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

[Manuel Spínola]

Thank you very much Robert, I need CRTM05 and according the information that you sent me it will be: +proj=tmerc  + lon_0=-84 + lat_0=0 + k=0.9999 +datum=WGS84 I guess I only need to set the 0.9999 instead of 0.9996. It make sense? Best, Manuel On 16/10/2010 02:32 p.m., Robert J. Hijmans wrote: 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 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/ 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 <mspinol...@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_crs everything 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.vill...@utu.fi phone: 00358 (0)2 333 5049 Skype Use open source and free softwares _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://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 mspin...@una.ac.cr mspinol...@gmail.com Teléfono: (506) 2277-3598 Fax: (506) 2237-7036 Personal website: Lobito de río Institutional website: ICOMVIS _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://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 mspin...@una.ac.cr mspinol...@gmail.com Teléfono: (506) 2277-3598 Fax: (506) 2237-7036 Personal website: Lobito de río Institutional website: ICOMVIS

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