-
> The opinions I express are my own and are not representative of the
> official policy of the U.S.Fish and Wildlife Service or Dept. of the
> Interior. Life is too short for undocumented, proprietary data formats.
>
>
> *Tim Keitt *
> Sent by: gdal-
rg
Subject
Re: [gdal-dev] re-gridding to a coarser grid
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).
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 o
Sorry for the noise that I introduced by mixing the GDAL and GMT's
lists. I already replied to Andreas only because I though my message
went only to him, but since it didn't here is a copy of it.
Joaquim
"
Andreas,
I'm very sorry but I sent that message to you by mistake as it was meant
as a
Andreas
I think thats referring to my suggestion of GMT to do part of the work
On Thu, 2011-12-15 at 14:00 +0100, Andreas H. wrote:
> Joaquim,
>
> > nearneighbor is not really a good thing to use. Grid it with surface.
>
> What do you mean by "grid it with surface"? In my GDAL (1.8.1), I o
Joaquim,
> nearneighbor is not really a good thing to use. Grid it with surface.
What do you mean by "grid it with surface"? In my GDAL (1.8.1), I only
have the following choices:
Available resampling methods:
near (default), bilinear, cubic, cubicspline, lanczos.
thanks for your insi
Hi,
gdaladdo [1] provides some more interpolation methods. It is designed
specifically for down-sampling.
To create a new GeoTIFF, use it with the -ro option and the levels set to
2,4,8 and 15.
The value 15 makes sure you get an overview at 1/15 th of the original
resolution.
[1]: http://www.gdal
The only option that you do *not* have is "mode" (the dominant value),
which can be useful in the case of categorical (integer) data. That
question has been answered here:
http://www.osgeo.org/pipermail/gdal-dev/2011-August/029692.html
On Wed, Dec 14, 2011 at 1:35 PM, Travis Kirstine
wrote:
> A
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
worki
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. wrote:
> Travis,
>
> thanks for your answe
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
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 r
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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