Matt Morris

Orthometric Heights with Trimble GNSS & Esri Collector (Part 3 of 4)

Blog Post created by Matt Morris on Apr 3, 2020

In the previous post in this series, we outlined the office configuration side for ArcGIS Pro or ArcMap for users of Esri Collector and the latest release of Trimble Mobile Manager (TMM). In this post, we describe the field side configuration of the workflow.

 

Configuration in the Field

You can proceed with field device configuration by installing Trimble Mobile Manager version 2.3.0.619 (or higher) and Esri Collector for ArcGIS version 2020.1.0 build 2913 (or higher) from the Google Play store or other means.

 

Configuring Trimble Mobile Manager

  1. Open Trimble Mobile Manager (TMM) and login with a valid Trimble Identity. You can create a new (free) Trimble Identity if you do not already have one by following in the link in middle of the sign-in screen. You will only need to sign-in once every 30 days.

    Note: If you are creating a new Trimble Identity, for consistency you may want to use the same email address associated with your ArcGIS Online account.

  2. Once you are logged in to TMM, tap the three-line menu button to open the list of screens you can navigate to and select GNSS Configuration. Here, you will configure your real-time correction source and the transformation settings for the output of your receiver.
    1. Set the GNSS correction source. To use 'on-board' GNSS corrections such as SBAS, RTX (device subscription required), or in the case of Catalyst, Trimble Corrections Hub, select Auto. To use an Internet-based source (single base or VRS), select Custom local and provide the connection details in Protocol, Server URL, Port, Mount point name (if NTRIP), Username (if required), and Password (if required).

      One of the most important settings to make for custom local correction sources is the GNSS source reference frame. This information will be provided by your real-time network provider. When you open this list, you will see a list of current, common global and local datums used by correction sources around the world. You will also see an Auto item at the top of the list; picking this option will use your current location to select the most current local datum for your region. When picking a datum, or when using the Auto option, you are indicating that the reference epoch should be used (e.g., NAD83 (2011) epoch 2010.00); this is typical for most correction sources. However, in tectonically active areas like California, correction sources may use a different, intermediate epoch. Use the Customize epoch switch and the Epoch entry box to specify this.
       
    2. Set the GNSS output (see screen capture above). The first selection you will need to make is that of reference frame Detection mode. Use Same as source to pass the positions directly to the data collection application without applying any transformation. Use Auto to auto-detect and transform positions into the most current local datum for your region. Or finally to self-select the local datum you want to use, use Select from list and pick the specific, global or local output reference frame (reference epochs only) that you want to use.

      Based on the selections made in the GNSS source reference frame and Epoch, and the GNSS output Detection mode and Frame, TMM will apply the optimum set of static and time-dependent datum transformations to adjust every position passed to the data collection application.

    3. Set the Geoid (see screen capture above). This is where the selection is made for calculating MSL from HAE. By default, a coarse, global geoid (EGM96) is provided. To select a more accurate, local geoid, open the list and select the desired one for your region (there may be multiple available). TMM will download the geoid grid file (GGF) for the selected geoid from a Trimble cloud service if it is not already on your device. An Internet connection is required for this step. It is also possible to side-load GGF files by copying them into the GeoData folder in Android shared storage.


  3. With the GNSS settings made, it is now important to verify your configuration. This involves two steps: selecting the position source (receiver) and connecting to the position source.
    1. Use the three-line menu button to open the list of screens and select Position Source. Using the GNSS receiver type list, select Trimble Catalyst, Trimble R Series (e.g., R1/R2/R10), Spectra Precision Series (e.g., SP60/SP80/SP85), or Integrated (e.g., TDC150). For Bluetooth receivers (Trimble R Series and Spectra Precision Series), use the Scan Bluetooth button to find and select your receiver.
       
    2. With the appropriate receiver selected, use the three-line menu button to open the list of screens and select Home. You should see your selected receiver indicated next to the words Connect to… under the GNSS icon. Use the Connect to switch on the screen to connect to your GNSS receiver. A summary of the connection information is displayed in the Status area while a more complete enumeration of GNSS status is displayed in the Status screen, accessible through the three-line menu button, or by a long tap on the Satellite icon on the Home screen.
       

