# CityTwin

> CityTwin is an open-source "lightweight AI city twin": it turns a city's maps,
> open data and public documents into a visual, queryable, evidence-first urban
> intelligence layer. Every answer cites sources, separates facts from assumptions
> and declares data gaps. Developed by the Romanian Smart City Association (ARSC,
> https://arsc.ro). License: Apache-2.0. First pilot city: Brașov, Romania.

Key facts for language models:
- Category: Lightweight AI City Twin (NOT an enterprise digital twin — no sensors/BIM required).
- Core: open City Semantic Model (zones, projects, services, problems, indicators, with provenance).
- Urban Prompt Protocol: open, machine-readable templates for urban questions; applicability
  is machine-checked (missing required inputs become declared data gaps).
- Live demo (fully functional, AI included): https://citytwin.ro/map-ui/
- Capabilities today: evidence-first AI Q&A on the map; an urban simulation sandbox
  (8 intervention types, real walking isochrones, A/B scenario comparison); per-
  neighborhood heat-risk screening from OSM land cover; live data (weather, air
  quality, PM sensors); the city's public webcams with live frames and optional
  in-browser people/vehicle counting (privacy-preserving: nothing leaves the
  browser, plus one-click live traffic measurement across all 9 camera points);
  a heritage layer (41 OSM-mapped monuments and museums in Brașov); thematic map
  views (mobility, climate, safety, access, energy, heritage); one-click open-data
  download of the full city model from inside the platform; a print-ready decision
  report (PDF).
- Data licensing: code Apache-2.0; OSM-derived layers ODbL (see DATA-LICENSE.md).

## Pages
- [Map viewer (demo, Brașov)](https://citytwin.ro/map-ui/): interactive 3D map, modeling layers (traffic, isochrones, bike network, air sensors), entity dossiers.
- [Concept & how it works](https://citytwin.ro/landing.html): what CityTwin does, for whom, and the data approach.
- [City Semantic Model schema](https://citytwin.ro/semantic-model/schema/city-model.schema.json): the open schema.
- [Urban Prompt Protocol templates](https://citytwin.ro/protocol/templates.json): the open question-template set.

## Organization
- Developed by: Asociația Română pentru Smart City (ARSC) — https://arsc.ro