[Talk-us] Highway Shield Rendering

Phil! Gold phil_g at pobox.com
Mon Apr 2 19:27:51 BST 2012

* stevea <steveaOSM at softworkers.com> [2012-04-02 10:55 -0700]:
> I was a bit surprised to see shields beginning to render only at
> zoom level 11, and spottily at that.  Shields at zoom levels 10, 9
> and even 8 and 7 (maybe Interstates only?) would be helpful, if
> crowded in spots.

Shields are supposed to start rendering at zoom 10, but they're not.  This
is a bug.  What the rendering should be is: motorway shields at zoom 10,
plus trunk and primary at zoom 11, plus secondary at zoom 12, plus
everything else at zoom 13.  I'm working on just doing Interstates (and
the Trans-Canada Highway, pending some discussion about how to properly
tag it on talk-ca@) starting at zoom 7, but that's not in the tiled
rendering yet.

> Yes, 12, 13 and up to 14 work, but 15 and above just display pink tiles.

It depends on where you are looking.  If you're getting a lot of pink
tiles, that's probably because they haven't been rendered yet and the
server is taking too long to render them, so your requests are timing
out.  There should be an error tile suggesting that you wait a bit and try
back later, but that doesn't always load properly.  Everything up to zoom
12 is prerendered.  Zooms 13 and 14 can be slow to render, but 15 and up
normally go quickly except in dense urban areas.

> Most specific shields in California look "good and familiar," as you
> make correct distinctions between Interstates and state routes.
> However, "county routes" (designated by a "regional letter" and a
> number, such as "S 21") are not rendered with proper shields at all.
> This is a critical component for many areas.

I'm deliberately leaving county routes for a second phase and focusing on
state routes for the moment.  (New Jersey is an exception, but it was an
experiment and I don't actually believe we're using the proper shields for
all of its counties.)

> And oddly, in the San Diego area, "CA 209" and "CA 75" (Point Loma
> and Coronado, respectively) don't render with your newer shields,
> but the old style Mapnik shields.

It looks like there aren't route relations for those routes yet, so the
rendering falls back to the old shield style for them.

> Also, there are some toll ways in Orange County (California, e.g. CA
> 73, CA 241) which don't render specifically as toll, but as there is
> no distinct shield in California to distinguish toll roads, I'm not
> sure this is a defect in your algorithm or renderings -- the regular
> state route shield is displayed, apparently correctly.

Do toll roads get any difference in signage, like a banner above or below
the shield?  If so, then we just need to make images that match and get
routes that identify them.  (Right now that would probably be with a
network of US:CA:Toll, but see NE2's and my emails about Florida toll

> I also see absolutely no business routes where I know them to exist.
> I'm still searching for some in your rendering, but haven't found
> any (yet).

They might not show up.  Based on previous discussions on this list, we've
chosen to look for the business designation (as well as others) in the
network tag on the route relation.  A lot of relations have the route
modifier in the ref tag, though (so they might be network=US:US,
ref=5 Business instead of network=US:US:Business, ref=5), so they don't get
rendered at the moment.  (And on top of that, there are slightly different
signs for spur and loop business Interstates, so I ended up looking for
networks like US:I:Business:Loop and US:I:Downtown:Spur even though no
one's actually doing that yet.)

There are some business routes that our rendering understands here:

...computer contrarian of the first order... / http://aperiodic.net/phil/
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