[Proj] Polyhedric projection

Jan Hartmann j.l.h.hartmann at uva.nl
Tue Jan 22 08:44:49 EST 2013

What happens when I georeference all those polyhedric maps, by just 
rubbersheeting them with the lat-lon coordinates written at the corners 
as control points? This will give me a seamless map, but how great would 
the distortion be? Is there a better way to get a seamless map?


On 12/26/2012 11:38 PM, Clifford J Mugnier wrote:


No, it is not possible to generate a correct global map using PROJ or any other application using the Polyhedric (Polyeder) projection.
It's an Aphylactic projection; not conformal, not azimuthal, not equal-area/authalic.
It IS easy to cast graphically from simple projection tables, which is why Aphylactics were popular in the 19th century by Topographers using plane tables and alidades in the field.  (Same goes for the Cassini-Soldner and the Polyconic.)

On 12/21/2012 02:44 PM, Jan Hartmann wrote:
> Hi all,
> I'm working with a large bunch of maps of Indonesia, dating from the 
> Dutch colonial period (1850-1946). Quite a few are in the so-called 
> "polyhedral" projection, a simple projection that fits the globe 
> locally for each separate map sheet. Works fine for a few sheets, but 
> for larger surfaces it is impossible to generate a fitting map. Has 
> anyone worked with this projection? Is it possible to generate a 
> correct global map using proj?
> Jan
> See this passage in Snyder's book:
> http://books.google.nl/books?id=0UzjTJ4w9yEC&pg=PA142&lpg=PA142&dq=polyhedric+projection&source=bl&ots=ZaeVIBxxA3&sig=Q437Wqb99b862kaqSYMRBTNS9f8&hl=nl&sa=X&ei=0WPUUPR0gaiEB7fjgKAE&ved=0CFwQ6AEwBg#v=onepage&q=polyhedric%20projection&f=false

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