[HOT] Damage evaluation tagging schema

Markware Software Services markwaresoftware at gmail.com
Fri Jan 23 04:02:43 UTC 2015


Hi Pierre, you should be asleep by now :) Hope the Snow is not too deep
either :)

I did not know about that the HOT Private Store. Is that rendered on the
OSm Layer or otherwise available? Would be interested in knowing a little
bit more about that.

Selecting objects in Sql is very dependent on the indexing. using + or <>
with an index is very efficient. Using Like "haiyan%" can be reasonably
fast if the data in the tag starts with the term you are searching for (eg:
"haiyan") (case conversion will have an impact depending on the size of the
string).

If your search term is in the middle of the key data, eg; "damaged: haiyan:
debris" it will be VERY slow as that will trigger a sequential scan

I have my own planetosm database, if the crisis is not a seperate tag, ie,
embedded within one tags data, I would set a trigger on the update that
extracted the crisis name, eg: haiyan, and stored it in an indexable
column. This is not particularly efficient, but I would have no choice as I
think it is very important to be able to extract data specific to a Crisis.

If you think about Overpass Queries, they would also not handle the data
embedded in the tag particularly well, I am sure they could do it, but it
would be subject to the same issue above.

One possible solution would be to use the Postgres HStore, which is
basically a text field. Postgres does have a unique ability to index data
withing the hstore, but I would not use this method on my production
database.

Osm does have these tags already defined, I am sure you are aware


   - building:condition
   <http://wiki.openstreetmap.org/wiki/Key:building:condition>=* *for the
   condition of the building*
   - ruins <http://wiki.openstreetmap.org/wiki/Key:ruins>=* - *for ruins of
   buildings*
   - abandoned <http://wiki.openstreetmap.org/wiki/Key:abandoned>=* - *for
   a building *


My thought would to NOT use these, as the fact that a building was tagged
as abandoned is relevant in assessing if you want to assess it in a
Humanitarian Crisis.






Regards

Mark Cupitt

"If we change the world, let it bear the mark of our intelligence"

See me on Open Street Map <https://www.openstreetmap.org/user/Mark_Cupitt>

See me on LinkedIn <http://ph.linkedin.com/in/markcupitt>



*See me on StackExchange <http://gis.stackexchange.com/users/17846/mark-c>*
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On Fri, Jan 23, 2015 at 11:41 AM, Pierre Béland <pierzenh at yahoo.fr> wrote:

> Mark
>
> About the prefix hot:, this is reserved for the HOT private store. Adding
> this prefix to objects in JOSM, the objects are saved in the HOT private
> store.
>
> Pierre
>
>   ------------------------------
>  *De :* Pierre Béland <pierzenh at yahoo.fr>
> *À :* Markware Software Services <markwaresoftware at gmail.com>
> *Cc :* HOT Openstreetmap <hot at openstreetmap.org>; S Volk <
> svolk2 at hotmail.com>
> *Envoyé le :* Jeudi 22 janvier 2015 22h30
> *Objet :* Re: [HOT] Damage evaluation tagging schema
>
> Hi Mark
>
> I agree, we have to consider also aspects like how easy to extract for an
> event. For Haiyan, we had a specific tag. But what, if it would have be
> necessary to add tags recently for Hagupit?
>
> About SQL queries, are-they any efficient way (time related) to say
> select objects where key contains "haiyan" ?
>
> Pierre
>
>
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