Re: [OSM-talk] Key:layer update

[Dave F.]

Could you give some visual examples, maybe temporarily creating them in 
OSM (& deleting them afterwards) to clarify what you mean?


Dave F.


On 09/03/2014 22:26, Matthijs Melissen wrote:

On 9 March 2014 10:30, Richard Z.  wrote:

for some time now I have been working on the wiki page to state the rules
as clearly as possible.. hope that most of the improvements are fairly
uncontroversial.

Thank you for doing this, it's very useful to have this properly
documented. I have been working on layering in the main CartoCSS
stylesheet, and found that at the moment, indeed not all aspects of
the layering model are defined precise enough.

A question: a single road can contain sections on multiple layers, so
there will be a point where the sections that are on different layers
meet. At that point, there might even be a side street. However, no
vertical ordering should be assumed at such a point. It is written
that "The vertical ordering established by the layer values is valid
exactly only in the point where the ways cross or objects overlap."
Perhaps 'crossing' should be interpreted here as crossing without
node, but that causes problems with bridge/waterway.

In other words, I am wondering for each of the following situations if
the roads should be interpreted as meeting on the same or different
levels:
- A node where two waterways on layer 1 and two roads on layer 2 meet;
- A node where two roads on layer 1 and two roads on layer 2 meet;
- A node where two roads on layer 1 and one road on layer 2 meet;
- A node where one road on layer 1 and one road on layer 2 meet.

Perhaps some text that answers questions like this should be added to
the Wiki-page.

-- Matthijs

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Re: [OSM-talk] Key:layer update

[SomeoneElse]

Dave F. wrote:
Could you give some visual examples, maybe temporarily creating them 
in OSM (& deleting them afterwards)


... or on the dev server:

http://api06.dev.openstreetmap.org/

Cheers,

Andy


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Re: [OSM-talk] Key:layer update

[Dave F.]

On 09/03/2014 12:21, Richard Z. wrote:


the same conceptual problem exists with pylons where they are shared by two 
bridges
or aerial tramways. Actualy every pylon breaks the rule by definition because it
connects "ground" with layer=0 with something else at a different level.
How do you want to model such cases better? Lifts in buildings?

In practice this rule is broken more often than you would think: Hamburg is full
of waterways connected with roads on bridges through a tag obstacle. France is
full of bridges sharing a node with the waterway bellow.


Could you link to an example please?

Dave F.

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Re: [OSM-talk] Key:layer update

[Dave F.]

On 09/03/2014 14:45, Martin Koppenhoefer wrote:


2014-03-09 13:17 GMT+01:00 Dave F. >:


it says which object is above and which below when they cross,
it is not only for rendering



I agree it does say which object is above another. For the benefit of 
the renderer. Who else needs that data? Certainly not routers.





For instance if you had an area tagged 'park' & another area
within it tagged 'lake' you could add a 'layer' tag to 'lake'
to ensure the render displayed it.

-1, you should not add any layer in this case (tagging for the
renderer)


The correct expression is 'don't tag incorrectly for the
renderer'. There's /nothing/ wrong in making OSM data clearer &
more accurate.



+1, but adding a layer=1 to a lake in a park isn't clearer or more 
accurate, they are both on the same layer, the lake is in the park, 
not above (usually).


Which confirms my point perfectly. You're are correct: The lake & park 
/are/ at the same level, which is why the layer tag is needed. It's used 
purely to let the renderer know which entity to put on top of the pile 
show it display properly.


Dave F.


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Re: [OSM-talk] Key:layer update

[Martin Koppenhoefer]

2014-03-11 15:52 GMT+01:00 Dave F. :

> I agree it does say which object is above another. For the benefit of the
> renderer. Who else needs that data? Certainly not routers.
>


well, everybody who tries to understand what this specific part of the map
represents will have to have this information in the case of objects that
overlap in 2D.




