lit=yes/no threshold

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lit=yes/no threshold

Mateusz Konieczny-3
Some cases of lit=yes are clear (direct lighting of street/footway by lamps)

Some cases of lit=no are clear (no lighting whatsoever)

But in cities there is also often strong or weak ambient light, for example:

- carriageway is directly lit with so powerful light that spillover light
makes footway well lit - clearly lit=yes

- spillover light is quite dim but enough to comfortably walk - also lit=yes

- there is some ambient light, but not enough to walk without own
source of light - lit=no

- there is an ambient light, one can carefully walk, but only slowly,
people with poor eyesight needs their own source of light - lit=no (?)

Overall, I am considering adding to https://wiki.openstreetmap.org/wiki/Key:lit
recommendation to consider "is it necessary to bring your own light source to see it properly"
as recommended threshold for footways/paths.

Any problems with that or ideas for a better threshold between lit=yes and lit=no?

disclaimer: I am trying to make lit=yes/no definition more precise as part of my grant
https://www.openstreetmap.org/user/Mateusz%20Konieczny/diary/368849

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Re: lit=yes/no threshold

Colin Smale

What problem are you trying to fix here? Usually it is pretty obvious if a street has artificial lighting or not. Instead of creating artificial boundaries quantising shades of grey into black and white, why not make it more objective and record the light level in lux on the centre line of the road? Or would it be better to do that on the footpath? That would complicate matters because the two sides of the road may differ.

I would say, don't over-engineer the model, and keep it fit for purpose. The more complexity you add to these rules, the lower the compliance will be.

Also, don't forget that whether a road is "lit" or not has consequences for traffic regulations, at least in the UK. There is a specific definition associated with this. If you break that link, there will be another interminable discussion about retagging.

My vote is to leave lit=* alone!

On 2019-07-06 12:24, Mateusz Konieczny wrote:

Some cases of lit=yes are clear (direct lighting of street/footway by lamps)
 
Some cases of lit=no are clear (no lighting whatsoever)
 
But in cities there is also often strong or weak ambient light, for example:
 
- carriageway is directly lit with so powerful light that spillover light
makes footway well lit - clearly lit=yes
 
- spillover light is quite dim but enough to comfortably walk - also lit=yes
 
- there is some ambient light, but not enough to walk without own
source of light - lit=no
 
- there is an ambient light, one can carefully walk, but only slowly,
people with poor eyesight needs their own source of light - lit=no (?)
 
Overall, I am considering adding to https://wiki.openstreetmap.org/wiki/Key:lit
recommendation to consider "is it necessary to bring your own light source to see it properly"
as recommended threshold for footways/paths.
 
Any problems with that or ideas for a better threshold between lit=yes and lit=no?
 
disclaimer: I am trying to make lit=yes/no definition more precise as part of my grant
https://www.openstreetmap.org/user/Mateusz%20Konieczny/diary/368849

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Re: lit=yes/no threshold

Ferdinand Schicke
In reply to this post by Mateusz Konieczny-3

What I couldsee work would be to have additional lit=* values like lit=weak or lit=spillover or lit=10lux

 

From: [hidden email]
Sent: Samstag, 6. Juli 2019 12:26
To: [hidden email]
Subject: [Tagging] lit=yes/no threshold

 

Some cases of lit=yes are clear (direct lighting of street/footway by lamps)

 

Some cases of lit=no are clear (no lighting whatsoever)

 

But in cities there is also often strong or weak ambient light, for example:

 

- carriageway is directly lit with so powerful light that spillover light

makes footway well lit - clearly lit=yes

 

- spillover light is quite dim but enough to comfortably walk - also lit=yes

 

- there is some ambient light, but not enough to walk without own

source of light - lit=no

 

- there is an ambient light, one can carefully walk, but only slowly,

people with poor eyesight needs their own source of light - lit=no (?)

 

Overall, I am considering adding to https://wiki.openstreetmap.org/wiki/Key:lit

recommendation to consider "is it necessary to bring your own light source to see it properly"

as recommended threshold for footways/paths.

 

Any problems with that or ideas for a better threshold between lit=yes and lit=no?

