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Does QGIS export/save as use a different projection system/process than gdalwarp? I am working with MASIE ice coverage data available here. My goal is to automate the process of reprojecting the daily images to EPSG 4326; source images are in EPSG 7239. Performing reprojection tests with gdalwarp provided unsatisfactory results, however when the file is manually saved from within QGIS (and providing a CRS of 4326 - see image below) the results are as expected).

My questions are:

  1. Does QGIS Export / Save as CRS projection perform a different reprojection than gdalwarp
  2. To use gdalwarp to achieve the desired output is there an intermediate step(s) required to reproject a raster from EPSG 7239 to EPSG 4326

QGIS Export / Save as with reprojection QGIS Export / Save as with reprojection

QGIS Export / Save as with reprojection results - desired output QGIS manual export reprojection

gdalwarp code used to reproject

gdalwarp -t_srs EPSG:4326 -r near -of GTiff "/Users/ryangarnett/OneDrive - Global Spatial Technology Solutions Inc/Documents/Data/masie_ice/source/masie_ice_r00_v01_2021005_4km.tif" "/Users/ryangarnett/OneDrive - Global Spatial Technology Solutions Inc/Documents/Data/masie_ice/temp/masie_ice_r00_v01_2021005_4km_4326.tif"

gdalwarp reprojection results - unsuccessful output gdalwarp reprojection

UPDATE

Output from gdalinfo based on comment request

Driver: GTiff/GeoTIFF
Files: /Users/ryangarnett/OneDrive - Global Spatial Technology Solutions Inc/Documents/Data/masie_ice/source/masie_ice_r00_v01_2021005_4km.tif
Size is 6144, 6144
Coordinate System is:
PROJCS["Stereographic_North_Pole",
    GEOGCS["WGS 84",
        DATUM["WGS_1984",
            SPHEROID["WGS 84",6378137,298.257223563,
                AUTHORITY["EPSG","7030"]],
            AUTHORITY["EPSG","6326"]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433],
        AUTHORITY["EPSG","4326"]],
    PROJECTION["Polar_Stereographic"],
    PARAMETER["latitude_of_origin",60],
    PARAMETER["central_meridian",-80],
    PARAMETER["scale_factor",1],
    PARAMETER["false_easting",0],
    PARAMETER["false_northing",0],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]]]
Origin = (-12288000.000000000000000,12288000.000000000000000)
Pixel Size = (4000.000000000000000,-4000.000000000000000)
Metadata:
  AREA_OR_POINT=Area
  TIFFTAG_DATETIME=2021:01:06 07:36:19
  TIFFTAG_DOCUMENTNAME=/share/apps/G02186/production/output/geotiff/4km/ice_only/2021/masie_ice_r00_v01_2021005_4km.tif
  TIFFTAG_IMAGEDESCRIPTION=IDL TIFF file
  TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
  TIFFTAG_SOFTWARE=IDL 8.3, Exelis Visual Information Solutions, Inc.
  TIFFTAG_XRESOLUTION=100
  TIFFTAG_YRESOLUTION=100
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (-12288000.000,12288000.000) (145d 0' 0.00"E, 21d29'36.71"S)
Lower Left  (-12288000.000,-12288000.000) (125d 0' 0.00"W, 21d29'36.71"S)
Upper Right (12288000.000,12288000.000) ( 55d 0' 0.00"E, 21d29'36.71"S)
Lower Right (12288000.000,-12288000.000) ( 35d 0' 0.00"W, 21d29'36.71"S)
Center      (   0.0000000,   0.0000000) ( 80d 0' 0.00"W, 90d 0' 0.00"N)
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  • What do you get with gdalinfo "/Users/ryangarnett/OneDrive - Global Spatial Technology Solutions Inc/Documents/Data/masie_ice/source/masie_ice_r00_v01_2021005_4km.tif"? – user30184 Jan 8 at 13:09
  • Thanks for the help, output is too long for the comments, so I will update the question to add the the gdalinfo output – Ryan Garnett Jan 8 at 13:27
  • I could reproduce the issue. Can you meanwhile confirm that with another file gdalwarp -t epsg:4326 masie_ice_r07_v01_2021001_4km.tif warp_test.tif the result is OK? – user30184 Jan 8 at 13:37
  • Sure let me do that – Ryan Garnett Jan 8 at 14:01
  • 1
    EPSG registry epsg.org/search/by-name does not know EPSG:7239. How do you know that it is the code to use? – user30184 Jan 8 at 14:01
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After some more testing and trials a colleague figured a process to make a successful transformation. Reprojecting the raster from 7239 to 9040, and then reproject from 9040 to 4326. This two step approach seems to work exactly as expected.

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