Collector (iOS version) always snaps GPS to nearest road

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11-30-2016 12:26 PM
JoeZuckerbraun
New Contributor II

Collector 10.4.0 running on iPad isn't displaying the true GPS position, but instead always snaps to the nearest road. Apparently location services does this to provide neater maps/ more accurate driving directions but it is no good for field data collection. Any ideas on how to use the true GPS stream instead?

This article makes reference to it:

“Snap To Road” in iOS 6 breaks accurate GPS recording | ilquest 

and indicates that it only occurs when moving at 'vehicular speeds', but I noticed it while walking.

This post

Jeffrey Friedl's Blog » The Scourge (or Beauty) of “Snap To Road” with iPhone Location-Tracking Apps 

includes some Apple developer documentation regarding the issue, but no fix...

4 Replies
MichaelDavis3
Regular Contributor

It looks like this phenomena is only triggered when the device has a network connection - Perhaps using Collector in offline mode and turning off cellular data will help.

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JoeZuckerbraun
New Contributor II

The IPads were using offline maps and don't even have cell network data. We were in farm fields so no possibility of catching a wi-fi connection either. I wish the solution were that simple.

I am truly surprised that the collector app for iOS doesn't exclusively use the raw GPS stream. The android version doesn't have this issue.

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MichaelDavis3
Regular Contributor

It doesn't really work that way on iOS.  Developers have to use Core Location to access GPS.  It sounds like ESRI are possibly using the wrong setting (they need be using CLActivityTypeOtherNavigation to avoid the issue).  It is possible to tap into the raw GPS data if connecting to an external bluetooth receiver,  I'd be curious to see if the road snapping still occurs when using something like an EOS Arrow or Bad Elf

I can't say I've encountered this phenomena in any of the apps we've created, although our higher-speed data collection is generally happening in areas that are nowhere near any roads.

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DarrenDe_Lange
New Contributor III

Hi Joe - did you ever come right with this issue? 

I am having similar issues for a team in my organization in plotting tree locations, the points keep snapping to near by line features and isn't giving true representation of where tree locations are. 

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