Why is the location tracking layer in WGS84?

[JakeJacobs]

We're implementing Tracker for ArcGIS on our ArcGIS Online organization.  Why is the location tracking hosted feature service  created as WKID 4326 (WGS84) when everything else on AGOL defaults to WKID 102100 (web mercator)?

[Anonymous User · Accepted solution]

That's a good question. The underlying location tracks data store in ArcGIS Online always stores it in GeoJSON format (WGS-84). In most cases, the data will be projected to Web Mercator when a client queries it so it would be projected regardless of the default spatial reference.

When it's uploaded from Tracker we use WGS84 so there's no projection required prior to inserting the features.

[JamesCrandall]

Of note: if you plan to use input geometry from another feature service to query the tracker feature service then it's important to have input geometry the same as the tracker service in that query.  For example, we have a polygon feature service (WKID 102100/3857) and loop thru each feature and query the ESRI Tracker service with that geometry but when we initially query the polygon service we set the output SR to WKID 4326 so that the geometries will align.

[Anonymous User]

You should be able to set the inSR parameter, when querying, to specify the spatial reference of your polygon. The feature service should project it correctly prior to executing the geometry operation.

[JamesCrandall]

Absolutely!