Re: [OSM-talk] Abuse of natural=cliff tag

[Warin]

On 12/09/19 00:13, Christoph Hormann wrote:

On Wednesday 11 September 2019, Vladimir Vyskocil wrote:

I read carefully your response and looked at the picture. I didn't
travelled exactly at this place but will go there in October !
However I've already been in Český ráj

Re: [OSM-talk] Abuse of natural=cliff tag

[Maarten Deen]

On 2019-09-12 06:30, Mark Wagner wrote:

On Wed, 11 Sep 2019 20:54:17 +0200
Vladimir Vyskocil  wrote:


> On 11 Sep 2019, at 20:20, Mark Wagner  wrote:
>
>
> On Wed, 11 Sep 2019 15:33:05 +0200
> Vladimir Vyskocil  wrote:
>
>> A even crazier area regarding the abuse of the cliff tag !
>>
>> https://www.openstreetmap.org/#map=15/50.9610/14.0724
>> 
>
> Doesn't look crazy to me.  From what I saw on the map, I expected
> there to be rock formations of the sort you'd find in south Utah.
> Switching to aerial imagery, I saw pretty much that, just with more
> trees.

https://www.openstreetmap.org/edit#map=20/50.96391/14.06867
 really ?


Really.  The lack of leaves-off imagery means I can't see what's under
the trees, but the shadows in some of the imagery options are not
inconsistent with the sort of stepped cliff it appears to be mapping.


Some imagery of the area: 



Not that I'm defending the tagging, it seems excessive to me, but the 
area is filled with cliffs.


Regards,
Maarten

___
talk mailing list
talk@openstreetmap.org
https://lists.openstreetmap.org/listinfo/talk

Re: [OSM-talk] Abuse of natural=cliff tag

[Mark Wagner]

On Wed, 11 Sep 2019 20:54:17 +0200
Vladimir Vyskocil  wrote:

> > On 11 Sep 2019, at 20:20, Mark Wagner  wrote:
> > 
> > 
> > On Wed, 11 Sep 2019 15:33:05 +0200
> > Vladimir Vyskocil  wrote:
> >   
> >> A even crazier area regarding the abuse of the cliff tag ! 
> >> 
> >> https://www.openstreetmap.org/#map=15/50.9610/14.0724
> >>   
> > 
> > Doesn't look crazy to me.  From what I saw on the map, I expected
> > there to be rock formations of the sort you'd find in south Utah.
> > Switching to aerial imagery, I saw pretty much that, just with more
> > trees.  
> 
> https://www.openstreetmap.org/edit#map=20/50.96391/14.06867
>  really ?

Really.  The lack of leaves-off imagery means I can't see what's under
the trees, but the shadows in some of the imagery options are not
inconsistent with the sort of stepped cliff it appears to be mapping.

-- 
Mark

___
talk mailing list
talk@openstreetmap.org
https://lists.openstreetmap.org/listinfo/talk

Re: [OSM-talk] Abuse of natural=cliff tag

[Vladimir Vyskocil]

> On 11 Sep 2019, at 20:20, Mark Wagner  wrote:
> 
> 
> On Wed, 11 Sep 2019 15:33:05 +0200
> Vladimir Vyskocil  wrote:
> 
>> A even crazier area regarding the abuse of the cliff tag ! 
>> 
>> https://www.openstreetmap.org/#map=15/50.9610/14.0724
>> 
> 
> Doesn't look crazy to me.  From what I saw on the map, I expected there
> to be rock formations of the sort you'd find in south Utah.  Switching
> to aerial imagery, I saw pretty much that, just with more trees.

https://www.openstreetmap.org/edit#map=20/50.96391/14.06867 
 really ?

