[Openstreetmap] How do we handle large amount of GPS points?
matt at matt-amos.uklinux.net
Mon Nov 22 00:43:22 GMT 2004
On Sunday 21 November 2004 22:45, SteveC wrote:
> * Petter Reinholdtsen (pere at hungry.com) wrote:
> > > Now, my table looks like lat,lon,alt,time,userid
> > My table includes (lat,lon)::point, altitude, quality
> > (0,1=gpx,2=dgps), satellites, and hor. dilution. I fetch data
> > using the GGA NMEA sentence.
> Ok, AFAIR talking to matt we need more than this. We need track
> numbers and stuff to do line extraction, and data for later dgps
> resoving. To clear this up, how does this scheme look where we
> ignore exactly how lat/long is stored (eg two columns or in a Point
> or what).
> lat float not null
> long float not null
> alt float not null
> hor_dilution float
> vert_dilution float
> track num bigint
> quality byte
> satellites (type spec for this?)
> timetamp long
why not "datetime"?
> time_dilution int
> uid bigint not null
whats currently giving me a headache, besides c++'s restrictions on
static constructors, is that a continguous track may become several
segments of road (in the TIGER meaning - each segment being
non-overlapping monotonous) and several non-contiguous segments of
tracks (e.g: if the lock keeps dropping in a city) might be one road
the association of roads should be backwards onto the points (i.e: the
points table is at some level more "basic" than the paths table), but
that doesn't fit very well with the relational paradigm... you'd end
up with a paths_segments table which maps points onto paths...
hmmm... maybe thats actually ok...?
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