Streets in the sea?

[P Wat]

Can someone explain why these streets are in the sea?

And a solution?

Location Shoreham by Sea near Brighton.

Latest updae of map Englanss SE is installed (today)

Running Osmand+ 3.9.6 on Android 7.0

Thanks

Paul W

[Harry van der Wolf]

It sometimes happens. 

Coastlines are complex (multi)polygons. It has been modified 3 months ago: https://www.openstreetmap.org/way/26491966#map=14/50.8409/-0.2730

But look at my map

It is the latest South-East roads-only map.

Harry

Op wo 17 feb. 2021 om 20:13 schreef 'P Wat' via OsmAnd <osm...@googlegroups.com>:

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[P Wat]

Thanks Harry - Understood -  Usdeful image.  Perhaps the polygons will be resolved in my phone before I have to drive down the submerged streets, or that the tide is out!  ;-)>

ATB
Paul W

[Harry van der Wolf]

I don't understand one thing.

You are talking about OsmAnd Live and of the 1 Jan map.

I am already using the 1 Feb map since a week or so. Why don't you have the 1 Feb map?

Harry

Op vr 19 feb. 2021 om 15:15 schreef A Thompson <thomp...@gmail.com>:

Yes, with the current England map (full, not roads-only) dated Jan 1st I see the same as you Paul. But with live updates it looks OK. So hopefully the Feb 1st snapshot captured in the map update expected in the next few days might fix it. I only recently subscribed to OsmAnd Live, so I can't test that by rolling back the updates.

[BTW I'm not trying to endorse live updates here - for navigation I disable the update files by renaming the "live" folder otherwise rendering is too slow for me.]

I seem to remember from reading Github issues that incorrectly tagging a modest inland body of water as "coastline" has also lead to OsmAnd "flooding" in the past, but Harry's explanation seems more likely in this case.

All the best!

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[A Thompson]

Something strange happened on Google Groups so my message didn't post there, but thanks for picking up on this, Harry.

I was accustomed to the all-England standard map update not being offered until about the 20th of the month. It was showing as up to date, but after your message I decided to delete and re-download... at which point I discovered that an all-England map isn't offered any more, only smaller regions. Other users should be warned to delete their old all-England map!

I'm not complaining at the change, though. The standard all-England map was over 2Gb. And I notice that in the nightly build there is a new facility to download all regions in one click. 

Going back to the original issue, the standard map for SE England now dated 1st Feb, does not show the flooding, even without live updates.

Thanks for spotting the anomaly Harry! It would have become a problem for me.

[Tom Crocker]

I also don't have a February England map yet. Actually, for that reason I decided to download the local area map and disable the England map. Current circumstances mean I don't have much need for further afield! That also seemed to improve the osmand live rendering speed, though may be to do with it being against the February map so fewer changes?

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[Harry van der Wolf]

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.

At first I didn't like the partial maps as you needed to download a lot more maps instead of one, but "normal" rendering (without live maps) has also improved due to this.

Harry

Op zo 21 feb. 2021 om 10:28 schreef Tom Crocker <tomcroc...@gmail.com>:

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[A Thompson]

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.

[Harry van der Wolf]

Op ma 22 feb. 2021 om 04:16 schreef A Thompson <thomp...@gmail.com>:

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.

Thanks. Subconsciously I knew this as I do make overlays and submaps from "raw" osm data, but I never got the brainwave to use it for something I changed in OSM and wanted to check immediately in OsmAnd.

Thanks for this tip.

Harry