Unsuccessful at getting Z-Value in Feet

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12-31-2020 06:53 PM
SheldonBina2
New Contributor II

Hello-

I am using Field Maps connected to a Leica GG04 GNSS Receiver.  I have created an expression using Geometry($feature).Z in my Web Map and also created an Elevation field and calculated geometry using the Point Z-Coordinate Property in ArcGIS Pro.  The value I get is the correct Mean Sea Level elevation, but it is in meters.  I am using the Geoid18 model and have the vertical coordinate system set as NAVD88 (height) (ftUS) in my feature layer, and have settings set to US Feet in the Leica Zeno Connect App.  I'm not sure if my workflow is complete or is this a limitation of collecting Z-Values in Field Maps?  Any guidance/assistance is appreciated.

Thank You!

2 Solutions

Accepted Solutions
KevinBurke
Esri Contributor

Hi @SheldonBina2 

Sorry for the delay.

The support for vertical datum transformations is something we hope to implement in the second half of 2021 within ArcGIS Field Maps. 

Thank you

-Kevin

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KevinBurke
Esri Contributor

Hi @SheldonBina2 

That is correct. In this case because the elevations are coming from Zeno Connect with a vertical coordinate system of NAVD88 in meters, once Field Maps supports vertical datum transformations, the app should be able to transform into NAVD88 in feet. However because Field Maps doesn't currently support vertical datum transformations, the elevations obtained from Zeno Connect remain as-is in units of meters.

This is why I suggested that since the elevation values themselves are accurate from Zeno Connect and all that's needed is a unit conversion, you could use the Project geoprocessing tool in ArcGIS Pro to vertically transform to NAVD88 in feet.

Or, if all that's needed is the actual elevation values themselves, you could use ArcGIS Pro to add the Z values from the features geometry into the attribute table and then simply use the Field Calculator to convert to feet. This of course doesn't update the values that are still part of the geometry still being in meters. 

With regards to horizontal transformations, yes, this happens in Field Maps per the Location Profile configured and the datums/projections chosen between the GNSS correction service and the web map's spatial reference. 

Thank you

-Kevin

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8 Replies
KevinBurke
Esri Contributor

Hi @SheldonBina2

Thank you for the feedback.

Currently by default, the units for Z-values stored with the feature geometry is in meters this is due to the NMEA standard also sending the elevation values in meters. 

ArcGIS Field Maps doesn't currently have support for performing vertical datum transformations to the desired vertical coordinate systems and in the desired units of feet. This is functionality that's on the road map to be supported in a future release. 

In this scenario because you've captured features using the Geoid18 gravity model from Zeno Connect and have confirmed the values themselves are correct, just in meters instead of feet using NAVD88, you could use the Project geoprocessing tool to perform a vertical datum transformation to output to the NAVD88 ft VCS in Pro. This will require the Coordinate System Data to be installed for ArcGIS Pro.  

- Have you configured a RTK correction source within Zeno Connect?

Thanks

-Kevin

SheldonBina2
New Contributor II
Hi Kevin,

Thank you for the information.

Yes, I have configured an RTK correction source within Zeno Connect. It is in NAD83 2011.

Do you have an idea on when this functionality will be released within Field Maps?

Thanks again,

Sheldon

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KevinBurke
Esri Contributor

Hi @SheldonBina2 

Sorry for the delay.

The support for vertical datum transformations is something we hope to implement in the second half of 2021 within ArcGIS Field Maps. 

Thank you

-Kevin

View solution in original post

SheldonBina2
New Contributor II
Sounds good Kevin. Thanks for the update!
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KevinBurke
Esri Contributor

Hi @SheldonBina2 I just wanted to follow-up just to check that I've answered your original question?

Thanks

-Kevin

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SheldonBina2
New Contributor II
Hi Kevin-
I believe so. I was hoping it could just be a "transfer" of the Zeno Connect NAVD88 elevation in feet to Field Maps or a simple calculation to feet, but it sounds like the datum transformation has to actually happen within Field Maps? I guess it brings up another question. Since it is possible to get horizontal coordinates in feet using Field Maps, is this transformation actually happening within Field Maps and not a simple "transfer" of the coordinates in feet from Zeno Connect?
Thank You for the follow-up.
Sheldon

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KevinBurke
Esri Contributor

Hi @SheldonBina2 

That is correct. In this case because the elevations are coming from Zeno Connect with a vertical coordinate system of NAVD88 in meters, once Field Maps supports vertical datum transformations, the app should be able to transform into NAVD88 in feet. However because Field Maps doesn't currently support vertical datum transformations, the elevations obtained from Zeno Connect remain as-is in units of meters.

This is why I suggested that since the elevation values themselves are accurate from Zeno Connect and all that's needed is a unit conversion, you could use the Project geoprocessing tool in ArcGIS Pro to vertically transform to NAVD88 in feet.

Or, if all that's needed is the actual elevation values themselves, you could use ArcGIS Pro to add the Z values from the features geometry into the attribute table and then simply use the Field Calculator to convert to feet. This of course doesn't update the values that are still part of the geometry still being in meters. 

With regards to horizontal transformations, yes, this happens in Field Maps per the Location Profile configured and the datums/projections chosen between the GNSS correction service and the web map's spatial reference. 

Thank you

-Kevin

View solution in original post

SharonUngerer_DNREC
New Contributor II

This post is super helpful thank you!  I just want to make sure I am on the right track because there is esri documentation out there that the location profile doesn't change the GNSS metadata fields collected from receivers. 

Is this true only of the metadata fields?  Does the location profile perform a datum transformation on the feature geometry and the metadata fields? 

"Latitude—Position received from the GPS receiver prior to applying data transformations in the location profile
Longitude—Position received from the GPS receiver prior to applying data transformations in the location profile
Altitude—Ellipsoidal height received from the GPS receiver (not orthometric height, as used for z-values)"

Collector: https://doc.arcgis.com/en/collector/android-phone/help/high-accuracy-prep.htm#ESRI_SECTION1_C992B4FE... 
Field Maps: https://doc.arcgis.com/en/field-maps/android/help/high-accuracy-data-collection.htm 
Collector (Classic): https://doc.arcgis.com/en/collector-classic/ios/create-maps/gps-map-prep.htm  

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