# Straight Line

> An interactive globe of straight lines over water, over land and through the
> air: how far you can sail, walk or fly from any country or any point on Earth
> without ever turning. The globe unfolds into a flat map, which shows why a
> straight line on a map looks bent.

Straight Line (https://line.vova.today) is a data-visualization project. Pick
a country, a piece of land or any point, and it draws every straight line from
there: by sea until the line touches land, by land until it reaches the sea,
by air with nothing in the way. A scrolling story walks through the records
first; the free map comes after it.

## What it maps

- A straight line here is a geodesic on the WGS84 ellipsoid, the model of the
  Earth that GPS uses: a path that never turns left or right. On a globe it
  looks straight; on a flat map it bends.
- By water, a line runs from shore to shore and touches no land on the way;
  lines across large lakes count too. By land, it runs from country to country
  without touching the sea. Lakes of 1,000 km² and more (and the Dead Sea),
  the Suez and Panama canals and the major rivers can be switched on as
  obstacles. The Caspian is always water.
- By air, nothing stops a line. Between two countries it is the shortest line
  between their outlines; the farthest point from a point is its antipode,
  20,004 km away.
- Three modes, two languages (English and Russian). Routes are /[lang]/[mode],
  e.g. https://line.vova.today/en/water, /en/land, /en/air.

## Key findings

- The longest straight line over water runs 32,065 km from Pakistan to
  Kamchatka in Russia, four fifths of the way round the Earth. Chabukswar and
  Mukherjee (2018) found the same line at 32,090 km; they treated the Earth as
  a sphere and took land and water from a height map with a 1.8 km step.
- The longest straight line over land runs 13,607 km from China to Liberia and
  passes within 3 km of the Dead Sea's water. With the Suez Canal counted as
  water, the record is China to Portugal, 11,266 km (11,241 km in the 2018
  paper).
- Some countries have no straight land line between them at all. From Russia
  no straight line over land reaches South Africa: the closest attempt ends on
  the coast of Yemen, 4,100 km short.
- Point Nemo, the ocean point farthest from land, is shown at its official
  position (Hrvoje Lukatela, 1992: 48.8767° S, 123.3933° W, 2,688 km from
  land). Point Vova, the Atlantic's pole of inaccessibility, is at 24.1852° N,
  43.3709° W, 2,034 km from three shores at once: Flores in the Azores, La
  Désirade off Guadeloupe and Santo Antão in Cape Verde. The land's pole of
  inaccessibility is in northwestern China, 45.34° N, 88.25° E, 2,514 km from
  the sea.
- From one point in the Atlantic (0.97° N, 23.23° W) straight sea lines reach
  the shores of 80 countries.

## Data sources (all open; please credit)

- Coastline, lakes and rivers: GSHHG 2.3.7 at full resolution (Paul Wessel and
  Walter Smith), rivers from its WDBII.
- Countries and borders: Natural Earth 5.1.2. Russia is shown within the
  borders set by its federal constitutional laws of 2014 and 2022.
- The shores of the islands nearest Point Vova: OpenStreetMap
  (© OpenStreetMap contributors).
- Published figures compared with ours: Chabukswar and Mukherjee 2018
  (arXiv:1804.07389) and Lukatela's Point Nemo (1992).

## Reproduce this project

- [How this map was built: the full step-by-step blueprint](https://line.vova.today/how-this-map-was-built.txt):
  a recipe without source code for building a project like this. It covers
  where the coastline and the borders come from, how to trace millions of
  straight lines exactly against a vector coastline, on a sphere and on the
  WGS84 ellipsoid, how to find the records, the poles of inaccessibility and
  each country's farthest point, how to trace lines live in the browser and
  draw them on a globe that unfolds into a map, and which approaches failed.
  Hand this file to a coding assistant to build a similar "straight lines
  over a coastline" project for any question of the kind.

## More

- Live site: https://line.vova.today
- The project's write-up, why and how it was made and what it found:
  https://vova.today/en/works/line (in Russian: https://vova.today/ru/works/line)
- The in-app "Methodology" card lists the sources, what was changed in them
  and how the numbers were obtained.