VASCO: visualizing and animating spatial constructs and operations

A video is used to demonstrate a set of spatial index JAVA applets that enable users on the worldwide web to experiment with a number of variants of the quadtree spatial data structure for different spatial data types, and, most importantly, enable them to see in an animated manner how a number of basic search operations are executed for them. The spatial data types are points, line segments, rectangles, and regions. The search operations are the window query (i.e., a spatial range query) and a nearest neighbor query that enables ranking spatial objects in the order of their distance from a given query object. The representations and algorithms are visualized and animated in a consistent manner using the same primitives and colors so that the differences between the effects of the representations can be easily understood. The video demonstrates the PR quadtree, PM1 quadtree, and R-tree. The applets can be found at: www.cs.umd.edu/~hjs/quadtree/.