Best Practice For Using Trimble GNSS Receivers with Esri ArcGIS Field Maps

Users of Esri® ArcGIS® Field Maps can take advantage of Trimble industry-leading high-accuracy GNSS receivers through direct integration into Esri’s software. In this blog, we’ll discuss how to configure Trimble® Mobile Manager (TMM) for use with Esri ArcGIS Field Maps for most users. Any users who are unsure if they are using the right settings should contact their administrator.

This blog assumes some knowledge of GNSS and coordinate systems. If the reader is at all unfamiliar with these topics, or wants a great refresher, we recommend reading the GPS 101 and Coordinate Systems 101 blogs.

How Trimble Mobile Manager and Field Maps work together

One can think of TMM as the control panel for Trimble GNSS receivers. Before using the Trimble receiver to enable high accuracy workflows in Field Maps, TMM is used to configure the correction source and reference frame (coordinate system) information needed. When you connect to a Trimble receiver in Field Maps by opening a map, it will automatically load the configuration. The configuration is loaded by Field Maps each time it connects to the Trimble receiver when a map is opened, enabling easy GNSS settings updates if the project requires it.

What needs to be done in Trimble Mobile Manager?

TMM provides a single interface to configure GNSS settings for all supported Trimble receivers, from the Trimble Catalyst™ DA2 GNSS receiver to the survey-grade Trimble R12i GNSS receiver. Users of Field Maps should configure their required GNSS configuration inside TMM before selecting the receiver and connecting to it in Field Maps.

Note: it is not required to connect to the Trimble receiver in TMM, although it can be useful for diagnostic purposes. If you are connected to the Trimble receiver you must disconnect from it in the TMM Home screen prior to connecting to the receiver in Field Maps. This blog article only addresses direct connection to the Trimble receiver on iOS and Android™ devices; it does not cover location-sharing workflows available on Android.

In TMM, select Configuration from the tab bar and configure the options as follows:

GNSS correction source

There are two options for GNSS corrections in TMM: Auto and Custom local. 

Leave this setting on Auto unless you have details for an NTRIP or internet-based correction source (i.e., RTK or VRS). If you need to specify details for your local correction source select Custom local.

Auto

The Auto behavior depends on whether you are using the Trimble Catalyst DA2 or an R-series receiver such as the Trimble R1 or R2.

Trimble Catalyst

Trimble Catalyst users can take advantage of Trimble Corrections Hub, which dynamically selects the best correction source for your location and connectivity from the following list:

1. Trimble VRS Now
2. Trimble RTX via the internet
3. Trimble RTX via satellite
4. SBAS

Trimble R-Series, Trimble TDC650, Trimble TDC150

Non-Catalyst receivers will cycle through the available correction sources¹ based on the best one available from the following list:

1. Trimble RTX via the Internet
2. Trimble RTX via satellite
3. SBAS

Note: RTX services will only be available if the receiver has a current RTX subscription installed. More information on RTX for Mapping and GIS customers can be seen here.

Custom local

When Custom local is selected you will be shown the current configuration with an option to Edit NTRIP Settings, tap the button to open the NTRIP Settings screen.

When entering details for your local correction source, it is important the GNSS source reference frame matches that of your correction source. In most cases, this will work when set to Auto, but if you know the reference frame we recommend setting it here. In general, Auto will use the most common or standard local reference frame (datum and epoch) for the current region. 

GNSS output

GNSS output allows you to specify the reference frame that will feed into Field Maps. We recommend that unless you know otherwise, leave this as Auto as in this mode TMM will automatically select the reference frame most suited to your current location using the same logic described above.

Geoid

Field Maps consumes both the GNSS default ellipsoidal heights (HAE) as well as the more useful orthometric heights (e.g., height above mean sea level or MSL). At the time of feature collection, the former is stored to Esri’s standard GNSS metadata fields while the latter is stored to feature geometries (if Z-enabled). If you know your local geoid, you should select it in the list in TMM, otherwise the EGM96 (Global) geoid model is available for use worldwide. 

If your required geoid is not listed, you can load your own geoid into TMM using a procedure described on the Mapping and GIS Community here.

An example of what your GNSS configuration screen would look like is shown here:

Field Maps users should leave the Apply antenna height option switched off, any antenna height settings should be applied within Field Maps.

