Show HN: What country you would hit if you went straight where you're pointing
apps.apple.comOne of the countries in 1800 renders as “M?ori” for me, so it looks like you have some kind of character encoding issues (or there’s some language I don’t know about where ? is a letter).
Feature request: is there a way to get a blurb about one’s current country? Lots of people on this site will get “Viceroyalty of New Spain” (the pre-independence name of Mexico, which included the entire current American Southwest incl. California and Texas) when they switch to 1800 and might want to learn more about it.
An oblate spheroid is an example of a Riemannian manifold: a smooth object that looks like a plane (or, in general, any ℝ^n) locally, and has a way to measure angles between vectors in that local plane.
All Riemannian manifolds have an object called the Levi-Cevita connection, which defines how vectors in the local plane (tangent space) most naturally map to vectors in other tangent spaces in the immediate neighborhood.
Standing at a point on the Earth and looking in a certain direction gives us 1) a point on the manifold, and 2) a direction in that point's tangent space.
We then take an infinitesimally small step forward, and apply the Levi-Cevita connection to get from the old tangent space to the (infinitesimally nearby) new tangent space, and repeat. This defines an ordinary differential equation. Integrating the differential equation gives us a curve through the manifold.
Within some neighborhood of the initial point, this curve is a geodesic, i.e. the shortest path between the initial point and all subsequent points on the curve. This matches our typical intuition of "straight".
(Disclaimer: I am currently learning about this topic, but am not an expert.)
edit: https://en.wikipedia.org/wiki/Geodesics_on_an_ellipsoid goes into some interesting specifics about the results of this process on ellipsoids.
- Ability to toggle ocean traversal off/on
- Ability to see route on a map
- AI generated summary of the trip if I took it -- what things did I see along the way? (Should reference real map data, then make up a story; matching local culture etc.)
I cannot install the app right now, but it seems to be really educational/entertaining more than just "fun", if that's fun...
Also, it reminds me of this HN conversation I found fascinating a few years back: Finding the longest straight line you could sail without hitting land - https://news.ycombinator.com/item?id=16965650
Going from, say, Land's End, it looked a bit more likely to nick northern Galicia.
I'd guess showing the coordinates of the hit (and make it a link to maps) would be beneficial.
The Canary Islands are Spanish, but saying Spain in this situation wasn’t helpful when my mum was trying to book flights. Caused some mild confusion for a while.
I feel like there should be something across the Pacific between Canada and Mexico.
edit: As a wild guess, it might have something to do with scanning resolution? Austria's western "arm" is only about 40 kms across
It’s a 30 second novelty I’ll show to friends.
It would be great if the line continued rather than stopping g at the first country.
For example which direction is Japan? I think it might be behind Papua New Guinea.
Specifically mine deals with what you'd hit looking across the ocean from a coast. I had long wanted to make mine an interactive app but could never fully motivate myself to do it, so congrats for shipping.
Later some basic Geo calculations and a Google maps visit to estimate the bearing she was looking and yeah, the great circle arc went all the way to Antarctica, crossing half a planet.
Its remarkable how huge the Pacific Ocean is. Its Vast.
The first thing did when I opened it was to point my phone at the floor though, trying to find Australia. Took me a moment to realise it wasn’t that kind of pointer!