In my project I needed to convert TIFF file to SRTM data and came up with following warning/error.
gdal_translate -of SRTMHGT Terrain.tif Terrain.hgt
Output:
Warning 1: The source projection coordinate system is PROJCS["RGF93 / CC48",GEOGCS["RGF93",DATUM["Reseau_Geodesique_Francais_1993",SPHEROID["GRS 1980",637813
7,298.257222101,AUTHORITY["EPSG","7019"]],TOWGS84[0,0,0,0,0,0,0],AUTHORITY["EPSG","6171"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.017
4532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4171"]],PROJECTION["Lambert_Conformal_Conic_2SP"],PARAMETER["standard_parallel_1",47.25],PARAMETER[
"standard_parallel_2",48.75],PARAMETER["latitude_of_origin",48],PARAMETER["central_meridian",3],PARAMETER["false_easting",1700000],PARAMETER["false_northing"
,7200000],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["X",EAST],AXIS["Y",NORTH],AUTHORITY["EPSG","3948"]]. Only WGS 84 is supported.
The SRTMHGT driver will generate a file as if the source was WGS 84 projection coordinate system.
Warning 1: The corner coordinates of the source are not properly aligned on plain latitude/longitude boundaries.
ERROR 1: Image dimensions should be 1201x1201, 3601x3601 or 1801x3601.
Here is the gdalinfo of the Terrain.tif file.
Driver: GTiff/GeoTIFF
Files: Terrain.tif
Size is 375, 375
Coordinate System is:
PROJCS["RGF93 / CC48",
GEOGCS["RGF93",
DATUM["Reseau_Geodesique_Francais_1993",
SPHEROID["GRS 1980",6378137,298.257222101,
AUTHORITY["EPSG","7019"]],
TOWGS84[0,0,0,0,0,0,0],
AUTHORITY["EPSG","6171"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9122"]],
AUTHORITY["EPSG","4171"]],
PROJECTION["Lambert_Conformal_Conic_2SP"],
PARAMETER["standard_parallel_1",47.25],
PARAMETER["standard_parallel_2",48.75],
PARAMETER["latitude_of_origin",48],
PARAMETER["central_meridian",3],
PARAMETER["false_easting",1700000],
PARAMETER["false_northing",7200000],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["X",EAST],
AXIS["Y",NORTH],
AUTHORITY["EPSG","3948"]]
Origin = (1350983.998099997639656,7223238.974300000816584)
Pixel Size = (2.000000000000000,-2.000000000000000)
Metadata:
AREA_OR_POINT=Point
Image Structure Metadata:
INTERLEAVE=BAND
Corner Coordinates:
Upper Left ( 1350983.998, 7223238.974) ( 1d41'25.74"W, 48d 6'48.59"N)
Lower Left ( 1350983.998, 7222488.974) ( 1d41'23.54"W, 48d 6'24.35"N)
Upper Right ( 1351733.998, 7223238.974) ( 1d40'49.55"W, 48d 6'50.06"N)
Lower Right ( 1351733.998, 7222488.974) ( 1d40'47.35"W, 48d 6'25.82"N)
Center ( 1351358.998, 7222863.974) ( 1d41' 6.54"W, 48d 6'37.21"N)
Band 1 Block=375x5 Type=Float32, ColorInterp=Gray
NoData Value=0
Best Answer
From the GDAL doc:
The output of your
gdal_translate
command is pretty clear. Your data needs to be in WGS84 (epsg 4326), be 1201x1201 (cellsize=0.00083333333) or 3601x3601 (cellsize=0.0002777777) columns x rows in size (1 degree by 1 degree) and have its origin exactly on a a longitude, latitude boundary (i.e 133, 45 not 130.2, 45.6)However, after seeing your edit with
gdalinfo
output, I will say that you won't be able to convert your data to HGT.Well you can, but it will be useless.
The smallest cellsize supported by the HGT driver is 0.0002777777° (~30m) and your data is 2m. You'd need to resample to 30m pixels... Are you sure you need to convert from a standard GeoTIFF format to an unusual format which was designed for a very specific dataset (SRTM) not for general DEMs?