[Tagging] Highway property proposal "covered=yes"

Anthony osm at inbox.org
Sat Oct 31 16:04:47 GMT 2009

On Wed, Oct 28, 2009 at 5:04 PM, Randy <rwtnospam-newsgp at yahoo.com> wrote:
> In addition to providing a proper tagging method, there is an added
> benefit. There has been a continuing series of rendering bug reports about
> roads being on top of buildings rather than under them, independent of
> layering. This property tag would also make it much easier for renderers
> to render the way differently than on top of the building (or other
> structure), independent of rendering sequence. My proposed rendering would
> be parallel dashed lines with transparent fill, similar to a tunnel,
> without the entries/exits being drawn.

I've been thinking about this, and I do support your proposal.
However, renderers should take care of this even if it isn't tagged
this way.  If a highway and a building cross at the same layer, the
building should be made partially transparent so the way can be seen
to be covering it.  In my opinion, only if the way is at a layer less
than zero should the lines be dashed.  Thus one can see from the map
whether the way goes through the building or goes under it.

To my mind tags like "covered" and "shaded" are more appropriately
used by the routers than the renderers.  I don't have a problem with
them, but the renderers should be able to render without them.

I'm still not sure if my example should be tagged with "tunnel" or
not.  To my mind something doesn't become a tunnel just because you
build something over top of it.  According to the wiki, "The tunnel
tag is used to map ways that runs through an *underground* passage."
Emphasis mine.  Though people tend to not agree with me when I nitpick
wiki definitions :).


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