In densely mapped areas, warn the mapper to prefer realign the imagery with the features, not the other way around

[IgorEliezer]

Description

Hello,

After importing buildings from a geopositioned map or a thoroughly mapping (such as this or this), from time to time a (oftentimes new) mapper moves a huge amount of features, because they see the features don't align with the imagery.

Firstly, according to the imagery as is, they realign a few existing features or add a new way or a building. Then they see the newly added/edited features look off to the surrounding features (curbs, sideways, street poles or buildings). Then they move these. They then see objects overlapping the others, then they move entire city block, then entire neighborhoods and so on -- here they might have quit midway.

I also found out mappers who deleted existing buildings to "fit" their own, since the imagery was "off" and they might thought those buildings no longer existed, but they are there IRL.

Also, we have those teams who go wild "fixing up" things. They add new ways or realign the existing ones according to the imagery as is. They leave ways overlapping existing features, or they move only the surrounding features, ending up with overlapping buildings/features.

The issue will likely repeat, because the imagery providers update their sets almost yearly with new image, terrain model or other orthorectification method. Streets, buildings etc in the image may "move" up to 10 meters relatively to the previous imagery (as noted here https://community.openstreetmap.org/t/maxar-esta-atualizando-suas-imagens-e-sobre-apple-data-team-adt/92494 - discussion in Portuguese).

Obviously in these cases, it's better and easier for the mapper to align the background image with existing features. Otherwise they might jeopardize future imports/additions.

So I propose:

1. In densely mapped areas, iD editor should warn the mapper to prefer realign the imagery with the features, rather than the other way around. It will save both their and our time.

2. Along with, could also offer a "Show me where I align the imagery" link/button, and iD opens the Background panel and highlights Imagery Offset tool.

3. If not already, the introduction tutorial could also have a step where the new mapper is taught about the Imagery Offset tool, and they should prefer to realign the image before editing in already-mapped areas.

Regards,

Igor Eliezer

Screenshots

Example of well mapped area with geopositioned material provided by city hall and the imagery. An invitation for the issue described above:

Yesterday I had to fix one of these cases:

https://overpass-api.de/achavi/?changeset=162801310&zoom=16&lat=-23.65070&lon=-46.53229 It took a while to fix and it is not perfect.

The mapper is not who to blame. I had a conversation with them. They did it in good faith and didn't know the background imagery can change over the time.

[tordans]

We know of the problem and there are old issues in this repo like #4764 that discuss possible solutions. #4166 started on a possible solution but to my knowledge that database did not take off.

We closed similar issues as duplicates #9663 (comment) but lets keep this one open to discuss the possibility to inform (new) mappers:

How could that work? When do we inform then? How do we make sure this is not annoying for most of the users, because it is only relevant in some regions or for some image layers.

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One idea I have is, that we could ask the editor layer index to introduce a flag like likelyRequiresManualImageryOffset: true. This way we can show the warning only for those layers that mappers know about that have issues.
(We could maintain that list in iD first, to speed things up, of course.)

The question remains when to show the warning.

• Showing it below the selected imagery in the imagery list is a good place for those cases when mappers switch the image layer. We could add a jump-link to the offset UI there with a text like

  Check if any imagery offset is required to align the background layer with existing mapping. [Adjust the imager offset…]

• We could add a step for this for new mappers in the wizard, but TBH I don't think that is the right place. It will get overlooked and users that need the wizard first need to understand basics before this.

• We could introduce a new information UI that shows when a session is started with an imagery that has the new flag. The UI could point to the side panel and remind mappers to use the offset feature first. Similar wording like above but inside a help-popover like UI.

  • That would work but requires adding a new UI and interaction which is quite a lot of work.

• We could add a red dot (or red exclamation mark) to the sidebar whenever the conditions are met to nudge users to open the sidebar with the offset UI. We could then pre-open the offset disclosure and show some text message there.

  The selected imager "NAME" likely requires a manual offset to adjust it to already mapped features. Adjust the imagery before adding new features to the map.

  • That would IMO be a good compromise in terms of effort and effect.