gpserror's Diary

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Well, today I checked in my first JOSM edits.

First was a boo boo. I cheated and used iD to revert… hah.

Second was what I intended as the first checkin - found out that iD was deliberately nerfed to not allow the edit I wanted to do. Still haven’t figured out the best way but oh boy, JOSM was much easier to move a node 10 miles away. Did a few in iD and that was really no fun.

Then a few more edits in JOSM… just to not get annoyed when iD nags “You didn’t fix the warning I flagged.”

“But I didn’t make the warning… and I don’t know enough to actually fix the warning!”

grumble grumble…

1 billion USA nodes

Posted by gpserror on 27 July 2021 in English (English).

Well, I just wanted to see what this feature does so I’m posting some useless stuff.

As listed on my profile page I muck with mkgmap and my Garmin Nüvi for the USA. These Nüvis can only handle 4GiB map files. So I look at the diagnostic output of mkgmap and noticed we’ve got a billion live nodes that need to be parsed for just the USA. Not exactly sure when it passed this mark, but it was fairly recent.

1 billion USA nodes, and each node has a longitude and latitude that if were represented by a floating point number (single precision float - 32 bits) would mean 4 bytes per longitude, 4 bytes for latitude. Then an identifier…

This would 8GB by itself, without ways to link the nodes. Impressive that osm.pbf can “compress” all these nodes, ways, relations, and all the tags into a (currently) 8GB file.

But anyway been trying to go through a bunch of the QA issues in the map data. I think I got through one pass of the roundabout routing issues that are shown in mkgmap. I was playing with OSRM and GraphHopper with the errors and with the fixes, I’m surprised that people haven’t found some roundabouts that OSRM/GraphHopper completely refuse to enter… they’re scared of roundabouts! Hopefully OSRM, GraphHopper, and even my Garmin Nüvi will now route through them properly.

Alright that’s enough for now here. If this text is even useful…