Just a guess: it doesn't align NS-EW? Being oblong but somewhat diagonal, it makes sense perhaps to have a grid that's aligned with the major axes of the landmass. Which is not aligned with compass points.
Good guess; the alignment of the spine of the two islands was the motivation for the type of projection used .. that leaves the what type, why complex, and why rare / unique bits.
Many years back I had the task of writing code for this (and many other types of projections) from first principles to compare against the "official" implementation released by the NZ cartographers .. it's a fun one.
defrost|7 days ago
Many years back I had the task of writing code for this (and many other types of projections) from first principles to compare against the "official" implementation released by the NZ cartographers .. it's a fun one.