GeoJSON export: some ways gets exported as polygons

[TobWen]

Ways with some tags get exported as polygons when exporting to GeoJSON.

Try this fake way:

<?xml version='1.0' encoding='UTF-8'?>
<osm version='0.6' generator='JOSM'>
  <node id='-76119' lat='51.5099031' lon='6.8806761'>
    <tag k='highway' v='footway' />
  </node>
  <node id='-76121' lat='51.5097885' lon='6.9040016'>
    <tag k='highway' v='footway' />
  </node>
  <way id='-76135' action='modify'>
    <nd ref='-76119' />
    <nd ref='-76121' />
    <tag k='highway' v='footway' />
    <tag k='man_made' v='surveillance' />
  </way>
</osm>

When exporting it to GeoJSON, it gets:

        {
            "type":"Feature",
            "properties":{
                "highway":"footway",
                "man_made":"surveillance"
            },
            "geometry":{
                "type":"Polygon",
                "coordinates":[
                    [
                        [
                            6.88067610000,
                            51.50990310000
                        ],
                        [
                            6.90400160000,
                            51.50978850000
                        ]
                    ]
                ]
            }
        }

Changing a non-closed ways into an area produces lots of trouble of course.

Furthermore, according to the wiki, man_made = surveillance is mainly used on points, but can also be used on ways and polygons.

[Don-vip]

Replying to TobWen:

Furthermore, according to the wiki, man_made = surveillance is mainly used on points, but can also be used on ways and polygons.

Where do you read that? The ​wiki states the exact opposite. And taginfo counts 48.143 nodes against only 449 ways and 14 relations.

[TobWen]

Replying to Don-vip:

Replying to TobWen:

Furthermore, according to the wiki, man_made = surveillance is mainly used on points, but can also be used on ways and polygons.

Where do you read that? The ​wiki states the exact opposite. And taginfo counts 48.143 nodes against only 449 ways and 14 relations.

Hm? That's what I said: it's mainly used on nodes (48.143), but is also used on ways (of course, not very few only). But this makes the behavior of JOSM's GeoJSON-export to polygon even more confusing :)

[TobWen]

Is "elemstyles.mapcss" controlling the GeoJSON export? That's the only place, where I've found k=man_made and v=surveillance as an area.

[Don-vip]

Yes, the polygon is guessed from tags based on standard style. But it should only concern closed ways.

[Don-vip]

In 12439/josm:

fix #14974 - geojson export: use Polygon only for closed ways

[TobWen]

Thx.

[Klumbumbus]

I think we should remove the area rendering of man_made=surveillance in the internal mappaint style. Any objections?

[Don-vip]

Replying to Klumbumbus:

Any objections?

Go on. It was added long ago in r1006 but it was a mistake (copy/paste).

[Klumbumbus]

In 12440/josm:

see #14974 - use man_made=surveillance only on nodes

[TobWen]

Maybe we should have a look here. It up to date and used in many applications: ​https://wiki.openstreetmap.org/wiki/Overpass_turbo/Polygon_Features