[Gdal-dev] gdalwarp

[Frank Warmerdam]

Norman Barker wrote:
> Hi,
> 
> thanks for the reply I have run gdalwarp on some geotiffs and it is
> successful, and on others it fails or returns a black image (with a sample
> landsat image).

Norman,

You will need to provide sample images for me to look into this problem.

> Also I have noticed the output of gdalwarp has to be viewed with a proper
> geotiff reader such as Erdas ViewFinder rather than the default tiff readers
> that come with Windows XP?

GDAL by default produces band interleaved (PLANARCONFIG_SEPERATE in TIFF
terminology) files when more than one band is being output.  These may be
unsupported by the WinXP tiff viewer.  You can try adding "-co INTERLEAVE=PIXEL"
if you think this is the problem.

> My question is what do you refer to as a 'properly labelled' geotiff?  Is
> there any more documentation of gdalwarp that I could read, as I said before
> I am a bit new to this, but am very interested!

I mean a file that has coordinate system information (ie. UTM 11 WGS84) *and*
a geotransform (ie. reference point and pixel size).

The gdalwarp utility documentation is at:

   http://www.remotesensing.org/gdal/gdal_utilities.html#gdalwarp

To learn about subtleties of how GDAL warping works, trying reading through
the Warp API tutorial and linked reference documentation:

   http://www.remotesensing.org/gdal/warptut.html

To learn more about the GDAL data model review:

   http://www.remotesensing.org/gdal/gdal_datamodel.html

To learn about characterstics of specific format drivers review their
individual documentation:

   http://www.remotesensing.org/gdal/formats_list.html

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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