> 
> (Is now tempted to map Bryce Canyon in excruciating detail.)
> 
> -- 
> Mark
> 
> ___
> talk mailing list
> talk@openstreetmap.org
> https://lists.openstreetmap.org/listinfo/talk

___
talk mailing list
talk@openstreetmap.org
https://lists.openstreetmap.org/listinfo/talk

Re: [OSM-talk] Abuse of natural=cliff tag

[Yves]

Vladimir, I see around https://www.openstreetmap.org/#map=15/50.9610/14.0724 an 
incredible work of micromapping, it can also look ugly in other context.
But OSM is glad to have climbing enthusiast in its ranks too! 
Probably worth opening an issue at 
https://github.com/gravitystorm/openstreetmap-carto the cliff pattern really 
looks messy.
Yves 

Le 11 septembre 2019 19:26:42 GMT+02:00, Vladimir Vyskocil 
 a écrit :
>Hi ! 
>
>> On 11 Sep 2019, at 15:33, Vladimir Vyskocil
> wrote:
>> 
>> A even crazier area regarding the abuse of the cliff tag ! 
>> 
>> https://www.openstreetmap.org/#map=15/50.9610/14.0724
>
>What I see there is far from reasonable and far for common sens, it is
>just wrong and mad...
>All this bad information about cliffs in that area ie what common sens
>think is a real cliff and what is explained in the openstreetmap wiki
>page about this tag impact the usability of the data and I even don’t
>talk about the rendering, we are not tagging for the renderer but we
>easily could see that this tag was not designed for this mess !
>
>Now have a look please at the Grand Canyon in USA, for example :
>
>https://www.openstreetmap.org/#map=14/36.0765/-112.1345
>
>
>This is useful information ! How do you think It had looked if every
>little stones or slopes were mapped as a cliff like it is in the area
>we are talking about ?
>
>Vladimir.
>
>> 
>> Vladimir.
>> 
>>> Le 11 sept. 2019 à 15:27, Vladimir Vyskocil
>mailto:vladimir.vysko...@gmail.com>> a
>écrit :
>>> 
>>> Hello Sarah,
>>> 
>>> I read carefully your response and looked at the picture. I didn't
>travelled exactly at this place but will go there in October ! However
>I've already been in Český ráj
>
>that is not too far from there and where the terrain is similar in many
>aspects.
>>> I still think that the usage of the tag is abused in this area…
>>> You may read the description of this tag here :
>>> 
>>> https://wiki.openstreetmap.org/wiki/Tag:natural%3Dcliff
>
>>> 
>>> «  A cliff  is a vertical or
>almost vertical natural drop in terrain topography as it occurs for
>example in form of coastal cliffs or escarpments. The face of the cliff
>usually consists of bare solid rock but can occasionally also consist
>of clay, compacted sand, ice or other solid materials.» 
>>> 
>>> 
>>> « 
>>> When not to use
>>> natural =cliff <>
>should not be used for ridges, i.e. crests where there is a significant
>drop in terrain to both sides and neither of them is close to vertical.
>Use natural =ridge
> or natural
>=arete
> instead. Also
>do not usenatural
>=cliff <> just for
>mapping an inclined bare rock surface, use natural
>=bare_rock
> instead.
>>> 
>>> " 
>>> 
>>> This is not what I see when I look at this mapped area, I agree that
>some mapped cliffs here are really what should be considered a cliff
>but they are lost in lots of wrongly mapped and not relevant ones. 
>>> 
>>> You might look at this as a example in many many more :
>>> 
>>> https://www.openstreetmap.org/#map=19/50.89893/14.28319
>
>>> 
>>> We are seeing it at level 19 and the density of cliffs is still
>crazy ! 
>>> 
>>> Or here : https://www.openstreetmap.org/#map=15/50.8791/14.3647
>
>>> 
>>> Could you tell me that all theses mapped cliffs really exists ? Or
>aren’t they just « a significant drop in terrain and neither of them
>are close to vertical » mapped as cliffs only looking at terrain model
>and that are completely disconnected from the reality of the terrain ?
>>> 
>>> Regards,
>>> Vladimir
>>> 
>>> 
>>> 
 Le 11 sept. 2019 à 00:17, Sarah Hoffmann > a écrit :
 
