Show HN: What country you would hit if you went straight where you're pointing

  • Posted 3 days ago by brgross
  • 79 points
https://apps.apple.com/us/app/leascope/id6608979884
This app was designed to answer my wife’s question “what country would we hit if we went straight” (generally posed while pointing her phone)

But with two additional twists:

1. It loads up historical maps from different years (right now 1 BC, 700 AD, 1000 AD, 1300 AD, 1800 AD, 1900 AD) so you can see what you would hit if you had a time machine AND you went in the direction your phone is pointing

2. Tap a country/territory for an (AI-generated) blurb on what you are pointing at

How it works: Starting from your phone’s bearing, we trace the great-circle in 200 km steps, prefilter candidate countries with bounding boxes (~5–10 instead of ~200), then check ~20 km points along each segment to catch coastlines and stop when the path first enters another country.

Great-circles (https://www.movable-type.co.uk/scripts/latlong.html) are why you can hit Australia from NYC, even though when you look at a flat map that can be hard to see.

There might be some weird stuff in the explanations, I haven’t read all 1,400 of them. If you see something weird let me know and I will update it!

The app is free and doesn’t have ads or tracking — your location and bearing are only used locally to figure out where you are and what you’re pointing at

Probably will work best if you hold your phone pretty flat :)

Thank you to André Ourednik and all the contributors to the Historical Basemaps project: https://github.com/aourednik/historical-basemaps)

21 comments

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