[R-sig-Geo] gdalwarp gives different cellsize when re-projected

[Swagath]

Hello,

Thank you very much for your reply. After some careful reading about 
GDAL i was able to change the resolution once i re-projected the grid.

i used the following command

gdalwarp outfile2.tif outfile3.tif -tr 0.05 0.05

outfile2.tif-0.065 resolution
outfile3.tif-0.05 resolution

Thanks,
Navin

On 3/7/13 2:52 PM, Alexandre Villers wrote:
> Hello,
>
> Well, given you went from a projected to a geographic coordinates
> system, you changed the unit of the grid from meters to degrees.
> So I wouldn't be surprised and I guess nothing went wrong as long you
> specified the correct EPSG for your original file.
>
> HTH
>
> Alex
>
> On 07/03/2013 15:29, Swagath Navin wrote:
>> Dear all,
>>
>> I have a large data-frame with Lon, Lat , Value . Coordinates
>> projected in EPSG:3035 with a resolution of 5 kmx5 km. I converted
>> this into a SGDF. My goal was to project the file into EPSG:4326 with
>> a resolution of 0.05. For re-projecting  i converted the file to tif
>> using
>>
>> writeGDAL(df, "file.tif")
>>
>> and used the gdalwarp
>>
>> gdalwarp file.tif outfile.tif -t_srs "+init=epsg:4326"
>>
>> However while comparing both files the cell size is different.
>>
>> getGridTopology(file1)
>>                         x       y
>> cellcentre.offset 2638500 1430500
>> cellsize             5000    5000
>> cells.dim             664     797
>> projargs: chr " +proj=laea +lat_0=52 +lon_0=10 +x_0=4321000
>> +y_0=3210000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs"
>>
>> getGridTopology(file2)
>>                            x            y
>> cellcentre.offset  -31.31150705  34.11186136
>> cellsize             0.06515996   0.06515996
>> cells.dim         1254.00000000 580.00000000
>>
>> projargs: chr " +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84
>> +towgs84=0,0,0"
>>
>> Can anyone please tell me where it went wrong.
>>
>> Thanks for your time.
>>
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>>
>
>