A VR Tool for the Visualization of CAD Models Eduardo T. L. Corseuil, Alberto B. Raposo, Romano J. M. da Silva, Marcio H. G. Pinto, Gustavo N. Wagner, Marcelo Gattass TeCGraf/PUC-Rio – Computer Graphics Group Dept. of Computer Science – Catholic University of Rio de Janeiro, Brazil . {thadeu,abraposo,romano,mhgpinto,gustavow,mgattass}@tecgraf.puc-rio.br Abstract: This paper presents ENVIRON (ENvironment for VIRtual Objects Navigation), an application that was developed motivated by the necessity of using Virtual Reality in large industrial engineering models coming from CAD (Computer Aided Design) tools. This work analyzes the main problems related to the production of a VR model, derived from the CAD model, which must provide an immersive sensation to the user and allow him to interact with it in real-time. ENVIRON format conversion and visualization aspects are detailed, and performance considerations are discussed based on tests made with real oil platforms models. 1. Introduction One of the main objectives of the engineering departments of large industries, such as automobile, aerospace, and oil & gas, are the construction of integrated information systems to control their projects. They look for computational systems that, besides accessing the data bases with project information, offer resources for the 3D visualization of their models with enough realism to be used for design review, change management systems, and training, among other activities. Virtual reality systems are being developed to accomplish these goals. In this kind of system, the efficiency is related to its immersion and interactivity capabilities, which requires a real time response of the system to the solicitations demanded by the users or by the model. The difficulties encountered in this process are basically due to the fact that the engineering models are not constructed to be visualized in real time. In some cases, the models are visually simplified representations, serving only as schematic representations of the characteristics to be analyzed. In other cases, there are situations in which the models are too large and complex to be visualized in real time. This is the case of CAD models, the topic of this work, where many components, which are important to the engineering project, are unnecessary in the context of VR. Even the components necessary to the visualization, in their majority, need to be optimized for achieving a real time performance, since they may have an excessive detailing. In this context, this paper introduces ENVIRON (ENvironment for VIRtual Objects Navigation), a tool developed to bridge the gap between CAD and VR models, facilitating the use of CAD models for VR applications. In this paper, we use the term "CAD model" referring to the engineering model, and "VR model" referring to the 3D model for real time visualization and interaction.