[Talk-ca] Import of large features in Canvec

Frank Steggink steggink at steggink.org
Tue Jan 26 00:08:36 GMT 2010


Hi Sam,

Thanks for your feedback. I agree with your suggestion to remove the ID. 
It is simply unmaintainable by us. I also saw that many of them were the 
same. This was already before my script started splitting large areas up.

The addition of canvec:sourceDate (valdate in the DB) is a good idea as 
well. Since it is an 8 char string, I'll leave it untouched. 
(Shp2osm.jar should strip any spaces though.) Note that the validation 
date of the wooded areas in the area I uploaded is "1982".

By the way, should the source reflect the current year (2010)? I don't 
think this is necessary, since the import was started in 2009, although 
not much progress has been made so far.

Cheers,

Frank

Sam Vekemans wrote:
> http://www.openstreetmap.org/browse/relation/393821
>
> attribution = Natural Resources Canada
> canvec:CODE = 1240022
> canvec:UUID = cad1acc2f7794480a0c17cadeef4d3b7
> natural = wood
> source = CanVec_Import_2009
> type = multipolygon
>
>
> That looks fine.  I would remove that canvec:UUID tag as since now it 
> is in the database it is free to edit, and to what we wish to.   But 
> that's just me.   BTW, in the USA Tiger data, the UUID was removed as 
> it has a 'power fit' where it was treated as more valuable than 
> regular users edits.   That part (power fit) is not acceptable with 
> OpenStreetMap.
>
> The canvec:sourceDate=* should be added (it available in the 
> datasource) since that tells the users how old the data is and gives 
> them a way to compare the data with their own datasets (ie. from 
> municipalities directly) or from physical observations.  Change on the 
> ground happens so fast that it's important to have it on all features.
>
> Its worth no note that this 'wooded_area' is simply just that, it has 
> no boundaries, it just states "at the time of surveying, this area has 
> trees, and the wholes (inner polygons) dont have trees".  
> This 'wooded area' is not a designated area, so it's neithor a 
> park/private land/protected area. 
> When you look at the yahoo imagery (and future imagery) you can easily 
> see what the currently status of the 'wooded_area' actually is.  But 
> on the ground, you'll see what it's like today.
>
> So in sum, when your out mapping, feel free to adjust the edges of 
> these polygons to accurately show where in fact the 'wooded_area' is 
> today.   And if you know what the designation of the area is. ie. 
> signs that say park area, you can add that in as an unfilled polygon 
> border.
>
> Great to see no edges, nice fix.
>
> Cheers,
> Sam
>
>
> On Sun, Jan 24, 2010 at 7:59 PM, Frank Steggink <steggink at steggink.org 
> <mailto:steggink at steggink.org>> wrote:
>
>     Hi all,
>
>     Today I have (finally) worked on large features in Canvec data
>     (forests,
>     water, etc.), and I have come up with a method how to deal with them.
>     This currently involves PostGIS, but maybe I'll use GEOS or another
>     method, so that it isn't necessary to load data in a DB. More details
>     will follow soon, since I need to clean up code / sort out things
>     a bit,
>     and eventually integrate it into the canvec_to_osm.py script.
>
>     Right now I've uploaded (only) wooded areas in the Charlevoix
>     region in
>     Quebec. This already makes the map look entirely different! The result
>     can be found here [1]. Changesets: [2] and [3].
>
>     You'll see faint horizontal and vertical lines crisscrossing the area.
>     This is an artifact of making the features smaller (0.1 x 0.05
>     degrees).
>     This will be dealt with with the "gamma" option which is part of
>     the new
>     Mapnik 0.7.0 release. This will probably be used in a couple of
>     weeks on
>     osm.org <http://osm.org>. See [4] for more info.
>
>     Cheers,
>
>     Frank
>
>     [1]
>     http://www.openstreetmap.org/?lat=47.625&lon=-70.25&zoom=11&layers=B000FTFT
>     <http://www.openstreetmap.org/?lat=47.625&lon=-70.25&zoom=11&layers=B000FTFT>
>     [2] http://www.openstreetmap.org/browse/changeset/3707953
>     [3] http://www.openstreetmap.org/browse/changeset/3708062
>     [4] http://trac.mapnik.org/wiki/PolygonSymbolizer
>
>
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>





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