You may need to configure your screen for specific settings if told to do so; an example of what that might look like for the NTRIP Settings and Configuration screens is shown here:

Once you have completed these steps, ensure you are not connected to the receiver in TMM, and switch to Field Maps. The best way to ensure this is to check that the TMM Home screen looks like this:

If you are still connected to the receiver in TMM, Field Maps will not be able to connect to the receiver. If you see Field Maps stuck on Connecting to device or GPS location not available, this is the most likely reason.

Unless you are changing the GNSS configuration, you will not need to interact directly with TMM again.

What needs to be done in Field Maps?

The information presented below is a Trimble-specific subset of configuration steps in Field Maps. For a more in-depth discussion of configuring Field Maps for high-accuracy data collection, please consult Esri documentation.

iOS only

If you are using iOS, the first time you launch Field Maps and connect to a Trimble receiver, you will be asked to select the TMM folder. This is to enable the preferences to be shared appropriately. Ensure you select the Mobile Manager folder in this step as follows:

1.  Select  Browse

2.  Navigate to the Mobile Manager folder

3.  Select Open

All users

The following sections are applicable to Android and iOS users:

Location Provider

Field Maps manages connections to GNSS receivers through Location Providers. In order to use a Trimble receiver in Field Maps, you will need to create a Location Provider entry for it using the steps below:

1.  Open the Profile screen by clicking on the user icon at the top of the screen. From there, choose the Provider option to open the Location Providers screen. If your Trimble receiver is already listed, skip to step 4 below.

2.  Add a new provider by clicking on Add (or Add provider, depending on the platform). Follow the directions to select the Trimble receiver that was previously paired via Bluetooth®. Click Next to proceed to the next step.

3.  Provide an Antenna height value in meters. This value should only reflect the height of the range pole; you do not need to include any internal antenna reference position/phase center (ARP/APC) offsets—these are handled automatically. Click Done to complete the new provider.

4.  Select your Trimble receiver from the list.

If you are using a Trimble Catalyst DA2 receiver, you may be prompted to sign in to your Trimble account using Trimble Mobile Manager. Simply sign in when prompted and you will be returned to Field Maps.

Location Profile

In order to make sure that Field Maps handles the GNSS coordinates properly, you need to create a Location Profile to define the (geographic) coordinate system of the incoming GNSS stream, the coordinate system of the web map(s) you intend to you use, and if necessary, the datum transformation between the two. 

For this blog, we will assume that the web map is using a default ArcGIS basemap and hence the coordinate system will be WGS 1984 Web Mercator Auxiliary Sphere. The coordinate system of the basemap will generally define the coordinate system of the web map. To configure your profile, follow these steps:

1.  In Field Maps, open the Profile screen by clicking on the user icon at the top of the screen. From there choose the Profile option. From the Location Profiles screen, select Add (iOS) or Add profile (Android) to create a new profile.

2.  Select the GNSS Coordinate System that matches the GNSS output (see above) of TMM. Assuming you have GNSS output in TMM set to Auto, you should select the item that corresponds to your location as shown in the list here. If you have selected a specific reference frame in TMM then select the corresponding one here. The list of coordinate systems is filtered to geographic coordinate systems supported in this version of the software. Remember from the Coordinate Systems 101 topic that a geographic coordinate system is inextricably tied to a datum and the naming will reflect that. Use the well-known ID (WKID) code for an easier search or lookup.

3. For the Map Coordinate System, select WGS 1984 Web Mercator Auxiliary Sphere.

4. You will now see a Map Extent screen. Zoom in to select the extent of the work area—this will enable Field Maps to provide a list of applicable datum transformations, sorted by accuracy.

Note: You must be online for this step, otherwise you will skip to the next step.

5. Select the top (default) Datum Transformation from the next screen unless you have been told otherwise by your GIS administrator or Trimble distributor.

6. Give the profile a Name and save it.

7. Finally, select your location profile from the list.

You can see an example profile for default settings in the continental US here:

Note: A location profile is not the only use of datum transformations in a Field Maps data collection workflow—any differences in coordinate system between basemap and feature layers, or feature layers and geodatabase, would require additional datum transformations selected in the ArcGIS components. Please consult Esri documentation for additional information.

You should now be ready to use your Trimble GNSS receiver to collect high-accuracy data in your Esri ArcGIS Field Maps web maps.

¹If no correction sources are available the receiver will output autonomous (non-corrected) positions.