[OSM-talk] Abuse of natural=cliff tag

Christoph Hormann osm at imagico.de
Wed Sep 11 14:13:12 UTC 2019


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
> <http://www.cesky-raj.info/en/contacts/bohemian-paradise-association/
>> 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/



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