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I found and corrected some double mapped buildings and Im curious if someone is able to explain this feature. Is the license change responsible for it ? There also a lot of ditches / streams not connected. Is the area beiing worked ?

asked 28 Jul '12, 23:19

Hendrikklaas's gravatar image

accept rate: 5%


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(29 Jul '12, 09:00) andy mackey
(30 Jul '12, 19:42) andy mackey

Hi OSmers, Thanks for the update Ill correct it (little bits) if possible. And I was curious about the source of it. Im not in for landscapes but came up against it here and there and even stumbled over a wooded area (5.03741-52.04155) since I couldnt get it right in the original manner. Whats the different between Potlach and JOSM ?

(03 Aug '12, 20:25) Hendrikklaas

Older building outlines in the Netherlands are mostly traced from relative inaccurate Yahoo imagery. (Which was the best data available at the time.) Next came the 3dShapes building import. This had more and more accurate building data. In most places the duplicate buildings resulting from this import were "fixed" relative soon after the import. In some places (mostly) were there are less mappers, they still remain. When editing OSM and using the Bing aerial imaging background, it fairly easy to see which outline is best. You can simply delete the other one.

"inconsistent topology" is from the 3dShapes landuse import. The source data came to OSM in tiles. Sometimes objects on tile boundaries didn't match what was on the other side. Then the objects got this tag. It's a kind of "FIXME" tag that simply means that a mapper has to go there sometime to look what's really there.

The ditches not matching with the landuse boundaries is again a historical artifact. The ditches were traced from Yahoo imagery before the landuse was imported from a more accurate source (3dShapes).

The double bus stop is simply an error by me. Two (other) people have imported bus stop data in The Netherlands in the past. The license status of those had been unclear for some time. (Now after the redactionbot everything is clear of course.) So when encountering bus stops during my hikes, I made pictures of them and "remapped" them. In this case I simply forgot to delete one of the imported nodes.

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answered 03 Aug '12, 18:13

cartinus's gravatar image

accept rate: 27%

A quick scan finds two duplicate bus stops, here and here. The more recent of the two is from 2011, so not redaction related (and the changeset comment of the more recent one suggests it's normal mapping, not an import).

Perhaps you could post a link to some specific duplicate buildings and to some non-connected waterways?

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answered 30 Jul '12, 15:40

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SomeoneElse ♦
accept rate: 16%


Hi SomeoneElse, The coordinate of another building with a double roof is 5.07570 / 52.29201. The outlining of the surrounding fields is a little bit rough, not accurate ? At 5.17143 / 52.09423 is a inconsistent topology. Is there an explanation for or is it computerized ? I dont dare to teckle it, since I expect it to be complex and I once started to ad footpaths in a wooded area, 5.03713*52.04209 and youre still be able to see what I did. Some fields are light- and some are dark green and Im not able to correct it. It looks okay, but I know better, help !

(30 Jul '12, 16:46) Hendrikklaas

Re the double building, this one was added in 2009, and this duplicate one was imported by 3dShapes in 2010. The wiki page for that user says that they're contactable, so I'd do that (there's probably been discussion in the Dutch community about how to resolve duplicates).

Re the "inconsistent topology" that just looks like the 3dShapes data doesn't match the Bing imagery and is incomplete. I don't know how up-to-date the Bing imagery is there. According to this forum topic the 3dShapes data is from 2008 and the standard approach is to adjust it where it's wrong, but I'd definitely ask in the NL forum to get several local opinions.

That area does (post 3dShapes import) look fairly horrible to edit. This relation is a multipolygon with one outer and many inners, including some adjacent to each other. It looks OK in the standard Mapnik rendering, but it looks like it's not getting rendered as "landuse=grass" in Potlatch 2. Basically, don't worry what colour things appear in the editor (or on the standard Mapnik map for that matter) - try and make sure that it's an accurate representation of what's on the ground.

One tip that might be useful to know when editing nodes that form part of multiple ways - if you press "/" when a node is selected you can cycle through all the ways that a node is part of. See this page for details (Nederlands).

(30 Jul '12, 18:13) SomeoneElse ♦
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question asked: 28 Jul '12, 23:19

question was seen: 3,278 times

last updated: 04 Aug '12, 11:45

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