[Gdal-dev] Warping an ecw

[SteveC]

* @ 14/11/05 03:19:44 PM warmerdam at pobox.com wrote:
> On 11/12/05, SteveC <steve at asklater.com> wrote:
> > Hi
> >
> > I'm trying to transform an ecw but always get errors. Any help/pointers
> > appreciated.
> >
> > I get
> >
> > $ gdalwarp -tr 0.001 0.001 -t_srs "epsg:4326" -of GTiff foo.ecw foo.tiff
> > Creating output file that is 784P x 648L.
> > :0.ERROR 1: NCScbmReadViewLineBIL failed.
> >
> > $ gdalwarp -t_srs "epsg:4326" -te 0 50 10 60  -ts 30 30 -of GTiff foo.ecw foo.tiff
> > Creating output file that is 30P x 30L.
> > :0..10..20...33..40...50...61..ERROR 1: NCScbmReadViewLineBIL failed.
> >
> > $ gdal-config --version
> > 1.3.1
> 
> Steve,
> 
> I'm not sure what is going wrong.  What version of the ECW SDK are
> you using?  I will warn you that even if this works, it will be very slow

libecwj2-3.3

That cool?

> since the warper will always load the source chunks at full resolution.
> I gather you are wanting to use gdalwarp to dramatically downsample
> the data?
> 
> You might want to try something like "gdalinfo -mm foo.ecw".
> This should force one read pass over the whole file computing
> the min and max.  If this fails, then we can suspect there is
> something wrong with the file, or with the ECW SDK in
> simple access situations.  If that works fine, then it may be
> something more complex.

It failesd :-(

Lots of lines like

ERROR 1: TryWinRasterIO() failed for blocked scanline.
ERROR 1: IReadBlock failed at X offset 0, Y offset 25043

> I have submitted a bug report to ERMapper where I had crashes in
> the ECW SDK when doing many small windowed reads on a large
> file.  I haven't heard back if they were able to reproduce it.   You
> might be running into something similar.

Oh dear. I'd hoped this would be easy :-)

have fun,

SteveC steve at asklater.com http://www.asklater.com/steve/