[Proj] Unknown projection?

Gerald I. Evenden geraldi.evenden at gmail.com
Sat Sep 13 12:56:36 EDT 2008

On Saturday 13 September 2008 11:42:29 am support.mn at elisanet.fi wrote:
> "Gerald I. Evenden" <geraldi.evenden at gmail.com> kirjoitti:
> > On Saturday 13 September 2008 10:59:24 am Paul B. Anderson wrote:
> > > - Janne,
> > >
> > > Your map graphic appears to be in the Winkel Tripel map projection. I
> > > would also suggest that it is using Oswald Winkel's original selection
> > > of 50.46667 degrees as the Special Parallel.
> > >
> > > Note that by the 1950s John Bartholomew was using a special parallel of
> > > 40 degrees for his version of the Tripel, giving his graphic a more
> > > flattened appearance in the Y direction.
> >
> > This is exactly why I include the projection math in the manual.  The
> > factor Anderson is discussing is +lat_1 option for the +proj=wintri
> > projection. Select your own option value and name a new projection.  ;-)
> Ok, now the problem seems to be that "wintri" does not have any inverse
> projection available. What is the reason not to have inverse projections
> for all routines in the library... math is too hard?
> Janne.

Sometimes yes; sometimes no; sometimes lack of interest.  The are several of 
the projections in this azimuthal category that do not have inverses and, 
based upon a quick look, are probably solvable.

Do you know for sure that the projection you showed is Winkel Tripel?  You do 
not need an inverse to determine this.

The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939) British psychologist

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