[Gdal-dev] file size balloons when converting gml to tab, shp with ogr2ogr

[Ethan Alpert]

Another option is to use one of the language bindings to do the
coversion. This way you could set the string widths when you define the
output file. It's about 40 lines of code in perl.

-e

-----Original Message-----
From: gdal-dev-bounces at lists.maptools.org
[mailto:gdal-dev-bounces at lists.maptools.org] On Behalf Of
Peter.Rushforth at statcan.ca
Sent: Thursday, May 18, 2006 9:05 AM
To: warmerdam at pobox.com
Cc: gdal-dev at lists.maptools.org
Subject: RE: [Gdal-dev] file size balloons when converting gml to
tab,shp with ogr2ogr

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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