About Collector App and High Accuracy Data

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06-24-2019 11:29 AM
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New Contributor II

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!

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New Contributor II

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. 

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New Contributor II

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. 

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New Contributor II

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!

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New Contributor II

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. 

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New Contributor II

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!

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New Contributor II

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

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New Contributor II

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. 

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MVP Regular Contributor

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...

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New Contributor II

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!

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MVP Regular Contributor

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.