3D Icons and Architectural CAD

3D computer input has been a recurring challenge to engineers developing effective CAD systems. The approach adopted in this paper attempts to address a specific type of 3D input which is applicable to architecture and some engineering design tasks. In these processes, the object being designed is often an assembly of defined components. In a conventional graphics based CAD system these components are usually represented by graphical Icons which are displayed on the graphics screen and are arranged by the user. The system described here consists of 3D modelling elements which the user physically assembles to form his design. Each modelling element contains an element processor consisting of a machine readable label, data paths and control logic. The CAD system interrogates the elements. The logic within the element processors and the data paths are then used to interrogate other adjacent elements in the model. This system can therefore be considered as a "user generated""machine readable" modelling system. In an architectural application this provides the user with a system of 3D Icons with which to model and evaluate the built environment.     

CAD for process plants: an update

We review the availability of CAD software for the process design activities of physical properties generation, unit operation design, flowsheeting and dynamic flowsheet simulation. Similarly we look at CAD software for materials control, piping documentation and pipe stressing. We report conclusions drawn from our research into the provision and use of CAD turnkey systems for producing schematics at the conceptual design phase, and for equipment specification, layout, piping design and 3D modelling at the engineering design phase.By reviewing the shortcomings of current CAD systems along with developing CAD technology, we were able to specify the requirements of the next generation of process plant CAD.     

Automatic digitization of printed circuit layouts

A new technique for automatic input of printed circuit layout data to a computer graphics system, providing a powerful alternative to the existing manual digitization method, is described. The technique is based on optical scanning and graphics recognition. Substantial reduction in the digitized data is made possible by using the properties of printed circuit art work. The technique has been extended to encompass some areas of engineering documentation.     

Environment for rapidly creating interactive design tools

The Garnet toolkit was specifically designed to make highly interactive graphical programs easier to design and implement. Visual, interactive, user-interface design tools clearly fall into this category. At this point, we have used the Garnet toolkit to create three different interactive design tools: Gilt, a simple interface builder for laying out widgets; Lapidary, a sophisticated design tool for constructing application-specific graphics and custom widgets; and C32, a spreadsheet interface to constraints. The features of the Garnet toolkit that made these easier to create include use of a prototype-instance object system instead of the usual class-instance model, integration of constraints with the object system, graphics model that supports automatic graphical update and saving to disk of on-screen objects, separation of specifying the graphics of objects from their behavior, automatic layout of graphical objects in a variety of styles, and a widget set that supports such commonly used operations as selection, moving and growing objects, and displaying and setting their properties.     

USE of computer graphics instruments in application-oriented training

Training in the field of computer graphics usage is important for all engineering courses. Both in design and in production, as well as in technical marketing, graphic representations constitute an important means of expression for the engineer. In connection with the training of engineers, three directions of training can be discerned: basic principles of computer graphics, computer-aided design (CAD) systems with their design and application and employment of CAD systems as a new aid for the designer. Methodical didactic training constitutes a precondition for profitable application of the methods of computer graphics.     

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.     

CAD系统集成和集成技术剖析

系统集成能从根本上解决工程CAD技术应用中的分散独立和低水平重复问题,是进一步发掘计算机潜力的有效途径。文章以集成化的桥梁CAD系统的开发为背景,提出了由界面、工具和数据等三个层次组成的桥梁集成CAD系统结构,并针对软件工业的最新发展介绍了实现CAD系统集成的软件开发技术,包括面向对象的程序设计、图形界面和基础类库、软件构件化开发及数据库图形库连接等。     

An AutoCAD-Based Expert System For Plant Layout

This paper describes the development of a plant layout system implemented in AutoLISP on an IBM PS/2 computer. This system combines computational algorithms, human expertise, and computer graphics in one program for plant layout design and drafting. The objective is to develop a computer system for automation of the layout design and documentation process.

This system emulates a plant layout expert in the last step of plant layout process. The input to the system includes department dimensions, between-department material flows, and aisle width. The system generates and evaluates layout alternatives according to given objectives. AutoCAD commands are called to plot the layout when an alternative layout is being created. This system ensures that each department has an access to the aisle and the travel distance between two departments are measured along the aisle. As both design expertise and computer graphics are programmed in the same environment, the interfacing problem between them is easily eliminated.     

A transatlantic research and development environment [3D virtualgraphics]

Distributed 3D virtual environments can help researchers conduct experiments globally with remotely located participants. We discuss challenges and opportunities for the shared work environment. Our world is entering an age where our current understanding of telecommunications and graphics computing is constantly challenged. With the availability of global information highways, 3D graphical intercontinental collaboration will become a part of our daily work routine. Already, world class auto makers are attempting to reduce car development time to two-year cycles, enlisting global engineering teams. However, this process requires new tools such as shared 3D CAD and distributed product data management systems. The Fraunhofer Center for Research in Computer Graphics (CRCG) in the United States and the Fraunhofer Institute for Computer Graphics (IGD) in Germany, are looking ahead into this new age by establishing a transcontinental computer graphics research effort and a proposed G-7 testbed. We are studying how 3D computer graphics and virtual environments can aid global collaborative work. We have focused our research efforts on determining how computer networks can transform the distributed workplace into a shared environment, allowing real time interaction among people and processes without regard to their location     

Computer assisted plant layout using a graphics editor

Computer assisted plant layout has been available to industrial engineers, in one form or another, for a number of years. In this paper a semi-interactive computer graphics approach to layout planning is described. A graphics editor, CMASK, developed for designing integrated circuits was utilized to create plant-facility layout. The method based on a “layer by layer” approach to creating a layout is flexible and gives the layout designer a complete control to the layout generation process.     

