Arc refuses changes

Hi, since the latest update, Arc refuses to accept the changes I make in the individual segments. It keeps setting them
back to the original data.
For instance: Arc records a walk, but part of that walk I was actually stationary at home. So I go to the ‘edit individual segments! and Arc indeed recognised that I was stationary…I correct the data as being ‘at home’, go back to the timeline and there the whole period again shows up as a walk. The only way Arc accepts the ‘at home stationary’ change is when I chose a different place and call that ‘home’. If I put these two places together, Arc makes it into a walk again. Very change… this happened with al the changes I made since the latest update.
Do you have any ideas (I already restarted my iPhone). Thanks.

Hi @MZwart!

This doesn’t sound something specific to the latest update, but instead specific to the data you’re editing.

To give some background: Arc decides which samples are inside or outside of a visit based on the centre and radius of the visit. Samples at the start or end of the visit which are outside of the visit circle will get kicked out into the adjacent trip item.

When you try to assign those samples to the visit, they will initially be moved into the visit as requested, but then the processing engine will see that they fall just outside of the visit’s radius, and will kick them out again. If however you assign those samples to a new, different visit (eg instead of Home you assign them to Driveway, thus not merging them into the Home visit), the samples will be part of a new visit, and will define the new visit’s centre and radius independent of the Home visit. The processing engine will then have no reason to kick the samples out of the visit.

This is a weakness in the processing engine in that it isn’t able to recognise visits with more than one “centre of gravity”. So for example if you spend 5 hours of a Home visit inside your living room, then go to your garage for a few minutes before driving away, the samples recorded while in the garage won’t have as much “weight” due to only adding up to a few minutes, so might not be enough to sway the centre of gravity and visit radius to contain them. The processing engine then won’t accept them as part of the single visit, and will either require them to be a part of the following trip item, or put into a separate standalone visit in the timeline.

I hope that explanation makes sense!

It’s something that is on my todo list to improve in a future update - the ability for the processing engine to recognise visits with more than one centre of gravity (eg recognising that you spent time in more than one area of a larger building, but that they should be considered all part of the same single visit).

In the meantime, the best available workaround is to assign the samples to a new smaller visit.

My typical daily use of this workaround is to split out a brief “Bicycle Parking” visit outside my condo, for where I walk out to my bike and fuss about for a minute before heading off for the day. That allows me to have the timeline like “Home → walk → Bicycle Parking → cycling”, instead of the “walk → Bicycle Parking → cycling” being all merged together, making the cycling trip appear a longer duration than it was.

thanks for your reply, that does make sense. So I guess I sort of applied the workaround you describe already.
Thanks for the explanation.

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