Openstreetmap-carto: Render natural=stone

[polarbearing]

wiki: https://wiki.openstreetmap.org/wiki/Tag:natural=stone
usage: 16.5k, of which 13.7k on nodes, 2.6k on ways, 3.3k with names

Rendering proposal: a dot, like barrier=block

Slightly related to #2616.

[kocio-pl]

Probably similar to natural=rock rendering proposition: #2616

Both are quite popular and the difference is that one is attached to the bedrock, while the second one is not. How to show the difference on the map?

[polarbearing]

Are we obliged to show the difference?

[kocio-pl]

Nope, we don't have to, it's just better for the feedback if we can.

[Tomasz-W]

We could use the same icon for both rocks and stones, but it would be good if somebody make a research for potential places where rendering natural=stone would cause map clutter.

https://gist.github.com/Tomasz-W/e2bcbebf5f5ebb05c01272ba16325d24

[kocio-pl]

Maybe we could show the difference only for nodes - here is how JOSM shows them:

https://github.com/openstreetmap/josm/blob/6d4bcded2b6c2efb1a0f12354cf7493bcd6f4e42/images/presets/misc/rock.svg

https://github.com/openstreetmap/josm/blob/6d4bcded2b6c2efb1a0f12354cf7493bcd6f4e42/images/presets/misc/stone.svg

[wilmaed]

Here my Proposal for nodes.

14px Stone:

SVG:
https://github.com/wilmaed/foo/blob/master/stone.svg

14px Rock

SVG:
https://github.com/wilmaed/foo/blob/master/rock.svg

14px Cairn (Pile of Stones)

SVG:
https://github.com/wilmaed/foo/blob/master/cairn.svg

man_made=cairn
https://wiki.openstreetmap.org/wiki/Tag:man_made%3Dcairn

Usage of cairn: 3 744 Entries (Landmark for Hiking)
https://taginfo.openstreetmap.org/tags/?key=man_made&value=cairn

Wikipedia
https://en.wikipedia.org/wiki/Cairn

[kocio-pl]

I'm happy with all the proposed shapes and with adding cairns to the stack (thanks!). Since most of them are tagged on nodes anyway, common rendering on areas looks like a plausible solution to me.

[polarbearing]

I like the shapes too, and used cairns for orientation myself. Not sure what "common rendering on areas" means. If it means to render a symbol from both node or area, that's fine for me.
Remains the colour. For man_made=cairns, man_made grey would be obvious. Would that do for the other two?

[kocio-pl]

I meant the same abstract pattern for rock, stone and cairn areas, since areas are not too popular, so it's not a big loss for the feedback. See https://github.com/gravitystorm/openstreetmap-carto/issues/2616#issuecomment-446070453.

[polarbearing]

Understand. Are we talking about pattern + icon, or pattern only?

[kocio-pl]

I guess pattern only would be enough.

[polarbearing]

Thus a node gets one of the icons, and an area the pattern? I'd find that confusing, and I have found people micromapping 1 meter stones as an area.

[kocio-pl]

What would you propose instead?

[polarbearing]

Icon only, whether mapped as area or node. None of the 3 wiki pages sees them as a landcover. They are singular objects, more comparable to a mountain peak (regarding the singularity). Only 10% of rock or stone, and 1% of cairn are mapped as area anyway.

[kocio-pl]

It depends on how big the area is. If it's big usually, I would rather choose pattern, but if that's just for small groups of them, then single icon is OK for me. Who's gonna make some checks?

[kocio-pl]

Is anybody interested in coding it? It looks like we have a general idea how should it be depicted on the map.

[Adamant36]

I'll do it. It seems like an issue with a small chance of being derailed. So why not. At least for icons. I agree with @polarbearing that area's are probably unnecessary.

[Adamant36]

@wilmaed, it seems your icons aren't in 14px or they just aren't displaying correctly for some reason. Would you mind looking into it?

[wilmaed]

Would you mind looking into it?

I will resize the files

[wilmaed]

https://github.com/wilmaed/foo/blob/master/rock14.svg

[wilmaed]

https://github.com/wilmaed/foo/blob/master/cairn14.svg
https://github.com/wilmaed/foo/blob/master/stone14.svg

[Adamant36]

Thanks. Rock seems to be fixed at least. I'll check the other ones later when I get some time.

[jragusa]

I'm wondering about using two different icons for natural=stone and natural=rock. According to the wiki, the difference lies in the fact that natural=rock are attached to the bedrock. However, when looking to the photographs on the same page, photographs 2,3 and 4 look like to natural=stone. Please take a look especially at photo 3 (the block in grassland), how do you define that this block remains attach to the bedrock despite the grass cover ? Note also that block can outcrops like an iceberg, some part of the body could remains in the ground and people will guess that the block is attached to the bedrock.

Moreover, I do not see any reason to distinguish both stone and rock on a map for general purpose.

[wilmaed]

Maybe because of: rock can be larger and rawer?

https://www.quora.com/Whats-the-difference-between-rock-and-stone

One of the key characteristics of a rock is that is relatively large. They are also immovable. They are usually formed in raw form within or surface of Earth.
...
A stone can be lifted

"Rock more typically denotes the raw material that the planet earth is made of, especially in unfinished form; stone often denotes the material of an object that has been (or is intended to be) shaped by humans."

[jragusa]

I'm not a native English speaker so I can not really debate about the different meaning of stone and rock. The only available rule is the grain-size. Here you can find an example of chart extended to large blocks.

But again, what would be the improvement to differentiate _immovable_ rock to _movable_ stone on a map for a general purpose ? IMO it's superficial. It would fit to a map of risks but not to this style.

Moreover, I'm wondering about the process to create isolated block attached to the bedrock such figured in the wiki. You can find such features on a crest of a mountain, build by erosion, but not in a plain, excepted if the lithology is really different and again... IMO I suspect that all of these blocks are _movable_ stone but I can not confirm without knowing the area.

[jragusa]

An other problem is what does it mean _movable_ ? by human(s), a machine ? A block of few meter width can easily reach the ton. This definition is too broad to be applied accurately.
And again, _movable_ block can be semi-buried. No one will check in the ground if there is a contact with the bedrock.

[Adamant36]

It would be worth asking what the differences are in either the related wiki pages or even better the tagging mailing list. I'll wait to do anymore work on it until things are clarified. It seems to me there would be no way of knowing what rock is attached to the bedrock or not in most cases anyway and it seems like a superficial difference if there is. Except maybe in the case of rock outcroppings.

As far as I know in America a stone is a smaller rock. Whereas, a rock is usually larger and can't be moved, but I agree with @jragusa that its to broad a definition in this case.

[jragusa]

It's not just a tagging question, is it really necessary to differentiate both of them ? Especially with regard to #3635.

[Adamant36]

If they have different tags for different features, yeah. Some people say they are, some people say they aren't (others think the wiki isn't clear). Which is why it's a tagging question in my mind. So, worrying about #3635 at this point is putting the horse before the cart. There's no hurry to render it.