[OSM-talk] Advanced highway tagging

[Dave Stubbs]

On 22/11/2007, Simon Hewison <simon at zymurgy.org> wrote:
> Andy Allan wrote:
> > Do you have any *specific* examples? For example where two motorways
> > in Google Maps are rendered in different colours?
>
> http://maps.google.co.uk/?ie=UTF8&ll=50.927492,1.93119&spn=0.104087,0.233459&z=12&om=1
>
> (Calais, France)
>
> Okay, so one of them (A26) is an autoroute péage, and one (A16) doesn't
> charge a toll. The distinction is obviously there in the underlying Tele
> Atlas database; and someone at Google decided to render a french
> autoroute péage in a darker orange than non-péage.
>
> Google have also decided that UK and Ireland are used to seeing maps
> with motorways in blue (like Ordnance Survey / AA), and that the french
> are used to seeing them in orange (like Michelin). On the ground,
> they're pretty much identical (aside from the french prefer driving on
> the right).
>

The point was subjective versus objective.
The subjective says, we're gonna paint this road green and this one
red, because we think this road is a green road, and this one is a red
road... lets mark all our roads on a scale of 1 to 10 depending on how
green or red we think they might be.

Objective says we're gonna paint toll roads a different colour to
non-toll roads, and roads located in the UK a different colour to ones
in France. You could see these roads will have different tagging.
Well, the ones in the UK and the ones in France might be tagged the
same, but its a reasonably trivial process to work out which country a
road is in if you're not too obsessed with the exact location of the
border.

I think Andy's point here is that what everyone is assuming is
Google(whoever)'s subjective choices are probably choices based on
some objective feature set of the road: so lets not stick in random
subjective feelings, but instead just extensively tag all the features
of a road to let the renderer decide based on those.