Surface Reconstruction Using Alpha Shapes

We describe a method for reconstructing an unknown surface from a set of data points. The basic approach is to extract the surface as a polygon mesh from an α-shape. Even though alpha shapes are generalized polytopes having complicated internal structures, we show that manifold surfaces, with or without boundaries, can be efficiently generated, and these surfaces completely describe the α-shapes to the extent that they are visible from outside. Unlike the original α-shapes, the polygonal surfaces can be easily simplified to yield compact models suitable for a variety of geometric modeling applications such as surface fitting.     

基于Gauss Ball+的二次曲面细分解与识别

首先利用主曲率对网格进行粗分解,然后利用Gauss Ball 方法对每片子区域进行二次曲面的类型检测、细分解和重聚合,最后对细分的子网格区域中的二次曲面进行参数识别.实验结果表明,利用该方法可以自动、快速、准确地分解出零件中存在的二次曲面,可以很好地应用于逆向工程中二次曲面参数反求.     

数字水印的高斯低通滤波鲁棒性测试

随着网络技术和数字技术的发展,数字水印在版权保护、数据鉴别、数字产品认证领域有着广泛的应用前景。本文介绍了数字水印的基本原理和实现数字水印嵌入和提取的DCT算法,并在matlab环境下,对高斯低通滤波后的图像实现了水印的提取,测试了它的鲁棒性。     

Higher-Order Gauss–Lobatto Integration for Non-Linear Hyperbolic Equations

Least-squares spectral elements are capable of solving non-linear hyperbolic equations, in which discontinuities develop in finite time. In recent publications [De Maerschalck, B., 2003, http://www.aero.lr.tudelft.nl/∼bart; De Maerschalck, B., and Gerritsma, M. I., 2003, AIAA; De Maerschalck, B., and Gerritsma, M. I., 2005, Num. Algorithms, 38(1–3); 173–196], it was noted that the ability to obtain the correct solution depends on the type of linearization, Picard’s method or Newton linearization. In addition, severe under-relaxation was necessary to reach a converged solution. In this paper the use of higher-order Gauss–Lobatto integration will be addressed. When a sufficiently fine GL-grid is used to approximate the integrals involved, the discrepancies between the various linearization methods are considerably reduced and under-relaxation is no longer necessary     

基于高斯映射下自由曲面的形状分析及边界计算

测定单一类型（凸或马鞍）区域和计算其边界是进行自由曲面的形状分析与控制研究的基本内容之一．目前这方面的研究局限于一些特殊曲面，如可展曲面，对自由曲面则无来境的理论和方法．本文提出了一些对复杂自由曲面进行形状分析的几何结论．通过计算高斯抛物线，划分了曲面的单类型区域．设计了算法判断单类型区域、分离单类型区域，并计算其边界，对自由曲面整体的形状有了较好的把握．最后蛤出了算法对两个例子的计算结果．     

Using Neural Network Method to Blend Surface Based on Digitized Points

In this paper, a neural network approach was employed to deal with blending problem with surface construction based on digitized points, and some related computational cases were presented. Compared with the NURBS method, this neural network based approach doesn't need the complex formula derivation as long as a limited number of offset points are got, and its accuracy can meet the general engineering needs.     

Properties of Digital Homotopy

Several recent papers have adapted notions of geometric topology to the emerging field of digital topology. An important notion is that of digital homotopy. In this paper, we study a variety of digitally-continuous functions that preserve homotopy types or homotopy-related properties such as the digital fundamental group.Laurence Boxer is Professor of Computer and Information Sciences at Niagara University, and Research Professor of Computer Science and Engineering at the State University of New York at Buffalo. He received his Ph.D. in Mathematics from the University of Illinois at Urbana-Champaign. His research interests are computational geometry, parallel algorithms, and digital topology. Dr. Boxer is co-author, with Russ Miller, of Algorithms Sequential and Parallel, A Unified Approach, a recent textbook published by Prentice Hall.     

模块结构的数字化仪表墙系统的集成

针对信息技术和工业控制技术的飞速发展,为适应现代化发电企业的信息建设需求,提高企业自动化水平和管理水平,提出了电厂模块结构的数字化仪表墙(digitalwall)系统概念,并对电厂模块结构的数字化仪表墙系统的结构、显示平台、控制平台等整体的集成方案及设计选型等进行简要叙述。     

Patch‐type Segmentation of Voxel Shapes using Simplified Surface Skeletons

We present a new method for decomposing a 3D voxel shape into disjoint segments using the shape's simplified surface‐skeleton. The surface skeleton of a shape consists of 2D manifolds inside its volume. Each skeleton point has a maximally inscribed ball that touches the boundary in at least two contact points. A key observation is that the boundaries of the simplified fore‐ and background skeletons map one‐to‐one to increasingly fuzzy, soft convex, respectively concave, edges of the shape. Using this property, we build a method for segmentation of 3D shapes which has several desirable properties. Our method segments both noisy shapes and shapes with soft edges which vanish over low‐curvature regions. Multiscale segmentations can be obtained by varying the simplification level of the skeleton. We present a voxel‐based implementation of our approach and illustrate it on several realistic examples.     

