[OSGeo Africa] UTM latitude bands

[Peter Newmarch]

Hanlie,

UTM only has Longitudinal bands. Their are no, and have never been, any 
Latitude bands.

There is distortion on the central meridian of 4cm per 100m, and the 
same at the 3 degree edges on either side. At 1 1/2 degrees from the 
central meridian - the scale is 1.

Regards

Peter

Peter Newmarch
Professional Land Surveyor
4Y GeoInformatics Pty Ltd
Tel       : +27 31 5642856
Fax       : +27 31 5643074
Mobile    : +27 82 5705859
eMail     : newmarch at land-surveyors.com

On 2014/08/25 12:05 AM, Tim Sutton wrote:
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> Hi Hanlie
>
> On 13/08/2014 08:26, Hanlie Pretorius wrote:
>> Hi,
>>
>> I've noticed that GIS packages such as QGIS and libraries such as
>> PROJ4 (which QGIS uses, I think) don't use the latitude bands in
>> the UTM grid.
>>
>> Does anyone know why the full UTM grid with latitude bands is not
>> implemented? Does it result in any additional distortions as one
>> moves away from the equator?
>>
>> I have Googled about this and have not been able to find the
>> answer.
> I guess this is an upstream question for the epsg, gdal and proj4
> projects (which we rely on for most of the projection work in QGIS). I
> am not aware if it results in additional distortions as you move away
> from the equator or if the bands simply provide false northings for
> convenience. My limited understanding is that their distortion will
> increase as you extend away in the longitudinal direction but not in
> the latitudinal.
>
> Regards
>
> Tim
>
>> Thanks Hanlie _______________________________________________
>> Africa mailing list Africa at lists.osgeo.org You can UNSUBSCRIBE at
>> http://lists.osgeo.org/mailman/listinfo/africa
>>
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