[OSM-talk] Historical Data in OSM database

[Peter Wendorff]

Am 09.11.2010 13:46, schrieb Lester Caine:
>
> As I have already said, simply adding a starT_date to a way is all 
> that is needed for probably 99% of historic mapping ....
>
If it would be as simple....
I fear, it is not.

Historic data is often targeted to single properties of an entity: A 
track being paved at a certain point in time, a mid-age hollow way 
changing to a asphalt highway with four lanes - or vice versa to simple 
grassland with a line shaped lower part, a church abandoned at war and 
rebuild later (e.g. Frauenkirche, Dresden, often jewish synagogues 
especially in Germany burned down by the Nazis, too few of them rebuild 
- like the one in Berlin Oranienburger Straße[1]).
Big churches are often build over a time of several hundred years, 
changing shape and importance, even name - not to mention denomination 
or more than that religion) - think about Notre Dame in Paris [2] with a 
build time of nearly 200 years.

That in mind as examples - far from complete - neither start_date nor 
start_date and end_date are enough to describe historical data in a good 
way to be useful.

It's much more work to build timelined values to OSM and the API in a 
useful manner.

A few thoughts about problems arising with that task:
- even more than locational data ancient geodata is unsharp in the 
timeslot. Often a way is "mentioned first at year X", but not as a 
rebuild way - more as current fact. Location descriptions are similar - 
mapping an old map to our standardized coordinate system is very 
difficult - the reason, why archaeological research often searches at 
wrong places with a ancient map availlable.
- how to describe something like "way build between 700 and 1000, in use 
(not disused, to use OSM terms) at least until 1435"
- second example: "ford over some years in midage, disused for some 100 
years in between, reanimated due to the rise of City X (between 1700 and 
1850), wooden bridge build in the 1760s, stone bridge since 5th July 
1822 (date of completion); now disused due to stability issues, while 
the new concrete bridge next to it takes over the traffic"

regards
Peter

[1] http://en.wikipedia.org/wiki/New_Synagogue_%28Berlin%29
[2] http://en.wikipedia.org/wiki/Notre_Dame_de_Paris