3

I've extracted a geojson data file from QGIS for a transportation layer. Now in the file, I can see multiple entries like the following:

        {
            "geometry": {
                "coordinates": [
                    [
                        [
                            482745.218106,
                            6656907.959327
                        ],
                        [
                            482785.825278,
                            6656836.299613
                        ],
                        [
                            482820.460806,
                            6656815.996028
                        ],
                        [
                            482967.36322,
                            6656599.822557
                        ]
                    ]
                ],
                "type": "MultiLineString"
            },
            "properties": {
                "_col": 4194,
                "_row": 5456,
                "_zoom": 13,
                "brunnel": null,
                "class": "service",
                "oneway": 0,
                "ramp": 0,
                "service": null
            },
            "type": "Feature"
        }

I guess in the coordinates are the latitudes and longitudes. Normally, the range of values should be between -180 and 180, but here it isn't. Why?

1

It looks like someone or some software has projected the co-ordinates into a projection system that is not WGS84 (Lat/Lon). This is not permitted according to the spec.

Since there is no metadata within the Geojson itself, you will need to ask whoever gave you the file what coordinate system it is in, or work it out based on where the data is, what projection people normally use, the bounds of those projections etc.

You can still open the file in software such as QGIS to see it, but without the crucial information of what co-ordinate system it is in you won't be able to project it, and therefore save it back as WGS84 with its real world coordinates for more general viewing. Having said that, your question doesn't make clear why you care / what you want to do with it afterwards.

| improve this answer | |
  • 3
    Other coordinate systems are OK according to the original spec geojson.org/geojson-spec.html. They CRS used should have been advertised with the "crs" member, though. – user30184 Aug 24 '18 at 10:49
  • yes, but that spec is clearly marked as obsolete – Stev_k Aug 24 '18 at 10:59
  • 3
    That's true, but the old spec is still widely used because people keep on thinking that they do need also other coordinate systems than WGS84 Long-Lat. It is for example the default output version for GDAL gdal.org/drv_geojson.html and GDAL requires creation option -co RFC7946=YES for the current variant. – user30184 Aug 24 '18 at 11:02
0

Coordinates are not in WGS 84 (EPSG 4326). Could be maybe EPSG 3857.

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  • This is more of a comment than an answer, agree the coordinates are not long/lat. – nmtoken Jan 1 '19 at 12:57
  • It's a (very short) answer to the question why the coordinates are out of range -180 to +180. – Mesa Jan 1 '19 at 18:36
0

You can use this site to convert coordinates:

https://mygeodata.cloud/converter/geojson-to-latlong

Upload your file. Then from the source coorrdinates search for the country that is being covered. That will usually give you the correct conversion choice. If not you will need to go through the systems until you find the right one.

Then select the output coordinates (for 180, -180, use World) and select your output format.

Then click convert.

And then download.

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