Object converted in non-standard crs about arcgis2geojson HOT 3 CLOSED

RFC 7946 does state WGS 84 should be used and removes the CRS member of the 2008 standard, but it does include the caveat

However, where all involved parties have a prior arrangement, alternative coordinate reference systems can be used without risk of data being misinterpreted.

so a GeoJSON file using a non-WGS84 CRS isn't strictly invalid. Refs

• https://tools.ietf.org/html/rfc7946#section-4
• https://tools.ietf.org/html/rfc7946#appendix-B.1

So this behaviour is intentional: We convert the file using the input CRS and emit a warning if its not 4326. It is out of scope for a simple format conversion tool to attempt to transpose between co-ordinate reference systems.

If you're looking for a way to emit ArcGIS JSON which isn't stored natively using WGS 84, your ArcGIS server can probably do it for you. If you're outputting from ArcGIS REST server, have a look at the outSR param. For example if I request:

https://ons-inspire.esriuk.com/arcgis/rest/services/Administrative_Boundaries/Combined_Authorities_December_2019_Boundaries_EN_BFE/MapServer/0/query?where=objectid%3D1&f=pjson

this outputs ArcGIS JSON using the server's default srid 27700, but if I append &outSR=4326

https://ons-inspire.esriuk.com/arcgis/rest/services/Administrative_Boundaries/Combined_Authorities_December_2019_Boundaries_EN_BFE/MapServer/0/query?where=objectid%3D1&f=pjson&outSR=4326

it will convert it to 4326 🎉

from arcgis2geojson.

Ah. Didn't see that exemption in the spec. Guess that's why ESRI's FeatureSet.to_GeoJSON preserves WKID 102100 and doesn't convert to WGS 84/4326. All I have access to is "item = gis.content.get(id)" (which returns "OperationalLayers"). I think a layer needs to be "published" for GeoJSON, etc. export options to appear. I didn't seem to see a way to do a REST query using an item id along with outSR.

I finally got a working Python script that converts the data to valid GeoJSON, also using json, pyproj, shapely, etc. libraries. Basically:

# EPSG:3857
# WGS 84 / Pseudo-Mercator -- Spherical Mercator, Google Maps, OpenStreetMap, Bing, ArcGIS, ESRI
# Alternatives codes : 900913 3587 54004 41001 102113 102100 3785
esriwgs = pyproj.CRS('EPSG:3857')
wgs84 = pyproj.CRS('EPSG:4326')
project = pyproj.Transformer.from_crs(esriwgs, wgs84, always_xy=True).transform

gis = GIS()
item = gis.content.get(id)
wm = WebMap(item)

for layer in wm.layers:
  fc = FeatureCollection(layer.featureCollection)
  fs = fc.query() # Only way to get a functional FeatureSet? This query apparently accepts no options.

  # print "type": "FeatureCollection", "features": [", etc.

  for feature in fs:
    # print "type": "Feature"...
    print('"properties": ' + json.dumps(feature.attributes))
    geom = arcgis.geometry.Geometry(feature.geometry)

    newgeom = transform(project, geom.as_shapely)
    print(', "geometry": ', geojson.dumps(newgeom))

I tried ArcGIS's "fc.query(out_sr=4326)" and "geom.project_as('EPSG:4326')" variations, but didn't seem to work. Anyway, I couldn't find any existing script or program out there that does this. Maybe I or somebody else could release one. :)

from arcgis2geojson.

Glad you managed to find a solution 👍

from arcgis2geojson.