Indexing Animated Objects

We examine the problem of indexing objects in animated movies. We consider an animated movie as consisting of a frame sequence where each frame is described by objects in a 2-dimensional space. The queries of interest are of the form: \\nd the objects that were in area S between frames fi and fj". The straightforward approach to index such objects is to consider the frame sequence as another dimension and use a 3-dimensional access method (like an R-tree) to index all objects. Instead we propose to reduce the problem to a partial-persistence problem, that is, use a 2-dimensional access method that is made partially persistent. We show that this approach leads to faster query time while still using space proportional to the total number of changes in the frame evolution.