#4198 closed defect (fixed)
Incorrect management of lambert 2 étendu (EPSG:27572) in gdal tools
Reported by: | tbouffon | Owned by: | warmerdam |
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Priority: | normal | Milestone: | |
Component: | Utilities | Version: | 1.8.0 |
Severity: | normal | Keywords: | |
Cc: |
Description
Hi, I have a few problems with the handling of lambert projected grids: Starting from a lambert 2 x,y,z file france.csv, I create a GMT grid with xyz2grd (see attached). This file does not have a coordinate system, so I add one with gdal_translate -a_srs . Three possibilities :
- gdal_translate france.grd -a_srs EPSG:27572 file1
- gdal_translate france.grd -a_srs '+proj=lcc +lat_1=46.8 +lat_0=46.8 +lon_0=2.337229166666667 +k_0=0.99987742 +x_0=600000 +y_0=2200000 +a=6378249.2 +b=6356515 +towgs84=-168,-60,320,0,0,0,0 +units=m +no_defs' file2
- gdal_translate france.grd -a_srs '+proj=lcc +lat_1=46.8 +lat_0=46.8 +lon_0=0 +k_0=0.99987742 +x_0=600000 +y_0=2200000 +a=6378249.2 +b=6356515 +towgs84=-168,-60,320,0,0,0,0 +units=m +no_defs +pm=paris' file3
If I run gdalinfo :
- file1 has odd geographic corners, I could not find any reason for them
- file2's corners lat/lon are shifted because the prime meridian are ignored
- file3's corners lat/lon are right
Verification is done thanks to cs2cs, because invproj ignores pm
If I gdalwarp these files to EPSG:4326 :
- file1 is shifted south by ~ 10°
- file2 is ok
- file3 is ok
If I use s_srs EPSG:27572 the result is ok in every case.
Attachments (1)
Change History (4)
by , 13 years ago
Attachment: | france.grd.gz added |
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comment:1 by , 9 years ago
I can confirm the odd results with GDAL 1.11.1 The EPSG file in the proj directory has the following line for 27572.
27572> +proj=lcc +lat_1=46.8 +lat_0=46.8 +lon_0=0 +k_0=0.99987742 +x_0=600000 +y_0=2200000 +a=6378249.2 +b=6356515 +towgs84=-168,-60,320,0,0,0,0 +pm=paris +units=m +no_defs <>
What is odd it that these two commands lead to different lat-lon corners:
gdal_translate france.grd -a_srs EPSG:27572 file1.tif gdal_translate france.grd -a_srs "+proj=lcc +lat_1=46.8 +lat_0=46.8 +lon_0=0 +k_0=0.99987742 +x_0=600000 +y_0=2200000 +a=6378249.2 +b=6356515 +towgs84=-168,-60,320,0,0,0,0 +pm=paris +units=m +no_defs" file2.tif
File1:
Upper Left ( 47500.000, 2676500.000) ( 7d56'33.24"W, 51d19'48.97"N)
File2:
Upper Left ( 47500.000, 2676500.000) ( 7d50'10.83"W, 50d50' 2.61"N)
lambert2 france grid