OpenStreetMap
Weird Parallel E/W Lines
Posted by bhietsch on 27 August 2020 in English. Last updated on 29 August 2020.Anyone know what the deal with these lines is? They seem to run between the prime meridian and the anti-meridian, but only render at zoom level of 4. My first thought was that they may have something to do with the arctic circle, but they look to be a degree or two south of it.
Discussion
Comment from highflyer74 on 27 August 2020 at 20:38
Not visible here though… I will check on a different computer tomorrow.
Comment from highflyer74 on 28 August 2020 at 05:30
Check done, no signs of lines.
Comment from imagico on 28 August 2020 at 09:38
These lines - as can be derived from where they are located - result from boundary line segments (here from admin_level 2 boundary relations) crossing the 180 degree meridian. Since practically almost all geodata processing software by default interprets line segments as if geographic coordinates were cartesian coordinates and therefore assumes any such segment no matter how short it actually is to wrap around the whole earth along the parallel you need to avoid such segments by splitting any geometry crossing the 180 degree meridian along the meridian. If a mapper not aware of this carelessly moves a node across the 180 degree meridian the result is like what you point out (in this case probably fixed in osm.org/changeset/88746336)