 Hi,
 
 On Fri, Sep 06, 2019 at 02:42:06PM +0200, Vladimir Vyskocil wrote:
> Around this area :
>https://www.openstreetmap.org/#map=16/50.9034/14.2763
>
>> there is a
>flagrant misuse and abuse of the usage of the natural=cliff tag. It is
>used to map the iso altitude lines and not real cliff as stated in the
>WIKI :
> 
> A cliff 

Re: [OSM-talk] Abuse of natural=cliff tag

[Mark Wagner]

On Wed, 11 Sep 2019 15:33:05 +0200
Vladimir Vyskocil  wrote:

> A even crazier area regarding the abuse of the cliff tag ! 
> 
> https://www.openstreetmap.org/#map=15/50.9610/14.0724
> 

Doesn't look crazy to me.  From what I saw on the map, I expected there
to be rock formations of the sort you'd find in south Utah.  Switching
to aerial imagery, I saw pretty much that, just with more trees.

(Is now tempted to map Bryce Canyon in excruciating detail.)

-- 
Mark

___
talk mailing list
talk@openstreetmap.org
https://lists.openstreetmap.org/listinfo/talk

Re: [OSM-talk] Abuse of natural=cliff tag

[Vladimir Vyskocil]

Hi ! 

> On 11 Sep 2019, at 15:33, Vladimir Vyskocil  
> wrote:
> 
> A even crazier area regarding the abuse of the cliff tag ! 
> 
> https://www.openstreetmap.org/#map=15/50.9610/14.0724 
> 
What I see there is far from reasonable and far for common sens, it is just 
wrong and mad...
All this bad information about cliffs in that area ie what common sens think is 
a real cliff and what is explained in the openstreetmap wiki page about this 
tag impact the usability of the data and I even don’t talk about the rendering, 
we are not tagging for the renderer but we easily could see that this tag was 
not designed for this mess !

Now have a look please at the Grand Canyon in USA, for example :

https://www.openstreetmap.org/#map=14/36.0765/-112.1345 


This is useful information ! How do you think It had looked if every little 
stones or slopes were mapped as a cliff like it is in the area we are talking 
about ?

Vladimir.

> 
> Vladimir.
> 
>> Le 11 sept. 2019 à 15:27, Vladimir Vyskocil > > a écrit :
>> 
>> Hello Sarah,
>> 
>> I read carefully your response and looked at the picture. I didn't travelled 
>> exactly at this place but will go there in October ! However I've already 
>> been in Český ráj 
>>  that 
>> is not too far from there and where the terrain is similar in many aspects.
>> I still think that the usage of the tag is abused in this area…
>> You may read the description of this tag here :
>> 
>> https://wiki.openstreetmap.org/wiki/Tag:natural%3Dcliff 
>> 
>> 
>> «  A cliff  is a vertical or almost 
>> vertical natural drop in terrain topography as it occurs for example in form 
>> of coastal cliffs or escarpments. The face of the cliff usually consists of 
>> bare solid rock but can occasionally also consist of clay, compacted sand, 
>> ice or other solid materials.» 
>> 
>> 
>> « 
>> When not to use
>> natural =cliff <> should 
>> not be used for ridges, i.e. crests where there is a significant drop in 
>> terrain to both sides and neither of them is close to vertical. Use natural 
>> =ridge 
>>  or natural 
>> =arete 
>>  instead. Also do 
>> not usenatural =cliff <> 
>> just for mapping an inclined bare rock surface, use natural 
>> =bare_rock 
>>  instead.
>> 
>> " 
>> 
>> This is not what I see when I look at this mapped area, I agree that some 
>> mapped cliffs here are really what should be considered a cliff but they are 
>> lost in lots of wrongly mapped and not relevant ones. 
>> 
>> You might look at this as a example in many many more :
>> 
>> https://www.openstreetmap.org/#map=19/50.89893/14.28319 
>> 
>> 
>> We are seeing it at level 19 and the density of cliffs is still crazy ! 
>> 
>> Or here : https://www.openstreetmap.org/#map=15/50.8791/14.3647 
>> 
>> 
>> Could you tell me that all theses mapped cliffs really exists ? Or aren’t 
>> they just « a significant drop in terrain and neither of them are close to 
>> vertical » mapped as cliffs only looking at terrain model and that are 
>> completely disconnected from the reality of the terrain ?
>> 
>> Regards,
>> Vladimir
>> 
>> 
>> 
>>> Le 11 sept. 2019 à 00:17, Sarah Hoffmann >> > a écrit :
>>> 
>>> Hi,
>>> 
>>> On Fri, Sep 06, 2019 at 02:42:06PM +0200, Vladimir Vyskocil wrote:
 Around this area : https://www.openstreetmap.org/#map=16/50.9034/14.2763 
  
