[OSM-talk] Indiscrimate layering

Sven Rautenberg sven at rtbg.de
Sat Dec 20 00:17:48 GMT 2008

David Earl schrieb:
> An anonymous user has being changing all bridges without layer tags to 
> layer=1 in my area. I suspect this is a bot.
> Because the continuity is better without changing layer along a road, 
> for streams I often set the stream to layer=-1, and leave the layer 
> alone and that is the case in many of these changes.

Please reconsider.

I hate it when I see rivers, streams etc. illogically marked as
layer=-1. There is no reason to do so, because a river usually is at the
top of the surface, and that is "no layer" or "layer=0".

Wherever a street crosses a stream, the street has to be split into the
normal part and the bridge part. As the layer tag is to help renderers
get the vertical ordering right, it is far less intrusive to add
"layer=1" to the bridge, instead of adding "layer=-1" to the stream,
because this layer usually applies to the whole way of the stream, most
likely affecting many other crossings of this stream.

Because the layer tag is only a relativ positioning, it's effects should
be kept as local as possible. That means to avoid tagging things with it
which are very long or very big.

> It looks like the change has been made blindly with no real reference to 
>   what the bridge is doing.

If the stream is layer=-1 and the bridge was layer=0 and is now layer=1,
I cannot see any problem here because nothing is broken.

> Humph. I'm going to change a lot of them back, but if this procedure is 
> run repeatedly this will be an edit war where I'm competing with an 
> anonymous robot.

Don't change it back, change it forward. Remove layer=-1 from the stream.


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