Measure the orthometric height in Field Maps

[Hegik]

What the Field-Maps App is doing:

Right now our measurement crews connect their GNSS-antenna to their iPad (iPad Pro 11”, 2nd generation running iOs 14.3) and add points to our web-feature-layer. The height, which the app is saving is known as “Height Above Ellipsoid”. Germany (and other European countries) use another height called the “Normalhöhennull” (orthometric height). The Field-Maps app can display the “Normalhöhennull” but it will only save the (for us useless) “HAE”.

What is the problem:

If we want to measure the height of the GNSS-antenna, we always need to open the app of the antenna manufacturer, copy the (orthometric) height, and then we paste it into a field of the feature layer we specifically created for this purpose. This adds human error to the process, which is unfortunate. Another workaround would be post processing the data, but that would need a person who does that, and would probably add calculation error, so we would like to have it shown correctly in the first place.

How this will help us:

In the past few months we’ve invested in a lot of hardware (e.g. GNSS-Antennas, iPads, etc.) with the goal to simplify the process of our measurements, but with the wrong height it is more of an obstacle than a relief to use it. At the moment the data that the measuring crews are gathering, needs to be fixed by an ArcGIS Pro operator before it can be further processed and analysed by our CAD or laboratory staff. This adds big delays to our workflow.

Why this is important:

We as a German authority must work with our official German standards especially when we are measuring things. The “Normalhöhennull” is the standard for every German authority, office, department and university. I would say, that every time someone is measuring the height somewhere in Germany, it will most certainly need to be the “Normalhöhennull” because it is the national standard since 1992. Because of that not only our authority has this problem, but everyone who wants to measure the height in Germany using Field Maps.

[LaurenceLanglois1]

I appreciate your in-depth explanation and how you detailed why it can't be done. However, I think it can be done and become a standard part of field maps, configurable through the GUI without extra code.

[tikola]

Thanks - I have spend a lot of time during my career on height related things and my comment was based on experiences over those years. Last couple of years my focus has been in water utilities and there height has a crucial role. Water flows always in downhill an it is an issue we must be aware all the time.

I agree - this probably can be more straightforward - I just do not know how. The main challenge in generally is that height is wanted in different fields depending on features you are mapping and there is no generic rule that software can apply for that task.

The customization we do is really minor - just read value from geometry to an attribute and that I agree it can be just a simple GUI based rule. 

[Y_Chau]

@LaurenceLanglois1 I second that. Geoid heights are supported in almost every other field software. Esri is reluctant to include any survey capability into Field Maps. Displaying scale bar, stakeout or displaying local coordinates with decimal places when the map is in web mercator. They do not want to step on the toes of their favorite partner.

[tikola]

• GeoidHeights are supported in Esri FieldMaps - just did that via external GPS and Ipad internal one. However I am not totally sure when I need geoid model from device and when not but you definetly get correct heights in Field Maps. Just did that and by that I say geoid based heights are supported in Field Maps.
• Scale bar in generally in ArcGIS Online appears when you move to printing or apps. It is not visible in any standard views - which is more or less same approach in ArcGIS Pro. I do not follow the need of scale bar in surveying? Why it is needed but I agree that maybe a simple scale bar in Field Maps might be good addon to someone. Is it a showstopper - I doubt.
• Local coordinates are shown with centimeter accuracy but I agree that not in when your map is in default web mercator. How you should do that - you want your map to be in lat long but you want to see coordinate in meters? This is probably doable again with some minor scripting but in generally you ask apples to be shown as oranges. If you switch the from Web Mercator to local system coordinates are immediately shown in local values no matter where in Esri ecosystem you do it.

Field Maps in my perspective is a very good surveying tool if source of location is any GPS. I am interested to hear if someone has joined Field Maps to some total station usage. I have never seen that yet. All other surveying tools that I see people to use are way more clumsy and typically old fashioned compared to Field Maps. The challenge I see is that surveyors are very used to their existing tools and are bit afraid to use Esri's modern mapping functionality.

Opposite comment to non Esri surveying tool - how you bring all attributes for mapped feature directly on the field while doing the mapping? I have never seen this functionality really in any other surveying tool.

[BillFox]

If ArcGIS Pro on a tablet in the field does the RTK ortho-metric height on-the-fly correctly, why can't Field Maps?

[tikola]

"If ArcGIS Pro on a tablet in the field does the RTK ortho-metric height on-the-fly correctly, why can't Field Maps?"

Simply installers, codes etc. are totally different but of course it can be done. However I have no idea why product idea from year 2021 is in that "ProductPlan" status as I have yesterday done RTK orthometric on the fly in iPad Field Maps using Leica FLX 100 external GPS as well as lower accuracy with iPhone internal GPS. Both mapped reference point in local coordinates and heights excactly as it should without any tricks or calculations - just like you map anything else in Field Maps. The only needed thing was to configure device settings and Field Maps location profile but that must be in anycase be done before you can expect to do any mapping. 

So simple answer is - Field Maps does RTK orthometric height in local coordinates on the fly correctly today. I got couple of centimeters accuracy in all directions which was more or less same as GPS device metadata reported and which is the system capabilities in generally.

So you say it can not - I say it can. I do not know can this discussion really proceed from this? What I do not know is coordinate systems used in other countries and their limitations. I am using this in local nationwide UTM and zone based GaussKruger projections and in both it works just as expected. Maybe not with a single click but with normal software settings setup in anyway. 

[Y_Chau]

@tikola There is no native support for geoid heights in Field Maps. Esri directs you to its GNSS partners who have coded geoid support into their go-between apps. Just a handful of them who want to charge a kidney for a unit. That is how your Leica works. Good for developed economies and large companies but not for others. So, people are questioning why esri has not done it when every other survey / GIS app in play store can do it? On the contrary they blocked mock location access in Field Maps which worked well in Collector. You wont know that because you use Apple. Only answer I can come up with is that they want to control which devices you use with their software. BTW I work for a esri shop.

[tikola]

Now we start to agree. You want any solution anywhere Esri mobile ecosystem use orthometric heights and I am looking it in perspective where all solutions I use can handle it already now. In my case it is water utility companies and they all use Trimble/Leica where this works perfectly. I also see that my iPhone does it directly in Field Maps as it should but I have a feeling that in Android there might be some issues. Or at least functionality is different between IOS and Android.

So our perspective difference is that all my solutions this thing works but in your solutions it does not. As commented in some of my posts above I am not sure is this so complex thing that is it realistic even expect to work in all scenarios.

What I agree is that I have looked ways to turn my phone easily to RTK capable and when looking such solutions in consumer level prices I have doubts is it doable immediately in orthometric. However I do not see that lack as a major issue as conversion can anyway be done easily. My instruction to my customers is always. No matter how you map there should never be a situation where it has gone so wrong that you have to go and redo the mapping work at site. Everything can be converted to something else in office easily.

My perspective is professional users in water utilities and for them couple of thousand euros/dollars is no major issue in mapping. They all do it and in that this is no issue at all.

[tikola]

I add one more comment. Google AI responded me that IOS returns height always in EGM96 geoid while Android seems to return always WGS84 ellipsoidal height. This fits perfectly on my experiences with internal location sources in Field Maps. ESRIGNSS_ALTITUDE field (GPS Metadata) is always same as Geometry Z and correct compared to local heights when using IOS devices and always same values are shown differently in WGS84 when using Android device.

EGM96 value is not correct height locally but when using mobile device internal GPS it is good enough representation of the truth. So in my perspective locally IOS devices gives always more or less correct height reminding the accuracy in generally and Android gives my 20m to high numbers.

So there is a difference depending are you using IOS or Android.