OpenStreetMap
One of the most common mistakes I find from new mappers is using Bing Imagery and not accounting for the offset. Admittedly, I was making this mistake for a long time before I realized that I had been messing up roads, houses, etc. that were already perfectly in place. Since learning about that, my preferred imagery sets have been ESRI Clarity (old sometimes, but very clear) and NAIP (blurry sometimes, but pretty new).
What puzzles me is why Bing is the default imagery choice when using iD. It’s not a big deal if it’s being used to clean up what would otherwise be a TIGER desert, but when trying to use it in an area dense with features (e.g. a university), it becomes practically useless. Even if new mappers go through the tutorial, they’re probably going to stick to whatever the default is until they get their feet wet, or like me, assume that Bing was made the default because it’s the best choice!
This is problem is well known and acknowledged on the Bing Wiki, so why hasn’t iD already set ESRI or something else as the default?
Discussion
Comment from pnorman on 21 July 2020 at 20:24
Different imagery sources are better in different places. All imagery sources can have offsets, so it’s not unique to Bing.
What’s needed is someone systematically evaluating the quality of Bing, Esri, and Maxar where mapping is done and deciding which is best overall.
Comment from n76 on 22 July 2020 at 00:55
The alignment varies with time too, not just location.
For a long while the MapBox imagery was the best as far as alignment in my area. But sometime in the last year or so I noticed that the Bing imagery was refreshed and the new imagery is as well or better aligned as the MapBox imagery. Not sure how long ago this happened as I only noticed when I had an area that I just couldn’t see the detail I was looking for (construction newer than the imagery) and so looked around at other imagery to see if there was newer stuff available.
Of course the best thing to do at the beginning of an editing session is to see if there are any GPX tracks in the area that can be used to check the imagery alignment. Don’t know about iD, but in JOSM you can adjust the alignment.
Comment from jidanni on 22 July 2020 at 16:03
Yes, village 1 gets mapped with offset 1, village 2 with offset 2, etc. until one day when their edges finally meet and one has to deal with the problem. P.S., here in Taiwan Bing is 10 years old.
Comment from bhietsch on 22 July 2020 at 17:34
Makes sense that the quality would vary by region, and definitely agree with systematic evaluation and checking GPX tracks. I was just always under the impression that Bing imagery in particular struggles with changes in elevation. Take for instance East Broad Street in my area, which goes up a hill with an average gradient of about 10%. As you can see, the building and road alignment changes quite a bit as you go up from Warren Street to Independence Road, despite only gaining about 160 ft.
So yes, n76, you can adjust alignment in iD, but it’s a little impractical because you’d need to be constantly adjusting it as you move around.
Another thing I’d like to start seeing is the date the image was taken… why hasn’t this been implemented yet? Seems like a simple thing to include next to the terms and conditions link in the bottom left, but is there something I’m missing that would complicate this?
Comment from jidanni on 22 July 2020 at 18:05
If you do F12 (Developer Tools) in your browser, and examine the headers, there is
Comment from e_barreira on 25 July 2020 at 19:17
The same here in Portugal. Bing imagery is not alligned and all the time I use or Esri or Esri (clarity). Maxar sometimes are ok to have an updated view for the same place.
Comment from jimkats on 26 July 2020 at 13:03
Same thing. I used Bing Imagery till recently because it was the default imagery. But at the same time having so many options for imagery makes it kinda difficult to decide what to choose if you are not sure which one is more aligned to the actual co-ordinates.
Now I use an imagery which even though is much more aligned and updated than Bing, it shows everything sideways and not from top, making it a bit tricky to properly draw outlines and difficult to see if there are driveways/footpaths among the buildings.