Re: [gdal-dev] Cannot set simple geotransform
That's great to know, thanks both. Really must get on with that upgrade to GDAL
3...
Thanks,
Jon
-Original Message-
From: gdal-dev On Behalf Of Even Rouault
Sent: 05 February 2020 18:31
To: gdal-dev@lists.osgeo.org
Subject: Re: [gdal-dev] Cannot set simple geotransform
> It's a known bug. There is some analysis at
> https://github.com/mapbox/rasterio/issues/524#issuecomment-156655258.
Actually, is a *past* known bug, at least for the GTiff driver
From GDAL 2.3.0 news:
* make it accept to write SetGeoTransform([0,1,0,0,0,1]) as a
ModelTransformationTag, and remove particular cases with the [0,1,0,0,0,1]
geotransform (#1683)
This fix also fixes (0,1,0,0,0,-1)
>>> from osgeo import gdal
ds=gdal.GetDriverByName('GTiff').Create('/tmp/test.tif',5,5,1,gdal.GDT_Byte)
>>> ds=gdal.GetDriverByName('GTiff').Create('/tmp/test.tif',
5,5,1,gdal.GDT_Byte)
>>> ds.GetGeoTransform()
(0.0, 1.0, 0.0, 0.0, 0.0, 1.0)
>>> ds.SetGeoTransform((0,1,0,0,0,-1))
0
>>> del ds
>>> ds=gdal.OpenEx('/tmp/test.tif',gdal.GA_Update)
>>> ds.GetGeoTransform()
(0.0, 1.0, 0.0, 0.0, 0.0, -1.0)
>>>
--
Spatialys - Geospatial professional services http://www.spatialys.com
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Re: [gdal-dev] Cannot set simple geotransform
> It's a known bug. There is some analysis at
> https://github.com/mapbox/rasterio/issues/524#issuecomment-156655258.
Actually, is a *past* known bug, at least for the GTiff driver
From GDAL 2.3.0 news:
* make it accept to write SetGeoTransform([0,1,0,0,0,1]) as a
ModelTransformationTag, and remove particular cases with the [0,1,0,0,0,1]
geotransform (#1683)
This fix also fixes (0,1,0,0,0,-1)
>>> from osgeo import gdal
ds=gdal.GetDriverByName('GTiff').Create('/tmp/test.tif',5,5,1,gdal.GDT_Byte)
>>> ds=gdal.GetDriverByName('GTiff').Create('/tmp/test.tif',
5,5,1,gdal.GDT_Byte)
>>> ds.GetGeoTransform()
(0.0, 1.0, 0.0, 0.0, 0.0, 1.0)
>>> ds.SetGeoTransform((0,1,0,0,0,-1))
0
>>> del ds
>>> ds=gdal.OpenEx('/tmp/test.tif',gdal.GA_Update)
>>> ds.GetGeoTransform()
(0.0, 1.0, 0.0, 0.0, 0.0, -1.0)
>>>
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Re: [gdal-dev] Cannot set simple geotransform
Hi Jon,
On Wed, Feb 5, 2020 at 10:15 AM Jon Morris wrote:
> I've just spent most of the afternoon banging my head against the desk
> because it appears that you cannot set a geotransform of (0, 1, 0, 0, 0,
> -1). Any other value works fine, but with this particular GT, the change is
> not saved when you close the ds. Is this a known issue? I'm using GDAL
> 2.2.0 on Python 3.6.8.
>
>
>
> IPython console:
>
>
>
> In [269]:
> ds=gdal.GetDriverByName('GTiff').Create('/tmp/test.tif',5,5,1,gdal.GDT_Byte)
>
>
>
>
> In [270]:
> ds.GetGeoTransform()
>
>
> Out[270]: (0.0, 1.0, 0.0, 0.0, 0.0, 1.0)
>
>
>
> In [271]:
> ds.SetGeoTransform((0,1,0,0,0,-1))
>
>
> Out[271]: 0
>
>
>
> In [272]: del ds
>
>
>
>
> In [273]:
> ds=gdal.OpenEx('/tmp/test.tif',gdal.GA_Update)
>
>
>
>
> In [274]:
> ds.GetGeoTransform()
>
>
> Out[274]: (0.0, 1.0, 0.0, 0.0, 0.0, 1.0)
>
>
>
> In [275]:
> ds.SetGeoTransform((0,1,0,0,0,-1.1))
>
>
> Out[275]: 0
>
>
>
> In [276]: del
> ds
>
>
>
>
> In [277]:
> ds=gdal.OpenEx('/tmp/test.tif',gdal.GA_Update)
>
>
>
>
> In [278]:
> ds.GetGeoTransform()
>
>
> Out[278]: (0.0, 1.0, 0.0, 0.0, 0.0, -1.1)
>
>
>
>
>
>
>
> Thanks,
>
>
>
> Jon
>
>
It's a known bug. There is some analysis at
https://github.com/mapbox/rasterio/issues/524#issuecomment-156655258.
Briefly: depending on the format driver, setting the geotransform can be a
no-op if the given transform is ~= the identity transform. For GeoTIFF,
both (0, 1, 0, 0, 0, 1) and (0, 1, 0, 0, 0, -1) are considered to be ~=
identity and are invalid inputs that are ignored.
--
Sean Gillies
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