topic Re: About Collector App and High Accuracy Data in ArcGIS Collector Questions

About Collector App and High Accuracy Data

NWEdisonTeam — Mon, 24 Jun 2019 18:29:36 GMT

Hi,

Would anyone who is using collector for high accuracy data collection care to give me a rundown on how your system works (High Accuracy Receiver preference, how it works, are you happy with the results, a basic rundown of work flow and set up, etc.). I am looking of installing collector on 5 IPADs for field work, and I am familiar that the accuracy on them is a few meters, but I would like to scale that down to a few inches/cms. Thanks!

Re: About Collector App and High Accuracy Data

KennethKlopp — Tue, 25 Jun 2019 17:46:44 GMT

Hello,

We are using the EOS Arrow Gold RTK with ArcGIS Collector (iPad) to improve the location of our assets in our GIS (electric & water utility). Our accuracy is always within a few centimeters and couldn’t be happier with the set-up – easy to configure and easy to use. Let me know if you have questions.

Re: About Collector App and High Accuracy Data

NWEdisonTeam — Tue, 25 Jun 2019 17:59:09 GMT

Hi Ken,

Thanks for responding. So my questions are this: Do you use land based RTK stations with your setup or does correction happen after collection and editing of data? If you do, is it easy to set up? I am asking because I would have to teach this to several young men who aren't to tech savy (yet). Do you carry the RTK around with you on a back pack or car (I am a bit confused on that myself tbh). Thanks!

Re: About Collector App and High Accuracy Data

KennethKlopp — Tue, 25 Jun 2019 18:24:31 GMT

We use a cellular connection to access the free RTK service provided by our state DOT (FL). This connection is managed by the EOS Tools Pro software (download from iTunes). Here is a link to a short video showing the RTK set-up: Arrow RTK Set-up. I set up the field staff's RTK usernames and passwords in EOS Tools before turning the equipment over to them. It took very little instruction to get our field guys up to speed on the data collection.

Re: About Collector App and High Accuracy Data

NWEdisonTeam — Thu, 27 Jun 2019 14:09:10 GMT

I have reached out and I am getting an Arrow Gold setup sent to me on a trial. We work in several states so, I found the free RTK service list online and I'll be holding on to it. Thanks for your help!

Re: About Collector App and High Accuracy Data

KennethKlopp — Thu, 27 Jun 2019 17:16:34 GMT

Great! - let me know how it works out for you.

Re: About Collector App and High Accuracy Data

LanceCole — Thu, 27 Jun 2019 21:21:40 GMT

Tirrell,

I am a little late on this questions but thought I would post anyway.

We are using iPads and Leica GG04+ high accuracy GPS with RTK corrections via the iPad cellular to our State VRS system. Overall we are very happy with the results typically in the 2cm accuracy range but can be variable as with any GPS dependent upon field conditions and location. Data collected over the past two years has averaged within about 6 cm accuracy.

For these types of setup, RTK is typically performed on the iPad via the app for your GPS being utilized. The app takes your raw GPS data and using a web based service determines the correction needed for the point being collected at that time and location. This can be performed after the data has been collected (post-processing) but as cellular is available almost everywhere real-time is the norm.

One advantage the Arrow setup, noted by Ken Klopp above, is it supports 3D point data directly to AGOL via Collector if Z data is important to you. Other vendors such as Leica and Trimble are still working on this but it is forthcoming. Elevation or Z data is still available but takes some post processing to calculate from the GPS metadata Latitude, Longitude and Altitude (height above ellipsoid) information collected.

One word of warning about iPad internal GPS - Don't. Yes, the data can be within a few meters but it can also be within a few 10's of meters. We have had data show on the wrong side of the street or even the next block over.

Hope that helps...

Re: About Collector App and High Accuracy Data

NWEdisonTeam — Fri, 28 Jun 2019 14:17:37 GMT

Will do. If this works for my company how you said it works for yours, it will allow us to roll out at least 11 more projects every year by my count. I am pretty excited.

Re: About Collector App and High Accuracy Data

NWEdisonTeam — Fri, 28 Jun 2019 14:26:53 GMT

Hey,

Regardless of your timing thanks for responding. I was hoping to get several responses from different scenarios so it helps.

Z data isn't important right now, but that doesn't mean it won't be in the future so that would be helpful. is the Z data limited to elevation only, or is there a way to apply it to feature collected in this scenario?

As far as the IPAD GPS, when you guy's had that happen, how did you correct it (before you got this system)?

It does help very much thank you!

Re: About Collector App and High Accuracy Data

LanceCole — Fri, 28 Jun 2019 16:14:12 GMT

Tirrell,

It is my understanding Arrow/EOS supports the direct collection of 3D data via Collector to AGOL. Other platforms you are currently limited to 2D data but you are able to store the GPS metadata which includes the raw Latitude, longitude and altitude information that can be utilized to create the 3D data should it be needed. This is the approach we are using.

Fixing the iPad GPS data was a pain. We were using 123 Survey integrated with Collector to perform field inspections on assets. Unfortunately the iPad GPS points frequently placed the inspection so far from the asset it was difficult to identify which inspection corresponded to which asset. We modified or Collector map to pass the x, y and asset ID from the feature to 123 Survey and override the iPad GPS coordinates. We had to manually identify the rouge points and correct their position using imagery and phots. Fortunately, we have access to very high resolution aerial imagery and Google - Street view became our new best friend. Some were just deleted as we could not ascertain which feature it was. We now no longer perform inspections on assets until after we have assigned an asset ID or have valid x,y data already collected.

Re: About Collector App and High Accuracy Data

NWEdisonTeam — Fri, 28 Jun 2019 17:23:28 GMT

So I imagine that you had to fix dozens, if not hundreds of asset locations on a regular basis? How far were your locations off?

Re: About Collector App and High Accuracy Data

LanceCole — Fri, 28 Jun 2019 17:40:29 GMT

Tirrell Brown,‌

We had a few hundred to fix before we caught the issue. Many had asset IDs for the feature so we could script moving the inspection to the asset coordinates but for those inspections we had not yet surveyed, using a high accuracy GPS, these had to be manually adjusted. Learning curve

Most points were within a meter and close enough you could pair the inspection to the asset. Others were over a 100 meters away and through the process of elimination we could figure out what is what. Internal iPad GPS are great for driving from A to B but just are not reliable enough to for single point positioning work.

Re: About Collector App and High Accuracy Data

Jean-YvesLauture — Sat, 29 Jun 2019 22:56:49 GMT

Hello Tirrell,

Re- “is the Z data limited to elevation only, or is there a way to apply it to feature collected in this scenario”

Not sure what you mean exactly, but to add to the very good points Lance and Ken mentioned, there is one thing to note on how the new Collector for iOS (19.1.0 released on June 24, not Collector Classic) works with elevations. The Z-value Is now available in the point geometry itself along with the x, y. With the Arrow receivers, this is where the orthometric height is stored as you collect your points and if you have defined high-accuracy GNSS metadata fields in your map, the ellipsoidal height is stored in the ESRIGNSS_ALTITUDE field.

Here is an article that shows how to set it up: How to Record Orthometric Heights in Collector v18.1.0 (Aurora) with Your Eos Arrow GNSS Receiver | Eos Positioning Syst…

Just in case you have not done so yet, I really recommend setting your high-accuracy GNSS metadata fields in Collector. Here is how to (webinar from Esri Water): How to Get Started with Collector for ArcGIS | Web Maps, Arrow & More

and a quick guide: How to Record GPS and GNSS Metadata in Collector for ArcGIS

Good luck...