[Talk-ca] Users in Ottawa and Geobase

[Sam Vekemans]

Hi James,
i know you sent it to Richard, but i'll chime in :-)

On Wed, Oct 28, 2009 at 12:13 PM, James A. Treacy <treacy at debian.org> wrote:

> Richard,
> A mapper notices a subdivision in openstreetmap does not jibe with
> his experience so he goes and traces it using his gps. He loads it
> into JOSM along with the current openstreetmap data and the geobase
> streets. He then notices that the existing data is worse than he
> thought: streets aren't joined, streets are substantially displaced
> from what the other data show and many streets are missing because the
> displaced roads caused RoadMatcher to drop them. Further, the mapper's
> trace and geobase are in good agreement.
>
> This is not an exceptional example. I have encountered similar
> situations many times.
>
> Are you really suggesting that the mapper should spend hours massaging
> the existing map into place and then adding the missing roads? The
> alternative is to replace the area using geobase and then do some
> road alignment from the gps traces, probably taking 1/4 the time.
>
> In Southwester Ontario, I have found that the geobase data is
> excellent for getting the topology right and quite good for location.
> On the other hand, the concession roads in SW Ontario mapped before
> geobase came along were 95% crap. That doesn't mean they should all
> be junked wholesale, but if data shows a road to be awful and causes
> a lot of roads to be dropped, I think it is fair to let a mapper fix
> things in the easiest way.
>
>
Well, just looking at the Canada Data Import Chart, all of the geobase roads
are available as stand-alone .osm files. ... These can be used how you like.


Provided that you have direct permission from the person who origionally
traced those roads to change them over.  Then it's fine to swap those OSM
roads, to add in geobase roads.   (But the whole point of our discussions is
that we need to act as a community, and work with those local mappers who
spent all that time, to locally decide if they want to manually adjust the
roads to be a bit better,  they want to replace it (that decision is to be
made by the person who originally drew in the road.  (if you cant contact
that person, ask on the talk list, we'll try :).   And if you still cant
reach that person, ask for help with manually adjusting.

I'll begin (or continue) converting the NTS tile areas for each of the tiles
where mappers are.    So that should be of assistance to everyone.

And so, if you find that there are missing .osm standalone geobaseRoads
files, from that chart, please post it to the talk-ca list, and someone with
the skills to use geobase2osm will be able to make those files available for
you. (were all volunteers, so it will take some time) :-)

So anyway, (if others dont mind).   What i'll do is make the Ottawa area
canvec data available, along with the  canvec roads (to be used as a
reference).   I'll go ahead and do a little adjusting.  Just like how
downtown Vancouver, and Victoria were off by 10 meters or so.   ... what i
did (and encourage others todo) is to ONLY move the road over when i'm doing
things like adding in a point of interest and i know its on 1 side of the
road, adding in points of interest on the other side of the road.   (this
adds VALUE to the map), then it's easy to fix up the map.

Even with WAAS enabled GPS's, having buildings around, it does mess it up a
little.  BTW, when we have 'mapping parties' these are the things that we
discuss, so everyone understand that there doing.   (If anyone want to host
a mapping party in Ottawa, i'm happy to be attending remotely via. cell
phone on speaker phone :-).

Cheers,
Sam

--
> James Treacy
> treacy at debian.org
>
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