[Talk-ca] Fredericton WMS Offset

nicholas ingalls nicholas.ingalls at gmail.com
Tue Jan 8 19:34:29 GMT 2013


Hello!

Yes I'm going to be moving to fredericton for university in a short time so
I thought it would be nice to get building polygons so I can easily add
addresses from foot surveys. Is the data that SNB (You and your
co-workers) provide available for use with OSM? As in is it possible to
trace off the aerial imagery? I've often lamented the fact that the GeoNB
viewer has excellent aerial imagery for much of the province while bing
imagery is terrible outside major cities. If it is avaliable is it possible
to get it as a WMS layer for JOSM? I've looked into the ArcGIS rest APIs
but they don't seem very friendly with JOSM.

In reference to the orientation problems, I generally orient according to
gps tracks and I also use the road centre lines from the fredericton open
data portal to ensure areas are correct. (I know the data hasn't been
cleared to use, I simply use it to check the bing imagery)

Cheers,
ingalls


On Mon, Jan 7, 2013 at 3:32 PM, Connors, Bernie (SNB) <Bernie.Connors at snb.ca
> wrote:

> Atmospheric errors are likely to small to be detected by your consumer
> grade GPS.  Satellite geometry and the number of visible satellites would
> have more of an effect and this varies constantly as the satellites transit
> across the sky and as you experience varying satellite visibility as you
> move past obstructions (buildings, trees, bridges, hills, etc.****
>
> ** **
>
> Bernie.****
>
> --****
>
> Bernie Connors, P.Eng****
>
> bernie.connors at unb.ca****
>
> New Maryland, NB****
>
> ** **
>
> *From:* nicholas ingalls [mailto:nicholas.ingalls at gmail.com]
> *Sent:* Thursday, 2013-01-03 15:24
> *To:* Andrew Buck; talk-ca at openstreetmap.org
>
> *Subject:* Re: [Talk-ca] Fredericton WMS Offset****
>
> ** **
>
> Yeah I did a bit more research afterwards to double check, including going
> and getting gps more gps traces and the current (Bing) imagery appears to
> be dead on. I also checked it with some centre lines from another data
> source (Not importing just to check the imagery) and they also verified
> that the Bing imagery is correct.****
>
> ** **
>
> Thanks for the feedback! I hadn't thought about the atmospheric
> interference. ****
>
> ** **
>
> Cheers,****
>
> ingalls****
>
> ** **
>
> On Wed, Jan 2, 2013 at 3:59 PM, Andrew Buck <andrew.r.buck at gmail.com>
> wrote:****
>
> Hi,
>
> I am not from the area, but I did want to post my 2 cents about this
> issue.  Your idea of how the offset got started sounds correct.  I
> would caution you though that GPS traces can be offset, too, due to
> atmospheric effects.  To really get a good trace with no offset you
> need to do a few traces on different days of the same road (or path is
> better since it is narrow) and through an area with few buildings
> around as these can cause offsets, too.
>
> Other than those issues, if you trust your traces then I see no reason
> not to fix the offset, but as I said make sure your traces are good
> first.
>
> -AndrewBuck****
>
> ** **
>
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