Bounding spheres and bounding rectangles SS-tree has regions with shorter diameters R*-tree has regions with smaller volumes How? Rectangles in -dimensions   Diameter: Between 0 and   Volume: Between 0 and 1 Spheres in -dimensions   Diameter: Between 0 and   Volume: Between 0 and Ideally, an index node should combine short diameter regions of SS-tree with small volume regions of R*-tree