Performance Modeling of Interactive, Immersive Virtual Environments for Finite Element Simulations

Interactive, immersive virtual environments allow ob servers to move freely about computer-generated three- dimensional objects to explore new environments. The effectiveness of these environments is dependent on the graphics used to model reality and the end-to-end lag time (i.e., the delay between a user's action and the display of the result of that action). In this paper, the authors focus on the latter issue, which has been found to be equally important as frame rate for interactive displays. In particu lar, the authors analyze the components of lag time result ing from executing a finite element simulation on a multi processor system located in Argonne, Illinois, connected via ATM to the interactive visualization display located in San Diego, California. The primary application involves the analysis of an automotive disk brake system that was demonstrated at the Supercomputing '95 conference as part of the Information Wide Area Year (I-WAY) project, which entailed the interconnection of various supercom puting centers via a high-bandwidth, limited-access ATM network. The results of this study indicate that the major components of the end-to-end lag are simulation, synchro nization, and rendering times; the use of the ATM network resulted in the network time constituting only a small fraction of the end-to-end lag time.