[OSM-talk] Argh, Canvec imports

[Frank Steggink]

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
>
>
>
>
>
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>

Hi David,

Did you already contact that user?
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