The Reach RX2 now supports for orthometric height output that allows you to stream NMEA with mean sea level elevations to ArcGIS Field Maps and other third-party app that do not support geoid corrections. 

The feature is available starting from the Reach RX2 firmware 2.10 and Emlid Flow app version 14.14.

Set up orthometric height output in Emlid Flow

In addition to the standard set of NMEA messages, enable orthometric heights output:

1. In the Integration with external devices tab, enable the use of the vertical datum.
2. Select the appropriate vertical datum from the list. If prompted, download the geoid.

Enable orthometric height use in Field Maps

Configure your web map in Field Maps Designer by adding a feature layer with Z-values enabled to it.

1. Create a feature layer and enable Z-values and GPS metadata.
2. Configure a coordinate system for the project in Advanced settings.
3. Open the Forms section and add a new Number → Double field for orthometric height values.
4. In the Calculated expression field, add the following Arcade expression:

   vargeom=Geometry($feature)
   if (IsEmpty(geom)) {
   returnnull
   }else {
   returngeom.Z
   }

5. Save the expression and the form configuration.

Once configured, the synced project in Field Maps will display orthometric heights stored as Z-values for the collected objects when used with the Reach RX2 receiver.

For more detailed steps, explore the Integration with ArcGIS Field Maps guide.