[Talk-ca] Users in Ottawa and Geobase

[Gerald A]

On Thu, Oct 29, 2009 at 12:36 PM, John Whelan <jwhelan0112 at gmail.com> wrote:

> 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.
>

Any map can be unreliable, and often providers of such maps don't know
where. The nice thing about OSM is if it isn't right, it can be made so.

Just because a road is GPS traced doesn't make it "better" then one done by
tracing.  Each has possibility for different errors, and done right, both
can be accurate and correct.


> 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.
>

I'm not a native to Ottawa, but
http://www.openstreetmap.org/?lat=45.4218&lon=-75.6907&zoom=14&layers=B000FTF
seems to line up quite well with what I remember.

Viewing in Potlatch, it also seems to align quite nicely with the
Yahoo imagery of the area. Now, the Yahoo imagery might be incorrectly
rectified, but it would seem that might need the data shifted around,
rather then a wholesale delete & re-import.

There are lots of tools to help correct and tweak things -- I'm sure we can
dig up a tool or two that will help find errant streets. We're a crowd
sourced project -- we depend on people coming out of the woodwork to do
stuff. I believe only a number of GPS traces would be needed, rather then a
complete re-mapping of the city -- but that is just my opinion.

What it sounds like to me is that the group is trying to suggest ways to
make the data better in the scope of the projects philosophy.

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.
>

OSM isn't perfect, and it'll never be finished, because there is always
something else someone will want to add on to it. But the current map, as it
exists, seems pretty complete.

If it's not up to the accuracy you want, then you are free to help improve
it. But improving != removing and re-importing.
Or, if you can wait, I'm sure someone will improve it.

Gerald
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