On Sunday, February 21, 2021 at 9:39:01 AM UTC hvd...@gmail.com wrote: > Data is both read from the offline map and from the live map and the > changes in the live map are merged or overlaid with the offline map, where > 99% of the data still comes from the offline map. (I do not exactly know > how it is merged/overlaid) > That is of course much faster with a 300MB (partial) map than with a 2GB > map, even though the data is indexed. >
The live updates become offline incremental updates to the main map file once they are downloaded - hourly, daily, weekly, or on-demand.(the files go into a folder called "live"). Presumably OsmAnd servers make an overpass query to determine how OSM has changed since the previous update, then run this through OsmAndMapCreator to make the update .obf file. Each time you update you get another file saying what has changed since the previous update, it doesn't go all the way back to the map creation date each time. The update files have a date/time suffix to their filename such that the most recent updates are later in filename sort order. An object in a later file replaces an object having the same ID in an earlier file. Objects with new IDs are added. An object is tagged with osmand_change=delete if it is to be removed. I hope someone finds that interesting! You can even customise your map by making local edits to OSM objects in JOSM, saving as .osm, then using MapCreator to make a .obf update file with a suitable filename. You don't need to be subscribed to OsmAnd Live for this to work. -- You received this message because you are subscribed to the Google Groups "OsmAnd" group. To unsubscribe from this group and stop receiving emails from it, send an email to osmand+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/osmand/18514666-b0a3-471e-b10b-0c5ca505e9c2n%40googlegroups.com.
