[OSM-talk] Lough Neagh

[Frederik Ramm]

Hi,

>> "natural=lake" is not a common tag; for lakes, "natural=water" is
>> normally used.
>
> It's listed in the Mapnik osm.xml in SVN, and Tiles at Home seems to
> render it fine.

I checkd with the Map Features page in the Wiki before I posted; if  
"natural=lake" is common usage then maybe the Map Features page  
should be edited to reflect that.

>> tiles at home will soon switch over to "water on the right" rule for  
>> lakes
>> (and forests, and other stuff) as well, allowing the lake  
>> coastline to
>> be split in any number of connected fragments as long as water is  
>> on the
>> right, but you will achieve the best "cross-renderer" results if you
>> make the whole coastline one single way (while not going into four- 
>> digit
>> numbers of segments as this threatens to break things elsewhere).
>
> Ah. Now that might be a problem. It's just over 1000 segments IIRC.
> What will this break?

With the new API, each time someone requests an area that contains  
just one bit of the long way, the whole way with all segments and  
nodes will be returned. This causes excessive strain on the API in  
case of very long ways and led me to split all ways with > 500  
segments into smaller portions last weekend. But there was some  
criticism of that and I might yet revert some of the changes as far  
as they applied to lakes, because lakes with broken coastlines do not  
render nicely ATM.

The "four digits" I  spoke of are just a guess; nobody has given a  
fixed number and the API surely has no enforced upper limit - it's  
just that the more large ways you have and the larger they are, the  
system tends to become more fragile. A very fuzzy issue.

Jury's still out on how to properly handle such large objects (one  
way but not return all of it every time? multiple ways? ways joined  
in a common superway?) but if it works for you at the moment then  
just leave it as it is.

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00.09' E008°23.33'