Offline map and 3D view

Offline map data

backend/app/basemap_data/ (17 MB) is built by python tools/make_basemap.py --all on a machine with internet (needs pyshp and osmium besides the app's libraries) and ships with the app: elevation grids (world ~11 km, Israel and surroundings ~500 m, Israel ~130 m) from the AWS "Terrain Tiles" (Mapzen / Tilezen: SRTM, GMTED2010, ETOPO1), Natural Earth (public domain), and OpenStreetMap from Geofabrik extracts (© OpenStreetMap contributors, ODbL). The app draws map tiles from them (backend/app/basemap.py, cached in ~/.signalviewer/tiles); the map shows the attribution. To refresh the data, run the tool again.

More detailed areas (packs). Any area can get the same detail as Israel: elevation (~130 m), OpenStreetMap roads down to regional ones, places down to villages, airports and runways:

python tools/make_basemap.py --pack cyprus --bbox 34.5,32.2,35.75,34.65 --countries europe/cyprus

--bbox is south,west,north,east; --countries the Geofabrik extracts covering it (comma-separated); --zoom 9 or 8 for coarser (smaller) elevation. The pack is written to backend/app/basemap_data/packs/<name>/ (pack.json, dem.npz, vectors.json.gz; ~1.4 MB for Cyprus) and the app uses every pack in that folder - copy a pack folder there on an offline machine.

3D view

CesiumJS (pinned, frontend/package.json) is loaded only when a plot is switched to 3D; its web workers and data files are copied into the UI build under /cesium/ (frontend/vite.config.ts), nothing comes from the internet. Terrain heights come from /api/terrain/{z}/{x}/{y} (the same bundled elevation grids as the offline map: sea at 0 m, the Jordan rift really below it). The object models are built by python tools/make_models.py into frontend/public/models/. Graphics: with a graphics card Cesium draws at the display's frame rate; drawn in software (virtual machines, remote desktop) it is slow - the app then uses one sample per pixel and less terrain detail (about 3x faster) and shows a note. Not in reports.