Offline Maps
Harlock includes an offline map system that lets you download map tiles in advance and use them without an internet connection during operations.
Downloading an area
- Go to Maps → Manage cache
- Click New area and draw a rectangle on the map
- Choose the zoom level (8–18 recommended; 18 = maximum detail)
- Click Download
caution
Zoom level 18 over large areas can require many GB of storage. Calculate the estimated size before downloading.
Tile providers
| Provider | Coverage |
|---|---|
| OpenStreetMap | Worldwide (streets) |
| Satellite (ESRI) | Worldwide (imagery) |
| Terrain (OpenTopo) | Worldwide (contour lines) |
You can change the provider under Settings → Map.
Offline usage
When the app detects no internet connection, it automatically uses cached tiles. Tiles that have not been downloaded appear as grey areas.
Cache management
- View used space — on the Manage cache page
- Delete area — remove a downloaded area
- Delete all — empty the entire tile cache
Limitations
- Tiles are saved in the app data directory (see Settings → Paths)
- The cache does not expire automatically; manually refresh areas if the imagery is outdated
- Downloading requires an internet connection; offline reading is always available