[Talk-us] armchair mappers putting errors back into the map

[Nick Bolten]

I like the idea of having information indicating the lack of certain
features, when necessary - such as the geometry with a note on it about
what not to map. It would be great if it could be done more formally, for
purposes of QA, such as how the construction tags work for buildings,
streets, etc - the tags say "this thing will exist, but it doesn't right
now, so don't map anything else in it".

I run into similar issues with pedestrian paths and wonder whether a more
formalized "this feature does not exist" tagging strategy (beyond free-form
text) could be useful. Example from personal experience: how do we know
which areas are in need of having "X feature" added, where the feature
requires a new geometry (like a sidewalk line)? You can't differentiate
between "nobody has attempted to add the sidewalks to this block" from
"there are no sidewalks on this block" without worldwide manual reviews -
but you could if there was a tag called "highway:exists=no" (e.g.). I know
that there are some potential hacks for sidewalks in particular, but it's
part of a general issue of the determining nonexistence vs "unmapped" for
features requiring their own geometry.

This is also something that could be helped via editors if there were a
"find similar historical" API to the OSM backend so that users could tell
if they were replicating / negating historical changes. For the case of the
driveway, it should (theoretically) be possible to ask, "has there been a
similarly-located + shaped geometry with similar tags been added here in
the past?" and show the results + changesets.

Apologies for the potential derailing.

Best,

Nick

On Sun, Mar 3, 2019 at 8:49 AM Mateusz Konieczny <matkoniecz at tutanota.com>
wrote:

> Mar 3, 2019, 5:09 PM by rwelty at averillpark.net:
>
> we've talked about this before, i guess we will never stop talking about
> it.
>
> i recently noticed in my OSMAnd display that an error got put back
> into the map about 1 mile from where i live. a short dead end
> was put in as a residential road (it's really an unnamed driveway)
> based on NYS GIS data. i removed it years ago (it was in tiger 2007).
>
> (...)
>
>
> what can/should we be doing about this sort of stuff? i'm really
> at a bit of a loss here.
>
> When I remove things visible in aerial images or other high quality sources
> I often leave geometry with note.
>
> For example on removed power tower (I made edit as crane lowered it,
> I just happened to be looking at it outside window) I changed
>
> power=tower node
>
> to
>
> note="power tower visible on aerial images was removed on <DATE>"
> survey_date=<DATE>
>
> to keep people from remapping it based on high quality aerial images
> available for my area.
>
> ---
>
> I also don't make risky armchair edit in areas with active local mappers.
>
> ---
>
> Is "NYS GIS data" something that can be considered nearly error free? If
> not then
> it should not be used for edits without verification with at least
> high-quality aerial imaged
> and this mapper should be reminded about it.
>
> If yes then leaving geometry with note is a good idea.
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