I'm interested in identifying the most common mapping errors you stumble upon from other OSMers (or that you make yourself).

If we could list some of the most common mistakes then we could use that information to drive improvements that may help to prevent the same mistakes being made in the future (e.g. by clarifying the wiki documentation, modifying the editor UI, writing scripts to find the mistakes etc).

This is obviously a very subjective question, but hopefully some people may find the answers useful. Please try to stick to definite actual errors, rather than simple differences of opinion.

This question is marked "community wiki".

asked 06 Oct '10, 15:01

GrahamS's gravatar image

accept rate: 28%

123next »

Not identifying the different segments of a road properly

Often different segments of a given road are given different names. (Typically, the name of the road changes after a major junction or roundabout.)

But often the mapper does not break the road into segments, or provide the correct names to these segments.

This is a common mistake of a mapper who is tracing an uncharted area just using the Bing satellite image, but without much local knowledge.

permanent link

answered 13 Mar '15, 07:29

NarayanAras's gravatar image

accept rate: 0%

To draw a building shape, the mapper traces its terrace, but does not move it to its base

This "parallax error" is an extremely common mistake in drawing shapes for highrises.

The mapper uses the Bing satellite image, and traces out the top of the building.

But he forgets that the satellite image is not exactly "top-down", about 15 degrees angle to the vertical. Thus the base of the building does not lie exactly under its top. In fact, the taller the building, the more this offset!

On the other hand, all map features having low heights are traced without such parallax errors. For example, roads, boundary walls, low-rise buildings.

As a result, many tall buildings appear to be shifted from their actual positions. Some even touch (or "crash into"!) the adjoining areas.

permanent link

answered 13 Mar '15, 07:20

NarayanAras's gravatar image

accept rate: 0%

Confusion between "Common Name" and "Operator" of a POI

For example, take a Citibank ATM.

  1. Is "Citibank" a 'common name' or 'operator'?
  2. Should "ATM" be a part of the Common name?

Another example: A Dominos pizza joint. Legally, "Dominos" is the brand, operated by a local franchisee (a separate business entity). So how to fill these attributes?

As a result, I have seen inconsistent entries in POIs.

Suggested solution: The mapping tools (iD/Potlatch) should have more explicit tooltips.

permanent link

answered 13 Mar '15, 07:03

NarayanAras's gravatar image

accept rate: 0%

Some of the varied mistakes I've seen that I remember:

  • Stuffing ad copy in places where it isn't appropriate: note=* tag, changeset comments, or notes. I have nothing against marketing/PR/SEO people (in fact I've been one for a while) but there's a time and a place for everything.
  • Taking over a road segment or other object to add a business listing. As bad as ad copy may be, this is much worse and much harder to clean up.
  • Vandalism of the road layout, such as dragging a bunch of points together that clearly don't belong.
  • Putting any old garbage in opening_hours=*.
  • Putting incorrectly formatted phone numbers (not international format) in phone=*.
  • Abbreviating street names, whether mapping the actual road or in an address.
  • Various other address bloopers, like trying to stuff the whole street address in addr:housenumber=*.

Of course, I'm sure I'll see some completely new, weird, and not-so-wonderful mistake right after adding this.

permanent link

answered 15 Dec '14, 07:00

skquinn's gravatar image

accept rate: 0%

In Africa highway mapping, track only goes to farmland.

So ruled in Highway_Tag_Africa.

"The road conditions in African countries do not always correspond to their economic and social role. A road typology should be based on the road importance and not on the surface or the visual appearance of a road."

This means, it may look like a track but, if it goes from a major road to a hamlet, it's an unclassified highway, except a 4x4 can't drive it because it wiggles too much (then it's a path). Ditto from hamlet to hamlet.

People new to Africa mapping always get this wrong.

permanent link

answered 13 Dec '14, 14:51

rwst's gravatar image

accept rate: 0%

That's not so different from other countries. The highway tag should be used to tag the road classification, not the road's look.

