[Proj] epsg parameters

Glynn Clements glynn at gclements.plus.com
Wed Apr 2 16:15:45 EDT 2008

Paul Kelly wrote:

> I think it's in general a bad idea to include datum transformation 
> information without any user interaction, because many users have the 
> misconception that there is somehow a "correct" set of parameters which 
> will always give them accurate results. When of course, as we've seen 
> discussed on this list many times, accurate datum transformation is very 
> much a localised thing: a transformation that gives accurate results in 
> one region of a country may give very inaccurate results in another 
> region, and a transformation that covers the whole country is in general 
> not very accurate anywhere.

There's also the issue that being "accurate" may be less important
than being consistent with whatever data you're using.

Glynn Clements <glynn at gclements.plus.com>

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