Orthometric Elevations

Bad Elf Flex: Ortho Everywhere - Flow Orthometric Height Elevations in ArcGIS Field Maps

Introduction

Using the Bad Elf Flex with RTK and ArcGIS Field Maps for elevations?
You may have noticed inaccurate vertical elevations. That’s because ArcGIS Field Maps records ellipsoidal heights in the ESRIGNSS_ALTITUDE field, while most users need the orthometric elevations (height above mean sea level) of their features.  Orthometric elevations use a geoid (gravity) model, and are the type of elevations typically shown on topographic maps used in engineering, construction, and surveying.

Field Maps does record orthometric elevations in the geometry if the feature class has Z-values enabled, however, they default to the EGM96 geoid (gravity model), which isn’t suitable for survey-grade RTK work.

To record accurate orthometric heights (ex: NAVD88 via GEOID18/12B), users previously needed to post-process their features. Now, with the Flow Points to Third Party App feature in the Bad Elf Flex app, you can send correct elevation data—including orthometric elevation, antenna height, and geoid/datum metadata—directly to ArcGIS Field Maps.

Info

What You’ll Need

To successfully collect offset metadata with ArcGIS Field Maps and the Bad Elf Flex, make sure you have the following:
  1. Bad Elf Flex→
  2. Bad Elf Flex app→
  3. ArcGIS Online License
  4. ArcGIS Field Maps app
  5. iOS or Android tablet/phone
  6. ArcGIS Pro 3.5+
  7. Toolbox from the Bad Elf Github→

How to Add Ortho Everywhere fields

Adding the Bad Elf Flex Toolbox to ArcGIS Pro

The Bad Elf Flex geoprocessing tool adds Esri's GPS Metadata Fields in addition to Bad Elf Ortho Everywhere fields.
Notes
You must be the owner of the point feature layer or an organization admin user.
Notes
While not required, we highly recommend enabling Z-values for 3D visualization capabilities for your feature class upon creation. 
Warning
This tool is not compatible with ArcGIS Enterprise feature services.
  1. Download the toolbox from the Bad Elf Github.→
  2. Drag and drop the .tbx file into your ArcGIS Pro 3.5+ project's toolbox folder found within the Catalog window, or right click and Add Toolbox.

  3. Open the tool.

Adding fields to a feature class

  1. Select the point feature class with the drop down menu under Feature Class in the Add Bad Elf and Field Maps GNSS Fields tool.   

      2. NotesOptional: If the layer will be used to perform offsets with a laser rangefinder, check the box to add Laser Offset Metadata.
  2. Run the tool.  Adding fields will take significantly longer with a feature service compared to a locally hosted file.
Info
IF UPDATING ARCGIS ONLINE FEATURE SERVICE: If you do not have admin privileges, you will not be able to add domains to the metadata fields for feature services.  Metadata fields will still populate without domains. Domains can also be added manually to the feature class by navigating to the feature class's item details page > Data > Fields > Click the relevant field > Create List. 
  1. ArcGIS GPS metadata field domains can be viewed through this link→
  2. Information on Bad Elf domains can be found through this link→
Alert
This script modifies the input feature class or feature service by adding fields and domains. It does not alter existing fields, but it will permanently change the schema of the feature class or service by adding new fields and domains.

Using the Flow Points to Third Party App feature

  1. Locate the Flow Points to Third Party App checklist under the Data Collection menu in the Bad Elf Flex App on either an iOS or Android mobile device.


     
  2. Complete the checklist by tapping to confirm the Pole height, Orthometric model, and Target app. Finally, tap the blue Turn on auto-flow button at the bottom so it turns orange as displayed below.
      1. Notes
        For the Orthometric model step, we recommend US users tap the blue arrow on the right and select USGG2012 and GEOID18 respectively. Geoids for other areas are available here for download. The orthometric model used depends upon the location, the correction mode and the corresponding datum being used at the moment.
      2. Info
        Ortho Everywhere settings that are used regardless of having the Flow Points to 3rd Party App feature activated are also accessible through the Elevation/Orthometric Height Flex settings (geoid selection screen), including:
        Use orthometric height model for NMEA output: This option overwrites the Z value in Z-enabled feature classes.
        Include datum/ortho metadata in NMEA station ID: Overwrites stationID with EPSG of datum
        Subtract antenna height prior to NMEA output (Enter 0 for antenna height in 3rd party apps): Ensure the antenna height is configured correctly on the Bad Elf Flex app when activating this feature.

  3. Flow Points is now turned on.  To populate the custom fields you’ve added, collect a point in ArcGIS Field Maps so the form is open and visible with your custom fields, but do not submit.
  4. To overwrite the custom Bad Elf fields as well as the z-geometry of the point, log an instant point on the Bad Elf Flex by either tapping Log instant point in the Standalone Data Collection menu, or by logging a point directly on the receiver by tapping the center/enter button twice from the accuracy screen under the home icon.  The Bad Elf Flex will beep and this will trigger the Bad Elf Flex app to send you back to Field Maps.
  5. The Update Point blue box on Field Maps will turn green with a check mark indicating it has been updated, and all relevant Bad Elf custom fields in the form should now contain a value.  You are now free to submit and save the point.
  6. Steps 4 through 6 should be repeated for every point you collect on ArcGIS Field Maps.