[HOT] Mapping Northern Nigeria ?

Rod Bera rod at goarem.org
Mon Jan 19 13:32:53 UTC 2015

Hi all,

The situation there will likely evolve. More destructions, more informal 
settlements from refugees, and (hopefully) ultimately rebuilding when 
things settle.

There might be an interest in keeping track of all these changes, and 
this can be done by looking at feature history or diffs on the OSM 
database between 2 dates.
Are there easy means of doing so? (overpass "newer" queries may be 
limited from that respect).

Aside from this, we can't be sure a change on-site is immediately 
followed by a change in the database (it can take time before we notice 
a house has been destroyed). Therefore a history tag could be added any 
time we have this information.

Third, with tags for damaged or destroyed buildings, I feel there should 
be a deeper thinking. there is a habit putting things this way, e.g. 
I am not convinced this is the best possible practice.

Whether the building used to be building=hospital or 
building=warehouse... is an information that remains important even when 
it is destroyed or damaged. But the aforementioned practice wipes this 
information out.

many people quickly search for buildings (building=*) with the idea they 
host people. But if no further attention is paid to those 
damaged/destroyed building (some may afford people in, some not), they 
might draw false conclusions (seek to bring relief to deserted 
areas...). We should at least communicate on the use of building=destroyed.

However, to address points 3.1 and 3.2 I would rather suggest we avoid 
construction/destruction state as values of tag building. This should 
rather come with a separate tag like e.g. "condition" (or 
state_of_repair, etc.). We could then make a difference between a 
[building=hospital; condition=destroyed] and a [building=warehouse; 

your opinion?

Best regards,


On 17/01/15 18:46, S Volk wrote:
> Thank you Michael, Blake, and Russell. I understand, wait for the 
> availability of images of DG in OSM for identification of devastated 
> buildings. Good to know that there was already this tag 
> "building=damaged/collapsed" (and sad), it renders very informatively 
> and solve it in just one tagging.
> Cheers, Sérgio.
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Rod Béra,  MCF Géomatique                /   Lecturer, Geomatics
            et SIG pour l'Environnement  /    and Environmental GIS
Agrocampus-Ouest|65 r.Saint-Brieuc|CS84215|35042 Rennes cedex|France
+33 (0) 223 48 5553 - roderic.bera at agrocampus-ouest.fr

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