Le 17/11/2022 à 16:01, Brendan Heberlein a écrit :
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?
There's no API in GDAL for it. You indeed have to set something like the
following
gt[1] = cos(angle) * pixel_x_size
gt[2] = -sin(angle) * pixel_x_size
gt[4] = sin(angle) * pixel_y_size
gt[5] = cos(angle) * pixel_y_size
I assume the above only works if the origin (gt[0], gt[3]) is the
lower-left corner coordinate, not the upper-one. And I might certainly
have got some signs wrong :-)
Slightly related code in the ENVI driver to transform the rotation angle
from its header file to a geotransform matrix (but conventions might be
slightly different):
https://github.com/OSGeo/gdal/blob/66d9fe0b1a34a8992c804c2444f7f23c2436b937/frmts/raw/envidataset.cpp#L1536
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.roua...@spatialys.com>
*Sent:* Saturday, November 5, 2022 4:36 AM
*To:* Michael Sumner <mdsum...@gmail.com>; Brendan Heberlein
<bheberl...@wisc.edu>
*Cc:* gdal-dev <gdal-dev@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 <bheberl...@wisc.edu
<mailto:bheberl...@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 <mdsum...@gmail.com
<mailto:mdsum...@gmail.com>>
*Sent:* Friday, November 4, 2022 6:57 PM
*To:* Brendan Heberlein <bheberl...@wisc.edu
<mailto:bheberl...@wisc.edu>>
*Cc:* gdal-dev <gdal-dev@lists.osgeo.org
<mailto:gdal-dev@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, <bheberl...@wisc.edu
<mailto:bheberl...@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 <mdsum...@gmail.com
<mailto:mdsum...@gmail.com>>
*Sent:* Friday, November 4, 2022 6:41 PM
*To:* Brendan Heberlein <bheberl...@wisc.edu
<mailto:bheberl...@wisc.edu>>
*Cc:* gdal-dev <gdal-dev@lists.osgeo.org
<mailto:gdal-dev@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@lists.osgeo.org <mailto:gdal-dev@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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