Data collected in Field Maps does not project properly in ArcGIS Pro

[ClintonKollars]

We use Emlid RX antennas, with RTK corrections to collect data in Field Maps. Using a Map with a NAD83 2011 Stateplane coordinate system, to project on the fly. The issue I am having is when projecting to Northing Easting survey feet, in ArcGIS Pro, the data is off anywhere from one to three feet. I've tried different maps and different coordinate system profiles in Field Maps but it all shows the same bust in the Northing and Easting. I've been testing against known control points using the Lat/Lon from the same data in other Projection tools and those project correctly. What am I missing here?

[JonathanLebowitz]

Hello. There are three coordinate systems that need to be taken into consideration when collecting data in ArcGIS Field Maps: the coordinate system of the map, the coordinate system(s) of the feature layer(s) in the map, and the coordinate system that the GNSS receiver is reporting latitude and longitude in (and orthometric height, if applicable). That said, are the coordinate systems of the feature layer containing the data and the map both in PCS NAD 1983 (2011) StatePlane US Feet? If the feature layer is in NAD 1983 (2011) StatePlane US Feet, the Northing and Easting values will be stored in US Feet regardless of the map's coordinate system. Please note that if you are using any of the Esri basemaps in ArcGIS Field Maps and/or ArcGIS Pro, the coordinate system of the map will either be in PCS WGS 1984 Web Mercator or GCS WGS 1984. From your description of the issue, it seems like a geographic transformation between NAD 83 (2011) and WGS 84 (e.g., WGS 1984 (ITRF08) To NAD 1983 2011) may be missing from your map in ArcGIS Pro.

[ClintonKollars]

When you create a map through Field Maps Designer in AGOL, I was under the impression that the first layer defines the coordinate system for the map. Sounds like this may be incorrect? So I should be creating the map directly from ArcPro instead, with the correct transformation?

[JonathanLebowitz]

Hello. The map's coordinate system is defined by the basemap. You can add feature layers in different coordinate systems to the map, but they will be re-projected on-the-fly to the map's coordinate system (this is only for visualization purposes, the geometry of the features in feature layer is not changed). The X and Y coordinates that you collect in ArcGIS Field Maps will be stored in the geometry of the feature layer in the feature layer's coordinate system. You can verify this by querying the feature layer at REST for the geometry or by running Add XY Coordinates (Data Management) in ArcGIS Pro.

[ClintonKollars]

It all makes sense. Thanks for your input. The transformation is there in ArcPro but when I calculate geometry to get the Northing/Easting, it comes out off a little under three feet on the Northing and about a foot on the Easting. We actually had hired a company that works in GIS to build the original maps, they had the same error in their projections. Have you personally tried gathering data on a DA2 or EMlid reach equivalent in Fields Maps and then make the projections on the back end? 

[JonathanLebowitz]

Hi Clinton. Three feet off in the Northing and one foot off in the Easting compared to what? NGS Survey control points? The NCAT tool? What is the coordinate system of your feature layer? I'm not clear what you mean by the "back end."

[ClintonKollars]

A few ways. Survey control points set by survey in the field. Creating a survey directly in Emlid flow app with the correct coordinate system. Also, taking the Lat/Lon from the Field Maps data and Projecting that in a conversion web site like Earth Point. All of them line up except the Calculated Northing/Easting in ArcPro. My apologies for not using language that might be more direct, "back end" meaning after collecting the data in the field in Field Maps and then calculating to get the survey feet in Northing/Easting.

[JonathanLebowitz]

Hi Clinton. The feature layer that you are adding data to in ArcGIS Field Maps is defined in GCS NAD 1983 (2011) or in one of the NAD 1983 (2011) State Plane Coordinate System zones?