浅论数字影像在GIS中的应用

数字影像在GIS中的应用,可系统归纳为三个方向:使用高分辨率遥感影像用作GIS矢量数据的更新;将数字影像与GIS矢量数据集成作为GIS的数据平台;以及将数据挖掘技术应用于数字影像,从而辅助实现GIS的空间分析和智能决策等高端应用。文中分别以实例验证说明了上述三种应用方向的技术可行性,并指出目前阶段各研究方向存在的技术问题。     

基于数字化校园的安全与集成性研究

针对数字化校园快速发展过程中各个部门系统之间不能耦合、相关数据冗余、不一致、不同步等问题。通过研究数字化校园体系结构和集群技术,将集群技术应用到数字校园中。采用该方法,提出了数字化校园在实施过程中安全策略和数据集成方法,从而实现数字化校园中各系统集成和安全的信息交换。     

建筑环境与数码艺术的结合

中国几千年的文明史积累了丰富的建筑经验,广泛地表现在各地民居建筑中。数码艺术的发展不局限于某个时期的风格和时尚,是一种延续性的艺术。既有过去的又有现在的甚至还有将来的形式。数码艺术利用现代的高科技更好的再现了古建筑和古文化,为现代和将来的人更好的服务。     

数字社区之间的集成方法研究与实现

提出了在各数字社区之上建立信息共享平台的数字社区集成方法和"逻辑集中适度分布"的数据组织模式以及数字社区信息共享平台的总体设计框架模型.采用Oracle9i大型分布数据库技术、PKI/PMI信息安全技术和J2EE WEB开发技术实现了数字社区之间的信息共享.解决了单个数字社区所存在的诸如用户少、信息资源少、服务项目少、管理难、成本高等实际问题.为"数字城市"建设中如何集成已有的数字社区系统探索了一条技术途径.     

数字社区之间的集成方法研究与实现

提出了在各数字社区之上建立信息共享平台的数字社区集成方法和“逻辑集中适度分布”的数据组织模式以及数字社区信息共享平台的总体设计框架模型。采用Oracle9i大型分布数据库技术、PKI/PMI信息安全技术和J2EEWEB开发技术实现了数字社区之间的信息共享。解决了单个数字社区所存在的诸如用户少、信息资源少、服务项目少、管理难、成本高等实际问题。为“数字城市”建设中如何集成已有的数字社区系统探索了一条技术途径。     

基于Delaunay三角剖分和高斯小波函数插值的三维表面重建算法

在稀疏数据的三维表面重建中,通过插值的方法得到更为稠密的数据点是一个很重要的环节。该文在比较其它插值算法的基础上,提出了一种三维表面重建算法。该算法在对原始数据进行Delaunay三角剖分的基础上采用二维高斯小波函数插值,它不仅能有效地处理非均匀采样的三维稀疏数据,而且能克服其它插值算法中需要定义权重或估计参数的缺点。最终的实验结果验证了该算法的有效性和实用性。     

数字福建政协云和档案技术的融合应用

随着科学技术的不断发展,传统的档案管理工作模式已经逐步淘汰,"数字福建政协云"的建设、应用赋予了档案管理应用技术新的使命.本文深入探究档案技术与"数字福建政协云"之间的关系,剖析出"数字福建政协云"中档案技术的特点,并列举出目前档案技术与"数字福建政协云"之间的冲突,最后提出相关的优化建议.     

海量影像无缝数据库管理系统的设计及实现

随着遥感影像获取手段的更新,其在国民经济中发挥了越来越重要的作用。面对海量影像数据,如何将其加以有效的利用,成为实际应用中迫切需要解决的问题。论文阐述了海量影像无缝数据库管理系统实现的若干基本原理及关键技术,利用面向对象数据库系统(ODBMS)实现一个多用户、多数据源、多时空、多分辨率的海量影像数据库系统,为各种用户提供影像数据的查询及更新需求。     

数字化校园中数据库集成技术的研究

以原有网络为基础,利用计算机技术、网络技术、通信技术等先进的信息化手段和工具,将原有教学资源通过数据库集成技术进行整合,实现从环境到活动到资源的全部数字化,在传统校园的基础上,构建一个数字化校园,拓展现实校园的时间和空间维度。