ABSTRACT
A non-spatial solution used to indicate movement is the origin–destination (OD) Matrix. It indicates the start (Origin) and end (Destination) of the movement. Jo Wood, Jason Dykes and Aidan Slingsby's begin to combine the best of the flow map and the OD matrix. 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 OD map has been implemented in the processing software environment which allows for all kind of interaction with the OD map content as well as with the linked flow map and the accompanying website gives some additional static examples. Wood, Dykes and Slingsby's discuss the problem of selecting the grid size in relation to the ability to recognize the geographic area.
