[OSM-newbies] layer essentials

Thomas Wood grand.edgemaster at gmail.com
Mon Nov 10 15:48:28 GMT 2008


2008/11/10 Ed Loach <ed at loach.me.uk>:
> Robert asked:
>
>> Also, does adding a bridge section with a layer of 1 mean
>> I should also tag the surface road with a layer of 0 or
>> is the default no tag (layer 0) good enough?
>
> I think no tag of layer 0 is good enough. I only add layer=1
> (usually; occasionally 2 on complicated junctions) to the bridge,
> and don't tag the layer 0 way(s).
>
> See
> http://wiki.openstreetmap.org/index.php/Key:layer
> and
> http://wiki.openstreetmap.org/index.php/Key:bridge
>
> Having said that, some tags assume certain layers I believe. I think
> for example landuse=<whatever> renders (at least in Osmarender) as
> layer -5 to be behind everything else.
Only for the internal layering structure - landuse areas are 'virtual
features' so should be rendered at the bottom of the stack, even
though they have no physical layering structure.

In short - only tag layer=* on physical features, not as a rendering hack.

> I'm sure I read somewhere that water features such as rivers and
> streams should be kept at layer 0 and any crossing ways then be set
> appropriately (something about water can't flow uphill to a higher
> layer), but I can't find that reference now.
I think that's the general view from mailing lists, I don't think its
explicitly documented anywhere though.



-- 
Regards,
Thomas Wood
(Edgemaster)




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