[diversity-talk] Anyone with an interest in history should not contribute to OSM?

[Serge Wroclawski]

 Rob,

That's a great question, and I since it's one that comes up often, I
think I can provide a little context that may help explain why you're
getting the responses that you are.

OSM has certain principles about how it maps (much like Wikipedia has
principles for article authors and editors). One of those is "ground
verifiable". In other words, can someone else than you go to that
place and verify what's there.[1]

This comes up in a number of ways. For example, just a month or two
ago, a mapper was creating artistic work on OSM based on his walking
patterns, and mapped these as features. But no one else could go to
the same field and see what he saw, so these were removed.

In the same way, historical mapping is not supported in OSM because
OSM is always a reflection of what is there on the ground now, at this
moment.

As an example, consider the earthquake in Haiti. When the earthquake
hit, buildings collapsed, and roads were damaged or destroyed. Those
features were not mapped, and if they were on the map, they were
amended to reflect the damage or deleted altogether., and in their
place were the features that existed, the tent camps and other
temporary shelters.

I live in New York City, and if OSM has existed in September of 2011,
we would have removed all the buildings which came down because those
buildings no longer existed.


A question that comes up frequently is "Coudln't we roll back the map
in time and see what was present then?" The answer is that we can roll
back the map to see what was present in the database at a given time,
but not what was present on the ground.

That's why a historical map would not work in OSM if the features on
that map are no longer present. It would be the same as the buildings
in Haiti.

So then what's to do?

There is a project for people with your same interest:
http://wiki.openstreetmap.org/wiki/Historical_OSM

I do not know how active it is, but it exists, and if you feel
passionately, you may want to  consider working with them, since they
have exactly the same interest as you. There are a number of technical
hurdles to overcome, but I suspect if there are smart, dedicated
people working on it, then you (collectively) could get very far.

I hope this answer has been informative, even if it's not the answer you wanted.

- Serge

[1] This brings up the question of political boundaries, which is a
complex topic and there is debate in the OSM community, but I will put
it aside for now.