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

[Michael Sumner]

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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