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, an open virtual world platform, has processed over 700 models using this method.

Near real-time event streams are becoming a key feature of many popular web applications. Many web sites allow users to create a personalized feed by selecting one or more event streams they wish to follow. Examples include Twitter and Facebook, which a user to follow other users' activity, and iGoogle and My Yahoo, which allow users to follow selected RSS streams. How can we efficiently construct a web page showing the latest events from a user's feed? Constructing such a feed must be fast so the page loads quickly, yet reflects recent updates to the underlying event streams. The wide fanout of popular streams (those with many followers) and high skew (fanout and update rates vary widely) make it difficult to scale such applications.