On Thu, 15 Jul 2021, Hill, David Foster wrote:
Hello. I asked this question a few weeks ago, but I think my
question was not complete enough, and I also think I did not attach
the right files. So, I would like to try again, if that is ok.
I note that your earlier message said:
The version is: GDAL 1.11.4, released 2016/01/25
I can reproduce your results with one of your files, with GDAL v1.11.5
but not with v1.9.2, v2.4.4 or 3.3.1.
Given that v1.anything is ancient, I suggest that you move to GDAL version 3.
I have a .nc file. When I do:
ncdump -c <file.nc>
I can inspect the coordinates in the x and y directions. When I do
this, it shows the x vector correctly as: 487200,
487300,âŠ625300. And it shows the y vector correctly as 4690100,
4690200,âŠ4937600. My file is in projected (EPSG:32612) coords.
Next, I use gdal_translate to change .tif. I do this as:
gdal_translate -of GTiff <file.nc> <file.tif>
This is my question â> after converting to tif, I can look at the header info
with gdalinfo. When I do this, I see:
****
Corner Coordinates:
Upper Left ( 486790.000, 4937650.000)
Lower Left ( 486790.000, 4690050.000)
Upper Right ( 624990.000, 4937650.000)
Lower Right ( 624990.000, 4690050.000)
Center ( 555890.000, 4813850.000)
****
The y coord of lower left is 4690050âŠcompare that to the info above
about the .nc file. I think this is ok. It is 50m
different. Presumably, ncdump is reporting on the coords of grid
centers and gdalinfo is reporting on boundaries (1/2 a grid cell
difference), so it is 50 m less. Fine. BUT, look at the x coord of
the lower left grid cell. It is 486790, compared to 487200 in the
netcdf file. In other words, the x coord of the tif file is like 410
m less than the netcdf file. I am very confused about the difference
in the x coordinate vector between the .nc and the .tif files.
Is there a different way that I should be using gdal_translate to
avoid this 400 m âoffsetâ? I can certainly override the limits with
-a_ullr, and that works fine, and gives me the expected coordinate
values and 100 m grid resolution, etc. However, that does not seem
like the most elegant solution.
Dave.
files here:
https://drive.google.com/drive/folders/1CclJGBj_L_Z-9hq_Xkse0ARKDdnNvKZJ?usp=sharing
<https://drive.google.com/drive/folders/1CclJGBj_L_Z-9hq_Xkse0ARKDdnNvKZJ?usp=sharing>
--
Andrew C. Aitchison Kendal, UK
and...@aitchison.me.uk_______________________________________________
gdal-dev mailing list
gdal-dev@lists.osgeo.org
https://lists.osgeo.org/mailman/listinfo/gdal-dev
