Unvisited location incorrectly keeps appearing in daily timeline

I am puzzled by the regular listing of a certain building in my daily timeline when I get within 1.5 km of the building. I’m not quite sure how to explain the problem without doxxing myself so I’ll use generic terms.

I have walked from Building 1 to Building 2 and the line tracking my movement shows the path I have taken. I have remained in Building 2 for several hours, but for two minutes in the middle, the daily timeline indicates that I am in Building 3 which is 1.5 km away, and there is no travel path to that building.

It’s a city, so there’s some GPS drift but only a few metres in any direction back and forth from Building 2 and absolutely nothing close in any way to Building 3.

Of particular note, Building 3 is the first building that I did genuinely travel to after downloading 3.6.0 last week in Building 2, and Building 3 is the first building that I actually used the ‘edit’ feature to recognise with a name using the nearby locations (until last week I had not used that feature). Perhaps something has become “sticky” for that reason in my data (though I’ve no idea how that could be)?

This problem has occurred for multiple days whenever I am in Building 2 and “close” to Building 3 (“close” being relative because sometimes I am tens of kilometres away from it and it does not appear in my timeline on those days). I have deleted it from timelines as a bogus listing, but can you think of any reason why this is happening?

I can share screenshots directly if that helps, but prefer not to do it in a public forum, thanks.

Hm. I think this could be one of two things (or a combination of both):

  1. iOS has had a weird glitch in some versions over the years, where it creates drifting location data while really you’re stationary, with the drifting often being in a consistent predictable direction and often quite long distances (hundreds of metres or even a kilometre or more).

    This glitch is what forced the creation of Arc’s “Bogus Location Data” feature. Whenever you see drifting location data like that, that’s more than 100 metres or so from the real location, you can go into Individual Segments and mark the nonsense segments as bogus, to remove it from the timeline. Though it sounds like you’ve already done that part!

    Aside: I hadn’t been experiencing the bogus location data problem almost at all, for maybe a year or more, but it recently came back with a vengeance in iOS 16. Though it seems to be gradually improving and disappearing on my main phone now, thankfully.

  1. The other possibility is if some visits have been incorrectly assigned to the wrong place without you noticing, that will fool the Place classifier into thinking that particular Place is much bigger than it really is, and will result in the classifier being over-eager to assign Visits to that Place.

    An example of this in my own data is the street market that happens in my neighbourhood for one weekend each year. Whenever the market is on I will assign brief stops to market stalls as visits to “Winterfest Street Market”. That has lead Arc to believe (I guess correctly) that the street market Place is really quite massive, encompassing my entire neighbourhood. So whenever it sees me stop anywhere in my neighbourhood that isn’t another well known Place (eg Home or Starbucks or 7-11 or whatever) it will think “oh, you must be at the street market!”. Sigh.

    You can spot these accidental mega-places by going into the details view for a Visit that’s been assigned to that Place, then looking on the map for the orange circle. The orange circle represents Arc’s understanding of the centre and radius of that Place (while the purple circles represent stationary segments of the current Visit when on the details view, and on the main timeline view the purple circles represent the whole Visit).

    So if you see a clearly nonsense orange circle on the map, that means there’s some Visits that have been assigned to that Place that shouldn’t be.

    The way to fix that is to scroll down to “Place Statistics” on the details view, then tap on “Total visits” to get to the list of all Visits to the Place. From there unfortunately it’s a tedious process of going through the list to find the mistakes, which won’t necessarily be obvious. Aside: It’s on my todos to have the “All Visits” view show you each Visit on the map while you scroll down, to make it easy to spot the ones that are in the wrong place.

Hi @matt,

  1. I don’t have predictable drift in a particular direction, and definitely not that distance, but after many hours in Building 2, I have what appears to be 50+ mini-drift trails marked as car, each of them maybe 20-50m long in every direction. I can delete them as bogus (because they continually return to Building 2). So yes, there’s drift, but probably not that big.

  2. I have seen the orange circle around Building 3. Of course, I can’t see it now. The daily timeline has eliminated it now after thinking for some time, but when it appears next, I will drill down and try that process of elimination.

Thanks for the suggestions, and apologies for so many questions. It’s an unfortunate confluence of v3.6.0 and me upgrading to a paid subscription all at the same time as these problems have arisen for the first time, so it’s a bit confusing. I appreciate your patience.

I’m entirely confused by this issue now.

I have been studiously removing any “visits” to Building 3 from my daily records though I have literally not attended that location at all since the first day 6.3.0 was available. However, it keeps appearing as a nonsense circle.

What’s even more frustrating is that yesterday I had to do a lot of editing around cycling/walking/transport and so I know 100% that Building 3 was not listed at all on the daily information for yesterday. I checked today and found that now Building 3 is listed as a nonsense orange circle “visit” yesterday.

This means that I didn’t visit the location in person, and the app didn’t record it as a nonsense visit yesterday, but sometime today has inserted it back into yesterday’s records. I have no idea why this has occurred.

When I click the detailed view, I’ve got 20 “visits” over 11 days, stretching back on random days to 3 July 2022, so I will delete them all again (except for the legitimate visit) and see if that resolves it, or if it sneaks back into my list of “visited” places for other days.

One thing to be careful of here is to only mark data as “bogus” if it’s more than about 100 metres from the real location you were at at that time. Otherwise it’s best to mark it as “stationary”.

Marking that drifting data as “stationary” will teach Arc that the phone produces noisy/drifting data while stationary at that place, and will adjust to accommodate. This lets Arc know to be less trusting of the phone’s reported location accuracy at that place, and will instead treat it as being less accurate than reported, which will reduce the noise over time, creating more stable data in future.

Marking data “bogus” instead removes it completely from the timeline, and is mostly only useful for getting rid of data that’s wildly wrong (eg more than about 100 metres from the real location).

No worries! It’s what I’m here for :smile: