Recent advances in parallel computing have made it possible for scientists to perform atomistic simulations of materials involving billions of atoms. An immersive and interactive virtual environment such as ImmersaDesk is an ideal platform for exploring complex material processes in these simulations. However rendering such large datasets at an interactive speed is a major challenge. To solve this problem we have developed a visualization system by incorporating parallel and distributed computing paradigms. The system uses a parallelized fast visibility-culling algorithm based on the octree data structure to reduce the number of atoms sent to the graphics pipeline. An adaptive multiresolution algorithm based on atomic density is employed to further reduce the load on the graphics pipeline. The resulting system renders a billion-atom system at nearly interactive frame rates on a dual processor SGI Onyx2 with an InfiniteReality2 graphics pipeline connected to a 4-node PC cluster.