 > there is a 
 flagrant misuse and abuse of the usage of the natural=cliff tag. It is 
 used to map the iso altitude lines and not real cliff as stated in the 
 WIKI :
 
 A cliff > is a vertical or almost vertical 
 natural drop in terrain topography as it occurs for example in form of 
 coastal cliffs or escarpments. The face of the cliff usually consists of 
 bare solid rock but can occasionally also consist of clay, compacted sand, 
 ice or other solid materials.  
>>> 
>>> I know that area very well and I can assure 

Re: [OSM-talk] Abuse of natural=cliff tag

[Martin Koppenhoefer]

Am Mi., 11. Sept. 2019 um 15:30 Uhr schrieb Vladimir Vyskocil <
vladimir.vysko...@gmail.com>:

> ... I didn't travelled exactly at this place but will go there in October !
>


great, so you can tell us more after you have visited the place. From what
I have seen here, I agree with Christoph and Sarah, and see no systematic
"abuse" of the cliff tag as defined in the wiki.

Cheers,
Martin
___
talk mailing list
talk@openstreetmap.org
https://lists.openstreetmap.org/listinfo/talk

Re: [OSM-talk] Abuse of natural=cliff tag

[Christoph Hormann]

On Wednesday 11 September 2019, Vladimir Vyskocil wrote:
>
> I read carefully your response and looked at the picture. I didn't
> travelled exactly at this place but will go there in October !
> However I've already been in Český ráj
> > that is not too far from there and where the terrain is similar in
> many aspects. I still think that the usage of the tag is abused in
> this area…

I suggest you be more specific here and point to individual features you 
consider inaccurately tagged as cliff.

I looked over the area and while i see some of the drawing of cliffs 
being a bit too slavishly drawn after the DGM there does not seem to be 
anything systematically wrong here.  Personally i think the focus on 
mapping details in cliffs is so far not adequately matched by a similar 
level in detail in landcover mapping - there are for example many 
cliffs mapped within a continuous forest area without there also being 
a bare_rock area mapped.  But it is every mapper's right to map 
selectively what they find interesting.

The mapping of cliffs strongly tied to the DGM leads to some derivations 
from the reality in situations like this with vertical or even back-cut 
rock faces where accurately mapped cliffs would often touch, near touch 
or even intersect and which the DGM essentially separates into a 
uniform stacking.  This is what you might have wrongly interpreted as 
contour line mapping with cliffs.  But IMO that is not really wrong, 
that is just somewhat inprecise (and really hard to do better 
practically).

-- 
Christoph Hormann
http://www.imagico.de/

___
talk mailing list
talk@openstreetmap.org
https://lists.openstreetmap.org/listinfo/talk

Re: [OSM-talk] Abuse of natural=cliff tag

[Vladimir Vyskocil]

A even crazier area regarding the abuse of the cliff tag ! 

https://www.openstreetmap.org/#map=15/50.9610/14.0724 


Vladimir.

