Principal authors: U. Kroszynski, B. Palstr9Sm 1.1 The evolution of concepts and specifications for CAD data exchange The CAD/CAM community has witnessed, during the last decade, the appearance of several specifications as well as proposals for standards which either attempt to cover wider areas or to be more reliable and stable than the others. With the rapid evolution of both hardware and software, the capabilities offered by CAD systems and CAD based application systems are far more advanced than they were only ten years ago, even when they are now based on micro-computers or personal comput ers. The situation with standards, however, is not and cannot be so. In order to be reliable and accepted by a wide community of both vendors and users, a standard has to be sta ble. This implies a life span of at least a decade. This also implies that the standard has to be general and flexible enough to accommodate present as well as expected future developments. 1.1.1 IGES The initial development of concepts for CAD data exchange is strongly influenced by the US Integrated Computer Aided Manufacturing (ICAM) programme, that dealt with the development of methods for data exchange. In September 1979, a subgroup was estab lished with participation of the National Bureau of Standards, the General Electric Com pany, and the Boeing Company. The result of this effort was the Initial Graphics Exchange Specification (IGES) that was published as a NBS report [61] in 1980.

This book is a result of the lectures and discussions during the conference "Theory and Practice of Geometric Modeling". The event has been organized by the Wilhelm-Schickard-Institut fiir Informatik, Universitat Tiibingen and took place at the Heinrich-Fabri-Institut in Blaubeuren from October 3 to 7, 1988. The conference brought together leading experts from academic and industrial research institutions, CAD system developers and experien ced users to exchange their ideas and to discuss new concepts and future directions in geometric modeling. The main intention has been to bridge the gap between theoretical results, performance of existing CAD systems and the real problems of users. The contents is structured in five parts: A Algorithmic Aspects B Surface Intersection, Blending, Ray Tracing C Geometric Tools D Different Representation Schemes in Solid Modeling E Product Modeling in High Level Specifications The material presented in this book reflects the current state of the art in geometric modeling and should therefore be of interest not only to university and industry researchers, but also to system developers and practitioners who wish to keep up to date on recent advances and new concepts in this rapidly expanding field. The editors express their sincere appreciation to the contributing authors, and to the members of the program committee, W. Boehm, J. Hoschek, A. Massabo, H. Nowacki, M. Pratt, J. Rossignac, T. Sederberg and W. Tiller, for their close cooperation and their time and effort that made the conference and this book a success.

Reiner Anderl The Advanced Modelling part of the CAD*I project aimed at the development of a new generation of modelling techniques as a basic functionality of future CAD/CAM systems. The methodology and concepts for advanced modelling techniques, their availability in the communication interface of a CAD/CAM system and their influence on internal interfaces in the software architecture of a CAD/CAM system are fundamental results of advanced modelling work. These results form the basis for the development of a new generation of CAD/CAM systems which are called product modelling systems. CAD/CAM systems today mainly support the geometric description of a technical part or its description as a technical drawing. Advanced geometric modelling capabilities deal with parametric design functions embedded into CAD/CAM systems. However, development strategies for future CAD/CAM systems are directed toward the following: 1. The development of product modelling systems and 2. the development of integrated systems based on CAD, CAP (Computer Aided Planning), CAM and other CIM (Computer Integrated Manu facturing) functionalities.

Edited for Working Group 2 (WG 2): Cisigraph, Cranfield Institute of Technology, Danmarks Tekniske Hojskole, Kernforschungszentrum Karlsruhe GmbH, NEH Consulting Engineers ApS, Universität Karlsruhe

In addition to the classical needs, competition on the global market requires from industry product innovations: quality, time to market, reduction of costs (Q,T,C). The modern process networks of product development and manufacturing passing the borders of countries and including several companies could not work without an extensive use of information technology. This is going far beyond the former idea of Computer Aided Design. Thus the 3'd Workshop on Current CAx-Problems did not focus on functionalities or methods aiding design like in the first two workshops but on "Digital Products - Living Data is the Future": problems of the virtual simulation of the entire industrial process, starting with the development of a product and covering the complete life cycle. The workshop aimed at bringing together the three groups: industry (mainly automotive manufacturers), system suppliers, and fundamental research. During the workshop, communication between these three groups had to be intensified, and especially also among competing companies of the same branch to pave the way for concerted actions, which are essential for all in the future.

In the latter half of the 20th century, forces have conspired to make the human community, at last, global. The easing of tensions between major nations, the expansion of trade to worldwide markets, widespread travel and cultural exchange, pervasive high-speed communications and automation, the explosion of knowledge, the streamlining of business, and the adoption of flexible methods have changed the face of manufacturing itself, and of research and education in manufacturing. The acceptance of the continuous improvement process as a means for organizations to respond quickly and effectively to swings in the global market has led to the demand for individuals educated in a broad range of cultural, organizational, and technical fields and capable of absorbing and adapting required knowledge and training throughout their careers. No longer will manufacturing research and education focus on an industrial sector or follow a national trend, but rather will aim at enabling international teams of companies to cooperate in rapidly designing, prototyping, and manufacturing products. The successful enterprise of the 21st century will be characterized by an organizational structure that efficiently responds to customer demands and changing global circumstances, a corporate culture that empowers employees at all levels and encourages constant communication among related groups, and a technological infrastructure that fully supports process improvement and integration. In changing itself to keep abreast of the broader transformation in manufacturing, the enterprise must look first at its organization and culture, and thereafter at supporting technologies.

Medical modelling and the principles of medical imaging, Computer Aided Design (CAD) and Rapid Prototyping (also known as Additive Manufacturing and 3D Printing) are important techniques relating to various disciplines - from biomaterials engineering to surgery. Building on the success of the first edition, Medical Modelling: The application of Advanced Design and Rapid Prototyping techniques in medicine provides readers with a revised edition of the original text, along with key information on innovative imaging techniques, Rapid Prototyping technologies and case studies.Following an overview of medical imaging for Rapid Prototyping, the book goes on to discuss working with medical scan data and techniques for Rapid Prototyping. In this second edition there is an extensive section of peer-reviewed case studies, describing the practical applications of advanced design technologies in surgical, prosthetic, orthotic, dental and research applications. - Covers the steps towards rapid prototyping, from conception (modelling) to manufacture (manufacture) - Includes a comprehensive case studies section on the practical application of computer-aided design (CAD) and rapid prototyping (RP) - Provides an insight into medical imaging for rapid prototyping and working with medical scan data