ABSTRACT
In this chapter, the authors present a new technique for the visual exploration of origins (O) and destinations (D) arranged in geographic space. They propose mapping OD vectors as cells rather than lines, comparable with the process of constructing OD matrices, but unlike the OD matrix, their preserve the spatial layout of all origin and destination locations by constructing a gridded two-level spatial treemap. The authors explore the characteristics of the technique through a software prototype that allows interactive query and visualization of 105–106 simulated and recorded OD vectors using a hash grid spatial data structure. Viewing static OD maps provides some insight into the structure of the geographic vectors under investigation. The OD map offers several advantages over the more commonly used flow mapping and OD matrix representations. Owing to aggregation of OD vectors into a regular grid, the OD map is scalable to large collections of vectors.
