Innacurate position recording

[matt]

Hi @ajlholt!

It sounds like there’s a few different things going on there.

On day one I made a drive to a place about 15 miles away but none of the journey was recorded although the destination did feature.

For this, as @more said, firstly make sure you’re not swiping the app closed. And if it’s happening a lot, then it can be worth restarting your phone, in case iOS has got itself confused.

The next step is to install Arc Mini, as a fallback recorder, in case of Arc App getting killed off unexpectedly. With both Arc App and Arc Mini installed, they will share the recording task, with one picking up where the other left off, if one is terminated. There’s effectively no extra battery use, and it reduces the risk of data gaps considerably.

Arc Mini 1.0 is live on the App Store!

Arc Min is finally available on the App Store! Now, this is a very rough app. At this stage it’s not meant to replace Arc App, and is merely intended as a companion app, to provide extra protection from iOS’s semi-random app terminations that lead to data gaps. With both Arc App and Arc Mini installed and running, one app will choose to be the current active recorder and the other will go into standby - alive, but not using up any battery and not doing anything other than lying in wait until…

Ok, next up, messy location data:

@ajlholt

On both days, it recorded me making lots of car journeys around the vicinity of the house which I did not do and also recorded a long string of different locations towards the south-east which I never went to.

Location data recorded by smartphones can be very noisy and messy. Both Arc App and the phone itself have ways of correcting for this and improving the accuracy over time. So typically the data is messiest the first time you visit a new place, and will improve quickly from then on.

1. The phone itself makes use of wifi hotspot triangulation to improve its accuracy when indoors or when in built up city areas. This is done automatically, and you typically will see much better results within a day or so.

2. Arc App then has another system on top - called Trust Factor - which makes use of your feedback (corrections of stationary data) to learn locations where the data is consistently untrustworthy.

   • To use this system, go into those nonsense segments or items, tap on the segments that have been classified as “car” or “airplane” or whatever other nonsense, and correct them to “stationary” (assuming you were stationary at the time).
   • Arc uses that feedback to learn how much the location data drifts about at that place, and corrects for that drift in future.

3. However if the recorded data is more than about 100 metres away from the real location, that amount of drift can’t be automatically dealt with by the Trust Factor system, because it can’t be distinguished from real data (eg walking around the block). So in those cases, instead of correcting the drifting segments to “stationary”, mark them as “bogus”. Marking a segment as bogus will remove it from the map, and from the containing timeline item, cleaning up the mess.

I hope that help to explain!