[R-sig-Geo] Reversed raster after readGDAL()

[Paul Hiemstra]

Hi,

What if you make an spplot, still the same problem?

cheers,
Paul

Agustin Lobo wrote:
> Thanks Sarah. But I think that package sp has an specific method of
> image() for objects SpatialGridDataFrame, which is the class returned
> by readGDAL(), and this specific method takes care of this problem. Check
> image.SpatialGridDataFrame in package {sp}
>
> Agus
>
> 2010/2/10 Sarah Goslee <sarah.goslee at gmail.com>:
>   
>> This may well be too simplistic an answer, but it might just be image().
>>
>> From the help for image:
>>     Notice that ‘image’ interprets the ‘z’ matrix as a table of
>>     ‘f(x[i], y[j])’ values, so that the x axis corresponds to row
>>     number and the y axis to column number, with column 1 at the
>>     bottom, i.e. a 90 degree counter-clockwise rotation of the
>>     conventional printed layout of a matrix.
>>
>> x <- matrix(rep(1:10, each=10), nrow=10)
>> x
>>      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
>>  [1,]    1    2    3    4    5    6    7    8    9    10
>>  [2,]    1    2    3    4    5    6    7    8    9    10
>>  [3,]    1    2    3    4    5    6    7    8    9    10
>>  [4,]    1    2    3    4    5    6    7    8    9    10
>>  [5,]    1    2    3    4    5    6    7    8    9    10
>>  [6,]    1    2    3    4    5    6    7    8    9    10
>>  [7,]    1    2    3    4    5    6    7    8    9    10
>>  [8,]    1    2    3    4    5    6    7    8    9    10
>>  [9,]    1    2    3    4    5    6    7    8    9    10
>> [10,]    1    2    3    4    5    6    7    8    9    10
>> image(x) # not what you might expect
>> image(t(x)) # this view matches the matrix representation
>>
>> What happens if you use plot(mygeotiff) instead of image(mygeotiff)?
>>
>> Sarah
>>
>> On Wed, Feb 10, 2010 at 11:17 AM, Agustin Lobo <alobolistas at gmail.com> wrote:
>>     
>>> I think I tripped on this same stone, but cannot find anything in my
>>> records, perhaps it's on the lost computer.
>>>
>>> The file test2.tif was made by plugin Interpolation in QGIS out of a
>>> vector layer of points with nitrate concentration values, just
>>> a simple inverse distance method. I think that the author f that
>>> pluginis Marco Hugentobler (Marco, sorry if it's not you) to whom I'm
>>> forwarding.
>>>
>>> Relevant info from the metadata in QGIS for this raster:
>>>
>>> Layer Spatial Reference System:
>>> +proj=utm +zone=31 +ellps=intl +units=m +no_defs
>>>
>>> Origin
>>> 424389,4.68549e+06
>>>
>>> Pixel Size:
>>> 279.887,-279.887
>>>
>>> NW corner in QGIS (interactive):424388.820,4685490.931
>>> SW corner in QGIS (interactive):424389.122,4635951.740
>>>
>>> Image with grid: http://sites.google.com/site/eospansite/dummy/test2gridqgis.jpg
>>>
>>> The weird thing is that QGIS uses gdal to read the geotif files.
>>>
>>>
>>> Agus
>>>
>>>       
>> --
>> Sarah Goslee
>> http://www.functionaldiversity.org
>>
>>     
>
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-- 
Drs. Paul Hiemstra
Department of Physical Geography
Faculty of Geosciences
University of Utrecht
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http://intamap.geo.uu.nl/~paul