基于适应性相关测试和点斜式查表求交的圆形窗口快速裁剪方法

在智能CAD、图形识别与理解等复杂图形应用系统中,由于图元数量多、 图元间关系复杂,且系统实时交互响应要求较高,现有圆形窗口裁剪算法较难满足要求。为 此提出圆形窗口对线段的一种新的快速裁剪算法。该算法由基于切线分隔的圆外线段快速适 应性测试方法、基于最小范围的圆内线段测试方法和基于点斜式查表的线段与窗口圆快速求 交方法三部分组成。通过按端点位置选择适应的测试方法、尽量避免不必要的操作、尽量以 简单操作代替复杂操作等措施,大大提高了圆形窗口对线段的裁剪速度。在图形识别及智能 CAD 等应用中的实验结果表明,采用文中算法可较大地提高效率。     

An approach to the formal specification of computer graphics systems

This paper discusses the approach to formal specification of computer graphics systems developed by the ANSI X3H3 committee (Computer Graphics Programming Languages) in the United States. ANSI's specification philosophy aims to gradually replace existing informal English language specifications with more formal ones without sacrificing the readibility and usefulness of standards documents. The specification techniques used are derived from those presently employed in the specification of computer communication protocols and the specification of software systems, not those used for the specification of programming languages. The specifications consist of three parts: the interface between both graphics and the host language and graphics and the graphical display device, the structure of the graphics system, and the functions that are performed by the graphics system. The specifications are based on abstract data types. These data types, together with the operations which can be performed on them, are used to describe the structure and functions of the graphics system. Using these techniques, X3H3 has developed a complete formal specification for a minimal graphics system. Extracts from this specification are included here.     

基于采矿CAD的硐室参数绘图系统设计及实现

CAD系统因其本身具有许多长处,得到了工程设计人员的广泛使用。但它只能处理图形的几何信息,真正具有工程实际意义的图形拓扑信息和参数约束信息均被抛弃了。为了保留更多的图形信息以及让工程设计人员更方便地进行硐室图形的绘制,文中根据采矿CAD图形的特点,把要绘制的硐室图形进行参数化分析,并通过编程调用采矿CAD的接口实现了硐室图形的自动绘制系统。此系统能根据用户输入的参数自动生成硐室的二维和三维图形,这大大减少了设计人员的工作量,提高了设计效率,也有利于计算机辅助设计的进一步发展。     

A formalization for the specification and systematic generation of computer graphics systems

A formalization of graphical processes in computer graphics systems is presented in terms of functions and their system of axioms. The concept of the viewing pipeline is formalized as operation sequence which is a sequential composition of graphical elementary operations. The formalization includes two kinds of operation sequences which are used as the formal specifications of graphics systems and display devices. In order to generate a graphics system using a display device, we introduced the concept of functionality-preserving transformation of operation sequences in terms of various types of commutations among primitive operations. A type of transformation, which is called extraction, plays a central role in the generation algorithm.     

DETERMINISTIC AND N0NDETERMIN1STIC PROGRAMMING IN ROBOT SYSTEMS

The modem results of artificial intelligence research have provided new techniques useful foi the design of more sophisticated and advanced industrial robots. The use of computer integrated assembly systems is becoming more and more important in industrial applications

The purpose of this paper is to illustrate how with the use of an automatic problem solver it is possible to achieve the automatic emergency recovery from a failure occurring during the assembly process. An experimental computer program implementing the required problem solving activity has been written in MICROPLANNER and tested on a UNIVAC 1108 computer.     

A display package for CAD of control systems

A multi-access computer system has been installed at the Control Systems Centre of the University of Manchester Institute of Science and Technology. The application of this computer to research into the computer aided design of industrial control systems involved the connection of two keyboard display terminals to the system. The ARDS storage tube displays chosen had the advantages of being teletypewriter compatible and not requiring the connection of a satellite computer A graphics package for the entry and structuring of data derived from the stability analysis of control systems was required as soon as possible after the installation was commissioned. The initial package enabled data to be entered by program and then selected and plotted by keyboard requests. Translation, scaling, alteration of the method of plotting (with points or vectors) and the selection of different items for the display were all carried out by keyboard interaction For long term CAD work a more extensive graphics package was required, the specification was determined following feedback from users of the initial package. It provided additional facilities for graphic interaction, alphanumeric annotation of the displays, specialized drawing and data entry functions and the storing of any pictures built up by the user, as well as a more linked data structure. The structure and facilities of this package are described.     

CATC — A Computer Aided Tolerance Control system

Computer utilization in manufacturing systems is increasing at a rapid rate. Developments thus far have been disjointed. Much work needs to be done in the area of integrating computer aided design and computer aided manufacturing (CAD/CAM). Tolerance control is an important component in the integration of CAD and CAM. Selection of design tolerances affects the build-ability of a product. The selection of manufacturing processes and sequence of processes affects process tolerance stacking. Unexamined process tolerance stacking leads to scrap and rework. A computer aided tolerance control (CATC) system is presented in this paper. This system is based on the tolerance chart technique. The CATC system is interactive and uses computer graphics for information display. The system can be used for computer aided process planning (CAPP) and for CAD/CAM integration.