[talk-au] Project of the Week / Month

Andrew Harvey andrew.harvey4 at gmail.com
Fri Nov 5 00:54:33 GMT 2010


On Fri, Nov 5, 2010 at 1:26 AM, David Murn <davey at incanberra.com.au> wrote:
> On Thu, 2010-11-04 at 10:55 +1100, Andrew Harvey wrote:
>
>> On Thu, Nov 4, 2010 at 10:37 AM, David Murn <davey at incanberra.com.au> wrote:
>>
>> > One question.. lit=yes is fine for ways where you want to indicate that
>> > a way is lit, but how does one tag individual lights that arent on a
>> > way, for example wanting to tag lights around a park, shopping area or
>> > parking area.
>>
>> What about adding lit=yes to the node/way/relation that has the
>> leisure=park, amenity=parking,... tag?
>
> A parking area may have lit/unlit parts, and most of these areas are too
> large to simply tag the whole area as lit/unlit.  Ive had a look through
> wiki and there doesnt seem to be anything documented, and a few searches
> have only turned up a few dozen or so various uses such as street_lamp
> or lamp as various values/keys or the like.

On Fri, Nov 5, 2010 at 11:16 AM, John Smith <deltafoxtrot256 at gmail.com> wrote:
> You could have 2 parking "areas" and mark one as lit and one that isn't...

>From a mapping perspective it would be good if there was one agreed upon method
that was documented on the Editing_Standards_and_Conventions wiki page for doing
this, because this is how I see the situation.

The two parking areas issue is the same issue as needing to split a highway in
order to tag different segments with different maxspeeds. For example if we have
(best read with a monospaced font),

A                         B   C                     D
|<--------- asphalt --------->|<--concrete blocks-->| <- surface
|<--------- 80 ---------->|<-------- 100 ---------->| <- maxspeed
|===================================================| <- road

One way to do this is to split the road at A,B,C,D where

   AB has highway=road,maxspeed=80,surface=asphalt
   BC has highway=road,maxspeed=100,surface=asphalt
   CD has highway=road,maxspeed=100,surface=concrete_blocks

Although another way is to again split the road at A,B,C,D but use relations so,

   AB,BC are in a relation tagged surface=asphalt
   CD is in a relation tagged surface=concrete_blocks

   AB is in a relation tagged maxspeed=80
   BC,CD are in a relation tagged maxspeed=100

   AB,BC,CD are in a relation tagged highway=road

I think the first approach is probably better as it's simpler, except where we
omit the highway tag and other tags that don't vary along the whole section of
the road (like name). These tags should be put into a relation that contains all
the smaller segments.

The problem is this is a very generic thing, basically any map feature could
potentially need to be split in order to do more detailed mapping, yet a lot of
the proposals focus on just one feature.

That relation that groups everything together could be type=multipolygon where
the road segments or parking lot segments are of role=outer. Or for the road it
could be type=collection
(http://wiki.openstreetmap.org/wiki/Relations/Proposed/Collected_Ways). Or I
guess you could just leave out the type and roles (is this allowed?) altogether.

I did this with http://www.openstreetmap.org/browse/relation/1253061 so I could
tag different parts of the outline of a park with different tags (in this case
different barrier tags, but the tags could be anything). Although as this is the
same as putting segments of a street together into a relation, why should a
different approach be used when we are doing the same thing?

So for the parking lot, when you split the parking lot to tag different parts
with different surfaces or different lighting I think the amenity=parking,
name=Joe's Parking Lot, capacity=1234 should all get shifted to the relation.

This it avoids duplication of things so if someone changes the name it doesn't
need to be changed on each individual way, it saves space and should lead to
less errors. But it also seems like the cleaner solution.

> With aerial imagery, its quite possible to accurately tag the exact
> location of the light itself, and even a lot of street lamps have unique
> ref codes which could be tagged also.  Id be quite happy to start
> tagging street lamps if there was an agreed upon tag.
>
> One thought, is that often street lights can share the same pole as
> power lines, so maybe utilising the existing pole/pylon/tower tags could
> be used in some way?

http://wiki.openstreetmap.org/wiki/Tag:highway%3Dstreet_lamp

They use man_made tags I think, so there shouldn't be a conflict.



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