Someone must've taken CMSC420 with Meesh :)
Curious, did you use any other information or was this a wild guess?
As a side note, if anyone wants to go into more depth, Samet's "Foundations of Multidimansional and Metric Data Structures" (http://www.amazon.com/Foundations-Multidimensional-Structure...) is an extensive survey of a lot of spatial data structures.