Add an optional LOOM schematic transit-map overlay

[Medformatik]

Integration request

Provider / source

LOOM (University of Freiburg), initially using its published weekly vector-tile service.

Website and documentation

• https://loom.cs.uni-freiburg.de/tiles
• https://github.com/ad-freiburg/loom

Domain

Schematic transit-map overlay for rail, metro/light rail, commuter rail, tram, and related stations/connections.

Authentication

The public tile endpoints currently document no API key. This must be verified before release, together with usage expectations and attribution.

Coverage and freshness

The public service describes global OSM-derived tiles rebuilt weekly, with geographic, octilinear, geo-octilinear, and orthoradial layouts and separate transit network groups.

License / attribution

LOOM software is GPL-3.0; source OSM data and the hosted tile service require a documented attribution/licensing review before enabling the integration.

Problem

OpenMapX renders geographically accurate transit routes but has no schematic network-map view for understanding dense systems at a glance.

Proposed solution

Add an optional map-overlay integration for LOOM MVT tiles. Start with the hosted weekly tiles so layout quality and product value can be evaluated before taking on a self-hosted LOOM build pipeline.

Acceptance criteria

• A manifest-backed integration declares endpoints, layouts, network groups, attribution, privacy, and availability.
• Operators can disable the remote source or route it through the approved proxy/cache boundary.
• Users can select supported layout and network group without confusing the overlay with live service status.
• MVT layers (lines, inner-connections, and stations) map color/width/identity attributes deterministically.
• Tile ordering, zoom visibility, selection, contrast, and label coexistence work with the base map.
• Attribution and hosted-service usage terms are verified and documented.
• Caching, rate limits, timeouts, unavailable tiles, and stale weekly data have clear behavior.
• A representative-city visual test covers dense, sparse, and multi-modal networks.
• Mobile performance and reduced-data behavior are measured.
• A follow-up decision records whether self-hosting LOOM is justified; it is not required in this first slice.

Contribution

External contributions are welcome after the data/licensing contract is settled.

[Medformatik]

Shipped in 1568735 as integrations/overlay-schematic-transit.

The overlay renders LOOM's hosted vector tiles (tram, metro/light rail, commuter rail, long-distance rail; geographic, octilinear and orthoradial layouts) with network and layout switching in the legend. Tiles are proxied through the API on the tile rate-limit tier (the upstream sends no CORS headers), empty upstream tiles become cacheable 204s, and the overlay is mutually exclusive with the geographic transit-lines overlay. Keyless and enabled by default; operators can disable it or point tileBaseUrl at a self-hosted LOOM. Attribution (ODbL / LOOM, University of Freiburg) flows from the manifest; docs at docs/docs/features/schematic-transit-map.md.

Not in this slice, on purpose: the geo-octi layout (currently 404s upstream for every tile), line-name badges, and the self-hosted LOOM pipeline — that decision stays open for a follow-up once we have usage data from the hosted service.