[Mapserver-users] Re: finding intersections

[pkishor_98]

--- In mapserver-users@yahoogroups.com, "Kieran J. Ames" <kames@k...> wrote:
..

> The data are in a MySQL database. Data and indices total about 2.9GB. (Almost
> 28 million point records.)

that is a lot of data. What is the performance like (on what kind of a machine and 
what kind of load)?

> I ended up with a database of street intersections and dead-ends.
> (...actually normalized street points that I query to derive intersection
> data. The intersection of Main and Broad would be 2 records, each with the
> same LAT/LON.) I'm using that to create a point layer that I include in my
> mapfile.

you could probably avoid storing "Main and Broad" and "Broad and Main" and 
potentially halve your number of records... just store one entry per road, and a its 
corresponding intersections in a related table. Although de-normalized data might be 
faster to lookup.


> it was easy (though tedious) to create the data. The
> problem is maintaining it and adding new information. I haven't crossed that
> bridge yet!


yup. that is the rub. But I am not sure if there is any easy way around that. As long as 
I can find a good method of locating the intersections, I am not going to worry about 
maintaining it... that is the problem that is going to come with this territory.

thanks.

> 
> pkishor_98 wrote:
> 
> > Someone asked me if mapserver could find intersections (constitution
> > and 16th). I replied that mapserver by itself can't but there is no
> > reason it couldn't be programmed. Then I realized I didn't really know
> > how.
> >
> > I could create a table of intersections for every road (line), but I
> > would have to start with a table of roads first.
> >
> > I could do some finagling with geocoding.
> >
> > Or I could...
> >
> > all ideas welcomed. In return, I will take the do-able ones and wiki 'em.
> >
> > Puneet.
> >
> > _______________________________________________
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> > Mapserver-users@l...
> > http://lists.gis.umn.edu/mailman/listinfo/mapserver-users

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