Initial Graphics Exchange Specification Research Articles

Converting 80-character ASCII IGES sequential files into more conveniently accessible direct-access files

One of the main drawbacks of the Initial Graphics Exchange Specification (IGES) is the difficulty of accessing and retrieving the required information stored in the IGES files. This is because IGES files created by CAD systems are sequential. This paper describes a module, called “readiges”, which is a general-purpose software package for re-storing IGES files in more conveniently accessible direct-access files. Hence, “readiges” can be used in any research projects that use IGES to integrate CAD systems with other software packages, for example with finite-element packages for mesh-generation purposes or computer-aided process-planning systems.

Rule-based automatic part feature extraction and recognition from CAD data

Automatic extraction and recognition of part features directly from a CAD (Computer-Aided Design) database can form a vital link between CAD and CAPP (Computer-Aided Process Planning). This paper reports the effort of developing such a system for rotational part features using the expert system approachs. Part geometric and topological data in IGES (Initial Graphics Exchange Specifications) format are read by a feature extraction data-compactor (a pre-processor of the system). Then a geomtry-to-feature translator captures manufacturing features in its decision logic expressed as production rules written in LISP. Successful functioning of the system is demonstrated by two illustrative examples. Future research to include a generic feature representation scheme for direct interface with CAPP is given by a framework for this integration.

Computer graphics standards for man modelling

The human being is arguably one of the most nonstandard and unpredictable components of all systems. Thus, in many application areas of computer-aided design, there is a need to model the physical aspects of humans alongside models of workplace and equipment. The paper briefly describes the Sammie systems, a long-established and succesful computer-aided design system that has fulfilled this requirement across a wide range of application areas. Recently, much development work has been aimed at incorporating a range of graphics and data-exchange standards into the Sammie software. These experiences are described, together with observations on their apparent limitations and advantages. In particular, the Programmer's Hierarchical Interactive Graphics System ( Phigs), its extension to Phigs-Plus, the Computer Graphics Metafile (CGM), the Initial Graphics Exchange Specification ( iges), and X-Windows with the Phigs extension ( Pex) are considered.

Data integrity in an IGES description of turned part geometry

There is a growing interest in converting manually drawn engineering drawings into computer databases in a Computer Aided Design (CAD) format such as Initial Graphics Exchange Specification (IGES). This conversion is done by a high resolution scanning device. CAD drawings resulting from the scan-conversion process often contain discontinuities. A draftman using manual drafting equipment may adjust and reposition the ink pen for ease of drawing. This could cause breaks in the drawing, which, though unnoticeable to the human eye, are identified as discontinuities in the electronic scanning process. The subsequent CAD representation may then have broken geometries in place of continuous ones.The work presented here is aimed at verifying the IGES file representing a scan-converted drawing. If any discontinuities are detected in the lines and arcs in the drawing, the breaks are mended. Algorithms are developed to identify and correct errors in the IGES files.The algorithms are coded in Common LISP. The program runs on a VAX VMS system and can handle drawings of turned parts. This research is part of a larger project dealing with feature recognition of turned parts. Extension of the procedure to other geometries is straightforward. The program has been tested on some test drawings obtained from a scanning company. The results are very promising.

Reconciling conflicting design-automation standards

There are four incompatible sets of guidelines for describing and communicating data for products ranging from components to systems. Representatives from the bodies governing the various standards have been trying to decide how to make the standards work together, a process they call harmonization. The standards involved are the Electronic Design Interchange Format (EDIF), the Initial Graphics Exchange Specification (IGES), some standards developed by the Institute for Interconnecting and Packaging Electronic Circuits (IPC), and the Very High-Speed IC Hardware Description Language (VHDL). A subcommittee has been set up, under the sponsorship of the American National Standards Institute, to bring about the harmonization. The tasks facing the subcommittee are examined.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Interpretation of CAD models through neutral geometric knowledge

