[GRASS-user] Re: r.in.gdal oddity

[Brian Oney]

Hi Markus M,
Thanks, it works. Cooking with gas now.

It is still odd though. It is not just an imprecision I am afraid. When 
I said "skinny", I was being modest.
If you look a bit closer, it is not a minor error in import. The map 
(and the rest as well) is w=-180 e=-179.999... and north and south are 
normal. It should have a global extent.

A bit of additional info: when the location lacks a projection, I don't 
have problems.

Anyways, I appreciate the help.

Cheers,
Brian




On 10/31/2011 09:15 AM, Markus Metz wrote:
> Helmut Kudrnovsky wrote:
>>> I am importing worldclim .asc files from the ipcc4 simulations
>>> (http://ccafs-climate.org/). These are latlong files with a global
>>> extent. I have compiled grass 6.4.2svn from source on ubuntu 11.10 and
>>> hope that I did everything correctly, according to the wiki.
>>>
>>> When importing, here is what I do and what happens:
>>>
>>> r.in.gdal -o input="/D/Documents/Spatial_Datasets/Climate/WorldClim/\
>>> hccpr_hadcm3_a2a_2020s_prec_2_5min_asc/prec_10.asc" output="prec_10"
>> tested here with
>> http://ccafs-climate.org/data/A2a_2020s/hccpr_hadcm3/hccpr_hadcm3_a2a_2020s_prec_2_5min_asc.zip
>>
>> gdalinfo hccpr_hadcm3_a2a_2020s_prec_2_5min.asc
>>
>> Driver: AAIGrid/Arc/Info ASCII Grid
>> Files: prec_10.asc
>> Size is 8640, 3600
>> Coordinate System is `'
>> Origin = (-180.000000000000000,90.000000000119996)
>> Pixel Size = (0.041666666666700,-0.041666666666700)
>> Corner Coordinates:
>> Upper Left  (-180.0000000,  90.0000000)
>> Lower Left  (-180.0000000, -60.0000000)
>> Upper Right ( 180.0000000,  90.0000000)
>> Lower Right ( 180.0000000, -60.0000000)
>> Center      (   0.0000000,  15.0000000)
>> Band 1 Block=8640x1 Type=Int32, ColorInterp=Undefined
>>   NoData Value=-9999
>>
> There is a tiny precision loss:
> Origin = (-180.000000000000000,90.000000000119996)
> Pixel Size = (0.041666666666700,-0.041666666666700)
> should be
> Origin = (-180.000000000000000,90.000000000000000)
> Pixel Size = (0.041666666666667,-0.041666666666667)
>
> pixel size is now as close as possible to 2.5 min.
>
> This is neither a gdal nor a grass bug, but a bug of the software used
> to produce these data.
>
> This can easily be fixed with e.g.
> gdal_translate -a_ullr -180 90 180 -60 prec_1.asc prec_1.tif
>
> then import the corrected tif.
>
> HTH,
>
> Markus M
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