GENIE Gridspec Diagrams Overlap

An overlap is a type of contact region suitable for describing the area formed where two grid tiles intersect. It is intended to support conservative regridding of scalar quantities; vector quantities are under study according to Balaji, which may lead to changes in the overlap specification.

The overlap consists of an exchange grid. Each cell in the exchange grid contains a pair of "parent cells", which comprise references to the overlapping cells on the parent grid tiles, along with a fractional area with respect to those cells.