A generalized approach to fast interpretation of objects and their features has so far eluded researchers. In manufacturing, this interpretation can be approached from the vision point of view or from the CAD data perspective. Presently, CAD systems are widely used in several aspects of manufacturing production. It is therefore more efficient to use CAD data for object reasoning in manufacturing, especially when systems will eventually be data driven. Components can be modelled on a CAD system using various modelling techniques and the representation of their geometric information is still CAD system dependent. However, the advent of the Initial Graphics Exchange Specification (IGES) now makes it possible to represent CAD data in a neutral and standard manner.This paper describes a scheme for recognizing and representing features for CAD data extracted using the IGES interface. The concepts developed are based on graph-based feature representation, where features are represented by a set of faces as well as their topological adjacency.Strategies for classifying features and methods of decomposing a complicated feature into several simpler features for recognition purposes are discussed.

Talking shop (CIM)

The barrier to growth of computer integrated manufacturing (CIM) posed by the difficulty in transmitting information from one machine to another is addressed. The Initial Graphic Exchange Specification (IGES), which was formed in 1979 to facilitate the exchange of product definition data between different CAD/CAM systems, is discussed. The use of a neutral file to reduce the complexity of solving the problem caused by the use of different encoding methods is examined. The use of computer networking to connect computer systems in a highly reliable way is considered. >

Linking Civil Engineering Design and Drafting Software via IGES

A Methodology for integrating application design programs and Computer Aided Drafting (CAD) packages is presented. Application of the methodology enables the automatic translation of the final design information into production drawings of the design, reducing the possibility of translation errors and increasing the engineering and drafting productivity. A model system to demonstrate the methodology has been designed and implemented, utilizing a reinforced concrete box culvert design program. The drawing files were generated using the Initial Graphics Exchange Specification (IGES), a neutral drawing file data format that can be utilized by a variety of CAD systems. The success of the model was demonstrated on three different CAD systems residing in the mainframe and microcomputer environments. One example problem is provided to illustrate the success of the methodology. Guidelines for implementing the methodology are summarized.

Applications of Digital Transfer of Computer-Aided Design Data for Production Usage

This paper addresses efforts to provide the capability to transfer data between computer-aided design (CAD) systems currently in use on the CG 47 contract. The paper discusses experience with the use of Initial Graphic Exchange Specification (IGES) and direct translators. The pros and cons of both approaches are addressed. The issue of transferring data between the two different hull-design and lofting systems in use in shipbuilding is explored.

Integrated CAD and the implications for design practice

The paper reports on specific work carried out using the initial graphics exchange specification (IGES) for data transfer between two proprietary minicomputer-based and microcomputer-based computer-aided design (CAD) systems. The purpose of this work was to pinpoint and highlight the problems that may, and can, arise through performing detailed reflection, transmission and closed-loop tests using IGES translation. As a consequence, the implications of these results for ‘integrated’ mechanical design practice are also presented.

Practical uses of IGES

This paper will discuss the reasons for wishing to transfer product definition data between dissimilar CADCAM systems and the practical use of the Initial Graphics Exchange Specification (IGES) to perform this task. The conclusions reached are as the result of practical experience in the use of IGES and other standards (specifications) over a number of years, beginning with the publication of IGES Version 1.01 in 1980.

Vision assisted NC milling path generation

Abstract CAD/CAM software are an interrelated mesh of computer programming systems that serve to monitor, process and control the flow of manufacturing data. Modern day techniques rely extensively on the integration of standards like the initial graphics exchange specification (IGES) with automated path planning modules. The intent of such an integration is to maintain the system as generic as possible. Integration of the various aspects of manufacturing systems provides total automation of the system. A machine vision system was used to generate the NC code to face mill any planar polygonal part. The vision system helps to capture the image of the face of a polygonal object. This image is decoded into edges and vertices by performing computations in software, based on simple image processing rules. Then the software passes the control to a path planning module. This module selects the most efficient tool path and generates the part program to face mill the part. This paper presents a detailed description of the algorithm developed along with its application environment.

