[OSM-talk] Argh, Canvec imports

David Groom reviews at pacific-rim.net
Thu Nov 17 20:24:13 GMT 2011


> ----- Original Message ----- 
> From: "Frank Steggink" <steggink at steggink.org>
> To: <talk at openstreetmap.org>
> Sent: Thursday, November 17, 2011 7:03 PM
> Subject: Re: [OSM-talk] Argh, Canvec imports
>
>
>
> On 17-11-2011 18:13, David Groom wrote:
>>> ----- Original Message ----- From: "Michal Migurski" <mike at stamen.com>
>>> To: "Talk Openstreetmap" <talk at openstreetmap.org>
>>> Sent: Thursday, November 17, 2011 7:40 AM
>>> Subject: [OSM-talk] Argh, Canvec imports
>>>
>>>
>>>
>>> A cry of frustration:
>>>
>>> I do bimonthly runs of the worldwide coastlines
>>> (http://metro.teczno.com/#coastline), and Canada seems to be a recurring
>>> source of problems. What the heck is going on up there? I consistently 
>>> see
>>> new imports of what seems to be Canvec data screwing up coastlines and
>>> making for some deeply broken renders:
>>>
>>> http://mike.teczno.com/img/broken-coast.png
>>>
>>> Most of that junk in the Atlantic Ocean is newly introduced within the 
>>> last
>>> few weeks, and is making it difficult to get out a clean coastline 
>>> suitable
>>> for rendering. It shows up in the main OSM mapnik tiles in Hudson Bay, 
>>> too:
>>>
>>> http://www.openstreetmap.org/?lat=55.7&lon=-83.6&zoom=5&layers=M
>>>
>>> I've been trying to fix problems as I encounter them and I've managed to 
>>> fix
>>> invalid coastilnes around Baltimore, Houston, Tampa and the dreaded 
>>> Montréal
>>> area in an effort to generate a usable map of North America, but this 
>>> Canvec
>>> stuff is absolutely killing me.
>>>
>>> -mike.
>>
>> I know, this just looks so wrong to me:
>>
>> http://www.openstreetmap.org/browse/relation/1619985
>> http://www.openstreetmap.org/browse/relation/1613190
>> http://www.openstreetmap.org/browse/relation/1618562
>>
>> and although these relations are not in themselves creating problems, 
>> there's an error at 
>> http://www.openstreetmap.org/?lat=45.11737&lon=-66.52564&zoom=15 , which 
>> is difficult to fix without knowing how the ways making up these 
>> relations are eventually going to end up.
>>
>> Although over the last few months I've been going round trying to fix 
>> coastline errors in the rest of the world, I'm afraid that I've virtually 
>> given up trying to do anything in Canada
>>
>> David
>> _______________________________________________
>> talk mailing list
>> talk at openstreetmap.org
>> http://lists.openstreetmap.org/listinfo/talk
>>
>
> Hi David,
>
> Did you already contact that user?

Frank

I haven't contacted the user, because from reading 
http://wiki.openstreetmap.org/wiki/Canvec  I could not find enough 
information to tell him what he should be doing.

I will however now contact him and copy the information you have given 
below, and suggest he ask on talk-ca if he has any other problems

Regards

David

> This error is caused because the prepared Canvec OSM files also contain
> waterbodies (natural=water) for areas which are actually in the ocean.
> Someone importing Canvec is supposed to convert the boundaries to
> coastlines (except for the sheet boundaries), and replace them with the
> existing coastline, joining up at the sheet boundaries.
>
> Frank







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