[Gdal-dev] gdal/ogr/proj and NAD83(CSRS)

[Matt Wilkie]

Hi Robert, thank you for contributing your insight, it helps!

> cs2cs -v is quite clear about what it's doing, OGR not so much.
>
> Using the "straight" Proj EPSG defs on my system:
> $ cs2cs -v +init=epsg:3579 +to +init=epsg:4617
...
> No datum transform will happen  (ellipses match, and +towgs84 is ommitted (ie ==0)).

Then I would say it is improper for ogr2ogr to write NAD83(CSRS) in
the output .prj. Proj4 and dependant projects may think WGS84, NAD83
and NAD83(CSRS) are synonymous but from my reading over the last
couple of weeks it is clear that while the first two were
interchangeable at one time, they are not now.

In future a person or program using data defined as NAD83(CSRS) will
reasonably expect sub-meter datum accuracy, for that is the purpose of
the datum. if this is not the case, it should not call itself such.

best regards,

-matt

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