Damage caused by MapRoulette (nodes to areas)

I noticed again that nodes are converted to areas based on a link from MapRoulette.

Such ‘automated’ edits are harmful to the map. I have seen for example a playground as node next to the path which is now an area over the path. This playground is not visible from the sky.

Is there any feedback to MapRoulette to acknowledge which challenges are helpful and which not?

The challenge is given without ANY consideration or hint that automated edits are not encouraged and perhaps harmful.

Could you share the location where you suspect damage in the map data? That would help us all to better assess the situation.

From my humble point of view, MapRoulette is not an “Automated Edit” but merely a task manager for structured processing of many tasks. This happens, at least in my use, always manually.

You can always contact the challenge creator and share your concerns. I have created challenges myself and was happy to get feedback if I could have made the overpass query even stricter.

For your example, here is a task of parking spaces that I think can be converted to an area without any problems:

MapRoulette Task
OSM Location
JOSM Preview:


The problem is not whether this or that POI should be a node or an area but the way in which the challenge is presented.

Edit: I misread your comment. I have already contacted the editor but I wouldn’t know how I can contact the creator of the challenge.

Maproulette gives the false illusion that there is something wrong with nodes. It should make clear that a node should only be replaced if the user can know that a POI would be better presentated as an area AND that there is sufficient information to draw the outline.

In the wiki it is emphasised on all pages that blindly editing is strongly discouraged. It would be helpful if MR would do something similar.


If logged in to MapRoulette, I see a “Get In Touch” link on the challenge, opening up a chat box.
Also, the project is listed as " World Binnette’s Project", thus most probably from Binnette , making it easy to contact the creator of the challenge…

+1 (not checked is MR wrong here)

MR may be wrong here, but I would not describe them as “automated”. Such edits may be bad, may be caused by MR, may need to be mass reverted: but by all indicators so far are done manually by humans.

EDIT: And human in this case is not used as mechanism like with “blindly change tag X into tag Y” challenges

If the human is just being used as a “mechanical turk” (i.e. the instructions just say something like “change tag x to tag y”), then they are in essence mechanical.

In this case the request is to do some tracing from aerial imagery, so it isn’t a mechanical edit. Perhaps the instructions should be more detailed and give more guidance about “don’t map it if it isn’t obvious from imagery”.

Where there are problems I’d suggest polite feedback to both the Maproulette challenge author and the person making the change, with the caveat that the person making the change might be new to OSM and might need some concepts explaining.


Hi @Binnette, I would like to draw your attention to this topic, as it concerns one of your MapRoulette Challenges. Maybe you can adjust the challenge description? Thanks a lot!


I agree, but in this case I hope that instructions do not have “draw circle with diameter of 25 meters if aerial fails to show playground shape” or something similar

The first thing that I checked was whether this is a new or experienced mapper, and the mapper is not new to OSM (>>1k).

Secondly, I was careful enough to write “automated” between single brackets.

I hope that this answers some questions.

Thirdly, do I understand correctly that mcliquid has notified BInnette, the initiator of the MR challenge? I don’t have an account there and I would greatly welcome this.

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They’ve done that via this platform. I just tested than with a secondary account of mine, and that did not result in an actual email notification. They may notice it if they happen to sign in to the forum, or it might be mailed out as some sort of digest later, of course.

Maproulette names are the same as OSM names, so you can just send an OSM private message to them.

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Maproulette gives the false illusion that there is something wrong with nodes. It should make clear that a node should only be replaced if the user can know that a POI would be better presentated as an area AND that there is sufficient information to draw the outline.

for surface and multilevel parkings at least, it is very likely that they are better represented with an area. Feel free to post examples that show exceptions where a node is preferable.

They are better represented with the CORRECT area, yes. If the correct area is not known (perhaps the mapper has never been to that location and it isn’t clear from imagery) then a node is preferable.

Also with some laybys, where there isn’t a well defined area, a node is best.


Hello guys, sorry for the late answer. Let me know how I should improve my “node to area” challenges.

Maybe I can be more “restrictive” on the instructions?


  • If the node is included inside an area with the same tags, consider merging the node in the area.
  • If there is no area and you can clearly see it on the aerial/satellite imagery, then draw a new area.
  • Merge the node with the new area to prevent deleting the node and avoid losing some tags from the node.


  • Do not draw an area if you can not see it on aerial/satellite imagery.
  • Do not delete current node, prefer to merge it with the new area to keep its history.
  • Do not change the map if you have any doubts, instead skip the task.

Any suggestions are welcome.

How about “actually visit the location” :grinning:

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Better late than never. Thanks for your response.

To start with, I agree with SomeoneElse. Actually these are mechanical edits without local data or survey.

Secondly, I wonder whether such changes do any good to the map. The play ground that I noted somewhere earlier in the discussion (IIRC) that was drawn as an area over the cycle way was a good example of the kind of edits that such challenges attract. But even more important is that there is no play ground at that spot.

At an other spot a play ground was already mapped as an area but this is a bit problematic. The area is now drawn as a grass field (more or less over the play ground area) but there are also parts with trees that should still be added to the map. Should the play ground include those trees? The play ground itself is just a collection of playing equipment at the centre of the lawn without any border of segregation. I will probably change this to a node when I’m finished with the landscape.

Thirdly, I am afraid that many people read your challenge as “We are porting play grounds from nodes to areas. Please help.” I will not insinuate in any way that your challenge contains any suggestion like that. People are just looking for directives. I conclude this from the kind of edits that I encounter. I haven’t seen the challenge so I can’t provide you with a good answer to the related questions.

And, finally, in a broader sense, I do wonder whether these mappers will ever become good at mapping. OSM is not only a place where people can develop a map, it also gives them the opportunity to develop themselves and learn more about the real world. I see too often that people are just moving data from one web source to another. This will not help them in any way.


Ok. So maybe I should disable the “node to areas” challenges that target ‘tiny features’ that are not clearly visible from aerial/satellite imagery. For example disabling the “playground” one sounds to be a good idea. But I will probably keep the “big features ones” like soccer pitch, etc. And I will try to rewrite the instructions and probably set the challenge to “expert” level to avoid “beginners” to make mistakes on the map.

Please let me know if there is more “solutions” I can apply. Have a nice day.


MapRoulette initial instructions are not yet mentioning that cases without good aerial should be ignored and skipped/marked as too hard.

That will keep most MapRoulette users away from here as the Dutch map is very detailed.

But what I don’t get is the following: why would someone go to MapRoulette and use aerial imagery if it is also possible to walk outside and see it for yourself. My biggest problem during mapping is that I don’t have the map with me. I would guess that people who own and use mobile phones would be the first to go outside and map in real-time. It would be a very strong combination.

Speaking as someone who maps almost exclusively from their phone, I mostly agree. Though sometimes I simply don’t have the time to map something in detail, so I’ll drop a node instead of tracing the area. I may or may not remember to go back and improve this later on, so an armchair mapper filling in the detail would be useful here.

Unsure how common this scenario is though - perhaps rather rare!

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