RS2: Issues with altitude on Arcgis Collector

Good day,

My question is probably more related to Arcgis Collector rather than Reach RS2. We are testing Reach RS2 for measuring utilities. So far our surveyors used Trimble but we are looking to involve more people into the survey process by letting them use Arcgis Collector and some external GNSS device. We are convinced that Reach RS2 might be the best solution for us. However, there are some issues that we observe with a new workflow.

First of all, out tests using ReachView app showed very nice results both in horizontal and vertical accuracy. Recently added vertical datum for our region (Iceland) works very well and all height values are in accordance with the National Land Survey data. However, when same locations are measured in Arcgis Collector, the altitude always varies within a 0.5 - 1m range. I did several tests and all of them showed stable altitude in Reachview but ranging values in Collector. I wonder if anyone has experienced the same issues using Reach RS2 with Arcgis Collector and what can be a cause of this behavior?


I’m not super familiar with Collector, but I would look at what kind of data type your features can record. For example, if only integers could be recorded, in a metric system you’d always be rounded up or down to an integer value, which fits with your symptom of fluctuating 0.5 to 1m away.

Thank you for your comment. All fields are specified as float so there should not be any issues with rounding numbers. The problem comes when a feature is recorded in collector. For example, if the altitude is 65.78m then Collector would record with up to +/- 1 m deviation from that value. This is a very strange behavior and I thought maybe someone else experienced it. Also, maybe I should address this issue to Esri rather than here because it looks like the problem on their side.

Are you sure that Collector is actually using the external receiver position and not the mobile device’s internal chip?

Yes I am sure about that. The receiver inuse by callector is Reach RS2 and the GPS information that is shown is definitely from the receiver and not from the mobile itself. The displayed accuracy is a centimiter accuracy.

I’ll have to try it myself this week. Sorry I don’t have a definite answer!

We use Collector - Field Maps with RS2 units.
We get RTK corrections in NZGD2000 as that is our national base for New Zealand through LINZ or other paid subscriptions.
The RS2 then output coordinates in NZGD2000 with HAE.
Collector and Field Maps only records the Z HAE in an Altitude field.
You would need to make sure that your feature sets have the GNSS metadata fields as per ESRI requirements.
If you need orthometric heights, you would need to post process.
The Reach3 app settings for coordinates and heights is only for survey within the Reach3 app.
It does not change anything within the RS2 unit for third party apps.

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Thanks for your input. Your workflow is exactly what we have in mind. We get RTK correction in local CS.

Our feature set has all necessary GNSS fields required. We also have a post-processing script that extracts Z value from geometry. The RS2 is connected to NTRIP service and the output position has correction for geoid undulation. Thus the Z value should be an ortho height if I am not mistaken. All good, but this value is not stable and ranges by some tens of centimeters. However, the measurement with ReachView 3 are stable and correct. And yes I am aware that ReachView is a separate thing and does not translate data into collector. I just used it for comparison.

I am still trying to figure out what is going on. Some of the users on Esri Community page have confirmed that they have similar problems with this setup, not RS2 but an external GNSS receiver in general. They are in Germany and the Netherlands.

At least we now know it’s probably an ESRI thing. :crazy_face: I hope you’re able to resolve this quickly!
The only field GIS I’ve used with an external GNSS is QField and I never noticed a similar issue, either with the old mock location trick or with the newer built-in BT connection to the receiver. Too bad you’re probably locked in the ESRI solution so it integrates directly with your DBs.

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