[Tagging] cliffs and embankents or anything else

[Friedrich Volkmann]

On 03.09.2014 14:25, Zecke wrote:
> Currently in OSM we have two tags to describe some kind of slope that also
> get rendered in the mapnik chart and a couple of others:
> natural=cliff
> embankment (in the form man_made=embankment (feature) and embankment=yes
> (attribute))
> 
> Is this categorisation sufficient for any type of slope?

1) This is not a categorisation.
2) We do not need tags for every type of slope, see below.

> There's the question whether "natural" is appropriate as there are also man
> made steep slopes.

I think that we do not need that kind of differenciation. There are also man
made water areas and trees, and we are doing fine without tags like
man_made=tree. They would only complicate things. Look at the landuse=forest
vs. natural=wood dilemma.

A cliff (or steep slope) cannot be man made on its own, because it can only
be created by putting up something on one side, or digging off something on
the other side. So it's actually the adjacent horizontal area that is man made.

> And there recvently arose the question whether the
> english term "embankment" only covers slopes beside a road/railroad/river
> etc. or a general slope.
> 
> The wiki defines embankments as accompanying a line object
> (road/railroad/river). For these the attribute form embankment=* is
> foreseen. However it only defines embankment=yes, ignoring the fact that an
> embankment con be only one-sided (left or right). This kind of tagging is
> also used.

This is only possible if the man made embankment is inside a larger natural
slope. So the embankment is not as notable a landscape component as compared
to freestanding embankments in the plains.

> There are cases where one needs to map slopes beside a line object that
> itself is man_made=*.

Needs? No mapper that I am aware of is forced to map anything. They usually
map what they believe is useful.

> So the slope should be an attribute to the line. Would
> embankment=yes/right/left/both be the correct tag in your opinion?

There are at least 3 aspects of that question:
1) The linguistic aspect: whether the word "embankment" suits assymetric
profiles.
2) The syntactic aspect: what's the differece between embankment=yes and =both?
3) The usage aspect: Do we really want to tag all mountain roads
embankment=left + cutting=right? Hey, we have DEMs nowadays, and everybody
knows that there are slopes on the mountains.

-- 
Friedrich K. Volkmann       http://www.volki.at/
Adr.: Davidgasse 76-80/14/10, 1100 Wien, Austria