Hammer interrupted projection

[beuan]

When selecting interruptions for Hammer projection, the following error is returned: IRangeMapError: The map is too big.
Is this a bug or Hammer Interrupted projection is not possible? I noticed in Snyder’s projection guideline for world maps that he does not suggests Hammer interrupted projection and I wanted to find out if there is some esthetic/distortion reason or mathematical constraint.

Thank you,
Bojan Savric

[daan]

Hello Bojan. It is good to hear from you.

You can apply simple, regular interruptions to the Hammer projection, such as gores or hemispheric. Some complex interruptions, such as Goode or Boggs are not possible because they depend on straight parallels and constant spacing of meridians along those parallels. Meanwhile Hammer has curved parallels, and the meridian spacing decreases outward from the central meridian.

Does that help?

Regards,
— daan

[beuan]

Dear Daan,

you confirm my suspicions. Thank you for your help.

Regards,
Bojan

[Piotr]

Also, not even Gores or Hemispheric work with Mercator and HEALPix, even though they both are pseudocylindrical. Why does that happen?

[Atarimaster]

Also, not even Gores or Hemispheric work with Mercator and HEALPix, even though they both are pseudocylindrical. Why does that happen?

Mercator is cylindrical, not pseudocylindrical.
While gores generally work for cylindricals, they probably don't look like you might expect. In this screenshot, gores are applied to the B.S.A.M. projection:

Bildschirmfoto 2017-03-28 um 12.09.54.png (321.8 KiB) Viewed 2161 times

As for Mercator, it can’t display the poles because they extend into infinity – I guess that’s the reason why you get that »IRangeMapError«.
Moreover, I can’t even begin to guess why anyone would want gores of a projection with heavy areal distortions… However, you might try gores on the van der Grinten projections.

Regarding HEALPix, I don’t know. Maybe the result are… strange (to say the least) because it already is an interrupted projection?

Kind regards,
Tobias

[Piotr]

Aren't all cylindrical projections pseudocylindrical, as they have straight parallels and equally spaced meridians too?

But is there an explanation for HEALPix?

[daan]

Aren't all cylindrical projections pseudocylindrical, as they have straight parallels and equally spaced meridians too?

Typically we talk about these classifications as mutually exclusive, even though cylindrical is a degenerate case of pseudocylindrical. So, pedantically you are correct, but that correctness impedes understanding. In particular, as Tobias showed, interrupting a cylindrical projection by usual means yields nothing of interest.

But is there an explanation for HEALPix?

As Tobias explained, HEALPix is already interrupted, so I, too, am confused by your question. Could you elaborate?

— daan

[Piotr]

No offense, but being given the answer right at your eyes and not understanding the question anymore is stupid.

And I actually expected that with cylindrical interruptions.

[Piotr]

Also, I noticed something weird: If the Mercator map is small enough to fit the document, you can set it to show the entire world, with an aspect ratio of 0.21924286 (4.56115189 times tall as it's wide). Isn't Mercator infinite?

Also, if I select Mercator, it isn't selected, in other hand, ellipsoidal Mercator is.

[Atarimaster]

No offense, but being given the answer right at your eyes and not understanding the question anymore is stupid.

Now, that’s a hell of a way to introduce yourself to a forum.