Photos are only mapped to GPX track if gps device had been running seamlessly

Started by stahl, October 01, 2023, 04:13:57 PM

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stahl

Hello,
I have just installed IMatch 2023 and I seem to have come across a new behaviour: When on tour, I often switch off my Garmin gps device when taking a break and not moving for a while. So far, IMatch 2021 has interpreted the position of photos taken during this time of switched-off gps device as being essetially where the last (or first?) position around the switched off period had been. I see that now such photos are, in contrast, not mapped to the gps track. 

I can see the logic behind this and in a way it is strictly correct, but still I would like to retain the old behaviour. I am pretty lost in finding the position of images taken during those breaks. Is there a switch I can set to achieve this?

I am attaching a typical GPX file and three images, two of which have been taken during breaks with my Garmin switched off.

Mario

The new behavior is more logical and has been requested and discussed often here in the community.
Users reported that because their GPS reception was bad, the GPX track log was sparse. And just assigning files to the "last" track log point produced really wrong GPS coordinate assignments - often miles away from the actual location the image was taken.

The threshold parameter in the track log import dialog introduced a while ago allows you to define the maximum time between a track point and a file timestamp to make them match. The default is 300 seconds (5 minutes).

I understand that you turn of your GPS and so the track has large gaps between the points, correct?
And that you take photos while the GPS is off or not receiving.
This means that you need to dial in a much higher threshold, e.g. 3600 seconds to allow for an hour between the track log point and the file time stamp to match them.

Have you tried this?
Your track log is nice, but I don't really have the time at the moment to produce some sample images matching your track log, with appropriate time stamps and all that.
-- Mario
IMatch Developer
Forum Administrator
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rolandgifford

I also found this a problem on my last trip as I had my track recording set so that it didn't record when I wasn't moving. I travel for and photograph birds so being in the same spot for a number of minutes is common. I have now changed my track recording so that it records regardless.

I considered increasing the threshold as Mario suggests but decided to change the logging instead as there are occasions where I forget to turn tracking on when I depart or turn it off when I think I have finished for the day but I haven't and I would prefer to have those with no coordinates rather than the start/end of the track

Mario

Some users prefer wrong coordinates over no coordinates, some don't.
The threshold option allows for both.
-- Mario
IMatch Developer
Forum Administrator
http://www.photools.com  -  Contact & Support - Follow me on 𝕏 - Like photools.com on Facebook

stahl

Thanks for the explanation and solution. Setting the threshold to 3000 did the trick.

I suppose I will just leave my gps device running in the future, now that I know.

Mario

Quote from: stahl on October 02, 2023, 11:09:18 AMI suppose I will just leave my gps device running in the future, now that I know.
This is usually best. It does not help if you are in a location where no GPS signal is available, and this will also create more or less large gaps in the track lock data.
The threshold allows you to tell IMatch what you prefer. Position the image on the "nearest" track point, even if there is a large time difference, or not assigning GPS data so you can tell that there was no good match.
-- Mario
IMatch Developer
Forum Administrator
http://www.photools.com  -  Contact & Support - Follow me on 𝕏 - Like photools.com on Facebook