NURBS曲线编辑COM服务器设计与实现

根据已有绘图工具在绘制自由曲线方面的不足,提出了基于COM服务器的NURBS曲线编辑器的思想并编程实现。该编辑器既可以实现单独NURBS曲线编辑,也可以被Office软件调用实现在文档编辑。该编辑器为用户编辑符合自己需要的自由曲线提供了一种选择。     

面向陶瓷3D打印的双尺度放样曲面建模

针对陶瓷3D打印的特点,提出基于放样曲面与周期参数曲线嵌入的双尺度轻量化交互式建模和制造工具.对于用户输入的2条封闭曲线,首先在它们之间插值生成中间截面采样点,并在免支撑、路径无干涉等陶瓷3D打印制造约束下对当前曲面形状进行调整,完成基于放样曲面的大尺度曲面建模;然后将采样点之间的直线路径用周期性曲线路径代替,通过调整曲线函数的周期和振幅完成小尺度几何纹理建模;最后按螺旋方式逐层连接各个截面采样点,直接生成单一连续的打印路径并制造.为验证文中方法的有效性,基于绘制的3组曲线进行建模并利用CERAMBOT Plus陶瓷3D打印机制造模型.实验结果表明,该工具为用户提供了充足的建模空间且模型生成效率高,能够有效地生成可直接进行陶瓷3D打印的带纹理放样曲面的G-code文件.     

基于物探技术的矿区岩土自动化检测数据采集系统设计

以矿区煤炭开采提供岩土数据为目的,设计基于物探技术的矿区岩土自动化检测数据采集系统。该系统以硬件支撑层为基础,利用物探技术的野外观测仪和工程电测仪采集矿区岩土自动化检测数据后,利用RS485总线将其存储到SQLite数据库内,业务层调用QLite数据库内矿区岩土自动化检测数据后,利用数据处理模块、报表管理模块、微动谱生成模块以及曲线绘制模块等对矿区岩土自动化检测数据进行处理后,将其发送到应用展示层内,该层为用户呈现矿区岩土自动化检测数据采集二维曲线、岩土微动谱以及数据采集日志等结果。实验表明：该系统运行较为稳定,可有效采集矿区岩土自动化检测数据并呈现其二维曲线和岩土微动谱,具备较为显著的应用效果。     

Delphi环境下控制系统实时数据采集曲线的绘制与打印

一、引言随着现代测控系统数据处理量的增大和对人机交互界面要求的提高,其主控系统采用高档计算机的越来越多。Microsoft Windows系统强大的RAD语言开发工具如Delphi等为用户设计优美的图形界面提供了方便,为测控系统建立高度友好的用户界面奠定了基础。在我们开发的计算机液氮制冷控制系统中,要求能够实时采集测量温度值,将实测温度值与时间的关系绘制成曲线显示出来,并能够放大、缩小和打印,以便观测并与给定降温曲线进行比较,查看控制效果。系统采用Delphi 5.0进行开发,利用32位控件Tsp_XYPlot和 Tsp_XYLine实现了实时数…     

京剧脸谱分析与合成

京剧脸谱的分析与数字化建模可以使人们深化对传统京剧艺术的认识,对于传统文化的保护与利用具有重要意义.首先分析京剧脸谱纹样形状特征并根据其语义信息将其分类,然后用Bézier曲线构造出矢量化纹样单元库;在合成脸谱阶段,用户只需按照脸谱绘制顺序逐层选取所需纹样,根据创作需要对各层的纹样进行组合得到最终的京剧脸谱图案;还提供一系列变形工具供用户对脸谱局部纹样进行编辑修改,以生成更多的、富有变化的京剧脸谱图案.与手工绘制京剧脸谱相比,文中系统可以用更灵活多变的方式,简单快捷地生成各种复杂的京剧脸谱.该系统在旅游产品开发、书籍装帧、建筑装饰、服饰设计、装潢设计、电子贺卡、京剧教学等领域有着广泛的应用前景.     

基于Visual Fortran和AutoCAD的Bezier曲线的自动绘制及应用

以Fortran90语言和AutoCAD图形软件为平台,开发了Bezier曲线绘制子程序,该程序能够保存、处理数据文件,形成直观曲线供用户输出,实现了计算机自动绘图的目的.基于该子程序编制了部分应用主程序体现出自动绘图子程序的应用价值.     

