On 27-5-2012 20:58, Ian Dees wrote:
On Sun, May 27, 2012 at 1:53 PM, Alan <grunthos...@yahoo.com
<mailto:grunthos...@yahoo.com>> wrote:
I object.
An ID tag is highly useful for future reconciliation and/or
synchronization later. And the "chicago:" namespace is, in my
opinion, definitely the correct way to do it, because it clearly
defines the scope of the id. The chicago:building_id should stay.
Not including it is "dumping data" into OSM; including it is
enabling collaborative use.
I've searched for a reliable way of doing this for years and have yet
to find anything worthwhile.
Leaving the external ID on the objects doesn't really help when others
remove or split the shape later on. On the other hand, they don't hurt
anything...
I tend to think that keeping the ID has no use. As Ian mentioned, users
can (and will) edit the data, so those features become split, merged
together, or erased. The way OSM 'works' makes it really hard to deal
with the ID's. There is also the principle that imports should not
override user-contributed data, so (I assume that) a part of the
building won't be imported at all. That will leave the set of ID's in
the OSM DB in an incomplete state, which makes it much less useful.
Updates, if done at all, could better be done by using geographical
matching. It would be great to have some generic tools with which an
external datasource can be compared with OSM. This will generate a set
of changeset files: one with matching features, one with modified
features, one with 'new' features (not existing in OSM), one with
'deleted' features (features which only exist in OSM). Then the user
taking care of the import would only need to look at the latter three,
to judge what has happened, and manually apply the changes he wishes.
In the Dutch community we've been discussing this a while ago, because
all buildings in the Netherlands are available in a high quality PD
dataset, called BAG (Basisregistratie Adressen and Gebouwen: base
registration of adresses and buildings). Ironically, exactly the reason
this dataset is existing and freely available, it makes it not worth
while the effort to import this into OSM, and impose the burden of
updating it onto ourselves. It is much more convenient to take OSM
without buildings (and addresses) and merge this with the other dataset.
Frank
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