 

disclaimer: I am trying to make lit=yes/no definition more precise as part of my grant

https://www.openstreetmap.org/user/Mateusz%20Konieczny/diary/368849

 


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Re: lit=yes/no threshold

Warin
On 06/07/19 20:47, Ferdinand Schicke wrote:

What I couldsee work would be to have additional lit=* values like lit=weak or lit=spillover or lit=10lux


I tired to use my mobile phone to gauge the amount of night light .. it did not work very well at all!

lit=weak is too subjective.

I too would leave lit alone. Either it is lit or it is not.

If you need some measure of 'lit' then I suggest if a map (OSM reference) cannot be read by the present light level then it is not lit. 


 

From: [hidden email]
Sent: Samstag, 6. Juli 2019 12:26
To: [hidden email]
Subject: [Tagging] lit=yes/no threshold

 

Some cases of lit=yes are clear (direct lighting of street/footway by lamps)

 

Some cases of lit=no are clear (no lighting whatsoever)

 

But in cities there is also often strong or weak ambient light, for example:

 

- carriageway is directly lit with so powerful light that spillover light

makes footway well lit - clearly lit=yes

 

- spillover light is quite dim but enough to comfortably walk - also lit=yes

 

- there is some ambient light, but not enough to walk without own

source of light - lit=no

 

- there is an ambient light, one can carefully walk, but only slowly,

people with poor eyesight needs their own source of light - lit=no (?)

 

Overall, I am considering adding to https://wiki.openstreetmap.org/wiki/Key:lit

recommendation to consider "is it necessary to bring your own light source to see it properly"

as recommended threshold for footways/paths.

 

Any problems with that or ideas for a better threshold between lit=yes and lit=no?

 

disclaimer: I am trying to make lit=yes/no definition more precise as part of my grant

https://www.openstreetmap.org/user/Mateusz%20Konieczny/diary/368849

 



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Re: lit=yes/no threshold

Mateusz Konieczny-3
In reply to this post by Colin Smale
6 Jul 2019, 12:35 by [hidden email]:

What problem are you trying to fix here? Usually it is pretty obvious if a street has artificial lighting or not.

Unclear desired tagging for footways lit by spillover lighting. As I mentioned it is usually obvious
but there are cases where it is not clear.

is path on top of embankment, without own lighting, poorly lit by street lamps on a street below it.

along well lit road but so far away that lighting is poor and faint

city light.

In most cases I already tagged something, but it would be nice to check whatever it is at least
sort-of similar to what others would map.
Instead of creating artificial boundaries quantising shades of grey into black and white, why not make it more objective and record the light level in lux on the centre line of the road?
It is not feasible to do for a typical mapper to record "light level in lux".
Also, don't forget that whether a road is "lit" or not has consequences for traffic regulations, at least in the UK. There is a specific definition associated with this.
I found it,

"A road's speed limit is 30 mph (48 km/h) if the road's street lights are "[not placed]
more than 200 yards apart" in England and Wales or "not more than 185 metres" in Scotland;"

but it is not helping with problem what would be a good threshold between lit=yes and lit=no
on footways

My vote is to leave lit=* alone!

So it is preferable that everyone has their own definition of what is lit=no/yes and
recommend that "in case of doubt is it lit=yes or lit=no feel free to choose either"?

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Re: lit=yes/no threshold

Paul Allen
On Sat, 6 Jul 2019 at 12:42, Mateusz Konieczny <[hidden email]> wrote:

It is not feasible to do for a typical mapper to record "light level in lux".

Sadly, however, it is the only objective way of specifying the light level.  And even then, it's
easy to do it wrong if you don't account for the angle of incidence.  Aim the sensor at the
light and you'll get a higher reading than if you lay it flat on the ground.

but it is not helping with problem what would be a good threshold between lit=yes and lit=no
on footways

In the UK, BS 5266 requires a minimum illumination of 1 lux along the centre line of
escape routes.  Up until 2011, BS 5266 required a minimum of 0.2 lux along the centre
line of escape routes.

IIRC, the 0.2 lux figure was approximately equivalent to the light of the full moon, which
was deemed adequate for some work in shipyards during WW II.  Certainly it's more
than necessary to take an unhurried stroll along a footpath after your eyes have
acclimatized to the darkness.  It may be the minimum that was once considered
adequate to allow evacuation from a dark building after a power cut (no time for eyes
to acclimatize) but it's not the minimum needed to follow a reasonable footpath if you're
not in a hurry.

