[Gdal-dev] Re: [GRASS-user] Little experiment: comparison of vector projection OGR and ArcGIS

[Dylan Beaudette]

Hi Frank,

Yes. The only discrepancy is with the default, and oddly named,
'NAD_1927_To_NAD_1983_6' "transform" present in ArcGIS 9.0. The NADCON
approach in ArcGIS matches the output from OGR which matches the
output from  the NGS NADCON webpage.

Thanks for your hard work!

Dylan

On 7/29/06, Frank Warmerdam <warmerdam at pobox.com> wrote:
> Dylan Beaudette wrote:
> > A while back I was wondering if ArcGIS and OGR would produce the same
> > output from the same projection operation...  Results where identical
> > for operations within the same datum, using a GCS -> UTM projection.
> >
> > A couple days ago I did another experiment, this time incorporating a
> > datum shift: GCS NAD83 --> UTM NAD27. I have summarized the results
> > here:
> >
> > http://casoilresource.lawr.ucdavis.edu/drupal/node/259
> >
> > of note:
> >
> > - the default tranform in ArcGIS does not produce the correct results.
> > - the 'NADCON' transform in ArcGIS produces the same results as OGR.
> >
> >
> > Any comments on some of the questions posed are welcomed.
>
> Dylan,
>
> I read over your post quickly, and my understanding is that the outstanding
> question relates to the different methods in ArcGIS, is that right?  And
> that OGR (and cs2cs) match the results of using ArcGIS with the NADCON
> method?   I'm just making sure there isn't an issue I need to be looking
> into.
>
> 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
>
>