[Talk-ca] Users in Ottawa and Geobase

[James Ewen]

On Thu, Oct 29, 2009 at 10:36 AM, John Whelan <jwhelan0112 at gmail.com> wrote:

> Let's recap, I've seen no substantiation for the statement that thousands of
> hours of work will be lost.

We've seen no substantiation that all of Ottawa is a bunch of garbage.
I'm not sure how you can believe that all of the work done so far in
Ottawa has been done without accruing many hours of work to get it to
the state that it currently is in.

>  I've seen nothing from any one else who has
> done any GPS traces in Ottawa.

Have you made any effort to contact ANY of the mappers in Ottawa yet,
besides posting messages on this forum? Have you sent requests to them
via OSM?

>  I've seen two different places where the
> existing OSM map is 100 meters out from a GPS measurement.

Okay, 2 instances over how many thousands of roads?

> Basically the map in Ottawa is unreliable but we don't know where.  There
> seems to be no way of knowing whether a road has been mapped by GPS trace or
> sketched in by hand.

Every map is unreliable. Even your ultimate GeoBase data is
unreliable. It is possible to see where GPS traces have been uploaded
to the OSM database. It appears most of the roads that I have looked
at were traced from Yahoo imagery, as they line up nicely with the
photos. The problem is that the photos may not be orthorectified
against reality, which can create displacement errors.

> The groups solution seems to be that in time enough people will magically
> come out of the woodwork with GPSes and remap the city.  It is likely that
> the same roads will be remapped over and over whist others will not be
> touched since no one knows what is happening.

Well, so far there has been at least one person that "magically came
out of the woodwork", and mapped what you see in the OSM database.
>From what I have seen, there are at least a dozen different usernames
associated with the data I've seen in Ottawa.

Mapping parties, as well as dedicated individuals can take the time to
align the existing data with measured information. The process is to
create, and enhance, not simply walk in, say "This is all garbage!",
delete and start from scratch.

> I don't think I can take that to any of the groups I talk to from time to
> time.  The quality just isn't there to build on.

Well, then maybe these groups that you talk to need to find another
FREE source of map data. Perhaps you can start your own mapping
project wherein you have ultimate control over data quality.

You seem to be missing the concept that this is not all about YOU and
YOUR "CLIENTS". The OSM map is a community based project. You need to
be aware of the fact that many others have invested in the project,
and you have no more right to the data than anyone else.

Get out there and enhance the data that exists.

I would hope that if you do go through with a wipe and replace that
the OSM community would revert that changeset to keep the existing
data.

Even if you were to guarantee that you would not only import the
GeoBase data, correct every error, remap every other node that all the
other mappers have added, and then continue to add more data to the
area of your concern, I would still oppose your plan. It goes against
the basic premise of OSM, where it is a COMMUNITY effort. You are
basically telling everyone in the Ottawa area that their contributions
are a waste of time, and that YOU will be the sole judge of what
should be included in the OSM database.


Even if the existing data were completely wrong, not even coming close
to representing the real world, you would find a lot of discussion and
queries happening before a wholesale deletion would happen. The
existing is not "wrong", it just may not meet with your accuracy
standards. What happens when you import the GeoBase data, and then
someone else comes along, and finds two points where the node is 3
metres from where it is supposed to be according to them? Do they have
the right to delete all the data you have imported and start again
just because they feel the data quality is garbage?

Join the community and enhance the data, just be aware of the impact
your actions will have on others.

James
VE6SRV