[OSM-talk] Request for Romano-British features
lester at lsces.co.uk
Sun Jan 15 12:35:02 GMT 2012
Martin Koppenhoefer wrote:
> 2012/1/14 Russ Nelson<nelson at crynwr.com>:
>> Lester Caine writes:
>> > yet there seems to be no way to create secondary databases of
>> > information which can be used in parallel but separately hosted.
>> Yes, we need *more* OpenStreetMaps from which you can fetch different
>> types of information. For example, any data which is externally
>> maintained and updated really *shouldn't* be imported into OSM.
> If you really want to connect the data you will have to have it in one
> database. Layers are only good for stuff that is not connected/linked,
> i.e. that is independent from each other (rarely the case for features
> like the ones we are talking about here, as existence of the roman
> road had an influence on the further development of the road grid).
> E.g. if you have a building of which the basement is roman and the
> upper parts are medieval (we can asume for this example that they both
> occupy the exactly same area), and you realign the upper parts (say
> you slightly move 2 corners) you will also want the lower one to
> follow this modification. The both are linked and for consistency a
> refinement of one will (in many cases) require also the other to be
> We would need to have a way to link 2 datasets like: this line in
> dataset A is the same as this line in dataset B (or this line in A is
> parallel to this line in B). If you continue to think this and think
> about the complexity of the real world (there is not only a few lines
> but many of them, and they are not only the same or parallel but also
> orthogonal, or in the middle/center, or ...) you will see that you
> either keep them in one dataset or you will loose all these relations.
> Layers work well if both are only loosely linked (say you have
> temperature measurements in a grid and overlay them with OSM data for
THAT is a nice summary of the problem ...
Certainly more complete than mine :)
Lester Caine - G8HFL
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