[Talk-ca] ACQTECH vs. Valdate vs. OSM User imput for CanVec HD

[Calgary Trail Maps]

The current OSM data is from my maps, which are based on my tracks, other
than the ATV bridge which someone else added.  You can see them clearly in
Google Earth.  I'm working on cleaning this area up for my next release and
I'll clean it up a bit more.
 
John

  _____  

From: samvekemans at gmail.com [mailto:samvekemans at gmail.com] On Behalf Of Sam
Vekemans
Sent: March 12, 2009 10:35 AM
To: simon at mungewell.org
Cc: Calgary Area Trail Maps; Talk-CA OpenStreetMap; Jean-Sébastien; Dale
Atkin; Richard Degelder
Subject: Re: ACQTECH vs. Valdate vs. OSM User imput for CanVec HD


Hi Simon,

So for the canvec data, it was recorded back in 1979 when the earth was flat
.. lol :-)
it also says that the technique is "vector data" . ... it also says the
planimeteric accuracy is "19" that would be 'meters' ... so your statement
of '15 meters' off makes the canvec data also 'right' in it's own sence.
If your GPS had a better accuracy, then best guess is all you can do.

And John,
Thanks, would u be able to upload all your GPX tracks to OSM? 
If not, i can upload that for you, on your request.

Using JOSM, i just download all the local area GPS Traces, and i only see 1
track (Simon's)

And everyone,

Well, i "think" when it says "GPS" as the source, would be from a 'trimble
differencial unit" (but not sure) .. and so, when canvec says it's a "7
Field completion" then we could says it's as accurate as any mapper account.

And so, looking at the contour lines on the Cyclemap, it looks pritty good.

Anyway,
I fixed the script so it reads as a "river" thats because it's a
"Watercourse, non isolated" for the "Watercourse, isolated" thats when i
list it as a "stream" and for all the "other" and "unknown" I list it as a
"stream" so then they can be manually upgraded.
So for some of them that are labeled... like "York Creek" it's hard to say
what it is.

I could change it so that "Watercourse, non isolated" is listed as a
"stream" would that be better?

Thanks,
Sam

P.S.
I now need to go over the whole set again and fix up the wiki charts.
Hopefully in the next few days it will be better. ... but of course, im
always looking for errors.  anyway i published the rules.txt file and added
the 'date-time stamp' from notepad so you can see how old it is.
http://docs.google.com/Doc?id=d2d8mrd_179gnhs54cw




On Thu, Mar 12, 2009 at 8:29 AM, <simon at mungewell.org> wrote:


> Hi, i have an area, which i found interesting.
> The York Creek (river) ish..


Are you perhaps refering to this spot?
http://www.openstreetmap.org/?lat=49.58793
<http://www.openstreetmap.org/?lat=49.58793&lon=-114.5186&zoom=17&layers=B00
0FTF> &lon=-114.5186&zoom=17&layers=B000FTF
http://www.flickr.com/photos/24244464@N03/2777260804/in/set-7215760682069942
4/

Where I sat with my doggie, having lunch on a fine afternoon last summer.

Looking at the sources available to me (OSM, OSM-GPX, CatMP and Canvec),
it appears that the Canvec waterway (coded 1470171) is about 15m too far
west.

That said, consumer GPS is not going to be very accurate. Look how the
(only!) GPX track is very noisy here. The only real way is to get multiple
GPS tracks going through the area an visually average/discount them to get
an approximately true location.

One thing that we have on our side when looking at waterways, is that
water is lazy and will take the easy route. So if you look at this area
with a contour layer you might be able to confirm which of the waterways
is in the wrong place.

Cheers,
Simon.




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