[OSM-talk] tagging and rendering highways in the USA and elsewhere

[Tom Hughes]

In message <005401c8a16f$7ac34b00$0200a8c0 at peter>
        Peter Miller <peter.miller at itoworld.com> wrote:

> The state roads are currently tagged on OSM variously with trunk (green)
> primary (red) and secondary (orange). Some pretty major roads a tagged with
> secondary (actually a very lowly road class in the UK below motorway, trunk
> and primary) and I suspect that this is because it renders with the correct
> colour. There is no 'secondary_link' tag for exit and entrance ramps because
> secondary roads are too minor to have such things so highways rendered as
> secondary are using 'secondary' tags for exist and entrance ramps as well.

There is no such thing as a tag that does not exist in OSM as we have
freeform tagging. In addition to which mapnik at least does render
things marked as secondary_link, so it seems to do a pretty good
impression of something that exists to me.

> If we can agree on the rendering rules and get both Mapnik and osmarender
> sorted out for the USA then people will be incentivised to tag
> appropriately. The moto 'render and they will come' probably applies here as
> elsewhere.

Agreeing on the rules or colour schemes is not the problem.

The problem is that we do not have the technology to render different
countries in different ways. I don't believe we even know of an efficient
way to do it, so we don't even know what the technology would look like
should somebody want to write it.

See the ongoing discussion about the difficulty of the problem of
determining efficiently what country something lies in for what I'm
talking about.

Tom

-- 
Tom Hughes (tom at compton.nu)
http://www.compton.nu/