[gdal-dev] Specify Grid Rotation for gdal.Warp() with Geolocation Arrays

[Brendan Heberlein]

Thank you, Mike & Even.

Supposing I wanted to have the output grid origin & dimensions computed automatically, but with a specified rotation angle, is that possible?

Anyway I can calculate these parameters myself, so it is not a big issue. Your suggestion worked for me.

Cheers!
Brendan

________________________________
From: Even Rouault <even.rouault at spatialys.com>
Sent: Saturday, November 5, 2022 4:36 AM
To: Michael Sumner <mdsumner at gmail.com>; Brendan Heberlein <bheberlein at wisc.edu>
Cc: gdal-dev <gdal-dev at lists.osgeo.org>
Subject: Re: [gdal-dev] Specify Grid Rotation for gdal.Warp() with Geolocation Arrays



Le 05/11/2022 à 04:33, Michael Sumner a écrit :
yes I see, well you can probably set a target GeoTIFF with the geotransform that you want - and gdalwarp to that as the target.

something like

out_ds = gdal.GetDriverByName("GTiff").Create("output.tif", width, height, number_of_bands, data_type, options = ["TILED=YES"])

out_ds.SetGeoTransform([ some geotransform with rotational terms ])

srs = osr.SpatialReference()

srs.ImportFromEPSG( xxx ) / srs.ImportFromWkt( xxx )

out_ds.SetSpatialRef( srs )

gdal.Warp(out_ds, src_ds, .... )



I don't believe you can do that with gdalwarp directly, and I have no idea with python - and finally I'm sorry to add irrelevant discussion - but this is interesting and I'm going to try it out in R and C++ and would love to see a python example too.

Cheers, Mike





On Sat, Nov 5, 2022 at 2:21 PM Brendan Heberlein <bheberlein at wisc.edu<mailto:bheberlein at wisc.edu>> wrote:
Hi Mike,

regardless of the map projection, it may be desirable to have the grid oriented in one direction or another, e.g. due to the spatial distribution of data points. Although the CRS/SRS designates the coordinate axes, these are not always aligned with the desired grid orientation.

So, basically I want to be able to specify an arbitrary geotransform array for the output grid. This would allow the grid to be assigned an arbitrary orientation within the CRS frame.

Thanks,
Brendan
________________________________
From: Michael Sumner <mdsumner at gmail.com<mailto:mdsumner at gmail.com>>
Sent: Friday, November 4, 2022 6:57 PM
To: Brendan Heberlein <bheberlein at wisc.edu<mailto:bheberlein at wisc.edu>>
Cc: gdal-dev <gdal-dev at lists.osgeo.org<mailto:gdal-dev at lists.osgeo.org>>
Subject: Re: [gdal-dev] Specify Grid Rotation for gdal.Warp() with Geolocation Arrays

well, the map projection does this - there are many possibilities. Or, do you have another geolocation array you want as the target?

If you have an example I'm happy to try a few things, but I'd assumed you had a target map projection in mind. What kind of crs to choose depends on your goal, or is purely to not have north up?

Perhaps there's something terminology wise I'm missing ...

Mike

On Sat, 5 Nov 2022, 10:50 Brendan Heberlein, <bheberlein at wisc.edu<mailto:bheberlein at wisc.edu>> wrote:
Hi Mike,

thanks for the response.

Can you clarify how I would go about specifying the grid orientation for the output raster? None of -te, -ts or -t_srs address this.


________________________________
From: Michael Sumner <mdsumner at gmail.com<mailto:mdsumner at gmail.com>>
Sent: Friday, November 4, 2022 6:41 PM
To: Brendan Heberlein <bheberlein at wisc.edu<mailto:bheberlein at wisc.edu>>
Cc: gdal-dev <gdal-dev at lists.osgeo.org<mailto:gdal-dev at lists.osgeo.org>>
Subject: Re: [gdal-dev] Specify Grid Rotation for gdal.Warp() with Geolocation Arrays

that's exactly what the warper does with geolocation arrays, set the target extent, dimension, and crs with -te, -ts, -t_srs with gdalwarp.

python will have those analogous controls for the warper.

Cheers, Mike



On Sat, 5 Nov 2022, 01:23 Brendan Heberlein via gdal-dev, <gdal-dev at lists.osgeo.org<mailto:gdal-dev at lists.osgeo.org>> wrote:
Hello,

I would like to be able to warp an image dataset using a geolocation array, while specifying the grid to which the output dataset is sampled. Specifically, I want to be able to warp the dataset to a grid which is not oriented North-up.

Can GDAL support this currently? Or, what is the likelihood this could be supported in the future?

I primarily rely on the Python bindings, so a solution within that framework would be ideal for me.

Thanks!
     — Brendan


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Michael Sumner
Software and Database Engineer
Australian Antarctic Division
Hobart, Australia
e-mail: mdsumner at gmail.com<mailto:mdsumner at gmail.com>



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