Reveal

Discussion of things we want in Geocart
daan
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Re: Reveal

Post by daan »

Piotr wrote: Thu Apr 02, 2020 9:47 am So you're saying that in random conformal projections including GS50 there is one singular point that many coordinates map to.
No, it’s whole regions that overlap.

— daan
Piotr
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Re: Reveal

Post by Piotr »

daan wrote: Thu Apr 02, 2020 10:35 am
Piotr wrote: Thu Apr 02, 2020 9:47 am So you're saying that in random conformal projections including GS50 there is one singular point that many coordinates map to.
No, it’s whole regions that overlap.

— daan
You formerly said "What happens is that two or more points from the spheroid project onto the same point on the plane.", as in a singularity.
daan
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Re: Reveal

Post by daan »

That’s because I was talking about what happens at the level of individual coordinates. Now spread that phenomenon out across regions.

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Piotr
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Re: Reveal

Post by Piotr »

daan wrote: Thu Apr 02, 2020 11:04 am That’s because I was talking about what happens at the level of individual coordinates. Now spread that phenomenon out across regions.

— daan
So, you're saying that there are so many non-conformal singularities that the bijectivity gets lost and the projection is no longer reliable beyond an uncomputable range.
daan
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Re: Reveal

Post by daan »

Piotr wrote: Thu Apr 02, 2020 11:15 am So, you're saying that there are so many non-conformal singularities that the bijectivity gets lost and the projection is no longer reliable beyond an uncomputable range.
No, they are not singularities. The projection is still conformal. It just overlaps itself, somewhat analogous to orthographic’s back hemisphere, but not nearly so orderly.

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Re: Reveal

Post by Piotr »

daan wrote: Thu Apr 02, 2020 11:43 am
Piotr wrote: Thu Apr 02, 2020 11:15 am So, you're saying that there are so many non-conformal singularities that the bijectivity gets lost and the projection is no longer reliable beyond an uncomputable range.
No, they are not singularities. The projection is still conformal. It just overlaps itself, somewhat analogous to orthographic’s back hemisphere, but not nearly so orderly.

— daan
Isn't back hemisphere only in Hammer retroazimuthal projection?

So you're saying GS50 would be conformal for the entire world, as long as it's printed in multiple sections?
daan
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Re: Reveal

Post by daan »

Piotr wrote: Thu Apr 02, 2020 8:34 pm Isn't back hemisphere only in Hammer retroazimuthal projection?
Hammer retroazimuthal is the only one I have implemented. The back hemisphere differs from the front, so there isn’t any other way to arrive at it. Orthographic back hemisphere is trivial and can be arrived at via Geocart’s UI as a transformation of the front.

— daan
Piotr
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Re: Reveal

Post by Piotr »

If the non-bijective errors aren't singularities, GS50 would be conformal for the entire world, as long as it's printed in multiple sections, right?
daan
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Re: Reveal

Post by daan »

Piotr wrote: Thu Apr 02, 2020 10:31 pm If the non-bijective errors aren't singularities, GS50 would be conformal for the entire world, as long as it's printed in multiple sections, right?
Mostly right, but I’m not sure the entire range is finite. The inflation goes crazy in most places away from the center. Some portions shrink toward nothingness as well.

— daan
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Re: Reveal

Post by Piotr »

daan wrote: Thu Apr 02, 2020 10:36 pm
Piotr wrote: Thu Apr 02, 2020 10:31 pm If the non-bijective errors aren't singularities, GS50 would be conformal for the entire world, as long as it's printed in multiple sections, right?
Mostly right, but I’m not sure the entire range is finite. The inflation goes crazy in most places away from the center. Some portions shrink toward nothingness as well.

— daan
Would such a map be in infinitely many pieces?
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