Surfer 软件在绘制GPS 水汽等值线中的应用

为了将GPS水汽资料以图形化方式展示给用户,在简要介绍GPS水汽反演原理和综述Surfer软件绘制等值线的应用场合的基础上,以福建GPS水汽监测系统为背景将Surfer软件引入GPS水汽资料应用中。通过设计GPS水汽等值线分布图生成系统描述了C#调用Surfer自动绘制GPS水汽等值线分布图的过程。结果表明该系统生成的等值线分布图能够实时有效的反映福建上空水汽含量的分布及变化情况,可以为相关气象预报提供参考依据。     

笔式三维草图绘制中的轮廓线技术研究*

详细介绍了三维模型轮廓线技术及其检测算法,并深入分析了轮廓线技术在三维草图绘制中的作用;然后设计并实现了一个三维草图绘制系统。该系统提供了用笔绘制三维模型的交互环境,通过轮廓线将三维模型与二维交互手势联系起来,使用户可以自由灵活地操纵和控制三维模型,获得自然、高效的交互体验。     

基于笔的概念图协同绘制工具

通过对实际教学中概念图和群体协同学习进行研究,模拟人们使用纸笔交互方式的习惯,用电子笔取代了鼠标键盘作为输入设备,实现了一个支持群体绘制的笔式概念图工具。使用该工具,多个用户可以在网络上协作绘制概念图,在绘制过程中,所有用户都能实时地感知整个概念图的绘制过程。为了方便用户讨论绘制过程中所遇到的问题,该工具提供了文字、音频和视频三种交流方式,用户可以选择任意一种或多种方式进行实时交流。     

基于ASP模式的个性化应用系统模型

对传统的企业信息化建设方法与ASP建设模式进行了比较分析，讨论了个性化应用服务的基本概念、需求以及Web相关信息的形式化描述方法，然后提出了一个基于ASP模式的个性化应用系统模型。该模型主要思想是将企业的一些具体业务应用系统从企业中独立出来，通过Web应用平台为用户提供各种个性化的信息服务和应用服务。与传统的建设方法相比，提出的基于ASP模式的个性化应用系统模型设计方法具有投资小、见效快、信息服务质量高等特点。     

保测地曲率的曲面曲线设计

给出一种在给定光滑曲面上进行曲线设计的算法．由于曲面上曲线的曲率向量可分解为测地曲率向量与法曲率向量的和,故可以通过设计平面源曲线,并将这条源曲线保测地曲率对应到给定曲面上,得到一条测地曲率和平面源曲线的曲率相同的目标曲线．取给定曲面上一点为初始点,逐次迭代跟踪得到整条目标曲线．该算法既可以用来进行曲面上的图案设计,也可用于求解光滑曲面上的测地线。     

基于STEP的三维表面有限元网格生成技术的研究*

研究了三维表面有限元网格自动生成的技术,利用映射法实现了模型表面的三角网格剖分。基于STEP文件格式的模型的导入和重建,将模型的每个表面映射至参数空间,利用推进波前法生成参数面网格,然后映射回三维表面。研制了一套网格剖分策略,运用该策略对多种类型表面进行了分析求解。     

基于曲线的纹理映射

本文提出一种纹理映射的新方法。二维平面中的一条曲线与三维曲面上的一条曲线相对应，两条曲线上的点再相对应。当对应曲线足够多时，就可获理完成纹理映射所需的足够信息。     

Constructing G 1 continuous curve on a free-form surface with normal projection

In this paper, we develop a new method for G ¹ continuous interpolation of an arbitrary sequence of points on an implicit or parametric surface with a specified tangent direction at every point. Based on the normal projection method, we design a G ¹ continuous curve in three-dimensional space and then project orthogonally the curves onto the given surface. With the techniques in classical differential geometry, we derive a system of differential equations characterizing the projection curve. The resulting interpolation curve is obtained by numerically solving the initial-value problems for a system of first-order ordinary differential equations in the parametric domain associated to the surface representation for a parametric case or in three-dimensional space for an implicit case. Several shape parameters are introduced into the resulting curve, which can be used in subsequent interactive modification such that the shape of the resulting curve meets our demand. The presented method is independent of the geometry and parameterization of the base surface, and numerical experiments demonstrate that it is effective and potentially useful in surface trim, robot, patterns design on surface and other industrial and research fields.     

