[gdal-dev] How to specify 'OUTPUT' when warping (reproject)

[afernandez at odyhpc.com]

Hi Ky,
I'm beginning to understand this a bit better. My original code actually 
passed the raster layer per se (rather than the tiff file) so that 
explains the previous error. After fixing it, QGIS is now reprojecting 
into the new CRS but, for some reason that I still need to troubleshoot, 
it's cropping the western side of the layer (the central and eastern 
side are fine) -this is hard to explain with words but easy to see with 
images-. Will let you know if any other issue comes up or if it finally 
works as anticipated.
Thanks.

On 2025-10-04 00:29, ky wrote:
> I believe you should check what is inside my_input_raster_layer, there
> should be a path to a input raster file like
> 
> gdal.Warp("output.tif", "input.tif", options=options)
> 
> On Fri, Oct 3, 2025 at 7:44 PM AF via gdal-dev
> <gdal-dev at lists.osgeo.org> wrote:
> 
>> Hi Nyall,
>> It was a typo (pretty clumsy at my end) as it should have read
>> 'my_input_raster_layer' rather than 'my_input_vector_layer.' The
>> source/input layer is a raster.
>> Thanks.
>> 
>> On 2025-10-03 21:30, Nyall Dawson wrote:
>>> On Sat, 4 Oct 2025, 2:00 am AF via gdal-dev,
>>> <gdal-dev at lists.osgeo.org> wrote:
>>> 
>>>> Hello,
>>>> A PyQGIS code needs to reproject one raster layer from a CRS to a
>>>> new
>>>> one. To begin with, I've tried to use only the minimal required
>>>> options
>>>> so the snippet reads:
>>>> parameters = {
>>>> 'INPUT': my_input_vector_layer,
>>> 
>>> Not sure if this is a typo (or a badly named variable, or ai slop
>>> code), but it looks like you're trying to warp a vector later to a
>>> raster layer? 🤔
>>> 
>>> Nyall
>>> 
>>>> 'SOURCE_CRS':
>>>> QgsCoordinateReferenceSystem(source_PROJ),
>>>> 'TARGET_CRS':
>>>> QgsCoordinateReferenceSystem(target_PROJ),
>>>> 'RESAMPLING': 1,
>>>> 'DATA_TYPE': 4,
>>>> 'OUTPUT': '/home/ubuntu/my_new_raster.tif'
>>>> }
>>>> terrain = processing.run('gdal:warpreproject',
>>>> parameters)
>>>> However, this doesn't do much as terrain is simply a dictionary
>> with
>>>> the
>>>> keyword 'OUTPUT' and my_new_raster.tif is never created.
>> Obviously I
>>>> 
>>>> must be doing something wrong and suspect that might be related
>> to
>>>> 'OUTPUT'. The documentation at
>>>> 
>>> 
>> 
> https://docs.qgis.org/testing/en/docs/user_manual/processing/toolbox.html#output-parameter-widget
>>>> 
>>>> didn't dissipate my doubts so I'm unsure how to proceed.
>>>> I also tried (an alternative method) calling gdal.Warp directly
>> (not
>>>> 
>>>> sure if this method is preferable to using processing.run) but it
>>>> keeps
>>>> saying that it only takes 2 arguments. I found a few examples
>> online
>>>> but
>>>> they all have more than 2 arguments. For example
>>>> options = gdal.WarpOptions(dstSRS=target_PROJ)
>>>> warp = gdal.Warp('/home/ubuntu/pepe.tif',
>>>> my_input_vector_layer, options)
>>>> warp = None
>>>> complains about including 3 and not 2 arguments. Same if I try
>>>> including
>>>> all arguments at warp.
>>>> Thanks.
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