[Proj] Potentially (theoretically) dangerous changes in Proj4 internal routines that affect the end results..

support at mnspoint.com support at mnspoint.com
Sun Nov 8 18:12:07 EST 2015


why not just add a new projection called "utm2" or "newutm" or "xutm" .. 
and use it like "proj=utm2" etc. I would like more if the new utm was 
called different so that the old references would stay where they always 
been.. just to stay consistent..

Regards Janne.


Thomas Knudsen kirjoitti 02.11.2015 14:15:
> If memory serves me right, you should use something like +proj=tmerc
> +x_0=500000 +lon_0=...   +scale=0.9996 to invoke the Snyder algorithm
> (fully analogous to what you had to do up until now to get utm using
> +proj=etmerc)
> /thomas
> 2015-11-02 11:42 GMT+01:00  <support at mnspoint.com>:
>> Hello,
>> basically it is always ok to switch to any calculation that is more 
>> accurate
>> or more formally correct ... but there should also be some kind of a 
>> method
>> to stay downwards compatible. At least some methods or go arounds to 
>> stay
>> compatible with old version should be given to users?!
>> What proj4 declarations should be used to keep the old calculation in
>> effect?! etc..
>> Regards: Janne.
>> -----------------------------------------------
>> Thomas Knudsen kirjoitti 28.10.2015 15:56:
>> As described in a recent thread, for the next release, proj.4 will 
>> switch
>> the default transverse mercator implementation from tmerc to 
>> etmerc......

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