Matt Morris

Orthometric Heights with Trimble GNSS & Esri Collector (Part 2 of 4)

Blog Post created by Matt Morris on Apr 3, 2020

In the previous post in this series, we summarized the new features in Trimble Mobile Manager 2.3 (TMM), and provided an overview of the workflow between Esri Collector and TMM. In this post, we describe the office side of the workflow in more detail.


Configuration in the Office

To take advantage of this new functionality, and record features with orthometric heights in the field, you will first need to make sure your ArcGIS web maps and feature layers are properly configured with Z-enabled geometries and Esri-standard GNSS metadata fields. Esri has a wealth of documentation available for this (try starting here), but the basic steps are:

  1. If you are starting with on-premise geodatabase infrastructure, use ArcGIS Pro or ArcMap to create point, line, and/or polygon feature classes that are Z-enabled and author a map document with the desired symbology.

    If you know of templates or existing feature layers in ArcGIS Online that are already Z-enabled and otherwise meet your needs, you can start with them. It is not currently possible to change an existing 2D feature layer into a 3D, or Z-enabled feature layer.
  2. For point feature classes in a geodatabase, use the Add GPS Metadata Fields geoprocessing (GP) tool in ArcGIS Pro, or a downloadable Python script for ArcMap, to add the Esri-standard GNSS metadata fields. (See Esri documentation here)

    The standard Esri Collector behavior for high accuracy workflows is to store the HAE value in the ESRIGNSS_ALTITUDE metadata field (for point feature classes) and the MSL value in the Z portion(s) of the feature geometry.

    If you are working with existing feature layers in ArcGIS Online, you can also use the same GP tool in ArcGIS Pro to add the GNSS metadata fields to them. If you are starting with templates, you will have the choice of adding all GNSS metadata fields when your new feature layer(s) are created.
  3. Esri Collector for ArcGIS uses web maps that contain editable feature layers. In order to create a web map, you can either publish your feature classes to a (web) feature layer and create the web map in ArcGIS Online, or you can publish the web map and (web) feature layer all from ArcGIS Pro. Regardless of how you create your (web) feature layers and the web map, you will need to make sure that the feature layers are editable by the desired field users, otherwise the web map will not be visible in Esri Collector. (See Esri documentation here)
  4. Both Esri Collector for ArcGIS and ArcGIS Online use the web map Pop-up settings to control how feature attributes are displayed. Once you have a web map, you can edit these pop-up settings to display the MSL height values. (See Esri documentation here)
    You will want to use an Arcade expression to display the Z value of the feature geometry. Here are sample Arcade expressions to display a rounded numeric value for MSL and HAE:
    MSL Arcade expression (meters)
    Round(Geometry($feature).Z, 2)
    HAE Arcade expression (meters)
    Round($feature["ESRIGNSS_ALTITUDE"], 2)
    Technically, this can also be configured through ArcGIS Pro prior to publishing the web map if you choose that publishing route.

    Note: As ArcGIS Online moves to a newer map viewer (available now in beta), functionality of Arcade expressions in the existing map viewer may be limited.
    Note: Both MSL and HAE values will always be represented in meters in this version of Esri Collector. If you require different units, you can add the conversion to the Arcade expression above.
  5. With an Arcade expression-enabled web map containing editable, Z-enabled feature layers with GNSS metadata fields, you are ready to move to the field device(s).


Continue to Part 3: Configuration in the Field...