Hello!
Take a look at this sequence 15ZeO8daWzrvwlbp6Bsgn4 ( Mapillary )
It’s clearly wrong GPS data, which practically makes this unusable for anything. Please take a look at this and fix/delete.
Incorrect placement of stills from a video is a recurring problem at Mapillary, and the main reason that I have stopped using video, switched to photo time-lapse; the issue is not related to one particular camera, as I have observed it from other contributors.
Other reasons were the apparent compression in video - thus loss of information, and the difference between the stated resolution in GoPro specs / and shown in their desktop player vs. Mapillary’s reduction from 5+K tot 4.
Might be helpful if Mapillary assumed camera clock isn’t synchronised at start of each sequence, and allows for camera being stationary at say traffic lights, but even then found that 90degree turns increased the position error.
By comparison the photo timelapse does have some error, but it is manageable as soon once one comes to the insight that location is taken 1½secs after the photo, then written to file - thus when you know that photo was actually taken ¾ of the interval between pics earlier you’ll be spot on - within the limitations of the GPS, of course.
1 Like
To continue with examples : know from experience that this photo is in the correct spot (although the ‘fan’ is pointing in the wrong direction) : .
Single-step forward with the > at the top : the scene is still the same, but the blue dot has moved onn :
Eventually the light turned green, blue dot is by now hundreds of metres ahead, while the camera is still at the lights.
Need I add that this isn’t particularly useful?
= = =
OK, pick another example :
Taken at the corner : , and to boot the orange fan points 180 degrees other way;
This was clearly not taken at an intersection : ;
I know the area where pictured here, and although the dot is at the underpass the pic doesn’t show that underpass (the underpass is on , which in turn is placed … well, not here.
Yet series by same contributor on 26 apr’24 is correct : far as I can spot, oics in all series were all in the correct spot - give or take couple of metres.
= = =
Met als immer vriendelijke groet,
1 Like
Sequence deleted. Must go there one more time, and capture in timelapse mode.
2 Likes
More sequences that need to be fixed/deleted @boris
lOVL1Q58beMPZca3SDGx7y
px6dvV7GDr3NC8SUbQucMh
btTPxwgWlEuSOYGFq5J4e7
0HjRsAvXNgiySOcD5qhtxU
jOQn3D9J5svMudkGrIitEg
TtgCuV1mDip4Z5a2hjvR7z
3pwiTv7dSH4uFIDJRsfbPt
ao6kJB2IMZv0QcAsEVNqy7
z0WJDuKiV1BtoGQECmAwI3
and ALOT more from user ‘dasza’ from that time take a look at the map, there are straight GPS lines
edit:
ac7LuWfoheFZQyxPKmqj2C
edit2: more at Mapillary
edit3: also somethink funky here Mapillary
edit4: another sequence Mapillary
You should really do something to automatically detect wrong GPS data, that does match SfM
edit5: another one form @inwazjamb Mapillary
Thanks @IreuN! We do have some low hanging fruit to better detect obviously wrong GPS.
For the future you can email support@mapillary.zendesk.com with these types of individual requests. Also cc: @mhogan to take a look.
1 Like
Thank you very much, does deleting the sequence also delete the detected features?
Maybe adding functionality to edit/correct positions on Mapillary map will be a good option? What software can do correction on video files? Better not command line. 
@IreuN - I believe deleting the capture does not currently delete the detected features (but I would say that theoretically it should, so don’t quote me on this) 
@inwazjamb - we are adding functionality to the desktop uploader to let you remove erroneous images from the map before upload (stay tuned). This is easier for imagery than video files. For videos you’ll want to extract the .gpx using exiftool, edit the .gpx using a tool like http://gpx.studio and then specify the updated .gpx file when uploading with the desktop uploader.
1 Like
Well then, if it is not, maybe it should? Not sure how it’s implemented, but API can return all images that contain certain feature. If there is no image that contain that feature than I think it should get removed, specifically if it’s position is outright wrong.
Data quality should be important in service like Mapillary
Agreed, its worth trying
I tried exiftools, and got error like this:
C:\Users\micha>for file in C:\Users\micha\Videos\mapillary\GOPRO\*; do exiftool -ee -p gpx.fmt "$file" > "${file%.*}".gpx; done
file was unexpected at this time.
Something is wrong, and I suppose that I need to change “file” for something else, but for what?
Or there is other way to make it working?
Hi @inwazjamb - you could try asking in the exiftool forum: ExifTool Forum - Index