Norway - Fix Spiky Buildings

Hi OSM Norway Community,

I’m excited to announce a new MapRoulette challenge: Norway - Fix Spiky Buildings (MapRoulette)! We’ve identified buildings on OpenStreetMap (OSM) with oddly sharp angles. Most building corners are close to 90 degrees, but this challenge focuses on buildings where angles are less than 15 degrees. While some might be real, many are likely incorrect data.

The Task:
Improve OSM data quality by reviewing the identified buildings and see if their shapes need correction.

Important Considerations:

  • Some buildings, especially historical ones, may have unique angles.
  • If unsure, consult the community forum for guidance.

Why Fix Spiky Buildings?
Accurate building shapes on OSM benefit everyone! They improve:

  • Data quality for various applications
  • Navigation services
  • Urban planning
  • Emergency response

Have Questions?
Feel free to reply to this message for help, modifying instructions, or suggestions on resources.
Thanks for your contributions!


Why is this building considered spiky?

Good catch @hansfn. you can skip it as it may be a false positive or already solved before.

Probably you can zoom in, here is the issue @hansfn

The “View OSM” button (and even the OSM History tab) on your site appears to go to some other place than the one shown.

E.g., give these a try:

  • Task 224388999 (the one posted above by hansfn) – “View OSM” leads to a place in France.
  • Task 224388641 – “View OSM” leads to a place in US.
  • Task 224388624 – “View OSM” leads to a place in Italy.

Thank you @anderfo. let me check what is going on there. do you mind sharing a screenshot of your findings?

Yes, I can zoom :grin: However, I thought the needle was used for indication of the location of the spike:


1 Like

Good point @hansfn . I will add to the description that the lead takes you to the building and not necessarily yo the spiky node

For the node/building posted by hansfn, it shows this:

The View OSM button takes me to this node in France: Node History: 940266375 | OpenStreetMap

1 Like

It’s mixed node and polygon / way ID :slight_smile:

1 Like

Good catch @anderfo! we will double check it and come back the soonest on this matter

Hi there OSM community in Norway and in particular @anderfo and @hansfn (as you already showed interest in this MapRoulette challenge.

We in TomTom just wanted to follow up with you on this challenge as we noticed that only about 13% of the cases is solved and we have some concern about the challenge. Is there anything else needed from our side to make that would help to make this challenge more approachable/attractive? Do you have any comments or concerns? We are as always listening :slight_smile:

The biggest problem was that many (most) of the issue I tried to fix, required zooming in (really close) on each node in the building to find the extra node that was causing the spike. It was just slow / cumbersome.

1 Like

With JOSM, I would say that the solution (assuming the building looks like it should have no non-90-degree angles) would be the following operation

  1. Orthogonalize (Q)
  2. Simplify way (CTRL+Y)

This should clear away all issues.

If the building has and should have non-90-degree angles, then only select the parts of the building (nodes) with 90-degree angles.

1 Like

Using Orthogonalize (Q) in iD didn’t work, maybe because the nodes was so close, and I didn’t find a simplify way in iD.