Show HN: Cartopolis, interactive globe-sized 3D world

A social map of the real world: see how a place is built, and talk about it with the people who are there.

A walkable 3D copy of the real world, built from open public data and shared between everyone looking at it. Runs in the browser, on the desktop and on Android. Free, open source, self-hostable. Public infrastructure

Built from the registers — buildings from BAG and 3DBAG, ground from AHN, street trees, lighting and paving from the national and municipal object registers, PDOK aerial photography, live transit. Every building has a card — year built, use, units, floor area, status, monument listing, addresses. Walk in and its storeys are there. The world around it — real sun, real weather, routing on foot, by bike or by car, and one continuous space from a doorway to orbit.

Sharing a place

Talk where you stand — avatars, local chat scoped by distance, proximity voice, world chat, end-to-end encrypted private chats. Point at it — a link opens your exact view in the browser or the app; saved places with photos and map pins. Put something there — place and script objects and 3D models, swap a building for an IFC model, export and import content over an HTTP API. Moderation — blocking, reporting and account deletion, enforced on the server; a web console for accounts and data pipelines.

For residents, communities, municipalities and governments, and planners and architects. Screenshots

Canal ring Ring road tunnel by DUO

Main station and rail yard Grote Markt and Martinitoren

Forum Groningen Building card: the town hall

Groningen from 3 km The city from 1.2 km up

Eemshaven Eemshaven from the Wadden Sea

Meeting on the Grote Markt Earth from orbit

Generated with cargo shots from docs/shots.toml. Where it works Map, sky, weather, routing and the shared world: anywhere on Earth. Register detail (measured buildings and their records, relief, street objects, aerial photos, transit): the Netherlands, plus municipal data where a city publishes it. Elsewhere the ground is flat and buildings come from OpenStreetMap. Each register is one pipeline in crates/atlas. Written in Rust on Bevy. Try it

Browser — cartopolis.org. Needs WebGPU. Desktop — Linux and Windows on the releases page, or build from source (macOS too). Published binaries need AVX2 and FMA (~2013+). Android — APK at cartopolis.org/apk (arm64, Android 9+). The full client, least tested of the three (notes).

Running from source cargo run -p cartopolis Starts offline. Sign in to a server from ☰ ▸ Sign in…. cargo run -p cartopolis -- --connect # split mode: connect to a live sim (TLS) cargo run -p cartopolis -- --offline # no sim: single user, no auth or persistence cargo run -p cartopolis_simulator # the sim server, standalone Needs Rust, a C compiler and a GPU driver; see the development guide. Run git lfs install before cloning — assets are in Git LFS and some are compiled in. Documentation

User manual — controls, getting around, authoring, the developer panel. Changelog — what changed, per release. Development guide — prerequisites, dev loop, tests, code map, conventions, CI. Server guide — deploying the sim and the self-hosted geo services. docs/notes/ — constraints and measurements; CLAUDE.md Known issues is the trap list.

Architecture

Crate Role

cartopolis_core Shared protocol types and tile/coordinate math

cartopolis_geo Bevy-free map geodata: MVT decode, road classes, tree scatter, the routing graph

cartopolis_e2ee End-to-end encrypted private chats (MLS); the server relays sealed bytes it cannot open

cartopolis_simulator The shared-world server (Tokio + SQLite): avatars, chat, voice, objects, accounts; no Bevy

cartopolis_atlas The register pipelines (BAG, 3DBAG, AHN, BGT, …), the terrain server and the operator web console

cartopolis Bevy client — rendering, ECS systems, UI

cartopolis_android The Android app shell around the client

big_space Vendored floating-origin fork, for planet-scale coordinates

Licence Source: MIT OR Apache-2.0 (LICENSE). Data, avatars and font carry their own terms; LICENSE-THIRD-PARTY.md is the canonical notice list (the credits below mirror it — add new sources there). Credits

Engine — built with Bevy. Floating origin — big_space by Aevyrie, MIT OR Apache-2.0. Vendored here as a fork ported to the Bevy release we track. Avatar characters — Quaternius Ultimate Modular Men/Women, CC0. Consider supporting the work on Patreon. Map data — © OpenStreetMap contributors, under the ODbL. Building detail and POIs come from Overpass, place search and reverse geocoding from Nominatim — both self-hosted, and usable against the public instances under the OSMF usage policies. Vector tiles — VersaTiles, in the Shortbread schema. Self-hosted mirror of their OSM-derived planet build. Buildings (LoD2.2) — 3DBAG by the 3D geoinformation group, TU Delft, CC BY 4.0 — derived from the Kadaster's BAG registry and AHN, both via PDOK. Netherlands only. Aerial photography — Beeldmateriaal Nederland, served as Luchtfoto RGB by PDOK, CC BY 4.0. Netherlands only. Street objects — street trees, lighting and containers from gemeente Groningen open data, CC BY 4.0. Groningen only. Elevation — AHN height rasters (DTM/DSM), served by PDOK, CC0. Netherlands only. Public transport — live departures and vehicle positions from OVapi, the open key-free feed of Dutch NDOV operator data. Netherlands only. Weather — forecasts from MET Norway, CC BY 4.0, and global cloud cover from the NOAA Global Forecast System, public domain. Night sky — star positions and magnitudes from the HYG Database v4.1 by David Nash, CC BY-SA 4.0 — a compilation of the Hipparcos, Yale Bright Star and Gliese catalogs. Type — Plus Jakarta Sans by Tokotype, SIL Open Font License 1.1.