[gdal-dev] Problem with gdalsrsinfo on some NOAA bsb/kap files

[Jaak Laineste (Nutiteq)]

Hello,
 Have you found workaround for this? I just created index bounding boxes
for all the NOAA BSB charts using GDAL for my Android solution, see
http://imgur.com/MpADB - as you can see there are quite many wrong
locations, Xmin-coordinate is 0. In the same time, Y and Xmax seems to be
correct, which is interesting also. I do not have the number, but there
seems to be significant number (1/4?) of the NOAA files positioned wrong.
Also QGIS seems to relay on this info and also offplaces same files.

Jaak


2012/11/10 Chris Barker <chris.barker at noaa.gov>

> On Fri, Nov 9, 2012 at 2:48 PM, Even Rouault
> <even.rouault at mines-paris.org> wrote:
>
> > ok, I see what happens. In _3 and _4 cases, the BSB driver manages to
> compute
> > a geotransform from the GCPs and then assigns a projection, in addition
> to the
> > GCP projection.
> > In the _1 and _2 cases, the BSB driver doesn't manage to compute the
> > geotranform from the GCPs (which is a known issue sometimes with this
> driver,
> > presumably because it has a too strict tolerance in the computation of
> the
> > geotransform from the GCPs), so the projection is only reported by the
> > GetGCPProjection() method, which the gdalsrsinfo never queries.
> >
> > In all cases, gdalinfo does show the projection and/or GCP projection.
> >
> > Perhaps gdalsrsinfo should also query the GCP projection if no regular
> > projection is reported.
>
> I've wondered for ages about this driver -- the *.kap files have
> redundant info -- the projection definition and related info is enough
> (always? or only north-up?) to provide a complete projection and
> geotransform, but there are also the set of GCPs.
>
> I've never checked to see if they always match to a good tolerance,
> and I don't know what  GDAL does with the redundant info.
>
> From your note, it sounds like GDAL prefers the GCP transform -- is
> that so? and I'm not sure that's the best option -- presumably the
> info in the header is exact? Why not prefer that?
>
> -Chris
>
>
>
>
> --
>
> Christopher Barker, Ph.D.
> Oceanographer
>
> Emergency Response Division
> NOAA/NOS/OR&R            (206) 526-6959   voice
> 7600 Sand Point Way NE   (206) 526-6329   fax
> Seattle, WA  98115       (206) 526-6317   main reception
>
> Chris.Barker at noaa.gov
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>



-- 
Jaak Laineste
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