[Gdal-dev] ESRI flt nbits issue

[Markus Neteler]

On Fri, Jan 20, 2006 at 08:34:15AM -0500, Frank Warmerdam wrote:
> On 1/20/06, Markus Neteler <neteler at itc.it> wrote:
> > Hi,
> >
> > I was trying to use an ESRI .flt file:
> >
> > gdalinfo edenglcc2kfor.flt
> > ERROR 6: EHdr driver does not support 1541835190 NBITS value.
> > GDALOpen failed - 6
> > EHdr driver does not support 1541835190 NBITS value.
> >
> > It seems that 'nbits' is not initialized if missing
> > in the header file:
> >
> > ncols         10018
> > nrows         8200
> > xllcorner     -20
> > yllcorner     6.17
> > cellsize      0.008333
> > NODATA_value  -9999
> > byteorder     LSBFIRST
> >
> > -rw-rw-rw-  1 neteler ssi        69 Oct 13 16:08 edenglcc2kfor.prj
> > -rw-rw-rw-  1 neteler ssi 328590400 Oct 13 16:08 edenglcc2kfor.flt
> > -rw-rw-rw-  1 neteler ssi      3598 Oct 14 12:51 edenglcc2kfor.xml
> > -rw-rw-rw-  1 neteler ssi       167 Jan 20 10:47 edenglcc2kfor.hdr
> >
> > Maybe the driver could be enabled to guess the nbits size if
> > missing inte the .hdr file?
> 
> Markus,
> 
> I have modified the code to default to nbits=8 if not specified,
> but that won't make this file work.  You will still need to add
> "NBITS 32" to the .hdr file.

Thanks, Frank.

Suggestion:
Couldn't the driver simply calculate nbits from the file size?

ncols         10018
nrows         8200
> 10018 * 8200
[1] 82147600

and
 -rw-rw-rw-  1 neteler ssi 328590400 Oct 13 16:08 edenglcc2kfor.flt

> 328590400 / 82147600
[1] 4

So I assume nbits=4 here.

I have received a number of files where the 'nbits' row is missing.

Best regards

 Markus