[Talk-us] Fwd: Re: [OSM-talk] Mapquest launches site based on OSM!

[Nathan Edgars II]

On Sun, Jul 18, 2010 at 6:28 PM, Phil! Gold <phil_g at pobox.com> wrote:
> I don't see any special cases for multiple route membership, and it looks
> like road segments that belong to more than one route don't get any
> shields rendered.  (That, to me, will be the biggest benefit of
> route-relation-based shield rendering, if anyone gets it working
> properly.)

I'm not so sure we need to use relations. We can use the following
procedure to generate the correct shields:
1. split the ref tag at semicolons and drop leading spaces
2. convert I *, US *, and CR/CH/CTH * to shields
3. remove other prefixes, and keep these and non-prefixed numbers in
ovals (there's no reason we need to render the shapes used on signs,
though Virginia and West Virginia may need special rules because their
*secondary* (county-based) routes use circles)
4. draw all the shields thus generated near each other

The main benefit of relations seems to be that the shields are
generated not per way but per route, so four adjacent short ways will
be treated as if they were combined. It may be harder to ensure that
all shields on an overlap are displayed, however.