Re: [R-sig-Geo] Error when transforming a shapefile with spTransform

[Michael Sumner]

Presumably there was valid coordinate system metadata for the first "corr",
but not the second.

See

proj4string(corr)

If the data is longlat on WGS84 you can override the missing (NA) coordinate
system with something like this before using spTransform:

proj4string(corr) <- CRS("+proj=longlat +ellps=WGS84")

but you should check carefully with the source of the data to ensure that
PROJ.4 string is appropriate - using the same as that reported by the first
data set may be right.

Cheers, Mike.
On Fri, Oct 22, 2010 at 6:45 AM, Manuel Spínola <mspinol...@gmail.com>wrote:

> Dear list members,
>
> I am trying to project some shapefiles with function spTransform but I got
> an error.
>
> My first shapefile was ok
>
> > corr = readOGR(dsn="C:/ProyectoRespacial/EvalHab_reporte",
> layer="corredor05unico") # en coordenadas geográficas
> > 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
> > corr = 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
> > plot(corr, axes=TRUE)
>
> but my second gave me an error.
>
> > cob = readOGR(dsn="C:/ProyectoRespacial/CBSS/LAINcambios",
> layer="coberturascsls2006_cr05") # en coordenadas geográficas
> OGR data source with driver: ESRI Shapefile
> Source: "C:/ProyectoRespacial/CBSS/LAINcambios", layer:
> "coberturascsls2006_cr05"
> with 6016 features and 3 fields
> Feature type: wkbPolygon with 2 dimensions
> > cob.transf = spTransform(cob, CRS("+proj=tmerc +lon_0=-84 +lat_0=0
> +k=0.9999 +datum=WGS84")) # para CRTM05
> Error en spTransform(xSP, CRSobj) :
>  No transformation possible from NA reference system
>
> Best,
>
> Manuel
>
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>
>
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>


-- 
Michael Sumner
Institute for Marine and Antarctic Studies, University of Tasmania
Hobart, Australia
e-mail: mdsum...@gmail.com

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