[R-sig-Geo] [R] how to image.plot a XY grid file into a lat-lon map

[Edzer J. Pebesma]

May I suggest you take a look at the Spatial Task View?

r-project.org -> CRAN -> Select Mirror -> Task Views -> Spatial.
--
Edzer

Linda Smith wrote:
> Could you please let me know more details about rgval package? I have never
> used it before. I only tried image.plot() where if you have regular lat and
> lon, a map() function can be used later to overlay state map onto it.
>
> On 4/5/07, Roger Bivand <Roger.Bivand at nhh.no> wrote:
>   
>> On Thu, 5 Apr 2007, Vladimir Eremeev wrote:
>>
>>     
>>> If your country or state borders are polygons or polylines, you could
>>> convert them to desired projection using the function project from the
>>> package rgdal.
>>>
>>> Latitude-longitude grid also could be added by generating desired
>>> polylines in lat-lon and converting them to the desired projection using
>>> project.
>>>
>>>       
>> Yes, the route would be to plot the image in its native projection, and
>> project the vector data (shorelines, countries) to the same projection.
>> Similar topics have been discussed on the R-sig-geo list, including the
>> reading of netcdf files (which are a bit picky) with functions in the
>> rgdal package which import the coordinate reference system directly.
>>
>> Please follow this up on R-sig-geo if you need more help.
>>
>>     
>>> Linda Smith wrote:
>>>       
>>>> I have a netcdf gridded file with LCC projection. I can easily use
>>>> image.plot to visualize it. However, as the axises are in X,Y, not Lat
>>>>         
>> and
>>     
>>>> Lon, I could not add state or country maps onto it (or lat lon
>>>> information).
>>>> I do have a grid2d file that describes the lat and lon for each (X,Y)
>>>> grid,
>>>> but the lat and lon are not regularly spaced, so I could not use
>>>> image.plot.
>>>>
>>>> Does anyone know how to plot this type of gridded data so that country
>>>>         
>> or
>>     
>>>> state borders can be easily added? Thanks a lot!
>>>>
>>>>         
>>> What do you mean by "grid2d file that describes the lat and lon for each
>>> (X,Y) grid"?
>>> If this are two rasters of the same size having corresponding latitude
>>>       
>> and
>>     
>>> longitude values in each raster cell, then you could use contourLines to
>>>       
>> get
>>     
>>> lat-lon grid. However, you, probably, will want to smooth it.
>>>
>>>       
>> --
>> Roger Bivand
>> Economic Geography Section, Department of Economics, Norwegian School of
>> Economics and Business Administration, Helleveien 30, N-5045 Bergen,
>> Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
>> e-mail: Roger.Bivand at nhh.no
>>
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>>
>>     
>
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