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Hi everyone.

I've done some reverse geolocation tests on osm boundary data. But at a closer look up I realized that there are some problems near boundaries that follow rivers. Because of lack of way details some city parts are choped off, so when you try to geolocate coordinates on that parts of the city you end up in another county or country.

Here is an example: alt text

I also encountered some strange boundary lines that doesn't seem logical to me: alt text

So I decided to rectify this ways best as I can. I would be gratefull if you could check the chanegeset sometimes and verify the correctness of the data.Any feedback is welcome.

Here is the link of the changeset: link text


I'd like to clarify what i'm doing. For example i found this scanned historical maps of Chilton County ,Alabama.As you can see the boundary clearly follows the river. alt text

In OSM it doesn't(gray line).The purple one is the modified version i've already uploaded. alt text

Now my question is that its ok to do this kind of changes? Thanks.

asked 19 Apr '14, 11:30

vitus's gravatar image

accept rate: 0%

edited 19 Apr '14, 14:12

Please don't change boundaries because they just don't "seem logical" to you. Boundaries aren't always logical. In OSM they should match the real boundaries.

Contact the local community and try to get a source for these boundaries that is compatible with OSM's license.

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answered 19 Apr '14, 11:57

scai's gravatar image

scai ♦
accept rate: 23%

edited 19 Apr '14, 12:03

I agree with you.I forgot to mention that before any change a try to verify myself from other sources(e.g. older scanned maps, of course compatible with OSM's licence).You're right boundaries aren't always logical,but in OSM often they doesn't match real boundaries.I will update my question with a specific example of what i'm doing.If you could take a look and tell me if its right or should I stop doing this and revert the changeset.Thanks

(19 Apr '14, 13:55) vitus

If you think you can improve OSM's data then just go ahead. I'm not quite sure what I should look for, because I don't know the real boundaries.

(19 Apr '14, 15:48) scai ♦

I also wouldn't move boundaries on this basis, the second image for example is very likely to reflect a river that changed his course, while the boundaries remained the same; could be the same for the last images you posted (how old is that map?), I wouldn't change it if not 100% sure, there's a number of cases in the US as far as I know, see: Additionally, look at objects history, someone may have moved or deleted inadvertently a piece of boundary.

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answered 19 Apr '14, 16:09

Alecs01's gravatar image

accept rate: 25%

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question asked: 19 Apr '14, 11:30

question was seen: 4,700 times

last updated: 19 Apr '14, 16:09

NOTICE: is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum