[R-sig-Geo] More problems with spTransform

[Robert J. Hijmans]

Dear Manuel,

What is it about the map that looks wrong? What do you mean it has a
"longitud 0" (the projected coordinates do not refer to longitude).
Perhaps it is shifted in EW direction? Google (CRTM05) suggests that
you need to use a false easting, +x_0=500000.

Robert


On Thu, Oct 21, 2010 at 3:50 PM, Manuel Spínola <mspinola10 at gmail.com> wrote:
> Dear list members,
>
> I know that this is not a problem with the function, but I am trying to work
> with CRTM05 (for Costa Rica) with these parameters ("+proj=tmerc +lon_0=-84
> +lat_0=0 +k=0.9999 +datum=WGS84") .  I am trying to project a map in
> geographic coordinates to CRTM05 but the projected map doesn't look right,
> it has a longitud 0.
>
>> corr = readOGR(dsn="C:/ProyectoRespacial/EvalHab_reporte",
> layer="corredor05unico") # en coordenadas geográficas
> OGR data source with driver: ESRI Shapefile
> Source: "C:/ProyectoRespacial/EvalHab_reporte", layer: "corredor05unico"
> with 1 features and 4 fields
> Feature type: wkbPolygon with 2 dimensions
>
>> corr.transf = spTransform(corr, CRS("+proj=tmerc +lon_0=-84 +lat_0=0
> +k=0.9999 +datum=WGS84")) # para CRTM05
>> writeOGR(corr.transf,
> dsn="C:/ProyectoRespacial/CBSS/Shapefiles_proyectados",
> layer="corredorCRTM05", driver="ESRI Shapefile") # para escribir el shape
>> corre = readOGR(dsn="C:/ProyectoRespacial/CBSS/Shapefiles_proyectados",
> layer="corredorCRTM05")
> OGR data source with driver: ESRI Shapefile
> Source: "C:/ProyectoRespacial/CBSS/Shapefiles_proyectados", layer:
> "corredorCRTM05"
> with 1 features and 4 fields
> Feature type: wkbPolygon with 2 dimensions
>
>> proj4string(corre)
> [1] " +proj=tmerc +lat_0=0 +lon_0=-84 +k=0.9999 +x_0=0 +y_0=0 +ellps=WGS84
> +datum=WGS84 +units=m +no_defs +towgs84=0,0,0"
>
> Am I missing some parameter to do the right projection?
> Best,
>
> Manuel
>
>        [[alternative HTML version deleted]]
>
>
> _______________________________________________
> R-sig-Geo mailing list
> R-sig-Geo at stat.math.ethz.ch
> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>
>