和制造的要求。     

Rendering of forest scenery using 3D textures

Visual simulation of forest scenery is a challenging problem which includes the following tough sub-problems: generation of vegetation, representation of trees, simulation of colour change of leaves, and rendering of numerous trees. Among those sub-problems, this paper treats mainly the last one. A conventional polygon-based rendering algorithm often produces troublesome aliasing effects when it is applied to the objects having complex fine surfaces, such as forest scenery. In this paper, we show that an extended volume rendering technique applied to 3D textures, i.e. volume data in this paper, of trees is effective in the concerned problem. Kajiya left, as further work, the problem of rendering forest scenery by applying his 3D texture called texel. Our rendering method consists of the following three steps: we first generate 3D textures of trees from their polygon-based geometric models, we next arrange the 3D textures, allowing their possible mutual intersections, on the surface of a given polygon-based terrain model according to a simulated vegetation, and we finally produce an image of forest scenery by applying the ray-tracing algorithm including our slightly extended volume rendering technique. © 1997 John Wiley & Sons, Ltd.     

PDM平台上的三维CAD通用集成框架

构建了PDM和三维CAD软件集成的基本模型和集成框架。该框架通过一致的数据模型,能够灵活地集成不同的三维CAD系统和PDM系统。在数据模型的表达上,采用了XML这种流行的易于扩展的技术方法;在集成框架设计上,采用了抽象工厂等成熟的设计模式,并提供了标准化的接口定义来扩展集成框架的功能。文章对集成框架的功能和具体实现方法进行了论述。     

OpenGL制作三维游戏的研究

介绍了使用OpenGL和VC＋ ＋制作三维动画桌球游戏的功能及编程原理.     

The design and implementation of the GINO 3D graphics software package

The design and implementation of a general purpose graphics software package (GINO) is described. GINO provides facilities for 3D graphics (co-ordinate transformation, clipping, intensity modulation) but is organized so that 2D facilities form a clean subset. It is device independent, permitting use of refresh CRT displays, storage tube displays and plotters. A characteristic feature is the use of small satellite computers attached to a large multiaccess computer (ATLAS 2) GINO takes the form of a subroutine library accessible from FORTRAN and other languages, and the case for this level of graphics software is argued. The reasons for not using a mandatory graphical data structure are also discussed. GINO is not biased towards any particular style of interaction, but two techniques are described; one based on the light pen and the other on teletype command languages Efficiency of implementation is achieved without loss of flexibility by use of a systems programming language (SAL).     

CAD中三维交互技术的研究与实现

本文研究了ＶＲ技术在ＣＡＤ几何造型中作为交互手段的应用,特别研究了三维交互技术在ＣＡＤ中的实现。通过提出一种用于三维交互的精确视觉线索方法,实现了对三维空间中不同信实体相互位置关系的精确感知。探讨了ＣＡＤ中在三维交互技术支持下的新的几何造型技术。     

三维重建中的剖视图处理

剖视图处理能够有助于更好地理解视图,提高三维重建的效率。基于对剖视图自身特点的分析,提出了三维重建中对剖视图的处理算法,即通过剖视图信息的智能提取生成基元体,将基元体同由视图轮廓生成的参照体进行布尔运算,从而得到最终的目标体。算法能够处理包括全剖视图、半剖视图以及平行剖视图在内的剖视图,最后给出了应用算例以验证算法的可行性。     

三维动漫制作与虚拟现实结合技术研究

基于为高校三维动漫教学提供良好的教学技术和实验平台,研究了三维动漫制作与虚拟现实技术相结合的方法,采用三维计算机图形技术CG(Computer Graphics)、影像技术和运动捕捉系统,实现高质量高效率的三维动漫制作。介绍了将动漫技术、虚拟现实VR(Virtual Reality)设备和网络技术相整合的交互动漫虚拟环境建设方案。     

Java3D鼠标交互功能的扩展与应用

分析了Java3D提供的鼠标交互功能,针对场景比较复杂,待拾取物体相对距离近的虚拟环境中用户拾取不准的问题提出了一种解决思路：在鼠标移动过程中实时创建一条连接空间中的视点与投影平面上的鼠标点的射线,检测沿射线的方向是否有物体与之相交,若有则返回距离视点最近的与射线相交物体所在的节点,并在该节点上添加一个动画效果提示用户该节点是预选节点。重点讲解了具体的实现过程,在最后的部分结合实际应用背景验证了该方法可以有效地方便用户的拾取操作。     

矿井煤仓三维计算机辅助设计

针对传统的矿井煤仓二维设计存在绘图复杂、抽象、易出错等问题,提出了一种矿井煤仓三维计算机辅助设计的方案;以恒源煤矿的-600煤仓和主井缓冲煤仓为例,详细介绍了煤仓三维计算机辅助设计及其动画演示的具体实现。该方案解决了复杂工程施工中设计者与施工人员的交流问题,为高质量、快速施工提供了基础保障。     

一种不同坐标系之间的变换矩阵的转换方法

在三维图形的研究和开发过程中,由于不同三维图形系统所使用的坐标系不统一,造成了在一个坐标系中的模型不能直接引入到别的坐标系中,针对野战战术三维环境原型系统ＢＩＴ－ＶＢＦＳ的开发过程中所遇到的将模型从右手坐标移植到左手坐标系的问题,提出了一种在不同三维坐标系之间寻找对应的变换矩阵的一般性方法,这种方法得到的是对于变换的转换矩阵,所以在对模型进行实际的转换时并没有增加计算的复杂度。