[Proj] cs2cs - specifying UTM zone on command line

[Even Rouault]

On lundi 29 octobre 2018 21:11:58 CET Kristian Evers wrote:
> Thanks for putting me straight, everyone. I guess there’s a case for such a
> projection afterall!
 
> How would this best be described in PROJ?
> 
>  +proj=zutm ? +proj=utm +zone=auto, as Robb suggested? Something else?

One possibility for complete generality could be to align on how it is 
described by EPSG:
https://www.epsg-registry.org/export.htm?gml=urn:ogc:def:method:EPSG::9824

(or more readable in "1.3.5.2 Transverse Mercator Zoned Grid System" in 
guidance 7.2)

And a more understandable example:
https://www.epsg-registry.org/export.htm?wkt=urn:ogc:def:crs:EPSG::32600

So that could be 
+proj=tmerc +lon_0=-180 +lat_0=0 +w=6 +k_0=0.9996 +x_0=500000 +y=0

The presence of the parameter w= could be the one that triggers the automated 
zone mechanism.

But yes as the only practical use is UTM, "+proj=utm +zone=auto [+south]" 
could be used as a shortcut.

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