Shape design sensitivity analysis and optimization of general shape arches

A method is presented for the shape design sensitivity analysis as applied to general arches whose shapes cannot be mapped on one plane. The shape design sensitivity formulation with respect to the perturbation in the direction normal to the middle surface of the shallow arch curve is derived using the material derivative and the adjoint variable method with the system variational equation expressed in a Cartesian coordinate system. A general shape arch is subdivided into segments each of which can be considered as a shallow arch. On each subdivision of the arch, a Cartesian coordinate system is installed and the shape design sensitivity for the shallow arch is applied. For numerical implementation, the finite element method is adopted and each finite element can be considered as such a subdivision. Numerical examples for sensitivity analysis and optimization are presented to illustrate the finite element sensitivity method proposed.     

Constructing up to G 2 continuous curve on freeform surface

This paper presents new methods for G ¹ and G ² continuous interpolation of an arbitrary sequence of points on an implicit or parametric surface with prescribed tangent direction and both tangent direction and curvature vector, respectively, at every point. We design a G ¹ or G ² continuous curve in three-dimensional space, construct a so-called directrix vector field using the space curve and then project a special straight line segment onto the given surface along the directrix vector field. With the techniques in classical differential geometry, we derive a system of differential equations for the projection curve. The desired interpolation curve is just the projection curve, which can be obtained by numerically solving the initial-value problems for a system of first-order ordinary differential equations in the parametric domain associated to the surface representation for the parametric case or in three-dimensional space for the implicit case. Several shape parameters are introduced into the resulting curve, which can be used in subsequent interactive modification such that the shape of the resulting curve meets our demand. The presented method is independent of the geometry and parameterization of the base surface, and numerical experiments demonstrate that it is effective and potentially useful in patterns design on surface.     

Automatic extraction of free-form surface features (FFSFs)

This paper presents a new algorithm for extracting Free-Form Surface Features (FFSFs) from a surface model. The extraction algorithm is based on a modified taxonomy of FFSFs from that proposed in the literature. A new classification scheme has been proposed for FFSFs to enable their representation and extraction. The paper proposes a separating curve as a signature of FFSFs in a surface model. FFSFs are classified based on the characteristics of the separating curve (number and type) and the influence region (the region enclosed by the separating curve). A method to extract these entities is presented. The algorithm has been implemented and tested for various free-form surface features on different types of free-form surfaces (base surfaces) and is found to correctly identify and represent the features irrespective of the type of underlying surface. The representation and extraction algorithm are both based on topology and geometry. The algorithm is data-driven and does not use any pre-defined templates. The definition presented for a feature is unambiguous and application independent. The proposed classification of FFSFs can be used to develop an ontology to determine semantic equivalences for the feature to be exchanged, mapped and used across PLM applications.     

A Geometric Representation Scheme Suitable for Shape Optimization

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吉林省西部区域蒸散时空变化分析

基于地表能量平衡理论,利用NOAA/AVHRR数据,采用SEBS模型,计算了研究区15年地表蒸散量,从年、季度和月等三个时间尺度对其进行时空变化分析。结果显示:(1)各年平均蒸散量相差较大,最大的是1988年,最小的是1996年;月平均蒸散量最大值出现在5月,最小值出现在12月,形成一单峰型曲线;第二季度平均蒸散量最大,第四季度最小,其分布曲线也为单峰型。(2)多年平均蒸散量的空间分布东半部明显大于西半部,最大的是扶余县,最小的是通榆县;各市县的月平均蒸散量分布仍为单峰型曲线,在5月达到最大值,12月最小,与全区的月平均蒸散量分布曲线一致;各市县第一季度和第四季度平均蒸散量相差不大,第二和第三季度相差较大,但总体分布趋势与全区一致,仍为单峰型曲线。以上结果表明:研究区区域蒸散时空分布极不均匀,强烈的蒸散作用为研究区生态环境恶化提供了有利条件。