Special issue of Computer-Aided Design on virtual and augmented reality technologies in product design

Virtual and augmented reality technologies were introduced more than three decades ago with the goal of providing sophisticated visualizing capabilities and multi-sensational human interfaces, and facilitating the development of new application systems for industrial and public use. Over the years, not only has the variety of virtual reality (VR) and augmented reality (AR) technologies grown, but their functional capabilities and usability have improved. VR and AR technologies have found their ways into critical applications in industrial sectors such as aerospace engineering, automotive engineering, medical engineering, and also in the fields of education and entertainment. The range of technologies that are currently used include CAVE environments, reality theaters, power walls, holographic workbenches, individual immersive systems, head mounted displays, tactile sensing interfaces, haptic feedback devices, multi-sensational devices, speech interfaces, and mixed reality systems. These technologies rely on the artefact modelling and manipulation capabilities of computer aided design and engineering systems, but they also extend the functionality of these systems in terms of spatial immersive visualization, multi-sensational interaction and behavioral simulation. This explains why the concept of virtual reality enabled CAD/E systems (VR-CAD/E) has emerged and is enjoying a growing attention in both scientific research and technology development. There are many hot issues for VR-CAD/E research and development. One of them is to achieve a trade-off between the investments in technology and application development and the obtainable benefits in general (non-critical) practical applications. This has recently shifted the attention of researchers from high end solutions to low cost (desk-top) solutions. A second issue thatwe believe important to be mentioned here is a relatively low level of cooperation between institutions and researchers/developers. This makes the total picture somewhat fragmented, the utilization of the intellectual assets and research infrastructure sub-optimal, and the outcomes more modest than what is expected based on a wider collaboration. A major technical issue is the integration of the various VR/AR technologies with each other and with commercialized CAD/E systems, geometric andphysicalmodelling kernels, and downstream application tools and systems. Due to the current limitations in scientific knowledge, as well as to the resultant complexities, technological incompatibilities, and human factors, this complex issue is often seen as neuralgic. Only moderate progress has been achievedwith sophisticated sensational technologies and with combining these technologies in order to provide a multisensational experience for users. There is still a long way to go before efficient and conveniently usable VR-CAD/E solutions will be available. While integration of VR/AR technologies with CAD/E systems manifests itself as a great opportunity for researchers and developers, it also remains