[FWTools] ECW Conversion and TIF Tiling

Roger Andre randre at google.com
Tue Dec 19 15:34:10 EST 2006

Hi Eric,

I agree with Frank, create a GeoTIFF with the projection and
georeferencing defined in it, before you tile the image.  I've attached
a little tiling script written in Perl that will work on a Linux machine
which has FWTools installed on it.  You can probably make it work in
Windows too, but I can't help you there.

The script allows you to specify a pixel dimension that is then used to
determine the tile size in both X and Y axes.  It basically creates a
bunch of "gdal_translate -srcwin" commands to cut up the image, and
passes those commands to the shell for execution.

It works for me, but your mileage may vary.

PS - This could be done much more elegantly in Python using the API that
comes in FWTools.  I didn't know either of those real well when I wrote

On Tue, 2006-12-19 at 20:31 -0500, Frank Warmerdam wrote:
> Eric Legge Smith wrote:
> > Hello List,
> > 
> > Newbie questions -
> > I'm looking for documentation on how to use FWTools to...
> > (1) convert an ECW raster to an indexed set of tiled TIFs?
> > (2) convert a 1.5Gb TIF with an external 'tfw' file to a set of tiled TIF's?
> > (3) crop the 1.5Gb TIF with external 'tfw' file and convert to  a GeoTIFF
> Eric,
> As I think Travis mentioned, there is no handing tiling tool in FWTools.
> I will mention that you could write a python script to do this, but it isn't
> exactly trivial.  The easiest approach is like to write a batch script of some
> kind using gdal_translate with varying -srcwin (or -projwin) windows for each
> tile.
> I will note that gdal_translate will by default produce a geotiff from a
> TIFF+tfw, but if you want to provide a coordinate system to you need to
> specify that on the commandline.  The following would read in.tif (and in.tfw)
> and produce an output out.tif GeoTIFF file with the georeferencing info and
> the coordinate system set to UTM 11 WGS84.
> eg.
> gdal_translate in.tif out.tif -a_srs '+proj=utm +zone=11 +datum=WGS84'
> Best regards,

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