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High Accuracy GPS , leica gg04 plus, Field Maps on Android. Altitude is incorrect

LaurenceLanglois1

I have 'Zeno connect' running on the Android Tablet. With This Result

This is the result From the point I took in Field Maps.

Field_Maps Results.png

The Altitude is not in meters, it is about a quarter of the live results on the screen.

Any suggestions?

This is the settings from the "Zeno Connect' screen.

I could not get Z values to show up.

Thanks in advance Larry

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LaurenceLanglois1

Thanks for the replies. I am going to make a new more specific post:

I just purchased a new GPS unit ‘Leica gg04 plus’

I am using an android tablet.

The 'Leica Connect app’ displays the correct elevation 72.23 meters Orthometric Height.

But in 'Field Maps' it stores an altitude of 44.09 (Height above ellipsoid (HAE)).

Does anyone have this Leica gg04 unit, and recording the elevation correctly without post processing?

All comments

BillFox

Hi Larry,

is this the ballpark you are in?

https://www.google.com/maps/place/42%C2%B007'12.0%22N+71%C2%B006'00.0%22W/@42.1248031,-71.1094468,12.81z/data=!4m4!3m3!8m2!3d42.12!4d-71.1

BillFox

https://gisgeography.com/survey-benchmark-monument-location-geocache/

BillFox

if so, can you try your rig out on one of the points near Lake Massapoag?

such as MY0482 in Sharon

BillFox

https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=MY0482

BillFox

looks like that one is on the steps of the Sharon Public Library at

11 N Main St, Sharon, MA 02067

LaurenceLanglois1

I was a block north in the bottom corner of the park. The point came up accurately in field maps.

LaurenceLanglois1

I was on a known benchmark where I took my point.

LaurenceLanglois1

Thanks for the replies. I am going to make a new more specific post:

I just purchased a new GPS unit ‘Leica gg04 plus’

I am using an android tablet.

The 'Leica Connect app’ displays the correct elevation 72.23 meters Orthometric Height.

But in 'Field Maps' it stores an altitude of 44.09 (Height above ellipsoid (HAE)).

Does anyone have this Leica gg04 unit, and recording the elevation correctly without post processing?

LuisaC

Not sure if this is something you're still working out, but we've run into this issue as well with our Trimble R2s. What we found is that when Field Maps is configured for high-accuracy recievers the ellipsoidal height is recorded in the altitude field, but the z-value captured in the feature's geometry should be the orthometric height from your reciever. There are some vague references to this issue in the field maps doc pages that I can track down if you're interested.

To display the correct elevation for our users, we did end up creating a new "orthometric height" field and copying the z-value to it with an arcade expression in our field maps collection form.

Hopefully this is is still relevant for you!

LaurenceLanglois1

Hello LuisaC,

I was able to calculate Z value, with an arcade value online. I could also do it with 'calculate geometry' in ArcMap pro. But I still wish it was automatic. I made an ESRI case to highlight this upgrade. I am working on changing the 'base map' in Field Maps to my State Plane projections, but I was unsuccessful on my first try.

I think my X and Y are off due to the projection changes also.

This is not as easy and seamless as I hoped.

Larry

JeremyJones1

Did you do your arcade expressions in AGOL? I've tried the pop up method and it just does not work. I also tried attribute rules in pro before publishing the layers for use in fieldmaps and that didn't seem to work either. I really wish they would fix this. My users really want to see the elevations in feet and accuracy in inches etc. when the data point is collected.

LaurenceLanglois1

I was able to get z to populate with command Geometry($feature).Z

When I created the feature, I checked the box for collect Z information.

This is somewhat worthless because it is post-processing procedure. I want the elevation taken during the point acquisition. I confirmed there is an official ESRI enhancement request for this to gather elevation in the feature. The elevation number shows up on my Zeno connect software. I used third party Apglos Survey Wizard and it collected the correct elevation.

tikola

I have now spend a lot of time with this topic in Finland and conclution in early 2025 is that Leica extenal GPS devices (FLX100 in my case) works like a charm if working in XY. It requires just adding additional location source via bluetooth and thats it - extremely simple.