> Le 11 sept. 2019 à 15:27, Vladimir Vyskocil  a 
> écrit :
> 
> Hello Sarah,
> 
> I read carefully your response and looked at the picture. I didn't travelled 
> exactly at this place but will go there in October ! However I've already 
> been in Český ráj 
>  that 
> is not too far from there and where the terrain is similar in many aspects.
> I still think that the usage of the tag is abused in this area…
> You may read the description of this tag here :
> 
> https://wiki.openstreetmap.org/wiki/Tag:natural%3Dcliff 
> 
> 
> «  A cliff  is a vertical or almost 
> vertical natural drop in terrain topography as it occurs for example in form 
> of coastal cliffs or escarpments. The face of the cliff usually consists of 
> bare solid rock but can occasionally also consist of clay, compacted sand, 
> ice or other solid materials.» 
> 
> 
> « 
> When not to use
> natural =cliff <> should not 
> be used for ridges, i.e. crests where there is a significant drop in terrain 
> to both sides and neither of them is close to vertical. Use natural 
> =ridge 
>  or natural 
> =arete 
>  instead. Also do 
> not use natural =cliff <> 
> just for mapping an inclined bare rock surface, use natural 
> =bare_rock 
>  instead.
> 
> " 
> 
> This is not what I see when I look at this mapped area, I agree that some 
> mapped cliffs here are really what should be considered a cliff but they are 
> lost in lots of wrongly mapped and not relevant ones. 
> 
> You might look at this as a example in many many more :
> 
> https://www.openstreetmap.org/#map=19/50.89893/14.28319 
> 
> 
> We are seeing it at level 19 and the density of cliffs is still crazy ! 
> 
> Or here : https://www.openstreetmap.org/#map=15/50.8791/14.3647 
> 
> 
> Could you tell me that all theses mapped cliffs really exists ? Or aren’t 
> they just « a significant drop in terrain and neither of them are close to 
> vertical » mapped as cliffs only looking at terrain model and that are 
> completely disconnected from the reality of the terrain ?
> 
> Regards,
> Vladimir
> 
> 
> 
>> Le 11 sept. 2019 à 00:17, Sarah Hoffmann > > a écrit :
>> 
>> Hi,
>> 
>> On Fri, Sep 06, 2019 at 02:42:06PM +0200, Vladimir Vyskocil wrote:
>>> Around this area : https://www.openstreetmap.org/#map=16/50.9034/14.2763 
>>>  
>>> >> > there is a 
>>> flagrant misuse and abuse of the usage of the natural=cliff tag. It is used 
>>> to map the iso altitude lines and not real cliff as stated in the WIKI :
>>> 
>>> A cliff >> > is a vertical or almost vertical 
>>> natural drop in terrain topography as it occurs for example in form of 
>>> coastal cliffs or escarpments. The face of the cliff usually consists of 
>>> bare solid rock but can occasionally also consist of clay, compacted sand, 
>>> ice or other solid materials.  
>> 
>> I know that area very well and I can assure you, that natural=cliff is no 
>> misuse
>> under this definition. The area is full of rock towers like those:
>> https://commons.wikimedia.org/wiki/File:20171124195DR_Lohmen_Basteiaussicht_zum_Sieberturm.jpg
>>  
>> 
>> 
>> That's what you see on the map.
>> 
>>> I already removed the natural=cliff ways mapped by MichaOSM after asking 
>>> him to fix this but without response the changeset comment was : 
>>> 
>>> "Felsen, Riffe, Topografie nach GeoSachsen digitale 
>>> Geländemodellhoehenlinien 2.5m, digitales Geländereliefmodell, DTK10, 
>>> topografische Karte”
>>> 
>>> For example this changeset : 
>>> https://www.openstreetmap.org/changeset/66373825#map=15/50.9016/14.3093 
>>> 
>>> 
>>> It say that it used a 2.5m topographic map to map all these false cliffs in 
>>> this area, he was mapping the topography (MNT) and this is 

Re: [OSM-talk] Abuse of natural=cliff tag

[Vladimir Vyskocil]

