Published by the IEEE Computer Society 0272-1716/09/$26.00 © 2009 IEEE IEEE Computer Graphics and Applications 91 Projects in VR Editor: Lawrence Rosenblum and Simon Julier Environ: Integrating VR and CAD in Engineering Projects Alberto Raposo, Luciano Soares, Gustavo Wagner, Eduardo Corseuil, and Marcelo Gattass, PUC-Rio Ismael Santos, Petrobras Research Center A main objective of large industrial-engineering departments is implementing integrated information systems to manage their proj- ects’ life cycles. Particularly, most industrial engi- neers in the oil and gas industry use 3D geometric models, which they create using CAD systems to interact with the information systems. This is pos- sible because modern CAD systems have evolved from drawing programs to collaborative design tools that combine geometric modelers with special- ized tools for tasks such as engineering-document management, physical-plant documentation, and computer-aided visualization. This combination relects the need for plant-information manage- ment systems—data warehouses that help reduce costs and enhance eficiency by improving control of the overall project’s life cycle. Since VR’s early development, it has been seen as a potential tool for engineering activities. Ini- tially, VR’s application in conjunction with 3D geometric CAD models was restricted to design review, virtual prototyping, and marketing pur- poses, mainly in the automotive and aircraft industries. These models are now showing their potential in VR applications for such diverse pur- poses as ergonomic studies, safety training, and physical-simulation visualization. However, a sig- niicant gap remains between CAD models and VR models owing to CAD and VR tools’ differ- ing purposes. CAD tools create detailed models, aimed at the execution process. VR tools support activities with a high visualization demand, to provide the best possible immersion in the physi- cal setting by means of the virtual model. To bridge the gap, researchers have proposed several VR-CAD integration solutions. One such solution is the Environ (Environment for Vir tual Objects Navigation) application. En- viron’s main goal is to offer 3D visualization re- sources for CAD models with enough realism to serve as an integration tool for several engineering activities in the oil and gas industry (see Figure 1). We devised Environ to help Petrobras (a Brazilian oil and gas company) visualize and manage its en- gineering assets’ life cycles by using CAD models. Challenges in VR-CAD Integration At least two main approaches exist to integrate VR techniques into CAD systems. From one perspec- tive, VR is an advanced form of human-computer interaction and is used in common CAD modeling tasks, such as picking and drawing. This line of research treats VR as an innovative interface for constructing CAD models. 1 With Environ, we’re interested in the other kind of VR-CAD integration: VR as an advanced form of visualizing the CAD model in real time and in- teracting with it through common CAD uses. 2 One challenge we face with this kind of VR-CAD integration is the complexity of CAD models, which weren’t conceived to be visualized in real time. The frame rates for complex CAD models are unsatis- factory, exposing all the geometry, especially in re- gions with a high concentration of objects. This is aggravated by the fact that the CAD-to-VR conver- sion normally increases model complexity. CAD-to-VR conversion poses other challenges, too. On one hand, VR formats generally don’t allow the representation of project information linked to CAD objects, which causes a loss of conversion se- mantics. On the other hand, CAD models generally don’t have material and texture attributes associated with objects (although many CAD systems provide this possibility). This happens because this infor- mation isn’t essential to the building process, which is CAD’s main purpose. However, this information is important for photorealistic visualization. An- other related problem is the inadequate treatment of geometry. During CAD-to-VR model conversion, geometry or precision loss normally occurs. This process commonly generates VR models of insuf- icient quality, containing errors such as normals pointing in the wrong direction and cracks. Several CAD tools are evolving with an eye on VR visualization. Some of them can deal with large amounts of data but lack integration with VR re- Authorized licensed use limited to: PONTIFICIA UNIVERSIDADE CATOLICA DO RIO DE JANEIRO. Downloaded on November 11, 2009 at 12:35 from IEEE Xplore. Restrictions apply.