[Gdal-dev] file size balloons when converting gml to tab,
shp with ogr2ogr
Peter.Rushforth at statcan.ca
Peter.Rushforth at statcan.ca
Thu May 18 11:05:04 EDT 2006
Hi Frank,
It is just the .dbf and the .dat files for mapinfo which grow too big.
I checked the mid/mif and found that you could edit the string field
definition and generate the tab file which then turned out to be about
the right size.
I was searching for a way to tell the gml driver how big the string
fields were in order that that info get passed on to the tab and shp
drivers. I tried editing the gfs file and adding a Width element, but
it seemed to be ignored. Would an xml schema work, I wonder?
Cheers
Peter Rushforth
Geography Division
Statistics Canada
Ottawa Ontario
K1A 0T6
> -----Original Message-----
> From: Frank Warmerdam [mailto:fwarmerdam at gmail.com] On Behalf
> Of Frank Warmerdam
> Sent: May 18, 2006 10:30 AM
> To: Peter.Rushforth at statcan.ca
> Cc: gdal-dev at lists.maptools.org
> Subject: Re: [Gdal-dev] file size balloons when converting
> gml to tab, shp with ogr2ogr
>
>
> Peter.Rushforth at statcan.ca wrote:
> > Hi,
> >
> > I've been experimenting with converting GML documents to
> mapinfo tab
> > and
> > esri shp
> > formats. I have the same files previously created with commercial
> > software with
> > exactly the same record layouts. The files I've created
> with ogr2ogr
> > seem to be up
> > to 5 to 10 times larger than the same file (and format)
> created with the
> > commercial software.
> >
> > When you view the files, they appear identical, line for line,
> > attribute
> > for attribute.
> >
> > Is there somebody who could point me in the right direction to
> > determine
> > why?
>
> Peter,
>
> Generally speaking string fields without a defined size will
> end up being very wide when translated to shapefiles since it
> is necessary for me to pick a string width when creating the
> shapefile, but without prescanning all the actual values that
> will be written. This may also be an issue with tab format,
> I'm not sure. I don't *think* it is an issue with .mid/.mif.
>
> So, is it primarily the .dbf file that is big for shapefiles?
> The .shp should generally be slightly more compact than the
> corresponding GML geometry format.
>
> Best regards,
>
> --
> ---------------------------------------+----------------------
> ----------
> ---------------------------------------+------
> I set the clouds in motion - turn up | Frank Warmerdam,
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush | President OSGF,
> http://osgeo.org
>
>
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