>
>
>
>>  For instance if you had an area tagged 'park' & another area within it
>>> tagged 'lake' you could add a 'layer' tag to 'lake' to ensure the render
>>> displayed it.
>>>
>> -1, you should not add any layer in this case (tagging for the renderer)
>>
>
>  The correct expression is 'don't tag incorrectly for the renderer'.
>> There's /nothing/ wrong in making OSM data clearer & more accurate.
>
>
>
>  +1, but adding a layer=1 to a lake in a park isn't clearer or more
> accurate, they are both on the same layer, the lake is in the park, not
> above (usually).
>
>
> Which confirms my point perfectly. You're are correct: The lake & park
> /are/ at the same level, which is why the layer tag is needed. It's used
> purely to let the renderer know which entity to put on top of the pile show
> it display properly.
>


no, it would be wrong to use the layer tag here, as it would move the lake
out of the park and above. OK, this sounds unprobable to a human, and he
might still understand what was the intention (by interpretation and common
sense), but the modelling remains "wrong" (IMHO).

Btw.: a lake is a physical object, while a park is an abstract object, so
they aren't on the same level anyway (but on the same layer) ;-)

cheers,
Martin
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Re: [OSM-talk] Key:layer update

[Richard Z.]

On Tue, Mar 11, 2014 at 02:51:23PM +, Dave F. wrote:
> On 09/03/2014 12:21, Richard Z. wrote:

> >In practice this rule is broken more often than you would think: Hamburg is 
> >full
> >of waterways connected with roads on bridges through a tag obstacle. France 
> >is
> >full of bridges sharing a node with the waterway bellow.
> 
> Could you link to an example please?

http://www.openstreetmap.org/node/1522876252

stupid question - suppose I have this node selected in JOSM - what is
the quickest way of getting an URL like the above?

Richard

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Re: [OSM-talk] Key:layer update

[Robert Kaiser]

Richard Z. schrieb:

On Sun, Mar 09, 2014 at 12:34:31PM +, Dave F. wrote:

On 09/03/2014 12:24, Richard Z. wrote:


it says "point", not "node" the difference probably needs to be emphasized
very strongly. There is a difference between mathematicaly precise and
intuitive formulations:((

https://www.google.co.uk/#q=node%20definition

"a point in a network or diagram at which lines or pathways
intersect or branch"


changed to "precise location" instead of point.. is that better?



+1 for "location", that's really hard to misinterpret but is clear on 
what it means.


Robert Kaiser


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Re: [OSM-talk] Key:layer update

[Richard Z.]

On Sun, Mar 09, 2014 at 10:26:59PM +, Matthijs Melissen wrote:
> On 9 March 2014 10:30, Richard Z.  wrote:
> > for some time now I have been working on the wiki page to state the rules
> > as clearly as possible.. hope that most of the improvements are fairly
> > uncontroversial.
> 
> Thank you for doing this, it's very useful to have this properly
> documented. I have been working on layering in the main CartoCSS
> stylesheet, and found that at the moment, indeed not all aspects of
> the layering model are defined precise enough.

just remembered, there is also a rather special rule for 
  tunnel=building_passage
"The layer has to be the same as the building, with the above mentioned
 exception when several tunnels are passing on different levels. "
https://wiki.openstreetmap.org/wiki/Key:tunnel#tunnel.3Dbuilding_passage

It makes sense but is so much different from normal tunnels that I am
wondering if it should not have been done with a different tag.

Richard


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[OSM-talk] MapQuest Open tiles not updating?

[Andrew Guertin]

It looks like the MapQuest Open tiles haven't updated since the 
beginning of February. I narrowed the last update down to sometime 
between https://www.openstreetmap.org/changeset/20325021 (Feb 1, 10 PM) 
and https://www.openstreetmap.org/changeset/20340010 (Feb 2, 7 PM)


Does anyone know what's going on with it?

--Andrew

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Re: [OSM-talk] MapQuest Open tiles not updating?

[James Mast]

See this tweet I got back from them asking the same question:
https://twitter.com/MapQuestTech/status/436876342861512704

-James
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Re: [OSM-talk] MapQuest Open tiles not updating?

[Andrew Guertin]

On 03/11/2014 05:12 PM, James Mast wrote:

See this tweet I got back from them asking the same question:
https://twitter.com/MapQuestTech/status/436876342861512704

-James


Thanks, that explains it.
--Andrew

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[OSM-talk] isolated odbl=clean nodes with no other tags?

[Richard Z.]

