A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Pike
Date: 2019 Oct 4, 12:38 -0700
Until 2000 NZ used the NZMG (NZ mapping grid) which was described as using a complex-number polynomial expansion. This had the advantage of exhibiting minimal scale distortion over New Zealand. However it was a projection unique to New Zealand and so could be difficult to use or program into computer software or positioning devices (eg, GPS receivers).
In 2000 a change was made to the the New Zealand Transverse Mercator 2000 (NZTM2000) projection. I understand that NZTM2000 is less accurate than the NZMG but the change was made for the reasons given above.
Why didn't they use an oblique Mercator running SW-NE like New Zealand? Cartoon courtesy of xkcd.com under Creative Commons Attribution-NonCommercial 2.5 License. DaveP