[Openstreetmap-dev] Streets in GPX
nick at hogweed.org
nick at hogweed.org
Fri Sep 23 17:43:25 BST 2005
> > Bus 219 route
> > StreetID Startnode Endnode
> > 286 50 63
> > 287 1 3
> > 90281 12 1
> > 2131 54 42
> > etc?
> Now you are starting to introduce structure. A new data type: bus route.
> May be you are able to share that datatype and label it "route". Still the
> resulting structure is more complex than the simple "tracks=routes=streets
> are vectors of street segments".
That's true, bus routes represented this way would probably have to go in some
other data format, not GPX (an argument for a custom data format in the
> If a part of a track segment has to be shared among different tracks, you
> could split up the segment into 3 pieces: The piece before the common
> track, the common track and the piece after the common track:
> Example: (enable fixed sized font)
> bus 13
> \ Baker street
> Baker street \
> \ bus 13
> If the track segment was former composed of a single track segment ABC, it
> is now split into A, which only belongs to "Baker Street", B which is
> assigned to both, the street and the bus route and C, which is only in
> "Baker Street" too.
How would one explicitly link a bus route to a street? I'm guessing it will be
as follows (but I'm probably wrong...)
Presumably the nodes (=trkpts) in the GPX will be tagged with an ID which
incorporates the street ID?
node ID = (Street ID * n) + node position within street
where n is some large number.
e.g. in the above example, how can we find out the bus goes along Baker
Baker Street: route ID 10
Baker Street segment A: nodes 10n to 10n+1
Baker Street segment B: nodes 10n+1 to 10n+2
Baker Street segment C: nodes 10n+2 to 10n+3
Bus route: incorporates nodes 10n+1 to 10n+2 (amongst others)
divide by n and we get 10, and we know this is a Baker Street segment, i.e.
the bus follows Baker Street.
Or will it just be the lat/long of the nodes?
I know I must be missing something though, as I am still puzzled as to the
necessity of the multiple two-point segments; the above can be done by
treating both streets and routes as (possibly multiple) segments of multiple
Even the "streets with gaps" scenario does not necessitate the two-point
segments; for example (as I said in another message) the A34 has a gap
between Oxford and Birmingham; it could be treated as two segments each of
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