[Talk-transit] [Spam] Re: Multiple tracks

Richard Mann richard.mann.westoxford at googlemail.com
Wed Jun 24 14:45:58 BST 2009


On Wed, Jun 24, 2009 at 1:40 PM, Frankie Roberto <frankie at frankieroberto.com
> wrote:

> Do relations solve the problem at all? If a track is part of a route
> relation, then could a renderer use that as a means of aggregating the
> tracks together?


My hunch is that relations probably don't actually help much, unless you
could rely on them being done consistently and accurately.

The way to do it would be to
1) break every way up into short sections, probably by identifying adjacent
nodes and creating extra nodes where required on the fly
2) ignore short ways that have nodes in common with other ways (ie
crossovers)
3) count up ways that are near-parallel and have closeby starts.

That wouldn't be particularly quick, and might be prohibitively slow. It'd
certainly be a bit fiddly to write, and not something for a
beginner-renderer (unless they've got a decade of hacking databases behind
them). It'd be a lot easier for the tagger to do, and then any renderer
could use the information.

Richard
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