I'd like to get some comment on these faults at these coordinates: 5.14889 & 52.08576. The water (stream) is colored blue, okay. But without the entrance of the drain marked at the right spot ? Why is there a discrepancy between these items ? How is it possible to exist on the map ? Is any mapper allowed to correct it ?

I'm curious...

asked 26 May '12, 00:15

Hendrikklaas's gravatar image

accept rate: 6%

edited 27 May '12, 11:01

SimonPoole's gravatar image

SimonPoole ♦

Is http://www.openstreetmap.org/?lat=52.08576&lon=5.14889&zoom=18&layers=M the place you are asking about?

A lot of data around that point seem to origin from 3dShapes imports. http://wiki.openstreetmap.org/wiki/3dShapes

(26 May '12, 00:34) gnurk

From looking at the Bing imagery, way 71411667 does look like it's in the wrong place by 3-4m to me as well. The Bing imagery may not be correct, though - a couple of things to note about that:

  1. It's at the south end of the end of one lot of Bing imagery (notice how it gets fuzzy just to the south of there?)
  2. There aren't really GPS tracks around to say with confidence that the imagery is correct here. Individual GPS tracks can be inaccurate, but on average, in a flat relatively low-rise area like Utrecht they shouldn't all be offset. Some nice traces on Erasmuslaan would really help.

The next question, then, is "how did it get there"? That's something that you'd have to ask the people that imported the 3dshapes data. How accurate was it supposed to be? Have other discrepancies in it been found elsewhere?

The answer to the final question "Is any mapper allowed to correct it ?" is "yes" - but with a couple of caveats:

  1. You'll need another source (in addition to Bing) that there's a problem - currently 3dshapes says one thing, and Bing another. At the very least you ought to be able to measure (with an actual tape measure) the distance between the drain entrance and the corner of Erasmuslaan. If it's 4m Bing is correct; if it's 8m 3dshapes is.
  2. The way that the 3dshapes polygons interact with each other might make editing quite difficult. You'll also need to work out whether the 3 other polygons that it intersects are offset as well.
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answered 28 May '12, 16:08

SomeoneElse's gravatar image

SomeoneElse ♦
accept rate: 15%

Small variations like this are not uncommon and it is minor. Often they are simple to fix as long as you can check aerial alignments but in this case the water polygon shares nodes with some other polygons. You could contact the mapper who created it, by using the josm editor which will reveal mappers name when you click on a node so you can then contact him or her and ask them. Beginners can create and correct things (we all started somewhere) and the wiki will show you how, so gain some experience then if its not corrected by then do it yourself. If you try an edit and mess up exit without saving and no harm will be done. Good luck.

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answered 27 May '12, 15:42

andy%20mackey's gravatar image

andy mackey
accept rate: 4%


"the josm editor which will reveal mappers name when you click on a node"

In Potlatch 2 you can do this by selecting Advanced mode then clicking the way/node ID at the top. This will open a list of who made what changes to the object.

(28 May '12, 10:04) Richard ♦

Thanks Richard took me a little while to realise that I should click on the ID number to get details of the mapper and their edit note, which will be useful in future.

(28 May '12, 12:38) andy mackey

Messing up is just what I did in an other area. Its a forest with paths, located near 5.03500 and 52.04230. Correcting the borders gave me some trouble. I tried, but like it looks 3dshapes connect them all together and I cant get back the green areas in the right colour.

(28 Jun '12, 23:12) Hendrikklaas

If you mess up please do not save your edit, and please use the permalnk tool to point to the area you have trouble with. see this question: http://help.openstreetmap.org/questions/25/how-do-i-add-a-marker-to-a-map

(28 Jun '12, 23:56) andy mackey

@Hendrikklaas - if a node is part of several different ways (which is common with the 3dshapes import in the Netherlands), in Potlatch2 you can click on a node and then press "/" (on British keyboards) or "#" (on german keyboards) to cycle through the ways that it's part of.

At the position that you mention the issue might be with the grass multipolygon here, although it actually seems to render OK in standard view on OSM.org (and the tiles are up to date), so maybe it's just Potlatch it doesn't render in?

(29 Jun '12, 01:02) SomeoneElse ♦
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question asked: 26 May '12, 00:15

question was seen: 6,061 times

last updated: 29 Jun '12, 01:03

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