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    Re: Death to the Mercator Projection
    From: David C
    Date: 2018 Aug 14, 19:26 -0700

    Frank wrote

    If these projections are Mercator "in name only" or only in a mathematical sense, then why did such charts become popular? When and why did Transverse Mercator become so popular in specialty applications, including in US military mapping after the Second World War? That I don't know. It's an interesting historical bit of trivia that would require some tough research. I'll speculate that it was an easy sell to "brass" --a familiar name with a modifying adjective.

    Transverse Mercator was being introduced as late as 2000. Prior to that date the projection used for New Zealad for 1 in 50,000 topo maps was the NZ Mapping Grid (NZMG). From the Land Information NZ  (LINZ) website:

    NZMG is not based on a geometric projection (transverse Mercator is based on a cylinder). Instead it uses a complex-number polynomial expansion. This has the advantage of exhibiting minimal scale distortion over New Zealand; however it is a projection unique to New Zealand and so can be difficult to use or program into computer software or positioning devices (eg, GPS receivers).

    In the year 2000 the NZTM2000 projection was introduced. It was described thus:

    NZTM2000 uses a Transverse Mercator projection and is based on the NZGD2000 datum using the GRS80 reference ellipsoid. It was chosen because it is an internationally recognised type of projection that exhibits a low level of distortion at its east-west extents. The projection is only applicable for the main New Zealand island group (North, South, Stewart/Rakiura and the smaller coastal islands).

    I cannot lay my hands on it but I recall reading a document that said that the switch from NZMG  to NZTM2000 increased distortion. The change was made to be consistant with international standards.

    It seems that Mercator is not dead in NZ!




    Finally I can assure you that I have not studied the following page and do not plan to!


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