Hello Sarah,

I read carefully your response and looked at the picture. I didn't travelled 
exactly at this place but will go there in October ! However I've already been 
in Český ráj 
 that is 
not too far from there and where the terrain is similar in many aspects.
I still think that the usage of the tag is abused in this area…
You may read the description of this tag here :

https://wiki.openstreetmap.org/wiki/Tag:natural%3Dcliff 


«  A cliff  is a vertical or almost 
vertical natural drop in terrain topography as it occurs for example in form of 
coastal cliffs or escarpments. The face of the cliff usually consists of bare 
solid rock but can occasionally also consist of clay, compacted sand, ice or 
other solid materials.» 


« 
When not to use
natural =cliff <> should not 
be used for ridges, i.e. crests where there is a significant drop in terrain to 
both sides and neither of them is close to vertical. Use natural 
=ridge 
 or natural 
=arete 
 instead. Also do not 
use natural =cliff <> just for 
mapping an inclined bare rock surface, use natural 
=bare_rock 
 instead.

" 

This is not what I see when I look at this mapped area, I agree that some 
mapped cliffs here are really what should be considered a cliff but they are 
lost in lots of wrongly mapped and not relevant ones. 

You might look at this as a example in many many more :

https://www.openstreetmap.org/#map=19/50.89893/14.28319 


We are seeing it at level 19 and the density of cliffs is still crazy ! 

Or here : https://www.openstreetmap.org/#map=15/50.8791/14.3647 


Could you tell me that all theses mapped cliffs really exists ? Or aren’t they 
just « a significant drop in terrain and neither of them are close to vertical 
» mapped as cliffs only looking at terrain model and that are completely 
disconnected from the reality of the terrain ?

Regards,
Vladimir



> Le 11 sept. 2019 à 00:17, Sarah Hoffmann  a écrit :
> 
> Hi,
> 
> On Fri, Sep 06, 2019 at 02:42:06PM +0200, Vladimir Vyskocil wrote:
>> Around this area : https://www.openstreetmap.org/#map=16/50.9034/14.2763 
>>  there is a flagrant 
>> misuse and abuse of the usage of the natural=cliff tag. It is used to map 
>> the iso altitude lines and not real cliff as stated in the WIKI :
>> 
>> A cliff  is a vertical or almost 
>> vertical natural drop in terrain topography as it occurs for example in form 
>> of coastal cliffs or escarpments. The face of the cliff usually consists of 
>> bare solid rock but can occasionally also consist of clay, compacted sand, 
>> ice or other solid materials.  
> 
> I know that area very well and I can assure you, that natural=cliff is no 
> misuse
> under this definition. The area is full of rock towers like those:
> https://commons.wikimedia.org/wiki/File:20171124195DR_Lohmen_Basteiaussicht_zum_Sieberturm.jpg
> 
> That's what you see on the map.
> 
>> I already removed the natural=cliff ways mapped by MichaOSM after asking him 
>> to fix this but without response the changeset comment was : 
>> 
>> "Felsen, Riffe, Topografie nach GeoSachsen digitale 
>> Geländemodellhoehenlinien 2.5m, digitales Geländereliefmodell, DTK10, 
>> topografische Karte”
>> 
>> For example this changeset : 
>> https://www.openstreetmap.org/changeset/66373825#map=15/50.9016/14.3093 
>> 
>> 
>> It say that it used a 2.5m topographic map to map all these false cliffs in 
>> this area, he was mapping the topography (MNT) and this is forbidden in OSM.
> 
> You missunderstood, he was mapping rock edges. A terrain model is more helpful
> for that task than arial imagery. We have permission to use the terrain model
> for OSM as far as I know.
> 
> I would kindly request that you reinstate deleted natural=cliffs for
> the moment. If you are still not convinced from the photo above that the
> tagging is correct then we need to have a fundamental discussion first about
> how to tag these kind of rock towers. But that would rather be something for
> the tagging mailing list (or talk-de if you want to get the locals involved).
> 
> Sarah

