Where Actually Are The Antipodes?

  • keywords:
    • software
    • python
    • cartopy
    • matplotlib
    • numpy
    • shapely
    • naturalearth
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Recently I was thinking about where actually is the antipode of the UK? and where actually is the antipode of the US?. I decided to write a little script to overlay the world on top of itself so that it would be easy to find each location’s antipode. I know that the Wikipedia article on the antipodes has such an image but I dislike it aesthetically as it only shows half the world (I realise only half the world needs to be shown but I just find it un-intuitive). This one is far better but of low quality, in my opinion.

The Python script that I wrote to achieve this is shown below. It is quite a bit longer than what it ideally should be because I ran into problems with countries that cross the meridian (the UK, France, Spain, Algeria, Mali, Burkina Faso, Togo, Ghana and Antarctica) not being plotted when they are transformed to their antipode. This is an example of software problems with the anti-meridian and needed to be fixed. My chosen way was to: split the world up into quadrants (positive and negative longitude and latitude); determine if a shape was going to pose a problem when transformed; find the four overlaps of the shape with the four quadrants; and plot them individually. This way no single shape would cross the anti-meridian (or the equator).

To view this source code snippet without JavaScript you can either download “find_antipode.py” directly or view “find_antipode.py” on GitHub Gist.

The image produced by this script is shown below.

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  4. 2,152x1,121 (2.7 MiB)

A couple of things strike me when I look at this image: