[OSM-talk] Rocky beaches

[Steve Hill]

On Mon, 14 Apr 2008, OJ W wrote:

> Just looking at wikipedia, they say that beaches need to be formed by
> gradual deposit of solids from dissolved in waves, which means (a) rocky
> shorelines might not be a beach, and (b) definition of beach is confusing
> enough that "rocky surface covered by tidal water" is a nice neat
> unambiguous description of the feature.

I'd suggest we depricate natural=beach and recommend people use 
surface=foo, water=tidal instead.  I'm not a big fan of putting ambiguous 
(or arbitrarilly decided) stuff on the map - far better to have hard facts 
such as what the surface is like and whether it is tidal and let the 
renderers decide how to render it.

Of course this brings up an interesting question - do we have beaches 
around large non-tidal lakes?  If so, maybe we still need a natural=beach 
tag (or equivalent) for them?

> Whether anything renders it is another matter... ;)

I don't think anything does.  Osmarender certainly seems to ignore the 
surface tag when rendering natural=beach.  A sensible way of rendering 
would probably be:

1. If it is tagged as water=tidal then there must be a surface tag and we 
can render it appropriately.
2. If it is tagged as natural=beach but there is no surface tag, assume it 
is sandy.
3. If it is tagged as natural=beach and there is a surface tag, render the 
appropriate surface.

Most professional maps do a good job of blending the different surface 
types together (e.g. where rocky areas meet sandy beaches) - presumably 
this is hand-crafted by the map makers and I'm not sure we can convince 
Mapnik and Osmarender to do a good job (but anything is better than the 
nothing we currently have :).

  - Steve
    xmpp:steve at nexusuk.org   sip:steve at nexusuk.org   http://www.nexusuk.org/

      Servatis a periculum, servatis a maleficum - Whisper, Evanescence