[Imports] Facebook's AI-Assisted Road Tracing for OSM

[Michael Reichert]

Hi OSM @ Facebook,

Am 2017-03-27 um 20:22 schrieb OSM @ Facebook:
> Why are there are no relations in those files?
> 
> Yes, currently we skip relations as we map in more rural areas. 

What is your definition of "rural areas"? Rural areas might have lots of
relations and damaging one of them by ignoring relations at all will
visually impair the map.

> Our enhanced iD currently skips updates/deletion to relations, and we
> have done a lot of testing against OSM devserver and verified that
> not including relations in the .osm files will not cause
> deletion/updates to the relations or their membership.

Your understanding of the OSM API is not correct. The API only does as
less validation of the input as possible. Editing a way which is
referenced by a relation is accepted by the API even if you do not
edit/adapt the relation itself. But getting a non-error response by the
API does not mean that the relation is still valid. Even moving nodes of
a way might invalidate a relation. That's why JOSM has a validator [2].

> We are aware that when splitting any way that is part of a relation, the new segment may not be part of the relation. Our principle is to have the least amount of changes to existing roads so we don't split existing ways. Our iD also checks for split of existing roads, so editors will not be able to save until checked and resolved. We do make minor modifications when necessary by adding nodes or connections to a way in a relation which shouldn't cause membership issues for the relation.

If your editor is not able to handle relations properly, you should not
do any edits on objects which might possibly invalidate relations.
MAPS.ME is an example for such a simple editor which is that simple that
it cannot edit relations in a harmful way. Your tools are written to do
heavier edits but we are still unable to review them.

> All relations in the area will be checked for integrity after changes, just to make sure nothing broke.

You are doing an import and we expect imports to be good. That's why
there are guidelines and the requirement for a discussion and review.

You should check if you break a relations *before* uploading them, not
afterwards. Experience from previous imports shows that most of the work
which was proposed to be done *after* the initial upload is never done.

I doubt that your team lacks the expertise it claims to have. A person
experienced in editing OSM data knows what issues relations can cause
and how difficult it is to write a tool which modifies OSM data (data to
be uploaded).

Best regards

Michael


[1] Additions and deletions are changes, too.
[2] which is not perfect
[3] iD's relation support ensures that splitting a way does not break
relations.

-- 
Per E-Mail kommuniziere ich bevorzugt GPG-verschlüsselt. (Mailinglisten
ausgenommen)
I prefer GPG encryption of emails. (does not apply on mailing lists)

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: OpenPGP digital signature
URL: <http://lists.openstreetmap.org/pipermail/imports/attachments/20170328/55f4adea/attachment.sig>