Build a 3D low-poly map of a city from open map data

u/OrestesGaolin set out to render central Warsaw as a 3D low-poly map that runs in the browser. They used Codex heavily, running through its usage limit three times, and filled the gaps with Claude. The map covers 6.85 by 7.2 km, cut into 144 tiles of 600 m each. Generic buildings come from OpenStreetMap with heights from the Polish national mapping agency's 2025 data, trees from the city's crown map and inventory, and roads, land use, traffic signals and transit stops from open data. Each of the 1,027 landmarks is its own small generated program that builds a low-poly model.

The site is live at tinywarsaw.app. It draws 17,941 buildings, 1,027 landmarks, 257,387 trees, 21,368 road segments with lanes, crossings, rails, tunnels and bridges, and 40,028 park, water and square areas. Landmarks total about 7.4M triangles at full detail, cut to 1.9M for distant views on desktop and 1.5M on phones. The landmark code alone is 91 MB of JavaScript. The author asked the subreddit for help with performance and plans to open source the repo after a cleanup.

The post does not say how the work was split between the two agents, and the Claude harness is not named. One generated program per landmark adds up fast: 91 MB of JavaScript is the cost of that approach, and performance on slower devices is the open problem the author raised.