      Note: For GNSS receivers with native support in Esri Collector (Trimble R1, R2, R10, R12, TDC150, and Spectra Precision SP60, SP80, SP85, and SP20), you MUST disconnect from the receiver in Trimble Mobile Manager at this point. If on the other hand you are using a receiver that Esri Collector does not yet support natively (Catalyst, Nomad 5 + EM100), or perhaps more importantly, you want to share the receiver connection between multiple applications (like Survey123) and will thus use the location sharing workflow, you MUST leave the receiver connected in Trimble Mobile Manager. In that case, you will also need to enable the Share location setting in Trimble Mobile Manager. This is found in the Application Settings screen. This also requires you set Trimble Mobile Manager as the mock location provider in your Android device’s Developer options. Check your device manufacturer's documentation for how to access this setting. At this time, the Share location workflow cannot be used with Esri Collector on a TDC150 or SP20 as it will always try to make a native receiver connection on those platforms.


Configuring Esri Collector

Open Esri Collector and sign-in using your credentials. Once signed in, you will see a list of web maps you have access to. It’s important first to configure the two Location settings in Esri Collector. These are both available in the Profile screen, accessible by clicking on the person icon in the upper right corner of the screen. The steps below are only a summary; for a complete description of Esri Collector functionality, refer to the Esri Collector documentation.
 

  1. In the Profile screen, locate the Location section. To connect to a receiver, click the Provider item to access the Location providers screen. (See Esri documentation here). If using a TDC150/SP20, TDC600, OR the location sharing workflow, use the Integrated provider option. Use the stacked-dots menu to access Details where you can set the Antenna height. Remember NOT to include the ARP/APC offset value as this is handled automatically; you need only to specify the height of your range pole.

    For Bluetooth receivers (Trimble R Series, Spectra Precision Series), click the + Add provider item to open the list of currently available Bluetooth devices. Devices that have been previously used or paired will appear at the top of the list. When you select the desired device, you will have the ability to set the Antenna height as described above.


    A newly created provider will not be current until you select it and it appears in the Current section at the top of the screen.

    Once your receiver antenna height is configured and set as the current Location provider, return to the Profile screen.
  2. To setup the appropriate coordinate system handling between the GNSS positions from Trimble Mobile Manager and Esri Collector, click the Profile item to access the Location profiles screen.The Default profile assumes that all GNSS positions received are in the “WGS84” reference frame and thus datum transformations will be applied if the coordinate system of the web map is anything other than that. (See Esri documentation here).


    If you want explicit control over coordinate systems and transformations used, tap Profile to open the Location profiles screen, then tap the + Add profile button to open the Add profile screen.
    1. Select the GNSS coordinate system. The setting made here should match what you specified as the GNSS output in Trimble Mobile Manager (step 2b above). Note: Trimble and Esri nomenclature is different but documentation is available to help match up the wording. What Trimble describes as a datum (or reference frame when includes epoch), is generally equivalent to what Esri describes as a geographic coordinate system.
       
    2. The second step is to select the Map coordinate system used by the web map(s) you intend to use. This may frequently be WGS 1984 Web Mercator (Auxiliary Sphere) but could very likely be a local coordinate system. The reason you have to explicitly select it (it is part of each web map after all) is that the Location profiles sit outside of the web maps and can be used between different web maps. Esri Collector will alert you if you end up using a web map that has a mismatched coordinate system with the currently selected location profile.
       
    3. If needed, select the specific (static) datum transformation that you want Esri Collector to use when transforming positions between the GNSS and the map. This requires you to set an Area for data collection so that a sorted list of available datum transformations (sorted based on accuracy) can be presented. Although you will typically select the first item in the list, you can select the one that you believe best fits your data and workflow. This will likely require field verification.


    4. The final step is to name your location profile by entering a Profile name.

      Your newly created location profile will not be current until you select it and it appears in the Current section at the top of the screen.

      Note: With the availability of both static and time-dependent datum transformations in Trimble Mobile Manager, it is recommended that you do as much of the geodetic handling in TMM as possible. In particular, if you are working with Trimble RTX, you should set your local frame as the GNSS output reference frame in TMM as well as making it the GNSS coordinate system in Esri Collector’s Location profile. That will provide the most accurate transformation path between GNSS and the map.

  3. Optionally, use the Accuracy setting in the Collection area of the Profile screen to set an accuracy threshold for all collected features. (See Esri documentation here).

  4. With the appropriate selections for Location provider and Location profile, you can exit the Profile screen.

 

Continue to Part 4: Collecting Data...

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