[Gdal-dev] ArcGrid to IMG conversion: huge file

[Markus Neteler]

Hi,

when converting the
  Landscan Global Population 2000 Database
from
  http://www.fao.org/geonetwork/srv/en/metadata.show?id=1261

which is
  504K    ./info
  167M    ./pop2000
big, a resulting IMG file becomes:
  3.5G    pop2000.ige
  8.0K    pop2000.img
which is pretty much more (for free :-)

I used to convert
 gdal_translate -of HFA pop2000 pop2000.img

Here the gdalinfo output:

gdalinfo -mm pop2000
Driver: AIG/Arc/Info Binary Grid
Size is 43200, 21120
Coordinate System is `'
Origin = (-180.000000,86.000000)
Pixel Size = (0.00833333,-0.00833333)
Corner Coordinates:
Upper Left  (-180.0000000,  86.0000000)
Lower Left  (-180.0000000, -90.0000000)
Upper Right ( 180.0000000,  86.0000000)
Lower Right ( 180.0000000, -90.0000000)
Center      (  -0.0000000,  -2.0000000)
Band 1 Block=256x4 Type=Int32, ColorInterp=Undefined
  Min=0.000 Max=159004.000   Computed Min/Max=0.000,159004.000
  NoData Value=-2.14748e+09

gdalinfo -mm pop2000.img
Driver: HFA/Erdas Imagine Images (.img)
Size is 43200, 21120
Coordinate System is:
LOCAL_CS["Unknown",
    UNIT["meters",1]]
Origin = (-180.000000,86.000000)
Pixel Size = (0.00833333,-0.00833333)
Corner Coordinates:
Upper Left  (-180.0000000,  86.0000000)
Lower Left  (-180.0000000, -90.0000000)
Upper Right ( 180.0000000,  86.0000000)
Lower Right ( 180.0000000, -90.0000000)
Center      (  -0.0000000,  -2.0000000)
Band 1 Block=64x64 Type=Int32, ColorInterp=Undefined
  Description = Layer_1
    Computed Min/Max=-2147483647.000,159004.000
  Metadata:
    LAYER_TYPE=athematic

Apparently the NoData isn't passed to IMG.
Is the created IMG file probably uncompressed
which leads to this big file size?

Best regards

 Markus