Development of an Initial Graphics Exchange Specification Capability

Industry has long recognized the importance of computerized data exchange. The concept of a neutral exchange format is the key to an efficient and maintainable data exchange capability due to the number of dissimilar CAD/CAM systems in use today. The capability to exchange computerized design data provides the opportunity to eliminate many redundant activities such as recreating computer data from computer-generated paper drawings. The resulting improved communication of design data between contractors, subcontractors, customers, and operation and maintenance activities can reduce costs and upgrade fleet operations. This paper focuses on the need for and the methods used to develop a, workable computerized data exchange capability. Topics of discussion include the merits of electronic data exchange, the limitations of direct translators, and the benefits of a neutral data format. A project is presented that addresses various aspects of digital data exchange within the shipbuilding industry. Emphasis is placed on two working groups that address the digital exchange of design drawings and product model data using the Initial Graphics Exchange Specification (IGES).

Neutral formats for product data exchange: The current situation

This paper identifies and places in context the acronyms associated with the exchange of product definition data generated by CADCAM systems. Having identified those which are neutral formats for the representation of such data, it is worthwhile to trace the evolution of IGES and its successors. Because the Initial Graphics Exchange Specification (IGES) is the current de facto standard neutral format, the mechanisms for realising its real potential in the period until a replacement becomes available are elaborated.

A study of product data transfer using IGES

The Initial Graphics Exchange Specification has become the most widely accepted means of transferring data between dissimilar CADCAM systems. This article reports the results obtained from a study of IGES Version 2.0 transfers between two commercial two-dimensional systems. A large number of test files were created and transferred, and by progressively modifying each file the boundaries of successful transfer were explored. The study showed that while data can be transferred there are some limitations.

IGES - the present state and future trends

Although the Initial Graphics Exchange Specification is not without its imperfections and critics, it is widely considered to be the best format currently available for the exchange of CAD data. However, IGES is seen as an interim measure, eventually to be superseded by a new international standard. This article reviews the present state of IGES and considers likely future trends in CAD data exchange.

Initial graphics exchange specification: Successes and evolution

The Initial Graphics Exchange Specification (IGES) arrived on the CAD/CAM stage in late 1979 and has enjoyed substantial attention from a broad set of users and implementors since. As the term initial reflected, the first release was only a beginning and IGES continues to be an active organization, as well as an evolving CAD/CAM specification. This paper reviews some of the key events and efforts of the IGES community in furthering the quality and scope of this important interface standard.

Interchanging CAD-CAM data bases

Fundamental incompatibilities among entity representations greatly complicate data base interchange between computer-assisted design-computer-assisted manufacture (CAD-CAM) systems. Even simple geometric entities, such as circular arcs, are represented by incompatible forms in many systems. To preserve the original intent of a CAD-CAM data base, the treatment of these incompatible representations in initial graphics exchange specification (IGES) processors must be carefully specified and verified. The challenge of IGES processor design is to meet these specifications within the framework of current IGES and CAD-CAM system architecture.

Industrial electronics: Our computers aren't speaking: Innovation in computer-based manufacturing has led to a pressing need for interface standards

Discusses the Initial Graphics Exchange Specification (IGES), a project of the US Air Force ICAM (integrated computer-aided manufacturing) program intended to meet the need for interface standards. IGES offers a solution to the interface problem for CAD equipment using wire-frame figures from different manufacturers. IGES is a communication file structure for data produced with and used by CAD and CAM systems. It serves as a receptacle for the data generated by interactive graphics design-drafting systems and is a common basis for the automatic interchange of data between these systems, for the transfer of data to and from external application programs.

Interchanging spline curves using IGES

Current CAD/CAM systems employ a variety of spline types, spline representations, and curve design algorithms. The IGES (initial graphic exchange specification) was designed to enable interchange of the more commonly used spline types among CAD/CAM systems, independent of the design algorithms originally used to create them. IGES supports parametric cubic splines through a piecewise polynomial representation. This paper describes the design considerations leading to the interchange common spline curve types. A short introduction to splines and spline representations is included.