[Proj] large difference while projecting utm to utm back and forth

Thomas Knudsen knudsen.thomas at gmail.com
Wed Feb 16 13:20:34 EST 2011

> I agree - I don't see that any of the wide field tmerc implementation
> made it into my PROJ.4.  If someone (ideally Gerald) could identify a
> preferred implementation I'd be willing to port it over or apply a
> patch if someone else wants to file a ticket with a proposed change.

Frank, I have just been on a journey through my mail archive and have found
a personal email from Gerald with his timing and roundtrip-precision tests
of the different wide field transverse mercator implementations. My
interpretation of his results is that the Engsager implementation sits in
the sweet spot between speed and precision. I will forward the material
(including source code) to your pobox.com address in a few minutes.


> 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    | Geospatial Programmer for Rent
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