This will bring in working with relations. This is quite an advanced topic. To properly solve it you would need to check the history of the multipolygon so see whether some other edits did break it.
You might restrict the challenge to relations in version 1 which are obviously not damaged by later edits. Also pay attention to not consider ones which had been created just (few hours) before the extraction date of the dump you are using, as it might be some unfinished work.
Relations with higher versions might be detected not because it should be a simple area, but because parts of the relations got damaged and should be restored.
I have no statistic on how many of these polygons are broken due to which case. You could try to get some statistics by looking at random 100 findings and deeply analyzing them.
Hello everyone, I’m Iko from Perkumpulan OpenStreetMap Indonesia (POI). I’m not open to new topics because there are already topics about MapRoulette here.
Currently, we’re under sub-contract for Meta (Facebook) to improve the data quality in OSM. We’ll be working in Thailand at MapRoulette with the theme “Line Crossing WaterBody” starting today and continuing for a few days. unfortunately, the challenge is not for the public, but this challenge was generated from this
To ensure we’re on the right track, sometimes we add discussion comments to learn more about the real situation.
please let us know if there is anything we should improve in the future
Can you maybe share a random sample of 20 reports of that challenge for review?
Most of the issues I saw had been because either the geometry was traces too rough or because people did not split ways to insert bridges or map tunnels.
How will you detect whether a specific violation is a bridge missing or a tunnel for the waterway missing? While for larger waterways you are frequently able to identify bridges from aerial imagery, this is not always possible for smaller ones.
Does this mean that every road crossing a waterway will be a bridge after your edit? This might lead to many cases where water is passed through a larger section of pipe under a road which would be a tunnel then incorrectly be tagged as bridge.
it’s around 1400 tasks in this challenge, but I realize there’re not only highway/building crossing with waterways. but also highways/buildings above water counted in this challenge. Therefore, we left some discussion just to make sure what the object looks like
to solve the warnings/errors in this theme we already have a guideline. in a short guideline like this:
left discussion comment if we need an explanation from previous mappers. For example such as giving or changing ford, changing road classification, changing road segments (because that’s all needed local knowledge)
but If there are Warnings/errors that can be solved only by looking at the imagery, we can change it. For example, there is a crossroad with a waterbody that has no bridge and is “clearly visible” in the imagery, cases like this can be changed immediately. However, if the imagery cannot provide the answers (Ex: the bridge is too narrow) we use Mapilary or Kartaview, if the Street view cannot provide answers too the last option we can do is we will use Fixme + description tag and left discussion comment
One small request from my side: could you please ensure that all changesets are kept as small as possible in terms of geographical area? Ideally, each changeset should cover only the local issue you are resolving.
Right now, some of your changes include multiple fixes across the country in one changeset and it makes it very difficult to visualize changes in OSM history and osmcha.org. e.g.
Thank you @cmoffroad for bringing this to my attention. I read your suggestion in a discussion comment about it as well, and as a follow-up, we agreed to split our work by country starting two weeks ago. Is it all right?
because dividing by city would be difficult for us because we were working on a random task at MapRoulette and didn’t know the specific city boundaries in Thailand
In the example below (changeset 130236908), you have 3 clear localized changes across the country spread by hundreds of kilometers (near Chiang Rai, Chiang Mai and Bangkok) There is no need to know the exact city or province boundaries, the distance separating the changes would be a sufficient factor here.
The entire bounding box of these 3 changes will be used in search results and history visualization, so someone watching changes in the middle of Thailand (e.g. Phitsanulok) will see your bounding box and will only understand your unrelated changes after loading and analyzing the specific changeset in osmcha, which is very unproductive.