On 28/11/2019 09:59, Paul Allen wrote:
On Thu, 28 Nov 2019 at 00:23, Graeme Fitzpatrick
<graemefi...@gmail.com <mailto:graemefi...@gmail.com>> wrote:
Question of my own - is there any particular reason that a berm
couldn't just be rendered the same as a wall?
That question prompts another question.
Why render it as a wall? Since a berm is a type of embankment, why
not render it as an
embankment?
I've rendered "2-sided embankments" at e.g.
https://map.atownsend.org.uk/maps/map/map.html#zoom=17&lat=54.024306&lon=-1.02141
as _their own thing_ for a while now. That example is at the end of a
firing range,
https://map.atownsend.org.uk/maps/map/map.html#zoom=15&lat=53.87324&lon=-1.23959
shows some for flood defences. In that second image to the northwest
you can see an embankment with a path on it.
OSM Carto, as far as I'm aware
* Doesn't have a concept of 2-sided embankments or a rendering for them
* Doesn't have the concept of "on an embankment" being a modifier for
highways / railways in a similar way to "bridge" and "tunnel"
Either way, if you render it the same as an existing object, and it
serves the
same purpose as an existing object, the carto people are likely to
veto it under their "no
synonyms" rule.
I wouldn't argue that a new tag for berm is "needed", because people
have found ways to tag these features already (such as "embankment=yes"
and various flood defence tags), but it could be argued that using one
tag for these features makes things clearer. Separately to that, even
if you say "render X like Y" it doesn't mean that X is a synonym of Y.
There are plenty of those in all renderings already.
Even if you persuade the carto people to render berms, it will go on
their long to-do list and
may take a long time to appear.
The usual answer here is "pull requests welcome"...
Sometimes people might not want to do that because they know it wouldn't
be accepted (if it makes more use of lua processing than the OSM Carto
folks are happy with, for example). I suspect that wouldn't make sense
to submit a pull request to OSM Carto for bus guideway handling to match
the way I do it because it'd depend on lua changing a bus guideway to be
a type of railway. That "busway as railway" handling is why
https://map.atownsend.org.uk/maps/map/map.html#zoom=17&lat=52.315008&lon=-0.05611
show a bridge but
https://www.openstreetmap.org/#map=18/52.31481/-0.05622
does not.
You also have the problem of having to inspect a lot of existing
embankments to see
if some of them should be retagged as berms. And the problem of
mappers, perhaps
newbies, wondering what the difference between the two is.
Others have proposed a berm=* subtag to differentiate types of
berms. Why not, instead,
use a subtag for embankments?
A two-sided embankment is fundamentally different to a one-sided one.
The renderer would need to split them out into a different feature
anyway to render them, so it's fairly irrelevant to it how they are
tagged (other than the extra complication in "select" statements if
people insist on sub-tagging features that mean something else).
Best Regards,
Andy
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