[Gdal-dev] issue warning to user when performing datum shift (OGR, GDAL )

[Dylan Beaudette]

On Monday 31 July 2006 13:58, Frank Warmerdam wrote:
> Dylan Beaudette wrote:
> > Hi everyone,
> >
> >
> > In light of some recent thought, experimentation, and discussion [1] I
> > am wondering if it would be at all possible or even desirable to warn
> > the user when a datum shift operation is about to be performed. Within
> > the US, and assumming that the NADCON grid was installed with Proj4,
> > transforming between NAD27 and NAD83 should work just as expected.
> > However, in other parts of the world, this may not be the case.
> > Therefore, it might be a good idea to follow the model used in GRASS,
> > where the user is specifically prompted for datum transform parameters
> > whenever defining a new locatio, in these situations.
> >
> > Any thoughts / reasons not to do this?
>
> Dylan,
>
> Well, the most obvious reason not to do it is that the GDAL utilities
> are not interactive.  So there is no opportunity to ask.
>
> I think it would be very nice if there was a mechanism to ask stuff
> like ogr2ogr to describe what it will do in a transformation but even doing
> that would be pretty challenging.
>
> Best regards,

Hi Frank,

Thanks for the quick reply. I suppose that this is a no-brainer issue for 
those that fully understand their data. Perhaps a warning message to STDERR 
when datum shifting ?

Cheers,

Dylan



-- 
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341