Recentering infinite projections idea

[Piotr]

I have an interesting idea: Recentering infinite projections (that cannot show some point) to show points on boundaries. I will show you the effects of two equatorial projections that cannot show the poles: Mercator and equatorial gnomonic, moving the center Northward so that North pole is at the top.

Doing this on Mercator allows both poles to be shown, at expense of clipping Alaska and Siberia.

80 degree truncation, with center at 10 degrees North:



60 degree truncation, with center at 30 degrees North:



On Gnomonic, this will show the North pole at expense of showing less of South hemisphere. It's interesting how the grid converges to the North pole.

75 degree truncation, with center at 15 degrees North:



60 degree truncation, with center at 30 degrees North:

[daan]

I used this technique in recommendations for my equal-area series of hybrid projections in 1992, appearing by default in Geocart 1 and Geocart 2. I did not carry those defaults into Geocart 3.

I used an 11°E centering to avoid cutting the Chukchee peninsula and an 11°S centering so that Antarctica would not get split.

— daan

[Piotr]

I used this technique in recommendations for my equal-area series of hybrid projections in 1992, appearing by default in Geocart 1 and Geocart 2. I did not carry those defaults into Geocart 3.

I used an 11°E centering to avoid cutting the Chukchee peninsula and an 11°S centering so that Antarctica would not get split.

— daan

Did it put the south pole on a boundary?

[daan]

Did it put the south pole on a boundary?

No. It moved the north pole to two locations on the boundary because the purpose was to avoid an interruption in Antarctica.

— daan

[Piotr]

Did it put the south pole on a boundary?

No. It moved the north pole to two locations on the boundary because the purpose was to avoid an interruption in Antarctica.

— daan

What did the Chukchee projection look like?

[daan]

Did it put the south pole on a boundary?

No. It moved the north pole to two locations on the boundary because the purpose was to avoid an interruption in Antarctica.

— daan

What did the Chukchee projection look like?

Try it: Center a pseudocylindric or lenticular projection at 11°E/11°S.

— daan

[Piotr]

You may embed only 3 quotes within each other.
No. It moved the north pole to two locations on the boundary because the purpose was to avoid an interruption in Antarctica.

— daan

What did the Chukchee projection look like?

Try it: Center a pseudocylindric or lenticular projection at 11°E/11°S.

— daan

So you used this centering by default with all possible pseudocylindrical and lenticular projections in some older Geocart?!

[daan]

So you used this centering by default with all possible pseudocylindrical projections in some older Geocart?!

No. I used it for the Strebe- series of lenticular projections only.

— daan

[Piotr]

Piotr: I have an interesting idea: Recentering infinite projections (that cannot show some point) to show points on boundaries.

daan: I used an 11°E centering to avoid cutting the Chukchee peninsula and an 11°S centering so that Antarctica would not get split.

Piotr: Did it put the south pole on a boundary?

daan: No. It moved the north pole to two locations on the boundary because the purpose was to avoid an interruption in Antarctica.

Piotr: What did the Chukchee projection look like?

daan: Try it: Center a pseudocylindric or lenticular projection at 11°E/11°S.

Piotr: So you used this centering by default with all possible pseudocylindrical and lenticular projections in some older Geocart?!

daan: No. I used it for the Strebe- series of lenticular projections only.

Umm. Then explain the words I marked bold

[daan]

Umm. Then explain the words I marked bold

No. They are clear. If you have something specific to ask, then ask.

— daan