[OSM-talk] Abuse of natural=cliff tag

Warin 61sundowner at gmail.com
Sat Sep 14 09:26:11 UTC 2019

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
>> <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.

I have just been walking in an area of vertical or near vertical (both + and - from vertical) sandstone cliffs.

In some places, part way up the cliff face, you can see groups of trees growing in the rock face.

Viewed from directly above there would not be much rock to map .. it is mostly trees.

There are far larger areas mapped as trees .. that are not trees. I'll concentrate on the bigger areas.

The cliffs are mapped, some not well.

>   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).

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