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<font face="Times New Roman, Times, serif">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? <br>
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Jan<br>
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<div class="moz-cite-prefix"><font face="Times New Roman, Times,
serif">On 12/26/2012 11:38 PM, Clifford J Mugnier wrote:<br>
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<pre><font face="Times New Roman, Times, serif">Jan,
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.)
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<div class="moz-cite-prefix"><font face="Times New Roman, Times,
serif">On 12/21/2012 02:44 PM, Jan Hartmann wrote:<br>
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<font face="Times New Roman, Times, serif"> Hi all,<br>
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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?<br>
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Jan<br>
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</font> <font face="Times New Roman, Times, serif"><br>
See this passage in Snyder's book:<br>
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href="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">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</a><br>
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