[Gdal-dev] HDF Georeference

[Carl Anderson]

On 12/04/2004 01:29:17 AM, wlx wrote:
> Hi,
>     My gdal is the latest cvs version(1.2.5),and my hdf4 dirver is  
> the
> second way that you mentioned, if this new hdf4 driver can not  
> support
> ASTEr L1b's georeference?
>

GDAL 1.2.0 has the old driver. GDAL 1.2.1 and later use the newer  
HDF4_EOS driver.

you can compile GDAL 1.2.0 or use the precompiled version in
OpenEV_FW 1.7.2 or use HEGTools to convert the HDF to a GeoTiff.

IIRC there was a discussion the the HDF4_SDS driver did not properly  
(with enough detail and precision) handle the transformation of the  
image using the GCPs in the HDF file.

so you might want to wait for the HDF4_EOS driver to be completed.

I personally find that the HEGTools introduces unwanted artifacts of  
another kind.

I have created 3 GeoTiffs as a sample of the handling in HEG and GDAL  
1.2.0   ( at http:/wms.co.fulton.ga.us/data/gdal/ )

to create the images I started with
  AST_L1B_00311012004163458_11122004131831.hdf
 and created
   http:/wms.co.fulton.ga.us/data/gdal/aster_heg.tif
          with HEGTools and used
          gdal_translate -projwin -86.94204 34.24418 -86.91528 34.21796
          to make a sample of the middle of the image
   http:/wms.co.fulton.ga.us/data/gdal/aster_trans.tif
          with gdal_translate (from GDAL 1.2.0)
          and then used gdal_translate -srcwin 1369 2583 225 220
          to make a sample of the middle of the image
   http:/wms.co.fulton.ga.us/data/gdal/aster_warp
          with gdalwarp (from GDAL 1.2.0) and then used
          gdal_translate -projwin -86.94204 34.24418 -86.91528 34.21796
          to make a sample of the middle of the image

certainly there are small displacements of pixels, comparing the three  
samples but the banding produced by HEGTools is visually distracting.

C.


>      Best regards,
> 
> LiangXu Wang
> 
> > On 12/02/2004 07:16:01 AM, wlx wrote:
> > > Hi all,
> > >      In the hdf4 format
> > >
> > homepage(http://www.remotesensing.org/gdal/frmt_hdf4.html),it
> > is sayed
> > > that gdal can support ASTER L1B data's georeference.
> > >     When I use gdal_translate utility to translate a ASTER's
> > > subdataset to a geotiff file,I find the geotiff file
> > include nothing
> > > about georefence.
> > >
> >
> > I do know that the HDF driver has been redone and works
> > differently in recent GDAL versions
> >
> > the old driver was
> >    HDF4_SDS:ASTER_L1B:
> >
> >
> > checking with gdalinfo recent GDAL version
> >    HDF4_EOS:EOS_SWATH:
> > is the driver for ASTER L1B file
> >
> > revert back to
> >   OpenEV_FW 1.7.2  (which ises the HDF4_SDS dirver) or
> > download HEG from
> >   http://eosweb.larc.nasa.gov/PRODOCS/misr/tools/geotiff_tool.html
> >   and run HEG on the HDF to produce georegistered bands as tiffs.
> >
> >
> > I have not had an opportunity to compare the results of
> > HEGtools and  the older HDF_SDS driver.
> >
> > If you get a chance to compare them
> >    is there any pixel shift between the two methods or are
> > they functionally equivalent.
> >
> >
> > C.
> >
> > carl anderson
> > GIS Manager
> > Fulton County Georgia
> >
> >
> >
> 
> 
> 
>