How frequently to capture the same stretch of the road?


#1

There have been some discussions and responses in the past about how frequent capture is suggested (one thread is How many times to take the same road? , and I recall somebody from Mapillary saying that once per month is their take on it - but cannot find that particular response right now).

If one sequence is taken forwards, then sideways sequence would still be useful on the next day - but could somebody from Mapillary please comment on how often would they like to see the same sections/directions captured?

Of course, assuming at least some daylight and usefulness of those images for OSM as a golden standard.


#2

There may be all kind of reasons to redo.
There has been a heavy storm this weekend, that is a good reason. Just before spring.


#3

As often as you want; as little as you like.


#4

The more the better. More footage allows better triangulation of object detections.


#5

This kind of raises another question. Object detection seems to be a function of resolution and frame rate. ie a 4K image at 1FPS maybe equivalent to 1080p size at 4FPS and 720p at 16FPS. So far my 4K images only look “as good” as 1080p size due to the quality loss of mp4-jpg conversion. Then there is uploaded filesize, ISP cost and quality. Is there a hard mathematical spec that Mapillary has defined as optimal?


#6

I suspect Mapillary might not appreciate having the same stretch of road uploaded every day, with 4 directional cameras.

As mentioned, I recall somebody from Mapillary saying monthly frequency is what “backend could support” - which I take as a combination of processing and storage costs. But that was some time ago.
I’d be very interested in the official position currently.

Of course, if a sequence was made yesterday, and a bridge is washed away overnight, new images today would be very useful. But I’m thinking more of a usual European city street - or a countryside road.