Ray Tracing and Graphics Standards

Existing standards for three-dimensional graphic representations are unable to produce any realistically shaded images (except PHIGS PLUS, which provides discrete shading only). Ray Tracing or Radiosity are not taken into account up to this time. This article is intended to show one way to integrate the Ray Tracing technique into the pipeline of the graphics standards GKS-3D and PHIGS. No modifications of the viewing concepts are required by our implementation.     

NBS's Role in Computer Graphics Standards

National Bureau of Standards The National Bureau of Standards is an integral part of standards evolution. Through its institute for Computer Sciences and Technology. NBS conducts research and provides support for the development of both national and international standards. Another NBS task is to promulgate Federal information Processing Standards (FIPSs). AAll these standards link off-the-shelf commerical hardware and software products from different manufacturers. Two of ICST's primary tasks are to develop test methods for graphics standards and to serve as registration authority for the International Organization for Standardization (ISO).     

Graphics Standards: The Pace Quickens

In recent months the pace of standards development for computer graphics has quickened. One standard has been adopted, accepted, and has already demonstrated its effectiveness. Another has now achieved the status of Draft International Standard, and is becoming an American National Standard as well. Several companies have made public announcements of their support for standards, and there has been extensive press coverage. This paper shall attempt to place all of this activity in perspective.     

Language Bindings for Computer Graphics Standards

Standard user interfaces to the new graphics standards are being developed for Fortran, Pascal, Ada, and C, and will be entering the standards review process in the next year. One after another, and sometimes concurrently, these interfaces (bindings) will be circulated for commnent from the public. This article, written by two participants of the group developing the graphics language bindingns, describes some principles being used to generate these bindings. Comparisons are draw with examples from the various draft graphics language bindings to illustrate specific?and in some cases controversial?features. Major topics are the handling of standard language subsets, mapping algorithms for naming, appropriate data typing, mixed-language environments, error-handling methods, new versions of languages, and multitasking.     

MB-OFDM UWB系统中的加窗算法设计

提出一种能抵抗超宽带系统中强窄带干扰的接收端加窗算法,它适用于多带正交频分复用(MB-OFDM)超宽带通信系统中采用的零值填充机制。相对于其他抗窄带干扰算法,接收端加窗算法具有算法复杂度低、无须对窄带干扰进行预估计等优点。在不同强窄带干扰源下的系统无线数据包错误率的仿真测试验证了该算法的有效性和可行性。     

使用MapX组件实现地理图形与数据库的结合

针对使用MapX组件开发配电网地理信息系统(Geographic Information System,简称GIS)的背景,讨论了实现地理图形与数据库结合的思路与方法。首先介绍了MapX组件的模型结构,然后分析了MapInfo(MapX)的空间数据结构,最后着重研究了使用MapX组件在双服务器模式下实现地理图形与数据库结合的方法。     

A Short Term Step in Development of 3D Graphics Standards

Few of the arguments deployed above have been either device dependent or application area dependent. Even if further discussion leads to a resolution of these and future issues differnt from the author's, the case is made that a Transformations chapter could be written which would be naturally included in most application-oriented 3D graphics standards.     

计算机辅助读图系统

论文提出了一个基于AutoCAD 平台的计算机辅助造型系统,该系统可用 于三视图的读图训练,帮助学习者培养空间想象和空间分析能力。该系统在读取三视图数据 后,能将三视图自动分割并提取各视图上的封闭线框,然后以特定的数据结构存储。在知识 库的引导下,该系统可通过人机交互快速生成对应的三维模型。     

The Pions Graphics System

During 1979, CERN began to evaluate how interactive computer graphics displays could aid the analysis of high-energy physics experiments at the new Super Proton Synchrotron collider. This work led to PIONS, a 3D graphics system, which features the ability to store and view hierarchical graphics structures in a directed-acyclic-graph database. It is possible to change the attributes of these structures by making selections on nongraphical information also stored in the database. PIONS is implemented as an object-oriented message-passing system based on Small Talk design principles. It supports multiple viewing transformations, logical input devices, and 2D and 3D primitives. The design allows full use to be made of display hardware that provides dynamic 3D picture transformation.     

实现牙体预备触觉交互仿真的图形显示

介绍了在牙科手术训练触觉交互系统的虚拟手术环境中,通过材料去除速率控制构成牙齿的网格变形实现牙齿被切削时材料去除过程的图形仿真.针对牙体预备操作和触觉交互装置输出力的特点,在交互系统的虚拟环境中,当工具与牙体模型发生接触时,所有进入工具空间范围的顶点都会沿着其外法线的反方向进行投射,投射量受控于材料去除速度,且网格变形速度不超过真实的牙齿材料去除速度,同时针对网格的变形位置绘制虚拟工具.通过限制网格变形可以动态的实现牙齿被切削过程的形状变化,图形显示逼真同时没有滞后.     

GIS中基于Web的图形查询系统

介绍了基于Web的地下管线图形查询系统（Web GIS)的设计思路和具体的实现。它的主要特点是采用了Ａctive技术,可以在已有代码的基础上,将现有的GIS系统中的部分功能转移到基于Web的三层C／S结构的新系统中,新系统不仅继承了传统GIS系统的优点,同时充分利用了计算机网络的优势,提高了系统的扩展性与利用率。     

结合图论和基团贡献法进行分子设计

提出了一种新的计算机辅助分子设计策略－－结合图论和基团贡献法的分子设计方法。提出基团触角数、基团特征因数、分子特征因数的定义和分子结构完整定理使基团组合为分子过程自动完成,通道予选基团、限定分子基团数及有机物分类法减小合成问题尺寸。给出了系统的设计和设计步骤,并编制了相应的计算机程序,通过无毒高温载热剂设计和芳烃与非芳烃分离的萃取精馏溶剂设计2个实例,检验了方法的可靠实用性。     

结合图论和基团贡献法进行分子设计

提出了一种新的计算机辅助分子设计策略—结合图论和基团贡献法的分子设计方法。提出基团触角数、基团特征因数、分子特征因数的定义和分子结构完整定理使基团组合为分子过程自动完成 ,通过予选基团、限定分子基团数及有机物分类法减小合成问题尺寸。给出了系统的设计方法和设计步骤 ,并编制了相应的计算机程序。通过无毒高温载热剂设计和芳烃与非芳烃分离的萃取精馏溶剂设计 2个实例 ,检验了方法的可靠实用性     

基于显卡直接分配的虚拟机图形加速系统①

介绍了设计并实现的基于显卡直接分配的虚拟机图形加速系统Gracias,它的思想是把显卡直接分配给某一台完全虚拟化的虚拟机使用。这样一来,虚拟机中显卡的设备驱动程序对于显卡的使用和访问操作就不会被虚拟机监控器所拦截,也不用通过软件模拟的方式来处理这些访问请求,而是直接交给真实的硬件去完成。这使得对图形处理要求很高的程序在虚拟机中可以获得比普通虚拟化方法高很多的性能提升。     

DSS中图形系统的设计研究

图形技术是进行DSS人机接口设计的一个重要方面。本文给出了在DSS开发和研制过程中常用图形的种类(统计图、地形图、象形图、图标、汉字图形);有重点地阐述了在微型计算机支撑下,这些图形的设计方法和技巧;对于在不同软件环境下,如何应用本图形系统,作出了详细的论述。本图形系统在DSS的研究范围内具有一定的通用性。