[Talk-ca] GeoBase PostGIS & OpenStreetMap

[Sam Vekemans]

Thanks,
I also got 2 comments about the french name tagging, so i added it to the
http://wiki.openstreetmap.org/wiki/Talk:GeoBase_Import page.
And tried my best to translate this talk about PostGIS. :)
Please edit, if you can :)

The part about the stressing the importance of not undermining OSM
contributions, needs to be highlighted more.  IMO

and
"Even if there is a single road
through an area there has to be a way to for us to match it within both
OSM and GeoBase.  "
By using the charts we already started, and the name tags... we can create
the set of rules that the PostGIS database import script will follow.
GeoBase Tag = OSM tag. .. and get as detailed as possable.

The realtime aspect (my last point on the talk) is still a little vague.

Cheers,
Sam

On Fri, Dec 5, 2008 at 10:11 AM, Richard Degelder <rtdegelder at gmail.com>wrote:

> On Fri, 2008-12-05 at 03:06 -0800, Sam Vekemans wrote:
> > I forgot to send it direct to you too. talk-ca takes a little longer
> > to send.
> >
> >
> Thanks.  I am starting to check the talk-ca site regularly anyways so I
> am seeing a lot of the discussion as it comes up.  I like the digest and
> use it to reduce the amount of traffic that I get.  But sending me an
> e-mail directly is appreciated.
>
>
> >
> > So from your idea i got:
> > 1. Merging the OSM reference id# database (our big Canada file) with
> > the GeoBase dataset onto a separate PostGIS database.
>
> Correct.  We find where there are common elements within both data sets,
> such as a street, and have a way of transferring the the reference id#
> from the one to the other.  A database would probably be an ideal way to
> do this.
>
> > 2. Purging the results of close lines/nodes. (street names maybe?) ...
> > creating a GeoBase/OSM database. Where it just looks for that, and
> > removes the extra OSM stuff that it doesnt need.
>
> Not exactly.  I would not really touch the OSM map, as far as the
> renderers see it, at all at this point.  The purpose of the database is,
> on the one hand, to eliminate redundant data from entering OSM but is
> also useful, at the same time, for adding additional metadata, in this
> case the GeoBase id#, into the metadata for OSM.
>
> > 3. Then importing it back to OSM.  .. purging it with the original OSM
> > Id's.
>
> Once we have the database showing the GeoBase data that already exists
> within OSM, such as the existence of a particular street, two things
> happen.  First the metadata, such as the GeoBase id# is given to that
> street or that way.  This will ensure that from that point on it is
> identifiable as having been in the GeoBase data and any subsequent
> updates to that GeoBase data that effects the particular street or way
> will know that it should also effect it within the OSM data.  This also
> allows for the addition of more data, such as street address data, when
> it becomes available for the area.  In essence any subsequent update
> from GeoBase will believe that the street that was originally within OSM
> really came from the GeoBase import.
>
> At the same time the database will be used during the import of the
> GeoBase data.  It would work in that any street or feature within the
> GeoBase data that has a matching item within the database, and so
> already exists within OSM, will not be imported into OSM as part of the
> GeoBase data import.  At the same time any feature within the GeoBase
> data that does not match anything within OSM would be imported.
>
> As long as the matching process is efficient then there is no need for
> eliminating any area from the GeoBase import.  Although there are likely
> going to be issues where something that is thought not to match, but
> actually does for some reason, gets imported it hopefully will be rare.
>
> The results of this effort would be to allow for the full GeoBase data
> set to be represented within OSM while not overwriting the contributions
> of those that have already entered data into OSM and to add the
> metadata, particularly the id# from the Geobase data, to allow us to
> update OSM as the GeoBase data is updated and extended.
>
> > Am i following that right?
> >
> >
> > Cheers,
> > Sam
>
> We have to consider that except where there is absolutely no data within
> OSM for an area there are going to be some conflicts between the GeoBase
> data and that already within OSM.  Even if there is a single road
> through an area there has to be a way to for us to match it within both
> OSM and GeoBase.  And I also believe that the content that already
> exists within OSM is important and should not be replaced by GeoBase
> data only for convenience sake and for expediency in importing the
> GeoBase data.
>
> Doing it for any road in an area is really not going to be any more
> complex whither it is an isolated road in the middle of nowhere or a
> residential street in the middle of Toronto or Montreal.
>
>
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