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This is more a question born out of curiosity than actual needs, but this seems like the right place for it.

Based on What is Centroid of all lands of Earth? I was wondering what world maps centered on the GC would look like. Has somebody played around with it and can link their results here(or even place it on wikipedia in this article)? I imagine a polar projection or a cylindrical projection with the GC as coordinate origin.

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Wojtek
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  • Right! No, actually its a really good question (I've up voted it!). I'd probably approach it by layering all national grids on top of each other using a common lat long for reprojection... but im far too busy trolling Germans on Stack Exchange! – Andrew Tice Oct 18 '15 at 11:09
  • I probably could do this myself, but it sounds like one of those sideprojects you start out of pure curiosity and end up spending more time on than the things you should be doing ;). I would just take a lon/lat coast datafile and shift all coordinates to the new origin, than do a merc projection with the new dataset. – Wojtek Oct 18 '15 at 11:22
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    This is a frequent and incomplete question: 'what is the best projection for my region'? You need to specify what qualities your projection ought to have. There are so many projections out there: some preserve areas, some angles, some distances, some compromise, ... – Martin F Oct 18 '15 at 22:30
  • As the planet is a spheroid (3 dimensional) the centroid would have to be somewhere deep underground... have a look at https://en.wikipedia.org/wiki/World_Geodetic_System coordinate origin of WGS 84 is meant to be located at the Earth's center of mass. The related post finds the centroid somewhere in Europe/Middle East because the coordinate system the data is in (presumably WGS84/Geographic) use a coordinate range -180 to 180 with 0 passing through 102.5 metres (336.3 ft) east of the Greenwich meridian, should you use a different latitude of origin you'll get a different answer. – Michael Stimson Oct 19 '15 at 04:44
  • @MartinF Did you READ the post? I did not ask for "my region" but a whole world map. And though I mentioned either a polar or cylindrical projection I leave it up to whoever is interested in doing one since it is rather an artistic request. – Wojtek Oct 19 '15 at 05:22
  • @MichaelMiles-Stimson For a World Map without evaluation this should not make any difference. The Web Mercantor EPSG3857 even uses a spheroid for the projection onto a cylinder, and the differences are only noticeable at smaller scales. – Wojtek Oct 19 '15 at 05:28
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    Voting to close as a duplicate of the linked question. It has a graphic using a planar projection with the point in the center. Creating coordinate systems with a particular point as the center is easy in ArcMap; should be possible in QGIS too. – mkennedy Oct 19 '15 at 17:30
  • EPSG 3857 still uses PRIMEM["Greenwich",0.. if you were to use something like WGS84 Pacific http://spatialreference.org/ref/sr-org/8268/ as your map your centroid would be very different as it uses the international date line as the prime meridian (PRIMEM["DateLine",-180]).... but all of them should have a centroid at or near the centre of the Earth. – Michael Stimson Oct 19 '15 at 21:46
  • @Wojtek - I used "my region" as a place-holder for whatever is the region of interest. (In your case, it's the whole world.) – Martin F Oct 19 '15 at 22:05
  • I vote to re-open as this Q does not ask where is the centroid but what projection to use, based on the centroid. – Martin F Oct 19 '15 at 22:08
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    @MartinF Exactly. I have specified my request in the Title, the question and the comments. To mark it as duplicate is as silly as it gets, since I linked the question of where the geographic center is to another question AND a wikipedia link. – Wojtek Oct 21 '15 at 11:58
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    @MichaelMiles-Stimson

    I am aware that the 3D center is, alas near or at the the center of earth. But obviously I am talking about the coordinate origin on the sphere surface. Since the ellipsoid of the earth deviates marginally from a sphere, it is negligible on the scale of a world map and that is why I mentioned Web-Mercator. The fact that the supposed projection would look very different from a Web-Mercator which uses the Greenwich Meridian, is exactly the point and reason for the post in the first place.

     – Wojtek Oct 21 '15 at 12:06

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