___
talk mailing list
talk@openstreetmap.org

Re: [OSM-talk] Abuse of natural=cliff tag

[Sarah Hoffmann]

Hi,

On Fri, Sep 06, 2019 at 02:42:06PM +0200, Vladimir Vyskocil wrote:
> Around this area : https://www.openstreetmap.org/#map=16/50.9034/14.2763 
>  there is a flagrant 
> misuse and abuse of the usage of the natural=cliff tag. It is used to map the 
> iso altitude lines and not real cliff as stated in the WIKI :
> 
> A cliff  is a vertical or almost 
> vertical natural drop in terrain topography as it occurs for example in form 
> of coastal cliffs or escarpments. The face of the cliff usually consists of 
> bare solid rock but can occasionally also consist of clay, compacted sand, 
> ice or other solid materials.  

I know that area very well and I can assure you, that natural=cliff is no misuse
under this definition. The area is full of rock towers like those:
https://commons.wikimedia.org/wiki/File:20171124195DR_Lohmen_Basteiaussicht_zum_Sieberturm.jpg

That's what you see on the map.

> I already removed the natural=cliff ways mapped by MichaOSM after asking him 
> to fix this but without response the changeset comment was : 
> 
> "Felsen, Riffe, Topografie nach GeoSachsen digitale Geländemodellhoehenlinien 
> 2.5m, digitales Geländereliefmodell, DTK10, topografische Karte”
> 
> For example this changeset : 
> https://www.openstreetmap.org/changeset/66373825#map=15/50.9016/14.3093 
> 
> 
> It say that it used a 2.5m topographic map to map all these false cliffs in 
> this area, he was mapping the topography (MNT) and this is forbidden in OSM.

You missunderstood, he was mapping rock edges. A terrain model is more helpful
for that task than arial imagery. We have permission to use the terrain model
for OSM as far as I know.

I would kindly request that you reinstate deleted natural=cliffs for
the moment. If you are still not convinced from the photo above that the
tagging is correct then we need to have a fundamental discussion first about
how to tag these kind of rock towers. But that would rather be something for
the tagging mailing list (or talk-de if you want to get the locals involved).

Sarah

___
talk mailing list
talk@openstreetmap.org
https://lists.openstreetmap.org/listinfo/talk

[OSM-talk] Abuse of natural=cliff tag

[Vladimir Vyskocil]

Hi !

Around this area : https://www.openstreetmap.org/#map=16/50.9034/14.2763 
 there is a flagrant 
misuse and abuse of the usage of the natural=cliff tag. It is used to map the 
iso altitude lines and not real cliff as stated in the WIKI :

A cliff  is a vertical or almost 
vertical natural drop in terrain topography as it occurs for example in form of 
coastal cliffs or escarpments. The face of the cliff usually consists of bare 
solid rock but can occasionally also consist of clay, compacted sand, ice or 
other solid materials.  

When not to use

natural =cliff <> should not 
be used for ridges, i.e. crests where there is a significant drop in terrain to 
both sides and neither of them is close to vertical. Use natural 
=ridge 
 or natural 
=arete 
 instead. Also do not 
usenatural =cliff <> just for 
mapping an inclined bare rock surface, use natural 
=bare_rock 
 instead. 

I already removed the natural=cliff ways mapped by MichaOSM after asking him to 
fix this but without response the changeset comment was : 

"Felsen, Riffe, Topografie nach GeoSachsen digitale Geländemodellhoehenlinien 
2.5m, digitales Geländereliefmodell, DTK10, topografische Karte”

For example this changeset : 
https://www.openstreetmap.org/changeset/66373825#map=15/50.9016/14.3093 


It say that it used a 2.5m topographic map to map all these false cliffs in 
this area, he was mapping the topography (MNT) and this is forbidden in OSM.

Regards,
Vlad.___
talk mailing list
talk@openstreetmap.org
https://lists.openstreetmap.org/listinfo/talk