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

Thomas Knudsen knudsen.thomas at gmail.com
Mon Nov 2 07:15:38 EST 2015

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


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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