We present iRun, a system for interactively volume rendering large unstructured grids on commodity PCs. Rendering arbitrarily large datasets has been an active area of research for many years. However, the techniques required for polygonal data do not directly apply to the more complex problem of unstructured grids. In this paper, we describe the data structures and algorithms necessary to store large datasets on disk, keep an active portion of the dataset in main memory, and render visible

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... ons to one or more displays. Our system leverages a combination of out-of-core data management, distributed rendering, hardware-accelerated volume rendering, and dynamic level-of-detail. On a commodity PC, our system can preprocess a dataset consisting of about 36 million tetrahedra in about an hour and can render it interactively with one or more PCs.