There are several damage subject pages in the wiki. I’ve been thinking about trying to bring all the information together on one page. Possibly an uphill task as some people view current, but changing information and/or recent history is not suitable for OSM. Yet it’s possible for a building to be slightly damaged by one event, then destroyed by a second. Some of the Jamaica images shows what looks like older damage or ruins. Hard to tell, made harder if not immediately recorded AND kept. If an ex railway line can be mapped, why not a damaged building and its status.
Also we should not make any assumptions about the use of damaged buildings. People do still live in damaged buildings. Just because a floor is visibly destroyed, people can live on lower floors and that can only be seen in ground imagery or survey.
I sometimes get the impression from some mappers that humanitarian information should not be in OSM, yet all mapping is basically humanitarian. Even if the subject is how cycle route relations should be mapped.
Mapping damage is totally fine - you see a building in disrepair, you can map exactly what is broken, no problem with that. No problem with mapping any humanitarian information that can be verified on the ground (exception: privacy - don’t map how many people of which age and gender live in a building. We’ve had that…) But don’t map the event that broke the building because you cannot see that (as you say yourself, the damage may accumulate over multiple events). If you want to map historic information, then OpenHistoricalMap is a place for that, not OpenStreetMap. If you want to be able to query “what damage exactly has been caused by event X”, then OpenStreetMap is not the tool to do that with.
I am a fervent opponent of mapping “ex railway lines” because they violate an important principle of OSM - mapping what you can see with your own eyes, or at least survey on the ground. It pains me to see that the violations that occur in that department are now spreading - already you are saying that “if we can map that, then why not this”. This is the wrong way round; if elsewhere in OSM things are done that violate our rules then those things must be stopped, contained, and removed - and we should not use them as a reason to violate rules in other places too.
Ah. Doing things right rather than doing the right thing.
I fully support the deletion of buildings that have been demolished, rubble removed and possibly replaced by a new buildings. Where the deleted feature should then be replicated I don’t know. OHM may be appropriate, maybe a environment in the humanitarian sphere. I suspect either should have an unchanged unique ID to be sure it represents the source object. Location may not be enough. The large numbers of redundancies in the humanitarian organisations currently occurring lead me to think that funding for an OpenHumanitarianMap system is unlikely. Probably a shame as I’d prefer to help people (Doing the right thing) rather than delete tags that don’t meet the needs of mappers who don’t agree that the use of such tags meets a particular guideline (Doing things right). Do some mappers really need to act a some kind of Wiki police, deleting anything that does not meet their interpretation of one wiki page over another?
If the building still exists in some physical form, then that object should remain in OSM. AND YES, personal information should not be recorded. Anywhere in the OSM database.
I don’t support ex railways in OSM, I just mentioned them because some mappers DO support them. Is there 100% agreement of any subject in OSM? I use maps for navigation, frequently printed. I don’t want to have plan to avoid a railway that doesn’t exist. Or have analysis affected by it. However, does the record of damage to an existing building actually do harm to a mapper? A mapper might not like it, but harm? Please don’t forget that such mapping also tends to add to or update the AOI. Mapping in OSM that might not otherwise happen. So it improves the map and helps people. Is that really a bad thing?
I wouldn’t want to play the ATYL joker card. I think that could lead to chaos, but the relatively short term tagging of the event or events causing damage based on a systematic convention does no huge harm to OSM. It might even add some further kudos to OSM. I hope so.
Mapping the shape of buildings makes only sense if that gets maintained after those buildings gets removed or repaired. Otherwise OSM is quite useless in the next event in the same area.
I agree to some extent. Shape, structure, materials, how drunk the builders were when mixing concrete. All may matter, we may never know how much each subject matters. But we should not mean we should not try.
An additional thought. OSM gets a small benefit from the immediate post disaster imagery that is sometimes available. No point in relying on sometimes very old standard imagery set commonly used.
To add to Adrian’s argument that tracking the event with the damage is useful:
If you have an event name e.g. ‘Melissa’ – afterwards it allows you to track back to the imagery available at the time to ‘see’ the damage in that moment, either through for exmaple OpenAerialMap or through Esri’s Wayback imagery
For sure tracking that somehow might be useful. But just not useful for OSM, which has no interest in historical data. If it’s damaged it’s damaged and if it’s repaired again then it’s a normal building again.
We heard from @SeverinGeo that architects from Mayotte shared that cracks from previous cyclone events can stay in buildings for a long, long time even after repairs have been carried out.
Maybe I don’t get your point here, but for OSM it’s only interesting if there are cracks/damage/… now and please understand, that a mapper might change this, once he can’t see any crack/damage/… (like after the repair)0.
I understand, that those information are some how important for you, but OSM is not the right place to maintain them.
So if there are cracks,… feel free to add that information to OSM. But please maintain the history and reason (earth quake, hit by truck, mining activities, … ) for the cracks elsewhere.
Is an approximate equivalent to this the widely used ‘start date’ and ‘opening date’ keys? Isn’t there some alignment here in the reasoning that it can be important to attach some time based information to the objects being mapped or updated?
IMO they are not equivalent. As the opening_date data disapears when the object that carries it is deleted. Those tags are to help mappers, that some feature is in construction and is used only in the context of landuse|highway|building=construction.
As some former existing features was changed to disused:shop=* previous to deleting the element, just to tell a mapped that comes after you that the object is no longer there, and maybe the aerial imagery, mapillary o r other source of data is outdated.
I don’t think the data supports that for start_date. There are more than 16 million buildings with this tag, and the range of dates (with significant volumes in each year from the 1970s onwards) shows that most of this is not related to current construction. I think a lot of the usage comes from imports of official housing data.
Even the image in the wiki shows a start date of 1903!
Kind of. start_date and opening_date are singular events. Like the current shop was opened 2 years ago. There will be no opening_date in the data from the 5 shops occupying the building beforehand.
That’s what I’m trying to express. You can map that there is damage. You can map a date, when the damage occurred. But both would get removed after the repair. If there was no repair before the next damaging event, damage:start_date would be still the date of the first damage.
That level of detail would be according to our guidelines.
