[OSM-talk] Global test area

[Jochen Topf]

There are always issues like "how to best tag certain features", "how to
best join those two streets when one is of type x and the other of type y",
or "how does renderer x renders this map feature" etc. Currently there are
some wiki pages addressing those issues, but their are hard to maintain,
because it has to be done manually, including getting screen shots of
relevant features from a renderer etc.

To help with all those issues I propose we create a "global test area", an
area on the map of the earth where we can put all these special (and 
normal) features in their context and in all variations necessary. This
area could be located on the North pole or somewhere in an ocean where
it doesn't collide with real features.

Data for this area would be stored in the normal OSM database. But to
get it out you would have to set a special flag which must be added to
the API. If an application doesn't set that flag, it will get the normal
view of the real earth. If id does set the flag, it will see the special
area in addition to the normal view. So nothing would change for legacy
clients, only clients supporting the new flag would see the data.

The easiest way of adding this flag would be to use a different base URL
for the map with the test data. That way no client changes are necessary,
because in most clients the base URL is probably configurable already. It
might still be better to have a button in the client which says "add test
area" or so, but for the moment thats not strictly necessary.

The database itself needs no changing, only on exporting the data, the
flag has to be checked and the test area has to be clipped if the flag
is not present.

Another option would be to create a completely separate planet for this.
That is certainly easier, because we only need to set up a separate
database and no software changes are necessary.

I am not sure whether the database integration with flag or the separate
database would be better. The difference would be most relevant when
you want to see both real and test data in the same application. I would
probably want to look at them side-by-side. I don't know about other
applications, but JOSM doesn't support different windows or views yet.
Using a separate database would mean that you have to set a source for
each window, with only one database this would not be needed.

Still another option would be to just have an .osm file with all this data
in it. This could be downloaded from the wiki. Advantage of this approach
is that no new software or services would be needed. But the big
disadvantage would be that we loose the interactive and collaborative way
to edit the data, which we are used to.

If such a thing would we deemed helpful and if somebody creates the database
or puts support for this in the current one, I would volunteer to start
populating that area with features. (Of course everybody can help doing
that, thats the point of the whole exercise.)

Jochen
-- 
Jochen Topf  jochen at remote.org  http://www.remote.org/jochen/  +49-721-388298