When you start measuring heights things get bit more complex and key player is the basemap used in WebMap. So Field Maps with external (and internal) location sources follow in recorded values the coordinate system used in basemaps. If you are working with Esri global basemaps you get coordinates in Web Mercator and height in WGS84 ellipsoid. To get them to your local orthometric height you must switch basemap to your local projections and elevation systems.

While doing this you must also remind that height in GPS metadata attributes might still differ from ones stored in geometry attributes.

So key thing if you end up in troubles with height systems is the basemap used in your webmap.

My case is Apple IOS and I have a feeling that we might see some differences in Android cases. In practise external GPS works more or less equally in both OS, but device internal GPS seems to work in Android in a way that heights tend to stick in WGS84 while with same settings Apple IOS gives local orthometric heights as expected. So there could be some difference how different OS provide GPS data to applications.

The key thing is that if you get either Ellipsoidal or Orthometric height the issiues is mainly a Field Maps basemap dependable.

LaurenceLanglois1

I have not been able to setup a Basemap on ArcGIS online using my Local State projection. And then choose it in field maps.
Larry

tikola

So are you saying that just opening any Local State data and using that as a basemap does not work? I can not help much on that as In Finland I have no Local State projection but this is the process I use with local files here. So I do not click the add data but I rather open the data dialog and there instead of opening it I just click use as a basemap option. I agree that getting your own data might be a bit hard as basemap should be some defined layer type. Not all feature layers can act as a basemap.

My screenshots are in Finnish language but you should find right clicks by following ones rounded with yellow. That path leads you to but some Tile Image layer as a basemap. This is how I have done it.

tikola

And our solution for this issue is that we have totally empty/transparent basemaps for each local Gauss Kruger zone. I use those empty maps as a basemap and in top of that I can add any valid layer for that zone that can act like a basemap though real basemap actually contains nothing.

JPowell

Hi all, this is NOT a solution to the poster's question. There is currently no way for a real orthometric height with a proper geoid model applied to write directly to attribute data within GIS. This shortcoming is not associated to the device, in this case Leica, but present in other devices like the Trimble DA2. The shortcoming lies with ESRI's GNSS metadata fields not having a field or other mechanism to write the numeric elevation into the data in real time. If there are devices that exist which have found a solution to this I'd be curious to know about them myself. Here is some other context:

If GIS data is prepped properly, with z-enabled, and GNSS metadata fields applied, the correct elevation is present in the collected GPS shot, but it ONLY lives in the z-geometry of the feature (in metric). You will not find any mention of this requirement in any help-documentation from ESRI.
Without a place for that information to be stored in GIS attribution, it requires a field calc in GIS of the z-geometry into a relevant field (e.g. rim elevation for a manhole).
This is the field calc I run - ROUND((Geometry($feature).Z)*3.28084,2).
Again, if Z-enabled feature classes are not present there is no z-geometry for that elevation to be stored, and without attribution elsewhere, you are wasting your time in the field.
It can be a common to assume the "altitude" field in GNSS metadata to be the desired value, but this measurement is typically only the HAE measurement and lacks the geoid model.

BillFox

@JPowellhave you already been through this thread? https://community.esri.com/t5/arcgis-field-maps-ideas/measure-the-orthometric-height-in-field-maps/idi-p/1058895#comments

BillFox

and this one? https://community.esri.com/t5/arcgis-pro-questions/converting-from-ellipsoidal-to-orthometric-height/td-p/1412362

JPowell

Thanks Bill, so many places this is arising. I'm following that idea, and I'll offer this same suggestion to that second poster as well.

JeremyJones1

@JPowell Is correct and this is what we have been doing and are requiring all features to have z-values regardless enabled. Only way We see accurate elevations in the field is to do expressions in the pop up so after the shot is collected the elevation displays for staff in the field. Its not recorded in the table but it allows them to see the elevation wit the antenna height taken into account. As the Zeno app does not have a place to place the antenna height.

ScottKiley

We should probably also submit an idea to simply improve the documentation.

In typical Esri fashion the messaging is all over the place on this. As @JPowell mentioned there's no mention of publishing Z-Enabled data in their documentation to Prepare for high-accuracy data collection, but a video from their Field Maps team walks through setting up Arcade to calculate the Orthometric height without ever mentioning that the data needs to be Z-Enabled: https://community.esri.com/t5/arcgis-field-maps-videos/tip-from-morgan-zhang-collect-orthometric-height/m-p/1412479#M21

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