[Gdal-dev] Re: [FWTools] conversion/transformation

[Mateusz Loskot]

Hi Christine,

Christine Spietz wrote:
> 
> Thank you for the detailed information. It helped a lot!

Cool!

> If I understodd right I use the -s_srs-parameter only if
> 
> - I have no prj-file (but know the geographic coordinates sytem of the
> input-file) or if I want to omit the prj-file.

Yes, but this rule does not only apply to Shapefile.
Simply, the rule is:
use -s_srs parameter if your (input) dataset does not include SRS
definition or you want to overwrite existing definition with your own
given as -s_srs.

For Shapefile such definition is stored in .prj file, but in other
datasets projections are handled in different way.

> - I transform from an Shapefile to something else (because only the
> Shapefile might have a prj-file)

Yes, but not exactly :-)
-s_srs parameter is not tight only to .prj file but applies to all
supported dataset.

I just used Shapefile in my examples because I know Shapefile format
best, so I didn't want to provide you with incorrect explanation.

Cheers
-- 
Mateusz Łoskot
http://mateusz.loskot.net