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Pocket Switzerland
Translated from French with the help of AI; the French text prevails.

Behind the scenes

This page is for the curious: what the map can do, how it is built, where its data comes from, and the workshop used to fine-tune it.

What the map can do

You pilot a hot-air balloon over a simplified Switzerland whose relief is nonetheless real: it comes from swisstopo’s terrain model, exaggerated by a factor of 1.6 so that the Alps stand out better from above. Day, dusk and night follow the time on your watch, and you can switch to winter.

There are 63 places to find: you have to land near a town, or fly over a summit, a lake or a glacier. The flight log keeps track of every discovery, and the backpack gathers the stamps, the patches and the treasures. Chests are hidden in the landscape, and quests lead from step to step to a grand chest. A speciality per canton waits in a basket to be picked up in flight, and every transport on the map has its ticket: you only have to land on it.

The nature guide brings together 31 species, from the lowlands to the glaciers, which you meet depending on altitude and on the way the slope faces. One of them, the alpine chough, can become a flight companion. Clotilde, the marmot, comes along on the first flight. And everything can be read in five languages: French, German, Italian, English and Romansh, the last one translated by machine.

How it is built

The map is a web application: a three.js scene, driven by React Three Fiber and written in TypeScript. The terrain is a single mesh, computed from an elevation grid with a 200 m spacing. One rule is not up for debate: the map must stay smooth on an 8 GB MacBook Air, at 60 frames per second, never below 30.

The site you are reading is made with Astro: static pages, written in markdown, in the map’s colours and typefaces. The code is written with Claude Code, Anthropic’s programming assistant, and the illustrations are created with gpt-image, OpenAI’s image model: they are not photographs.

Where the data comes from

  • The relief: the DHM200 digital terrain model and the swissNAMES3D geographical names, from swisstopo.
  • The border and the lakes: the generalised municipal boundaries of the Federal Statistical Office, through the swiss-maps package by Interactive Things.
  • The lakes of the Upper Engadine and the glaciers: swissTLMRegio, from swisstopo; the moraines are computed from the relief.
  • The railway line: the rail network of the Federal Office of Transport, published on opendata.swiss.
  • The places and sites: Switzerland Tourism, under the CC BY-SA 4.0 licence.
  • The Romansh translation: the Apertus model, through Public AI.

The workshop

During development, a toolbar opens at the bottom right of the screen. It never ships to the live site:

  • Flight feel: the seven numbers that tune the flight;
  • Collection: forget a place, or everything, to replay a discovery;
  • Gains: set the level, give or take away a reward;
  • Quests: set a quest to the step you want;
  • Teleport: go straight to a chest, a step, a basket, a transport or a place, to fly over it or land there;
  • Perf: draw calls, triangles, memory and frames per second, compared with the budgets;
  • Sky: launch a shooting star;
  • Nature: bring up a patch of nature in front of the balloon;
  • Render and Terrain: the rendering settings and the paper folds.

And a special address, ?perf, replays the most demanding route, from Interlaken to Zermatt by way of the Jungfrau, to measure smoothness.