[Proj] wgs84 northings and eastings

Greg Troxel gdt at ir.bbn.com
Tue May 24 09:14:57 EST 2011

Roger Oberholtzer <roger at opq.se> writes:

> I have had a request to provide locations (northings and eastings) in
> wgs84. Up to now, I have always worked with a specific projection

It seems likely that the person is looking for WGS84 UTM.  There's no
such thing as "WGS84 eastings and northing" without talking about some
projection (such as UTM or the many US state plane coordinate systems
and national grids).

> somewhere in the world. Such a projection seems rather senseless to me.
> But there you have it. My question is, given wgs84 lat/longs, how would
> I request wgs84 northings / eastings from proj. Would this be adequate?
> +proj=merc +lon_0=0 +k=1 +x_0=0 +y_0=0 +a=6378137 +b=6378137 +units=m +no_defs 
This looks to be 'spherical mercator'.

The real question is what the data is going to be used for.  UTM in the
right zone will likely have more useful properties, such as distances in
the grid being close to distances on the ground, angles being preserved etc.

> Equally worrisome is that I am unsure how to test this as the requester
> has no sample data. Sigh...

So how can they tell you didn't do what they want if you give them UTM?

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