Hi,

this caught my attention some time ago:

  http://www.openstreetmap.org/node/307673868

we could not figure out how it happened and what it was originaly. It seems 
none of the validators complains about the existence of such nodes so this 
may be an isolated mishap or a widespread problem.

Has anyone looked at this before?

Are those odbl=clean tags supposed to stay there forever?

Richard

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Re: [OSM-talk] isolated odbl=clean nodes with no other tags?

[Jo]

You can safely remove it/them. You could also reuse it, but there is no
point why you would do that, unless you figure out what the original mapper
tried to add to the map by resurveying the area.

Polyglot


2014-03-11 23:40 GMT+01:00 Richard Z. :

> Hi,
>
> this caught my attention some time ago:
>
>   http://www.openstreetmap.org/node/307673868
>
> we could not figure out how it happened and what it was originaly. It seems
> none of the validators complains about the existence of such nodes so this
> may be an isolated mishap or a widespread problem.
>
> Has anyone looked at this before?
>
> Are those odbl=clean tags supposed to stay there forever?
>
> Richard
>
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Re: [OSM-talk] Key:layer update

[moltonel 3x Combo]

On 11/03/2014, Dave F.  wrote:
> On 09/03/2014 14:45, Martin Koppenhoefer wrote:
>> For instance if you had an area tagged 'park' & another area
>> within it tagged 'lake' you could add a 'layer' tag to 'lake'
>> to ensure the render displayed it.
[...]
> Which confirms my point perfectly. You're are correct: The lake & park
> /are/ at the same level, which is why the layer tag is needed. It's used
> purely to let the renderer know which entity to put on top of the pile
> show it display properly.

Go fix your rendering stylesheet if you feel it should display lakes
on top of parks but doesn't. Stylesheets make this type of decision
for plenty of objects without needing a layer tag. The decision to
render a lake on top of a park isn't a universal one.

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Re: [OSM-talk] Key:layer update

[Richard Z.]

On Tue, Mar 11, 2014 at 02:52:02PM +, Dave F. wrote:
> On 09/03/2014 14:45, Martin Koppenhoefer wrote:

> >+1, but adding a layer=1 to a lake in a park isn't clearer or more
> >accurate, they are both on the same layer, the lake is in the
> >park, not above (usually).
> 
> Which confirms my point perfectly. You're are correct: The lake &
> park /are/ at the same level, which is why the layer tag is needed.
> It's used purely to let the renderer know which entity to put on top
> of the pile show it display properly.

if a layer tag is needed to display a lake in a park then you have some
other problem. Show us an example.

natural=water + layer has no meaning unless in combination with tunnel,
bridge or similar.

Richard

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Re: [OSM-talk] isolated odbl=clean nodes with no other tags?

[Toby Murray]

It was probably a member of a way that got removed. Maybe they forgot to
add the odbl tag to the way. Or it really wasn't clean. Hard to figure out
at this point.

But yeah, feel free to remove it. I know JOSM automatically removes the
odbl tag on any modified objects on upload. P2 and iD might as well. Don't
recall right now.

Toby
On Mar 11, 2014 5:50 PM, "Jo"  wrote:

> You can safely remove it/them. You could also reuse it, but there is no
> point why you would do that, unless you figure out what the original mapper
> tried to add to the map by resurveying the area.
>
> Polyglot
>
>
> 2014-03-11 23:40 GMT+01:00 Richard Z. :
>
>> Hi,
>>
>> this caught my attention some time ago:
>>
>>   http://www.openstreetmap.org/node/307673868
>>
>> we could not figure out how it happened and what it was originaly. It
>> seems
>> none of the validators complains about the existence of such nodes so this
>> may be an isolated mishap or a widespread problem.
>>
>> Has anyone looked at this before?
>>
>> Are those odbl=clean tags supposed to stay there forever?
>>
>> Richard
>>
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>
>
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Re: [OSM-talk] isolated odbl=clean nodes with no other tags?

[Richard Z.]

On Tue, Mar 11, 2014 at 06:32:01PM -0500, Toby Murray wrote:
> It was probably a member of a way that got removed. Maybe they forgot to
> add the odbl tag to the way.

that was our idea but the OSM Inspector or some other tool would have warned 
about that case.. so a  little mystery.

I am not worried about this one case but how it slipped through all
checks and how many other there might be.

Richard

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