Thanks Robert, I still haven't explored raster enough.
I tried as.matrix(projras) - have you considered adding methods like
this? I'm afraid I still don't know the structure of the raster data
sets enough to know if that makes sense, but I think sp returns
another orientation in this way:
as.matrix(spprojras)
Cheers, Mike.
On Thu, Oct 28, 2010 at 9:54 AM, Robert J. Hijmans <r.hijm...@gmail.com> wrote:
> After this:
>
>> projras <- projectRaster(r0, pr)
>
> You could also do plot(projras) or image(projras) and
>
> v <- getValues(projras, format='matrix')
>
> To get a matrix of values, with the advantage that values in this
> matrix are organized as on the map (probably what you would expect),
> which is different in matrix 'm' in Mike's example.
>
> Robert
>
> On Wed, Oct 27, 2010 at 2:16 PM, Michael Sumner <mdsum...@gmail.com> wrote:
>> This is a dummy example - especially in terms of made up coordinate
>> system details, but shows how you can reproject with the raster
>> package:
>>
>> library(rgdal)
>>
>> ## create a grid, with dummy coordinates / projection
>>
>> im <- image2Grid(list(x = 1e5 * (1:nrow(volcano)), y = 1e5 *
>> (1:ncol(volcano)), z = volcano), p4 = "+proj=laea")
>>
>> writeGDAL(im, "dummy.tif")
>>
>> ## now the process, using raster package
>>
>> library(raster)
>>
>>
>> r0 <- raster("dummy.tif")
>>
>> # proj.4 projection description
>> newproj <- "+proj=longlat +ellps=WGS84"
>>
>> pr <- projectExtent(r0, newproj)
>> ## (optionally) Adjust the cell size
>> ## res(pr) <- res(pr)/2
>>
>>
>> # project the values of RasterLayer 'r' to the new RasterLayer 'projras'
>> projras <- projectRaster(r0, pr)
>>
>> ## now go back to sp and extract matrix
>>
>> spprojras <- as(projras, "SpatialGridDataFrame")
>>
>> m <- as.image.SpatialGridDataFrame(spprojras)$z
>>
>> image(m)
>>
>>
>> I'm not sure if the coercion to SpatialGridDataFrame will
>> automatically give you all of the detail in the source by default for
>> large grids, but there would be a way.
>>
>> Cheers, MIke.
>> On Wed, Oct 27, 2010 at 7:03 PM, <fsan...@ujaen.es> wrote:
>>> Dear R community,
>>>
>>> I'm sorry, but I am newbie with GIS. I have to import a tiff using a
>>> geotiff tool, and convert it into a data matrix. The initial projection is
>>> Lambert Azimuthal Equal Area, and I would like to get the final matrix in
>>> a regular lat/lon grid.
>>>
>>> It is possible to do it with R?
>>>
>>> Thanks in advance.
>>>
>>> _______________________________________________
>>> R-sig-Geo mailing list
>>> R-sig-Geo@stat.math.ethz.ch
>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>>
>>
>>
>>
>> --
>> Michael Sumner
>> Institute for Marine and Antarctic Studies, University of Tasmania
>> Hobart, Australia
>> e-mail: mdsum...@gmail.com
>>
>> _______________________________________________
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>> R-sig-Geo@stat.math.ethz.ch
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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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