[R-sig-Geo] Help with latlong to UTM conversion when UTM zones are different

[Michael Sumner]

They are reasonable reasons, but traversing zones is a pain, you should see
if using one or the other is sufficient. I would check carefully the
distances you get against ellipsoidal calculations.

Cheers, Mike

On Sat, 28 Mar 2015 07:30 Andrew Duff <andrewaduff at gmail.com> wrote:

> A number of field folks prefer UTM because
>
> -it matches legacy paper USGS quad map series traditionally used for field
> navigation
> -units are in meters and can be used to gauge field distances from a
> coordinate readout
>
>
>
> > On Mar 27, 2015, at 10:48 AM, Michael Sumner <mdsumner at gmail.com> wrote:
> >
> > There is no good natural reason to use UTM, it mistifies me why our
> > community tolerates this bizarre default. I always use a local equal-area
> > projection unless some other compromise dictates a different choice.
> > Cheers, Mike
> >
> > On Fri, 27 Mar 2015 21:28 Barry Rowlingson <b.rowlingson at lancaster.ac.uk
> >
> > wrote:
> >
> >> If you have lat-long data that crosses two UTM zones then its
> >> generally okay to just pick *one* and transform all the points to
> >> that. Use the one that has the most points in. Basically use the UTM
> >> zones as guidelines to pick one UTM zone coordinate system. Unless
> >> your data spans several zones and you want quite high accuracy of
> >> distance measurements. Some points bleeding over into an adjacent zone
> >> are no problem.
> >>
> >> All projections are approximations to the earth's spheroid, so points
> >> that are within a single UTM zone have some distortion in their
> >> distance or angle relationships. Transforming points that are within
> >> an adjacent UTM zone is just an extension of that distortion. You can
> >> compute the precise distance error if you want for the furthest points
> >> by comparing with the geodesic distance.
> >>
> >> Alternatively you might find there is a coordinate system that spans
> >> your dataset nicely - often when a country or an island or a region
> >> crosses UTM zones there is an official coordinate system defined that
> >> is used by the authorities there.
> >>
> >> Also alternatively, there's nothing to stop you defining a transverse
> >> mercator system based on the centre of your data.
> >>
> >> Barry
> >>
> >>
> >>
> >> On Fri, Mar 27, 2015 at 7:44 AM, moses selebatso <
> selebatsom at yahoo.co.uk>
> >> wrote:
> >>> Hello
> >>> I have animal movement data that I have converted from Lat/Long to UTM,
> >> unfortunately the data falls in two UTM zones (34S and 35S). For some
> >> reason R cannot display both of them in the same window (the 35S data is
> >> way off the expected location).
> >>> The question is how do I convert the data such that R can correctly
> read
> >> it?
> >>> Moses SELEBATSO
> >>>
> >>> (+267) 318 5219 (H) (+267) 716 393 70 (C)
> >>>  (+267) 738 393 70 (C
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> >>>
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