[Proj] MGRS/USNG support?

Gerald I. Evenden gerald.evenden at verizon.net
Fri May 5 10:06:11 EDT 2006

On Friday 05 May 2006 9:09 am, Oscar van Vlijmen wrote:
> >From Eric G. Miller:
> >
> > I guess, for this to work the UTM handling would have to change. 
> > Currently, you have to specify +zone= and +south (as appropriate), but
> > the library should be able to figure that out and report it back in the
> > output.  The user should have the option of forcing a zone or allowing
> > the library to determine it. Perhaps this is too deep a change?
> >
> >From my remarks, April 26:
> >
> > Let the projection code calculate what the nearest central meridian is,
> > merely based on the input of the longitude of each point.
> > But: can (lib)proj do that?
> Is it really that obtrusive to change tmerc/utm so, that it calculates the
> nearest central meridian itself, if no zone or CM is supplied?
> Indeed, processing MGRS strings should be a pre/postprocessor task.

Yes it is!

UTM allows for a 1/2 degree overlap or extension beyond its normal
longitude range.  Given that factor, how do you know which CM to use?

Similarly, if the point lies exactly on the division between zones, which
CM do you use?

Also, some zones in the Scandinavian region extend beyond the normal
+/-3 degree limit, so again, explicit specification of the zone is required.

Jerry and the low-riders: Daisy Mae and Joshua
"Cogito cogito ergo cogito sum"
   Ambrose Bierce, The Devil's Dictionary

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