[Talk-ca] Users in Ottawa and Geobase

[john whelan]

My objective at the moment is to get something sane that can be used
by various groups in the city with GPS devices to tag trees, heritage
buildings etc.  If you are saying that provided I can do a couple of
GPS traces down some of the city center roads then based on that we
can adjust the road system wholesale to more nearly agree with the GPS
as was done in Vancouver etc. then I'm more than happy.

It's been a long time since I took a look at GIS systems
professionally and I'm not familiar with what is the best approach.  I
would prefer not to put too much load on others knowing they are all
volunteers.

I have a background in programming but its been 30 years since I was
involved in teaching computer science at university level.

On mapping parties realistically this is better done in the spring /
summer / fall time frame when bicycles can be used, Ottawa gets a bit
chilly at this time of the year for organising something in the next
four months.

Cheerio John

2009/10/28 Sam Vekemans <acrosscanadatrails at gmail.com>:
> 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
>>
>> _______________________________________________
>> Talk-ca mailing list
>> Talk-ca at openstreetmap.org
>> http://lists.openstreetmap.org/listinfo/talk-ca
>
>