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 sayselect
objects where key contains "haiyan" ?
Pierre
De : Markware Software Services <[email protected]>
À : Pierre Béland <[email protected]>
Cc : HOT Openstreetmap <[email protected]>; S Volk <[email protected]>
Envoyé le : Jeudi 22 janvier 2015 21h21
Objet : Re: [HOT] Damage evaluation tagging schema
Hi Pierre
Excellent Thoughts. Interestingly, I am working on a 3D rendering of buildings
project now, and was planning on extending this to HOT's work when done with
the commercial project.
Having everything in one tag "k=" as you propose helps the query and rendering
scenario a lot. The only downside from a database perspective would be if you
ever needed to query for data within the key data itself. This would be very
slow.
For Example: if someone wanted to display all Haiyan related data the query
would be something like WHERE k is Not Null and lower(k) LIKE "haiyan%" which
would trigger a sequential Pattern Match Scan. k would need to be indexed,
which would help somewhat.
One option would be to consider a couple of specific tags to help any searches
on columns that can be indexed, like
hot:damage=type of damage string (as per your proposal)hot:crisis=Haiyan
This would allow rapid extraction of all Haiyan related data using indexes with
a query like WHERE hot:damage is not null and lower(hot:crisis)="haiyan";
Also, consider adding "hot:" to the tag as this makes it very clear where the
data source is.
Just some thoughts for you to consider
Also, Do you have a summary of what tagging schemes were actually used during
Haiyan, I seem to recall building=damaged, or building=yes, damage=*
Regards
Mark Cupitt
"If we change the world, let it bear the mark of our intelligence"
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On Fri, Jan 23, 2015 at 9:33 AM, Pierre Béland <[email protected]> wrote:
>From the discusssion about mapping North of Nigeria, I open a distinct thread
>about the Damage evaluation discussion about the more technical aspects
>related to Damage evaluation and tagging schema.
This wiki page describes the schema used for the Haiyan
typhoon.http://wiki.openstreetmap.org/wiki/Damaged_buildings_crisis_mapping
As we discussed at the beginning of the Haiyan activation, while establishing a
temporary schema, this was be revised later to not affect tags such as building
or highway. Distinct tags should be added to reflect damages, road obstacles,
debris or any other damage related objects. Any modifications will also have to
be reflected in the humanitarian style to have the capacity to show damages on
the map as we did for Haiyan.
While the BaseMap is our priority, there might be some emergencies where we are
asked to collaborate to Damage evaluation. For each of these events, we have to
discuss among us and carefully evaluate if it is pertinent to do so.
Methodology is an other aspect. As it was discussed after Haiyan, there are
limits to what can be done with Imagery. We cannot have the same classification
/ hierarchy of damages from an aerial evaluation (often poor quality images in
the context of climate related disasters) and field evaluation.
While we might decide to not do these evaluations, it is important to establish
a good tagging schema and be ready for our next such action.
It dont think that this is a solution to have two attributes on the same key
like building="commercial; damaged". It would be more difficult to query and
this would breaks the rules for the map renderer styles.
There are also discussions about adding permanently tags to the database and
later not revising it. More then a year after Haiyan, there are still a lot of
damage related tags. I have started to analyze how to revise this. But not yet
processed.
There are various aspects to consider.
- Use a map style to render damages (like the Humanitarian style for Haiyan)-
Distinct methodology for aerial views or survey evaluations -> Specific role
+ limits of aerial views vs structure damages- Evaluation vs Revision (either
imagery or field survey)
The objects to evaluate can vary from one disaster to the other. From the
Haiyan experience, below I present proposals for tagging schema specific to an
event. In this example, in the context of the Haiyan typhoon damages. Tnis same
logic could be extended to objects affected by other type of disasters.
There are also various evaluation actions and status of actions that sometimes
need to be registered.- Type of action: aerial evaluation and revision, field
evaluation and revision- Status of the revision : cloud coverage limited the
evaluation.
The OSM key could be structured with various levels separated by semi-colons
(ie damage:evaluation:building:haiyan).
If both evaluation and revision key where present, the style renderer rules
could give a priority of revision over evaluation tags.
damage:evaluation:building:haiyan=no_damagewould supersede effect of
damage:revision:building:haiyan=collapsed
Level===========================
1 damage2. evaluation, revision
3. type, building, barrier, debris4. event (ie. haiyan)
key
value--------------------------------------------------------------------------------
damage:evaluation:type:haiyan imagery,
surveydamage:revision:type:haiyan imagery, survey
damage:evaluation:building:haiyan damaged, collapsed, no
damage:revision:building:haiyan damage, collapsed, no
Highway Barrier on nodes
damage:evaluation:barrier:haiyan debris, no
damage:revision:barrier:haiyan debris, no
Impassable highway sections
damage:evaluation:status:haiyan impassable, passable
Area Debris
damage:evaluation:landuse:haiyan brownfield, no
damage:revision:landuse:haiyan brownfield, no
Example
<tag k='building' v='yes' />
<tag k='damage:evaluation:type:haiyan' v='imagery' /> <tag
k='damage:evaluation:building:haiyan' v='damaged' />
<tag k='damage:revision:type:haiyan' v='imagery' /> <tag
k='damage:revision:building:haiyan' v='collapsed' />
<tag k='damage:revision:type:haiyan' v='survey' /> <tag
k='damage:revision:building:haiyan' v='collapsed' />
<tag k='highway' v='trunk' /> <tag k='damage:evaluation:haiyan' v='yes'
/> <tag k='damage:revision:haiyan' v='yes' /> <tag
k='damage:evaluation:barrier:haiyan' v='debris' />
<tag k='damage:evaluation:type' v='imagery' />
<tag k='damage:revision:debris:haiyan' v='no' />
<tag k='damage:revision:type' v='survey' />
<tag k=damage:haiyan' v='yes' />
Pierre
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