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

[Andreas H.]

Travis,

yes, thanks, I had already found that in the documentation. I'm just
wondering what e.g. 'bilinear' means when I go from a fine to a coarse
grid? If GDAL works in terms of "nodes", then I would assume 'bilinear'
means interpolation, which in turn would be a very different result from
working in terms of "cells" and then taking e.g. the average of all
"old" cells in the "new" grid.

I hope you see my problem / question.

Thanks for you insight,
Andreas.

Am 14.12.2011 16:35, schrieb Travis Kirstine:
> Andreas,
> 
> Yes gdalwarp support various resampling methods
> 
> To use different resampling methods use the -r flag followed by the method
> 
> eg
> 
> gdalwarp -r near ..............
> gdalwarp -r bilinear .............
> 
> etc...
> 
> 
> 
> 
> On 14 December 2011 08:26, 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.
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>>>
>>
>>
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