What's the opinion on image location accuracy, lagged - 20 secs out of sync with GPS location

Contributing and equipment 360° cameras
#1

What’s the opinion on re-correcting images for location accuracy ? What is an acceptable drift factor ?

I’ve just uploaded a whole bunch of 360° photos taken approx 1 second apart and they are now are appearing on the map. But I’ve noticed that they are lagging on one day roughly 20 seconds from the GPS location.

I was on a bike at the time, as you can see from this image of the overhead power grid on the right and the location on the map is roughly 20 shots to the map position.

1

Should I remove all my images for the day and re-process them with a 20 second time addition to correct the lag ? Or just leave them ?

Has anyone removed a whole sequence successfully and republished ?

#2

I edited the above and now I see a 1. Where I had my link, to the image of the over head power grid.

https://www.mapillary.com/map/im/C0tYkZSBf7Fr7x2jmR26TT

#3

Dear J Kingsley a,
1/ You’re correct in assuming that images which are clearly placed far from their location are best removed;
To help visualise the issue, as I’m not familiar with the area, in the bottom right corner selected Mapillary satellite imagery, picked a picture-dot on an intersection and clicked forward till I found an image depicting what looks like that intersection.
2/ To concentrate the mind : picture https://www.mapillary.com/map/im/mTGwaG2sMVtMDjpQMNuBRk seems to be taken where https://www.mapillary.com/map/im/6cR7y5jQxJsPHMMj8sXvHM is placed?
3/ That’d indeed be a 25 second lag.
4/ There are other series, https://www.mapillary.com/map/im/9kR7lvM2VplKVNQzGK5rNY looks like it was placed correctly?
5/ The pic under 4/ was taken on 2021-03-27 13:34 , the ones under 2/ are more recent, 2021-06-06 09:53;
6/ As there are only partial details on the Camera make and model : would you be geotagging the pics with the GPS track log from an external receiver? If so, how do you determine the difference between the clocks in GPS and camera, please? (For my geotagging take three photos of a screen on the GPS showing the time including seconds at start and finish of the day’s journey).
7/ Removing a sequence can be found (once you’ve picked a pic in the sequence) under the three dots in the bottom right corner : … > Editing > Edit current sequence > Delete sequence; may take a while, could be that s/o at Mapillary reviews the request; have not had problem in the past re-publishing incorrectly placed sequence.
Good luck, happy cycling, and many safe returns.

#4

Hey @koninklijke thanks for responding - and coming up with some great comments.

The 360 camera, a modified Insta360, doesn’t naturally maintain gps location with each shot so yes I’m using the first start shot time, adding a 30 frame/second difference to set the image time of the NEXT image and then geotagging the whole sequence. It has worked ok - But as you mention the clock speed on the camera over time appeared to have lagged, this happens when the camera stays in my bag. This lag is effectively reset when I communicate to the camera with the phone - so I’m got a new ‘startup’ procedure to ensure I communicate with the camera first, then I hit the buttons on the camera to start the video recording.

Also I’ve since updated my tagging scripts to allow adding a ‘fudge’ factor in the calculation of the tagging so I can + or - seconds of the image, before I map it with the geotagging gpx file.

I now also have started to take note of your point 1, and mark a intersection when I do some initial stills and noticed if I start the app first I gain approx +4 seconds on the image to the GPS location, so I can handle the drift more easily now.

Overall the recent server updates/privacy etc - it looks to my advantage that the servers have been reset and my June images have now gone :slight_smile: yay me. I’m waiting a few days to see what happens and see if things come back before re-submitting my changed images.
If the bad ones come back - I’ll try and remove them.

Again appreciate your comments