Help with latlong to UTM conversion when UTM zones are different

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)
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