[OSM-talk] osmarender slippy map rendering

[Tom Chance]

Ahoy,

On Thu, 26 Apr 2007 10:42:23 +0200 (CEST), Lars Aronsson <lars at aronsson.se> wrote:
> 1. The current definition of a place=city is one with more than
> 100,000 inhabitants.  This Malmö, Helsinki, Cambridge, Oxford and
> a lot of places.  But we should need another level for places
> bigger than 1 million inhabitants like Copenhagen, Riga, London
> and Berlin.  The current city names look small for these places.
> [snip]
> In combination, these wishes suggest that a place=megacity should
> be printed with a very large font, spanning very many tiles.

Actually, the population-based definition is still controversial. In the UK we seem to be sticking to the official classiciation system, which is silly and complicated, but means a tiny place like St Davids, a medium town like St Albans, a London Borough like Westminster and a sizeable city like Manchester are all technically cities. Actually Manchester may be a metropolis, I forget. This does mean the slippy map at the moment is a bit silly in the places it shows in the UK when zoomed out :)

How can we denote a big place? Physical area, population, political importance, official classification, position in the transport infrastructure, historical importance, other criteria? In my opinion it would be useful to collect each of these where a good schema can be concocted. As for rendering, either rely on some snazzy algorithm that combines then, or just introduce another fairly subjective tag for rendering priority with particular maps, like renderPriority:road=1/2/3/4/5/6 with a specified style at each zoom level for each value.

Until there is some conclusion to the wider question I'd oppose the introduction of the megacity value for "place=".

Regards,
Tom