I have attempted to change a dam from a simple way to an area to allow me to add a path crossing it [1]. So I took the original way, added nodes to make it an area, put steps going down from the upper road, a path across the dam joining the steps to the lower road. The steps and the path render properly, and the name of the dam shows, but not the dam itself.
What can I do to make the dam render properly?
Many thanks
Mohamed (RetiredInNH)
Am 31.08.2013 15:48, schrieb Mohamed Ellozy:
I have attempted to change a dam from a simple way to an area to allow me to add a path crossing it [1]. So I took the original way, added nodes to make it an area, put steps going down from the upper road, a path across the dam joining the steps to the lower road. The steps and the path render properly, and the name of the dam shows, but not the dam itself.
What can I do to make the dam render properly?
Many thanks
Mohamed (RetiredInNH)
[1] http://www.openstreetmap.org/#map=19/46.46421/7.06530
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Hallo Mohamed,
your tagging is correct. According to the wiki-page you even don't need area=yes, because closed ways should automatically handled as areas.
The problem is the rendering style or mapnik itself. There is not ONE correct rendering style, but every map could have his own style. Every map can decide what to render and what to ignore. But in this case you are talking about the style from openstreetmap.org. This syle renders waterway=dam as a way, but not as an area. This could be an error. Errors in this rendering syte can be reported at https://trac.openstreetmap.org. in this case this problem is already reported two years ago: https://trac.openstreetmap.org/ticket/3985
So you should not change the OSM data, but you can try to force the bug report or provide your own patch :-). Or just wait and hope sombody else will fix the problem in the future ...
regards
mdk
Hi,
On Sat, Aug 31, 2013 at 09:48:15AM -0400, Mohamed Ellozy wrote:
I have attempted to change a dam from a simple way to an area to allow me to add a path crossing it [1]. So I took the original way, added nodes to make it an area, put steps going down from the upper road, a path across the dam joining the steps to the lower road. The steps and the path render properly, and the name of the dam shows, but not the dam itself.
What can I do to make the dam render properly?
Dams are currently not rendered as an area, they have never been. The example map on the wiki looks suspiciously like a photoshop job. And there is an open ticket about dams: https://trac.openstreetmap.org/ticket/3985 which might be tackled in the next few months (no gurantees though).
I'd leave the mapping as an area as it is for now even if it is not rendered. It is not wrong and seems to be quite common practise.
There is also the option to add things like that to the Swiss style on osm.ch. If anybody is interested in looking into that. let me know.
Sarah
Many thanks ... merci vielmal ... merci beaucoup ... for your prompt responses. I will leave it as it is, we do not tag for the renderer!
Mohamed (RetiredInNH)
Hi Mohamed,
On 31.08.2013 16:53, Sarah Hoffmann wrote:
What can I do to make the dam render properly?
I'd leave the mapping as an area as it is for now even if it is not rendered. It is not wrong and seems to be quite common practise.
On 31.08.2013 19:56, Mohamed Ellozy wrote:
I will leave it as it is, we do not tag for the renderer!
"Don't tag for the renderer" is a general rule of OSM, which actually means "Don't deliberately enter data incorrectly for the renderer".
Personally I prefer to speak in a way that can be understood by the people I'm speaking to and in the same vein, I prefer to tag my data in a way that can be understood by my favourite OSM maps. So I can understand that it's frustrating if your work is ignored by a map that you care about.
One way to deal with it would be to draw the dam as a simple way instead of an area and tag it with waterway=dam and highway=*. 1136 or 1.21% percent of dams worldwide are tagged this way, e.g. in Montsalvens (http://www.openstreetmap.org/browse/way/37300714).
Having said all that, I'd like to add that your dam renders perfectly well on the latest OpenMTBmap (see attachment), so there are some renderers and maps out there that can make sense of dams as areas.
Best regards, Thorsten (Shernott)
Thorsten,
Many thanks for your helpful comments!
On Sat, Aug 31, 2013 at 2:02 PM, Thorsten Kurz tkurz@gmx.net wrote:
Hi Mohamed,
"Don't tag for the renderer" is a general rule of OSM, which actually means "Don't deliberately enter data incorrectly for the renderer".
Personally I prefer to speak in a way that can be understood by the people I'm speaking to and in the same vein, I prefer to tag my data in a way that can be understood by my favourite OSM maps. So I can understand that it's frustrating if your work is ignored by a map that you care about.
I certainly see your point here!
One way to deal with it would be to draw the dam as a simple way instead
of an area and tag it with waterway=dam and highway=*. 1136 or 1.21% percent of dams worldwide are tagged this way, e.g. in Montsalvens (http://www.openstreetmap.org/browse/way/37300714).
I was initially going to ask if that was legitimate, since it seemed the simplest solution. But I was not happy with that approach. I accept (not too happily) the highway=bridge construct, since the main purpose of the bridge is to carry the highway. But the purpose of the dam is not to carry the path :)
Mohamed,
I accept (not too happily) the highway=bridge construct, since the main purpose of the bridge is to carry the highway. But the purpose of the dam is not to carry the path :)
It probably depends on the granularity in which you are thinking. Some people approach OSM with the mindset of making a technical drawing and would love to enter all the details of the dam (ideally in three dimensions). My aspirations are much simpler and I think that sometimes it's not only ok but necessary to stylize in order to keep things simple and maintainable.
So is it the dam's purpose to carry the path? Of course not. ;-) But dam and path are physically and logically closely related. Like on a bridge the path runs on top of the dam, pretty much on the line where the dam and the water meet and without the dam there would be no path. Therefore I would even go a step further and make the way of the dam and path part of the multipolygon of the lake, to which it is also strongly related.
Thorsten (Shernott)
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Michael Kleidt -
Mohamed Ellozy -
Sarah Hoffmann -
Thorsten Kurz