Add crs to GeoJSON when not CRS84

[jkr-wrk]

Feature description

Wouldn't it be good practice to add the crs attribute to a GeoJSON when it is not the default crs?

For example:

{
"type": "FeatureCollection",
"name": "myname",
"crs" : {
"type" : "name",
"properties" : {
"name" : "EPSG:28992"
}
},
"xy_coordinate_resolution": 1e-10,
"features": []
}

Additional context

This is how other software implements using custom CRS with GeoJson.

[troopa81]

It has been done on WMS GetFeatureInfo and WFS #56600 and is already available in QGIS 3.38

Do you confirm that it fulfill your needs?

[jkr-wrk]

Using 3.38.0

Export with settings:
GeoJSON
CRS EPSG:28992

Coordinate Precision:10
RFC7946:NO
Write_BBOX: NO

Gives this:
{
"type": "FeatureCollection",
"name": "test_json_RFC7946_NO10_qgis3",
"xy_coordinate_resolution": 1e-10,
"features": [
{ "type": "Feature", "properties": { "fid": 8, "statcode": "PV27", "statnaam": "Noord-Holland", "jrstatcode": "2022PV27", "rubriek": "provincie" }, "geometry": { "type": "MultiPolygon", "coordinates": [] } }
]
}

There is no CRS attribute or something similar.

[rouault]

@jkr-wrk I do not replicate that when exporting a layer already in EPSG:28992 (or overriding its CRS in the dialog) as GeoJSON using the Export / Save Features As dialog box. The generated GeoJSON contains "crs": { "type": "name", "properties": { "name": "urn:ogc:def:crs:EPSG::28992" } }
Can you possibly share a project + layer ?

[jkr-wrk]

test_json_RFC7946_NO.json

This is the file I opened and saved as GeoJSON again.

I also tried with this service (using 3.39.0 just now):
https://service.pdok.nl/kadaster/bestuurlijkegebieden/wfs/v1_0?request=GetCapabilities&service=WFS

And coordinates are in 28992 but no crs attribute is available.

[rouault]

I somehow reproduce the issue, but in a different way. The CRS does get exported, but the geometry not.
I see an error "Warning 1: Infinite or NaN coordinate encountered"

{
"type": "FeatureCollection",
"name": "foo",
"crs": { "type": "name", "properties": { "name": "urn:ogc:def:crs:EPSG::28992" } },
"features": [
{ "type": "Feature", "properties": { "fid": 8, "statcode": "PV27", "statnaam": "Noord-Holland", "jrstatcode": "2022PV27", "rubriek": "provincie" }, "geometry": null }
]
}

[jkr-wrk]

Strange, I can't reproduce that using 3.39.0.

Would like to test 3.34.9 or 3.38.1 but OSGeo4W fails to install these versions. Looks like Windows Defender is preventing today.
Had success installing versions on friday, but not today.

[github-actions]

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[jkr-wrk]

Tried again today using 3.38.2:

{
"type": "FeatureCollection",
"name": "Test Export rfcno",
"features": [{
"type": "Feature",
"properties": {
"identificatie": "PV21",
"naam": "Fryslân",
"code": "21",
"ligtInLandCode": "6030",
"ligtInLandNaam": "Nederland",
"fuuid": "provinciegebied.d0a8a913-5680-4bb5-b28a-e56bab2f651d"
},
"geometry": {
"type": "MultiPolygon",
"coordinates": [[[[189491.268000000010943, 535832.616999999969266], [189494.21, 535842.547000000020489] , etc. etc. ]]]
}
}
]
}

Steps to reproduce...

Instal PDOK Services Plugin
Add Provincies WFS from the PDOK plugin
Select Fryslân
Dissolve Selected feature
Export feature with right click on the Dissove layer
Export as GeoJSON with RFCxxxx set to No

[agiudiceandrea]

@jkr-wrk, using QGIS 3.38.2 (OSGeo4W) with GDAL/OGR 3.9.2 on Windows 10

• I've created a new project having CRS EPSG:4326
• I've created a point layer having CRS EPSG:4326 and added a point randomly placed in the Netherlands
• I've exported such layer (via right click -> Export -> Save Features As... -> Save Vector Layer as...) changing the CRS parameter to ESPG:28992 and setting COORDINATE_PRECISION = 10, RFC7946=NO, WRITE_BBOX=NO:

{
"type": "FeatureCollection",
"name": "4326-28992",
"crs": { "type": "name", "properties": { "name": "urn:ogc:def:crs:EPSG::28992" } },
"xy_coordinate_resolution": 1e-10,
"features": [
{ "type": "Feature", "properties": { }, "geometry": { "type": "Point", "coordinates": [ 167453.3256934369, 497815.226271763 ] } }
]
}

• I've reprojected such layer to the CRS EPSG:28992 and exported the reprojected layer following the same procedure and using the same parameters (this time leaving the CRS set to EPSG:28992):

{
"type": "FeatureCollection",
"name": "28992",
"crs": { "type": "name", "properties": { "name": "urn:ogc:def:crs:EPSG::28992" } },
"xy_coordinate_resolution": 1e-10,
"features": [
{ "type": "Feature", "properties": { }, "geometry": { "type": "Point", "coordinates": [ 167453.3256934369, 497815.226271763 ] } }
]
}

So, it seems to me the crs attribute is correctly present in the exported GeoJSON layers.

[agiudiceandrea]

@jkr-wrk , afterwards I've imported the provided test_json_RFC7946_NO.json, assigned EPSG:28992 as the layer's CRS, and exported such layer following the same procedure and using the same parameters (leaving the CRS set to EPSG:28992):

{
"type": "FeatureCollection",
"name": "test_json_RFC7946_NO_28992",
"crs": { "type": "name", "properties": { "name": "urn:ogc:def:crs:EPSG::28992" } },
"xy_coordinate_resolution": 1e-10,
"features": [
{ "type": "Feature", "properties": { "fid": 8, "statcode": "PV27", "statnaam": "Noord-Holland", "jrstatcode": "2022PV27", "rubriek": "provincie" }, "geometry": { "type": "MultiPolygon", "coordinates": [ [ [ [ 150817.7896144802, 477979.2072202922 ], [ 150870.1662389686, 477927.4095703705 ], [ 150089.3342324059, 478192.6626739331 ], [ 150077.1968909417, 478439.1956211975 ], [ 150672.9224872852, 478433.978409293 ], [ 150977.1665158421, 478163.0254149203 ], [ 150817.7896144802, 477979.2072202922 ] ] ], [ [ [ 131307.2914809157, 482947.1495827798 ], [ 131146.2443887191, 482908.4246546297 ], [ 131104.3021696125, 483250.8019863805 ], [ 131247.3499429776, 483245.0803827818 ], [ 131429.9798880598, 483096.9133843749 ], [ 131307.2914809157, 482947.1495827798 ] ] ], [ [ [ 134232.8620112413, 484164.4973444095 ] ...

Even this time it seems to me the crs attribute is correctly present in the exported GeoJSON layer.

[github-actions]

The QGIS project highly values your report and would love to see it addressed. However, this issue has been left in feedback mode for the last 14 days and is being automatically marked as "stale".
If you would like to continue with this issue, please provide any missing information or answer any open questions. If you could resolve the issue yourself meanwhile, please leave a note for future readers with the same problem and close the issue.
In case you should have any uncertainty, please leave a comment and we will be happy to help you proceed with this issue.
If there is no further activity on this issue, it will be closed in a week.

[github-actions]

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