Icosahedral Projection

General discussion of map projections.
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Maezar
Posts: 14
Joined: Wed Jan 21, 2015 10:43 pm

Icosahedral Projection

Post by Maezar »

Greetings,

In the past, you've helped me with a dodecahedral projection.
I need to work with some Icosahedral projections. It won't matter how the faces are arranged as long as I can edit the projection center and rotation.

Is there any option or advice that might help me achieve this? I may be overlooking something simple.

Thanks kindly,
daan
Site Admin
Posts: 977
Joined: Sat Mar 28, 2009 11:17 pm

Re: Icosahedral Projection

Post by daan »

Hello Maezar.

You have several choices in Geocart:
• Chaise lounge
• Dymaxion-like conformal
• Polyhedron conformal face
• Gnomonic

In the case of the dymaxion-like conformal, a couple of the faces have been split and moved; you may need to reassemble them.

In the case of the polyhedron conformal face, you choose the polyhedron as a parameter and create a face at a time, with the face number being another parameter. You can choose the projection center you want for a particular face, copy that for each other face, and change the face number. That way, you end up with 20 face that, together, show the entire globe.

The gnomonic is the most troublesome; you would have to construct it completely manually by first specifying the triangle boundaries for one, and then copying it, changing the projection center for each face using a table of known geographic centers. You also get kinks at the edges, which is not a problem of conformal faces.

Cheers,
— daan
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