[Gdal-dev] NAD83 vs. WGS84

[Norman Vine]

Grabowski, Hank writes:
>  
> My program's internal conversion to WGS84 has the exact same difference,
> so I figure once I determine how to get the conversion working in
> ogr2ogr I should be able to map it over to my internal code as well.  Is
> it such that NAD83 is the best I can do with OGR? If that's the case
> that's fine.  I just need to make that fact known to our users.

Set up a custom Datum conversion to go from your internal code
to the outside world.

I believe all you need to do this will be the semi-major and sem-minor
axis.

As others have pointed out there are minor discrepancies between
these between the various conversion systems you have been discussing.

FWIW - I use this for WGS84
http://earth-info.nima.mil/GandG/tr8350_2.html

HTH

Norman