So it is preferable that everyone has their own definition of what is lit=no/yes and
recommend that "in case of doubt is it lit=yes or lit=no feel free to choose either"?

It's hard for most mappers to accurately measure.  It's hard to agree on a suitable
figure, because the amount of light necessary depends very much on the nature of the
path (an asphalted footpath can be safely followed with far less light than is required for
an unmade path over rocky terrain).  OTOH, if there are lights along the path, it is clear that it is lit.
If it's the sidewalk of a lit road, it's lit.  In any other cases, it's probably safer to say it's unlit.

--
Paul


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Re: lit=yes/no threshold

Tobias Zwick
In reply to this post by Mateusz Konieczny-3
> I am trying to make lit=yes/no definition more precise

I think that your suggestions would make the definition actually less precise because they add a fair level of subjectiveness: "necessary to bring your own light"

The least subjective definition is to map the physical presence of street lanterns on the way, not the light they emit. (This definition (though) would mean that a footway close to a lit street would be mapped as unlit as long as it does not have own lanterns.)

Tobias

On July 6, 2019 12:24:18 PM GMT+02:00, Mateusz Konieczny <[hidden email]> wrote:

>Some cases of lit=yes are clear (direct lighting of street/footway by
>lamps)
>
>Some cases of lit=no are clear (no lighting whatsoever)
>
>But in cities there is also often strong or weak ambient light, for
>example:
>
>- carriageway is directly lit with so powerful light that spillover
>light
>makes footway well lit - clearly lit=yes
>
>- spillover light is quite dim but enough to comfortably walk - also
>lit=yes
>
>- there is some ambient light, but not enough to walk without own
>source of light - lit=no
>
>- there is an ambient light, one can carefully walk, but only slowly,
>people with poor eyesight needs their own source of light - lit=no (?)
>
>Overall, I am considering adding to
>https://wiki.openstreetmap.org/wiki/Key:lit
><https://wiki.openstreetmap.org/wiki/Key:lit>
>recommendation to consider "is it necessary to bring your own light
>source to see it properly"
>as recommended threshold for footways/paths.
>
>Any problems with that or ideas for a better threshold between lit=yes
>and lit=no?
>
>disclaimer: I am trying to make lit=yes/no definition more precise as
>part of my grant
>https://www.openstreetmap.org/user/Mateusz%20Konieczny/diary/368849

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Re: lit=yes/no threshold

dieterdreist
In reply to this post by Colin Smale


sent from a phone

> On 6. Jul 2019, at 12:35, Colin Smale <[hidden email]> wrote:
>
> Instead of creating artificial boundaries quantising shades of grey into black and white, why not make it more objective and record the light level in lux on the centre line of the road? Or would it be better to do that on the footpath? That would complicate matters because the two sides of the road may differ.


how would you do this? Usually street lighting is not very homogeneous, especially on footways (where the information is most interesting, because vehicles bring their own lights anyway), you can only measure the amount of light at a single spot, but you will surely get very different measurements according to the exact location you choose.

My criterion for pedestrian spaces lit or not would be: can you see dog poo, or a hole in the ground? If not it is not (sufficiently) lit.

Cheers, Martin
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Re: lit=yes/no threshold

dieterdreist
In reply to this post by Tobias Zwick


sent from a phone

> On 6. Jul 2019, at 14:07, Tobias Zwick <[hidden email]> wrote:
>
> The least subjective definition is to map the physical presence of street lanterns on the way, not the light they emit. (This definition (though) would mean that a footway close to a lit street would be mapped as unlit as long as it does not have own lanterns.)


the presence of street lights indicates the road could be lit, it has no implications whether it is actually lit. For example last summer I went to an island where all streets had relatively new street lights, but half the island they kept them off so that light pollution was reduced.

In small villages in Germany, street lights are often turned off at a certain time (e.g. after 23h), etc.


Cheers, Martin
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Re: lit=yes/no threshold

bkil
In many parts of Hungary, vegetation can overshadow street lights,
especially if they are placed high enough. They may make efforts to
protect roads against this, but they rarely consider footways. Hence I
know a lot of streets where road illumination is fair, but the
sidewalk right beside it (maybe 1-2m from the road) is dark along the
majority of the road.

