[Gdal-dev] EHdr/ESRI .hdr to read SRTM is no longer working

[Joaquim Luis]

Hi,
The recipe of reading SRTMs by generating a ESRI .hdr file is no longer 
working
with  GDAL1.4 but it does work with 1.3.2
The problem seams to be that data is converted to unsigned short int 
instead of signed short int.

Joaquim Luis


---------------- With GDAL1.4.0

D:\programas\GDALB140\bin>gdalinfo -stats d:\img_samples\N18W071.hgt
Driver: EHdr/ESRI .hdr Labelled
Size is 1201, 1201
Coordinate System is `'
Origin = (-71.000416666666666,19.000416666666666)
Pixel Size = (0.000833333333333,-0.000833333333333)
Corner Coordinates:
Upper Left  ( -71.0004167,  19.0004167)
Lower Left  ( -71.0004167,  17.9995833)
Upper Right ( -69.9995833,  19.0004167)
Lower Right ( -69.9995833,  17.9995833)
Center      ( -70.5000000,  18.5000000)
Band 1 Block=1201x1 Type=UInt16, ColorInterp=Undefined
  Minimum=0.000, Maximum=65535.000, Mean=2873.507, StdDev=11834.425
  NoData Value=-32768

---------------- Now with GDAL1.3.2


D:\programas\GDALB132\bin>gdalinfo -stats d:\img_samples\N18W071.hgt
Driver: EHdr/ESRI .hdr Labelled
Size is 1201, 1201
Coordinate System is `'
Origin = (-71.000417,19.000417)
Pixel Size = (0.00083333,-0.00083333)
Corner Coordinates:
Upper Left  ( -71.0004167,  19.0004167)
Lower Left  ( -71.0004167,  17.9995833)
Upper Right ( -69.9995833,  19.0004167)
Lower Right ( -69.9995833,  17.9995833)
Center      ( -70.5000000,  18.5000000)
Band 1 Block=1201x1 Type=Int16, ColorInterp=Undefined
  Minimum=-39.000, Maximum=2833.000, Mean=459.681, StdDev=572.878
  NoData Value=-32768
  Metadata:
    STATISTICS_MINIMUM=-39
    STATISTICS_MAXIMUM=2833
    STATISTICS_MEAN=459.68081074608
    STATISTICS_STDDEV=572.87797657624

and the header file is

# N18W071.hdr

BYTEORDER     M
LAYOUT        BIL
NROWS       1201
NCOLS       1201
NBANDS        1
NBITS         16
BANDROWBYTES  2402
TOTALROWBYTES 2402
BANDGAPBYTES  0
NODATA        -32768
ULXMAP        -71
ULYMAP        19
XDIM         0.000833333333333
YDIM         0.000833333333333