ChartTiles

Open-source vector chart pipeline and viewer for NOAA Electronic Navigational Charts.

Safety notice — not for primary navigation. ChartTiles is reference and planning software. Mariners are responsible for maintaining redundant, type-approved navigation systems aboard their vessels. The data here is derived from NOAA ENCs and is subject to publication delays, processing errors, and the absence of any quality-management certification. Do not use as a primary nav aid.

Status

Pre-v0.1 — Shilshole inspection prototype implemented. A local pipeline downloads selected NOAA ENC cells, clips a small Shilshole Bay area, builds PMTiles, and checks feature retention at maximum zoom. A browser viewer supports local use and attribute inspection. Ivan completed the manual NOAA source checks and reported no discrepancies on September 26, 2026. Next: Puget Sound expansion.

For the larger regional benchmark, run npm run charts:puget followed by npm run build. See Puget Sound scope and measurements.

See the prototype guide for scope, validation and limitations. The broader planning documents describe future work, not completed capabilities.

What ChartTiles is

ChartTiles compiles NOAA's Electronic Navigational Charts into modern vector tiles, packaged as a single PMTiles archive per region. The same archive serves:

• A browser viewer, via MapLibre GL JS + pmtiles.js reading HTTP byte ranges directly from object storage. No tile server.
• An offline / onboard viewer, via a small nginx serving the PMTiles file from local disk on a Raspberry Pi or mini-PC at the nav station.

The whole system is static files plus a weekly cloud build. There is no GIS database at runtime.

Architecture in one diagram

  NOAA ENC (S-57)
        │
        ▼   weekly build: ogr2ogr → tippecanoe → pmtiles convert
  Single PMTiles archive (e.g. pnw.pmtiles)
        │
        ├──────────────► Cloudflare R2 + CDN ──► Browser (MapLibre + pmtiles.js)
        │                          ▲
        └──────────────────────────┴──► Onboard sync (aria2c) ──► nginx ──► Nav-station browser

Full C4 model and sequence diagrams in docs/architecture/.

Repository layout

chartiles/
├── README.md            # this file
├── docs/                # all docs (start here)
│   ├── README.md        # docs index
│   ├── implementation-plan.md
│   ├── business-plan.md
│   ├── roadmap.md
│   ├── glossary.md
│   ├── risks-and-safety.md
│   ├── architecture/    # C4 levels 1–3 + data flows
│   └── adr/             # architecture decision records
├── pipeline/            # NOAA acquisition, extraction, packaging and validation
├── web/                 # local MapLibre inspection viewer
└── tests/               # pipeline safeguards and browser integration

Documentation

Start with docs/README.md for the full index. Highlights:

• docs/implementation-plan.md — phased v0 → v1 plan with deliverables and exit gates
• docs/business-plan.md — market, customers, revenue model, KPIs
• docs/roadmap.md — 18-month timeline with funding strategy
• docs/architecture/ — system context, containers, components, data flows
• docs/adr/ — architecture decisions, including why PMTiles instead of the Btrfs scheme this project originally proposed
• docs/risks-and-safety.md — safety posture, technical and strategic risk registers
• docs/glossary.md — marine, GIS, and tile-format vocabulary

Scope of v0.1

• Geographic: Pacific Northwest only — Salish Sea, Puget Sound, San Juans, Strait of Juan de Fuca, coastal Washington to the Columbia. See ADR-0004.
• Data: NOAA ENC. No other hydrographic offices in v0.1.
• Deliverable: a single pnw.pmtiles archive plus a working web viewer plus an onboard configuration.
• Not in v0.1: routing, AIS overlay, weather, crowdsourced soundings, native mobile SDKs.

Quick start

Requires Node.js 22.12+, Python 3.10+, GDAL and tippecanoe. On macOS:

brew install gdal tippecanoe
npm ci
npm run charts
npm run build
npm run preview

Open the local URL printed by Vite. The built viewer works with internet disconnected while the local server stays running. Click features to inspect their attributes. This is a basic inspection style, not a navigational portrayal.

See docs/shilshole-prototype.md for tests and data provenance.

Contributing

Contribution guidelines will be added before v0.1. In the meantime:

• Read the ADRs before proposing architectural changes.
• File issues for missing edge cases in the docs, unclear safety language, or factual errors about the maritime / GIS domain.
• PRs against docs/ are welcome now.

License

MIT — see LICENSE (to be added).

NOAA chart data is in the public domain. We attribute NOAA in the viewer chrome and in PMTiles metadata as a matter of credit and provenance even though no attribution is legally required.

The license rationale, including why MIT over Apache 2.0 and the relationship to the safety disclaimer, is in ADR-0008.