File:Mercator projections vs rotation.gif
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Mercator_projections_vs_rotation.gif (800 × 339 pixels, file size: 4.22 MB, MIME type: image/gif, looped, 101 frames, 10 s)
Note: Due to technical limitations, thumbnails of high resolution GIF images such as this one will not be animated.
This file is from Wikimedia Commons and may be used by other projects. The description on its file description page there is shown below.
Summary
| DescriptionMercator projections vs rotation.gif |
English: Projecting a sphere on a surface can only be done at the price of some distortion.
Mercator's projection is very useful is you are sailing, but strongly distorts sizes. And if we can change what is at the centre of the map we can see how much. |
| Date | |
| Source | https://twitter.com/j_bertolotti/status/1529775116976017414 |
| Author | Jacopo Bertolotti |
| Permission (Reusing this file) |
https://twitter.com/j_bertolotti/status/1030470604418428929 |
Mathematica 13.0 code
world = CountryData["Countries", "SchematicPolygon"];
swap[c_] := {c[[2]], -(c[[1]] - 90)};
tmp = Flatten[world[[All, 1, 1]], 1];
tmp = Join[tmp, CountryData[\!\(\*
NamespaceBox["LinguisticAssistant",
DynamicModuleBox[{Typeset`query$$ = "antartica", Typeset`boxes$$ =
TemplateBox[{"\"Antarctica\"",
RowBox[{"Entity", "[",
RowBox[{"\"GeographicRegion\"", ",", "\"Antarctica\""}], "]"}],
"\"Entity[\\\"GeographicRegion\\\", \\\"Antarctica\\\"]\"",
"\"geographic region\""}, "Entity"],
Typeset`allassumptions$$ = {{"type" -> "Clash",
"word" -> "antartica",
"template" -> "Assuming \"antartica\" is a \
continent${separator}Use as ${desc} or ${desc} instead",
"count" -> "3", "pulldown" -> "false",
"default" -> "{\"C\", \"antartica\"} -> \
{\"GeographicRegion\", \"dflt\"}",
"Values" -> {{"name" -> "GeographicRegion",
"desc" -> "a continent",
"input" -> "{\"C\", \"antartica\"} -> \
{{\"GeographicRegion\", \"a continent\"}}"}, \
{"name" -> "CountryClass", "desc" -> "a class of countries",
"input" -> "{\"C\", \"antartica\"} -> \
{\"CountryClass\"}"}, {"name" -> "Desert", "desc" -> "a desert",
"input" -> "{\"C\", \"antartica\"} -> {\"Desert\"}"}}}},
Typeset`assumptions$$ = {}, Typeset`open$$ = {1, 2},
Typeset`querystate$$ = {"Online" -> True, "Allowed" -> True,
"mparse.jsp" -> 0.773653`6.340091207439451,
"Messages" -> {}}},
DynamicBox[ToBoxes[
AlphaIntegration`LinguisticAssistantBoxes["", 4, Automatic,
Dynamic[Typeset`query$$],
Dynamic[Typeset`boxes$$],
Dynamic[Typeset`allassumptions$$],
Dynamic[Typeset`assumptions$$],
Dynamic[Typeset`open$$],
Dynamic[Typeset`querystate$$]], StandardForm],
ImageSizeCache->{225.2265625, {8.11328125, 17.11328125}},
TrackedSymbols:>{Typeset`query$$, Typeset`boxes$$,
Typeset`allassumptions$$, Typeset`assumptions$$,
Typeset`open$$, Typeset`querystate$$}],
DynamicModuleValues:>{},
UndoTrackedVariables:>{Typeset`open$$}],
BaseStyle->{"Deploy"},
DeleteWithContents->True,
Editable->False,
SelectWithContents->True]\), "SchematicPolygon"][[1,
1]]];
world2 = Reap[For[j = 1, j <= Dimensions[tmp][[1]], j++,
Sow[\[Pi]/180 (swap /@ tmp[[j]])];
];][[2, 1]];
ToSphere[c_] := {Cos[c[[1]]] Sin[c[[2]]], Sin[c[[1]]] Sin[c[[2]]], Cos[c[[2]]]};
sphereworld = Reap[For[j = 1, j <= Dimensions[world2][[1]], j++,
Sow[(ToSphere[#] & /@ world2[[j]])];
];][[2, 1]];
ToMercator[c_] := {c[[2]], -Log[Cos[-(c[[1]] - \[Pi]/2)/2] - Sin[-(c[[1]] - \[Pi]/2)/2]] + Log[Cos[-(c[[1]] - \[Pi]/2)/2] + Sin[-(c[[1]] - \[Pi]/2)/2]]};
sinstep[t_] := Sin[\[Pi]/2 t]^2
frames = Table[
m = RotationTransform[-2 \[Pi] sinstep[t], {0, 1., 0}];
rotatedsphereworld =
Reap[For[j = 1, j <= Dimensions[sphereworld][[1]], j++,
Sow[(m /@ sphereworld[[j]])];
];][[2, 1]];
mercatorworld =
Reap[For[j = 1, j <= Dimensions[rotatedsphereworld][[1]], j++,
Sow[(ToMercator[#] & /@ (CoordinateTransform["Cartesian" -> "Spherical", rotatedsphereworld[[j]]][[All, 2 ;; 3]]) )];
];][[2, 1]];
mercatorworld2 =
Reap[For[j = 1, j <= Dimensions[mercatorworld][[1]], j++,
Sow[Split[mercatorworld[[j]], Abs[#2[[1]] - #1[[1]]] < 1 &]
];
];][[2, 1]];
GraphicsRow[{
Graphics3D[{Thick, Line /@ rotatedsphereworld, LightGray, Sphere[{0, 0, 0}, 1]}, Lighting -> "Neutral", Boxed -> False, ViewPoint -> {2, 0, 0}]
,
Graphics[{Line /@ mercatorworld2, Thick, Line[1.01 {{-\[Pi], -\[Pi]}, {-\[Pi], \[Pi]}, {\[Pi], \[Pi]}, {\[Pi], -\[Pi]}, {-\[Pi], -\[Pi]}}]}, PlotRange -> 1.*{{-\[Pi], \[Pi]}, {-\[Pi], \[Pi]}}, AspectRatio -> 1/1.61803, ImageSize -> 500]
}]
, {t, 0, 1, 0.01}];
ListAnimate[frames]
Licensing
I, the copyright holder of this work, hereby publish it under the following license:
| This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication. | |
| The person who associated a work with this deed has dedicated the work to the public domain by waiving all of their rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law. You can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission.
http://creativecommons.org/publicdomain/zero/1.0/deed.enCC0Creative Commons Zero, Public Domain Dedicationfalsefalse |
Captions
Earth projected using Mercator as a function of north-south rotation.
Items portrayed in this file
depicts
some value
26 May 2022
image/gif
4,423,542 byte
10.1 second
339 pixel
800 pixel
b1e4e6ac41eb1cb864b813b8a13b4b66c459ba1e
File history
Click on a date/time to view the file as it appeared at that time.
| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 10:26, 27 May 2022 | 800 × 339 (4.22 MB) | wikimediacommons>Berto | Uploaded own work with UploadWizard |
File usage
The following 2 pages use this file:
