[gdal-dev] re-gridding to a coarser grid

[Tim Keitt]

If you need complete control, and your data are not too massive in
number, I have had good results pushing pixel coordinates as points
into postgis and then using spatial queries to aggregate in various
ways (eg averages a hexagonal grid). It seems round-about, but it
works. I've actually done it on some pretty massive grids.

THK

On Wed, Dec 14, 2011 at 7:26 AM, Andreas H. <lists at hilboll.de> wrote:
> Travis,
>
> thanks for your answer!
>
> Regarding the resampling methods: Do they all just interpolate the data? I
> mean, when downsampling, usually I would use mean() or something similar
> to fill the new (coarser) grid cells. Doas gdalwarp actually do this and
> I'm not able to understand the documentation, or is it different?
>
> Thanks again!
> Andreas.
>
>
>> Andreas,
>>
>> gdalwarp can be used to resample images using the -tr flag or -ts flag.
>>
>> For example resample 1m image to 10m using cubic resampling and
>> "target resolution'
>>
>> gdalwarp -r cubic -tr 10 10 input_1m.tif output_10m.tif
>>
>> You may have an issue determining the output resolution as I believe
>> the resolution will be in decimal degrees rather than arc-seconds.
>>
>> Regards
>>
>> On 13 December 2011 14:52, Andreas H. <lists at hilboll.de> wrote:
>>> Hi,
>>>
>>> let's say I have a GeoTIFF file with a global grid in a 30 arc-second
>>> resolution. Which would be the appropriate GDAL command to spatially
>>> down-sample this file to say 0.125°?
>>>
>>> Thanks for your insight,
>>> Andreas.
>>> _______________________________________________
>>> gdal-dev mailing list
>>> gdal-dev at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/gdal-dev
>>
>
>
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-- 
Timothy H. Keitt
http://www.keittlab.org/