Jeff Terrace will present his preFPO on Thursday April 12 at 4PM in Room 302 (note room!). The members of his committee are: Michael Freedman, advisor; Adam Finkelstein and Phil Levis (Stanford), readers; Vivek Pai and Szymon Rusinkiewicz, nonreaders. Everyone is invited to attend his talk. His abstract follows below. --------------------- Metaverses are three-dimensional virtual worlds where anyone can add and script new objects. Metaverses today, such as Second Life, are dull, lifeless, and stagnant because users can see and interact with only a tiny region around them, rather than a large and immersive world. Current metaverses impose this distance restriction on visibility and interaction in order to scale to large worlds, as the restriction avoids appreciable shared state in underlying distributed systems. We present a brief summary of the design and implementation of the Sirikata metaverse server. The Sirikata server scales to support large, complex worlds, even as it allows users to see and interact with the entire world. It achieves both goals simultaneously by leveraging properties of the real world and 3D environments in its core systems, such as a novel distributed data structure for virtual object queries based on visible size. A virtual-world environment becomes a truly engaging platform when users have the ability to insert 3D content into the world. However, arbitrary 3D content is often not optimized for real-time rendering, limiting the ability of clients to display large scenes consisting of hundreds or thousands of objects. We present the design and implementation of an automatic, unsupervised conversion process that transforms 3D content into a format suitable for real-time rendering while minimizing loss of quality. The resulting progressive format includes a base mesh, allowing clients to quickly display the model, and a progressive portion for streaming additional detail as desired. Sirikata’s public, open-source content repository is currently using this method and has processed over 700 3D models. 3D meshes are large--often several megabytes in size. When a client enters a scene containing many objects, it can take a long time to download meshes, resulting in poor visual fidelity. A progressive mesh format allows a client to download a low-resolution version of a mesh at a much lower cost in bandwidth, but deciding how to order downloads has a huge impact on performance. Should a client download a higher texture resolution for one model, or stream additional vertices for another? Worse, underpowered clients might not be able to display a high resolution mesh, resulting in wasted time downloading unneeded content. We present the design and implementation of a framework for evaluating scheduling algorithms for progressive meshes and we perform this evaluation on several different algorithms. The result is a mesh scheduling algorithm that optimizes for visual fidelity given a fixed bandwidth constraint.