[Tagging] building=disused

Paul Allen pla16021 at gmail.com
Thu Jan 16 23:10:53 UTC 2020


On Thu, 16 Jan 2020 at 22:37, Warin <61sundowner at gmail.com> wrote:

> And that is a problem. A reduction in information caused by a render
> failing to render information.
>
Not quite.  As things stand, that information is being mapped.  The problem
is
that some people, such as you, are calling for changes to the renderer that
would lead to that information no longer being mapped.

> If the render were to render disused:* then I think all would be happy?
>
Nope.  The existing behaviour of not rendering disused:* is correct for
non-physical objects.  amenity=place_of_worship gets a religious
symbol determined by the religion (or a generic religious symbol
if no religion is specified).  disused:amenity=place_of_worship does
not get a religious symbol.  This is the desired behaviour.  You do not
want places which are no longer used for religious services to be
rendered as though they're still in use.

However, the current behaviour of disused:* is wrong for physical objects.
A house which has been empty for years but could be repaired fairly easily
is
still a house.  But disused:building=house doesn't render.  This is not
good.

One fix is to add extra logic to the carto toolchain to give different
behaviour
for physical and non-physical objects.  Which means checking every type of
object and figuring out whether it should be rendered or not, building the
logic,
and adding to the logic as other types of object are defined.  And there are
ALWAYS going to be edge cases that the logic gets wrong.

What we currently have works.  disused:* doesn't render, disused=yes
renders.
No matter how edgy the edge case, the mapper can decide which of the two
is most appropriate for a given situation.  This building is not in use but
it
should be rendered, so disused=yes.  This church is no longer used for
anything therefore should not get a religious symbol, so
disused:amenity=place_of_worship.

The problem is people occasionally pop up to say we don't need/shouldn't
use disused=yes because disused:* exists.  One of them amended the wiki
a few years ago to deprecate disused=yes (since partially reverted to make
an exception for some physical objects).

What we have works, and isn't inappropriate or tagging for the renderer.  It
also means we have all the information.  Dropping disused=yes, or making
disused=yes so it doesn't render, or making disused:* render will all lead
to
the loss of information (or moving such information into a free text note,
with
no guarantee that all will use the word "disused" in the note).

What we have works, at least on standard carto.  I don't know about other
cartos, but I suspect with sufficiently strong support from standard carto
and
this list, other cartos would eventually follow suit (if they don't
already).

-- 
Paul
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