[OSM-talk] Area Support /Osmarender

[Chris Morley]

Ben Robbins wrote:
> This topic reminded me.  I have labeled ponds/water and woods.  But what do 
> I do if there are islands in the water, or the woods are shaped in a polo 
> shape?   I then need the island to be a negative area, where it 
> de-waters/woods it...
> 
On the dev list there has been discussion on how to represent areas: the 
current method where an area is just a way i.e. a collection of 
segments; or an ordered list of nodes. An island in a lake would be 
straightforward to represent using the node-list method: the default SVG 
rendering would put the hole in the polo correctly. You wouldn't need 
any devious work-arounds. (It does get a little more complicated for 
more than one island.)

When drawing areas with the way method you have to watch that all the 
segment directions are correctly aligned. This is annoying (direction 
has nothing to do with area) especially when the segments are also used 
for other features like roads. And it may not always be possible. 
Node-list representation does not have this difficulty.

The opportunity to use the node-list method for areas is danger of being 
lost as areas become increasingly popular. Actually the two methods 
could co-exist. But even if the node-list method is not implemented, at 
least the <area> element should be reserved so that could be later.

Chris