[R-sig-Geo] Converting UTM to geographical coordinates

[Robert J. Hijmans]

Manuel,

Costa Rica Transverse Mercator is a type of Transverse Mercator (like UTM).

http://www.remotesensing.org/geotiff/proj_list/transverse_mercator.html

So we have, in proj.4 notation

+proj=tmerc

It is revealed here:
http://www.asprs.org/resources/GRIDS/04-2008-costarica.pd<http://www.asprs.org/resources/GRIDS/04-2008-costarica.pdf>

that the for *

"Proyección CRTM90-WGS84" the

*central meridian is 84 degrees so we have:

+proj=tmerc  *

+lon_0=-84

*
*


*
*

The same author and the document below (a search for "Proyección CRTM90-WGS84" )

*
*


*
*http://www.geotecnologias.com/Documentos/TSCArcGIS_9x.pdf*

provide some additional info such that I would think you are probably
dealing with :
*

+proj=tmerc

+lon_0=-84 +lat_0=0

+k=0.9996 +datum=WGS84

*

Although there might be *

CRTM90 projections with a different datum out there. And watch for
those false eastings and northings (horizontal and/or vertical shifts
to express the coordinates in smaller numbers. (I am assuming +

**

x_0=0 +y_0=0

**

)

*

http://spatialreference.org/ <http://spatialreference.org/ref/sr-org/6993/> did
not have it, but I have uploaded here, so that you can easily test it by
clicking on a map:

http://spatialreference.org/ref/sr-org/6993/

With this you could try your luck with spTransform

Best, Robert


On Sat, Oct 16, 2010 at 7:45 AM, Manuel Spínola <mspinola10 at gmail.com>wrote:

>  Thank you very much Alexander.
> I am looking at the website right now.
> In my case I have a very particular coordinate system (CRTM, Costa Rica
> Transverse MErcator) in this case, which parameter I need to know to make
> the conversion?
>
> Best,
>
> Manuel
>
>
> On 16/10/2010 05:41 a.m., Alexandre Villers wrote:
>
> Hey Manual,
>
> One thing to do first would be to ask where you can find the information...
> here for example
> http://rwiki.sciviews.org/doku.php?id=tips:spatial-data:change_crseverything you look for is on that page
> And have a look a Applied Spatial Data Analysis with R (ASDAR) to
> understand the basics of Spatial objects in sp package and how to perform
> what you are looking for. It will be much more benefitial for you to learn
> it by yourself that simply copy a code one can provide you with...
>
> HTH
>
> Best regards
>
> Alex
>
> --
>  Alexandre Villers, PhD.
> Postdoc researcher
> Spatial Ecology & Population Dynamics
> Section of Ecology, Department of Biology
> University of Turku
> FIN-20014 Turku
> Finland
>
> @mail: alexandre.villers at utu.fi
> phone: 00358 (0)2 333 5049
>
> Skype [image: You can skype me (but think of using Ekiga instead !)]
> *Use open source and free softwares*
>  <http://cran.r-project.org/> <http://grass.itc.it/>
> <http://www.qgis.org/> <http://fr.openoffice.org/>
> <http://www.mozilla-europe.org/fr/> <http://www.mozilla-europe.org/fr/>
>
>
> _______________________________________________
> R-sig-Geo mailing listR-sig-Geo at stat.math.ethz.chhttps://stat.ethz.ch/mailman/listinfo/r-sig-geo
>
>
>
> --
> *Manuel Spínola, Ph.D.*
> Instituto Internacional en Conservación y Manejo de Vida Silvestre
> Universidad Nacional
> Apartado 1350-3000
> Heredia
> COSTA RICA
> mspinola at una.ac.cr
> mspinola10 at gmail.com
> Teléfono: (506) 2277-3598
> Fax: (506) 2237-7036
> Personal website: Lobito de río<https://sites.google.com/site/lobitoderio/>
> Institutional website: ICOMVIS <http://www.icomvis.una.ac.cr/>
>
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