I also agree with Martin's definition of being lit and I usually do it
like that.

I don't split ways by the centimeter to specify illumination - if a
stretch of path has too many shadows, you need to bring your own
lights anyway, so I consider that not being lit.

On Sat, Jul 6, 2019 at 2:39 PM Martin Koppenhoefer
<[hidden email]> wrote:

>
>
>
> sent from a phone
>
> > On 6. Jul 2019, at 14:07, Tobias Zwick <[hidden email]> wrote:
> >
> > The least subjective definition is to map the physical presence of street lanterns on the way, not the light they emit. (This definition (though) would mean that a footway close to a lit street would be mapped as unlit as long as it does not have own lanterns.)
>
>
> the presence of street lights indicates the road could be lit, it has no implications whether it is actually lit. For example last summer I went to an island where all streets had relatively new street lights, but half the island they kept them off so that light pollution was reduced.
>
> In small villages in Germany, street lights are often turned off at a certain time (e.g. after 23h), etc.
>
>
> Cheers, Martin
> _______________________________________________
> Tagging mailing list
> [hidden email]
> https://lists.openstreetmap.org/listinfo/tagging

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Re: lit=yes/no threshold

Mateusz Konieczny-3
In reply to this post by Tobias Zwick



6 Jul 2019, 14:07 by [hidden email]:
I am trying to make lit=yes/no definition more precise

I think that your suggestions would make the definition actually less precise because they add a fair level of subjectiveness: "necessary to bring your own light"

The least subjective definition is to map the physical presence of street lanterns on the way, not the light they emit. (This definition (though) would mean that a footway close to a lit street would be mapped as unlit as long as it does not have own lanterns.)
This may be less subjective but would be quite pointless - there are many, many cases (at least in my city)
where many footways are well lit without dedicated lanterns.

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Re: lit=yes/no threshold

voschix
In reply to this post by bkil
Just two additional aspects from my own experience on bicycle, to make things even more complicated:

1) cycle and foot path illumintion dramatically depends on the presence of leaves on the trees that are planted along the road. (don't get me wrong: I like trees)

2) another effect which is very annoying and normally completely neglected by road designers: in many cases cycle paths are being constructed in a way that you have to pedal against  the car flow on the "wrong" side of the road, i.e. you get the full blast of the assymmertic headlights of the oncoming motor vehicles on the main carriageway. Your are effectively blind even with high level of surface illumination. This is the price you pay two have two-way cycle paths on one side of the road (which is the desired situation from the daytime-use point of view).


On Sat, 6 Jul 2019 at 15:05, bkil <bkil.hu+[hidden email]> wrote:
In many parts of Hungary, vegetation can overshadow street lights,
especially if they are placed high enough. They may make efforts to
protect roads against this, but they rarely consider footways. Hence I
know a lot of streets where road illumination is fair, but the
sidewalk right beside it (maybe 1-2m from the road) is dark along the
majority of the road.

I also agree with Martin's definition of being lit and I usually do it
like that.

I don't split ways by the centimeter to specify illumination - if a
stretch of path has too many shadows, you need to bring your own
lights anyway, so I consider that not being lit.

On Sat, Jul 6, 2019 at 2:39 PM Martin Koppenhoefer
<[hidden email]> wrote:
>
>
>
> sent from a phone
>
> > On 6. Jul 2019, at 14:07, Tobias Zwick <[hidden email]> wrote:
> >
> > The least subjective definition is to map the physical presence of street lanterns on the way, not the light they emit. (This definition (though) would mean that a footway close to a lit street would be mapped as unlit as long as it does not have own lanterns.)
>
>
> the presence of street lights indicates the road could be lit, it has no implications whether it is actually lit. For example last summer I went to an island where all streets had relatively new street lights, but half the island they kept them off so that light pollution was reduced.
>
> In small villages in Germany, street lights are often turned off at a certain time (e.g. after 23h), etc.
>
>
> Cheers, Martin
> _______________________________________________
> Tagging mailing list
> [hidden email]
> https://lists.openstreetmap.org/listinfo/tagging

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