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Leon van der Meulen 2022-02-01 15:53:13 +01:00 committed by GitHub
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@ -5,8 +5,10 @@ This map shows all the blinking beacons from [OpenStreetMap](https://www.openstr
More specifically, it asks the [Overpass API](https://www.overpass-api.de) for all elements with an `seamark:light:sequence` or `seamark:light:1:sequence` attribute, decodes these, and displays them as coloured circles on the map using [Leaflet](https://leafletjs.com). It also tries to take the `seamark:light:range` and `seamark:light:colour` into account.
If you think a lighthouse or beacon is missing, please add or edit it on [OpenStreetMap](https://www.openstreetmap.org/).
## Overpass API
The current version uses an extracted dataset, but the code allows for directly querying the Overpass API. However, since a query like the one used here can take multiple minutes to complete it is not very useful do always do live queries.
The current version uses an extracted dataset, but the code allows for directly querying the Overpass API. However, since a query like the one used here can take multiple minutes to complete it is not very useful do always do live queries. Currently we're updating the data every night.
## Useful stuff
The `leaflet.indexedfeaturelayer.js` file contains an extension on Leaflet's GeoJSON layer that only add layers/features to the map that are (or are about to be) visible. It uses a spatial index to quickly query which features can be removed from the DOM, increasing performance.