(13 Dec '14, 17:13) scai ♦

Sometimes users forget to mark that location which is most important for the people during travel like signs of hospitals, fire brigade and shopping complex. Hope you can understand the fact behind mapping.

permanent link

answered 08 Jul '14, 06:37

denygarcia's gravatar image

accept rate: 0%

edited 08 Jul '14, 10:42

SomeoneElse's gravatar image

SomeoneElse ♦

I would not classify this as mistake, people are not obliged to map. Contributing something that you consider not the most important thing is NOT a mistake.

(16 Jul '14, 23:41) Mateusz Koni...

Deleting nodes whose tag's don't show up in Potlatch 2. I have seen situation where new users will "clean up" nodes whose tags are "Not recognised".

Hopefully this will be going away with the greater prominence of iD.

permanent link

answered 06 Jul '14, 13:58

InsertUser's gravatar image

accept rate: 23%

Using search-and-replace to do small 'mass edits'

New users tend to use the search-and-replace function of editors to do 'corrections' to a massive amount of nodes or ways in their area when they believe they found an 'error' of some kind.

Not mentioning here if the 'error' really is one or not (new users might have trouble understanding all the tagging schemes used in OSM), the mere application of such changes in an automated manner often destroys more valuable data than it fixes. This is also regularly used to fill in perceived "blanks", even if those blanks are left intentionally or are coverde by some kind of default.

Examples are

  • attaching addr:postcode or addr:city to all buildings in a region (overwriting manually set fringe cases where postal address doesn't match real location)
  • adding oneway=no to all highways which don't have oneway=yes
  • standardizing names of shops/food chains, even if there really are some that carry another name on their sign

This is often combined with the "leave no changeset comment" problem already mentioned.

permanent link

answered 19 Aug '13, 16:02

Chaos99's gravatar image

accept rate: 14%


Copying from non-free sources like Google Maps

This is a huge no-no. Because OpenStreetMap is an open-source project, it can only use data that are published as open-source. This means that OpenStreetMap can use:

Your own data

  • from GPS traces
  • from seeing places in real life
  • etc.

Data from freely available sources

  • certain local governments (always check)
  • other open-source projects
  • tracing freely available satellite imagery (Bing Maps is ok, Google Maps is not)
  • etc.

These data have licenses on their copyright that let anyone use and distribute it freely (sometimes with restrictions, for example, that any project that uses the data must also be open-source). Other data may have stricter licenses on their copyright that disallow anyone from using it, or force you to pay. Some may have licenses that allow free use, but not free redistribution, which is unusable for open-source projects like OpenStreetMap because we are redistributing the data. Freely available or open-source means that the data must be freely redistributable.

permanent link

answered 11 Aug '13, 22:40

Clorox's gravatar image

accept rate: 0%

edited 11 Aug '13, 22:44

Forgetting to add any tags to newly created nodes and ways !

I think this is a result of a combination of users mistakingly believing that they had deleted the untagged way or node, they didn't know at all that they created the node or way, a

permanent link

answered 10 Jan '13, 15:42

skorasaurus's gravatar image

accept rate: 12%

iD unfortunately makes it way too easy to do this. Potlatch 2 also lets you commit an untagged way without any sort of warning (in fact when I was still switching from iD to Potlatch 2 just to add parallel ways, and then switching back to do the rest of a dualize, I took advantage of this). JOSM will at least warn you, but how many newbie editors use JOSM?

(15 Dec '14, 07:02) skquinn
Your answer
toggle preview

Follow this question

By Email:

Once you sign in you will be able to subscribe for any updates here



Answers and Comments

Markdown Basics

  • *italic* or _italic_
  • **bold** or __bold__
  • link:[text](http://url.com/ "title")
  • image?![alt text](/path/img.jpg "title")
  • numbered list: 1. Foo 2. Bar
  • to add a line break simply add two spaces to where you would like the new line to be.
  • basic HTML tags are also supported

Question tags:


question asked: 06 Oct '10, 15:01

question was seen: 34,874 times

last updated: 13 Mar '15, 07:29

powered by OSQA