[OSM-talk] osmarender slippy map rendering

[80n]

On 4/26/07, Lars Aronsson <lars at aronsson.se> wrote:
>
> 80n wrote:
>
> > This is an intentional style.  As you zoom in place-names get
> > bigger but also become semi-transparent.  At some level they
> > become invisible, ideally when the extent of the place is larger
> > than the viewport.
>
> I like this, but there are two things to wish for:
>
> 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.
>
> 2. Tiles at home renders place=city as grey text at zoom=12, which
> means it should be black at zoom=11.  But t at h doesn't go that far.
> Instead, zoom=11 is created by lowzoom.pl by scaling down the
> zoom=12 image.  The result is that at zoom=11, =10 and =9 you see
> the town names (population 10,000 - 100,000) a lot better than
> city names.


Perhaps there should be a secondary version of each z12 tile that is used
just as the source for lowzoom.  This secondary version could have solid
black city names, thicker and bolder motorways, and leave out a lot of the
detail that is currently in the primary z12 tiles.

With the layer support that is now available in t at h this should be quite
feasible.


In combination, these wishes suggest that a place=megacity should
> be printed with a very large font, spanning very many tiles.
> This is of course problematic with respect to performance.
> Changing the megacity name would cause many tiles to be rendered.
> And rendering one tile would require a search of a large
> neighborhood (outside the current tile) for any megacities, parts
> of the names of which could touch this tile.  Rendering megacity
> names would also only affect zoom levels 7--11, which today aren't
> covered by the proper tiles at home, but by lowzoom.pl.  But perhaps
> a list of megacities (there really aren't that many in this world)
> could be extracted from the weekly planet.osm and supplied in svn
> as part of lowzoom.pl ?


Perhaps what's needed is a way of requesting a bbox for a much larger area
but only for nodes with selected tags (just megacity, county, state, and
country).  This can then be combined at the client end with the data for a
single z12 tile.

If the main OSM server is unable to do this then a separate mini-database of
just these nodes could be created from planet.osm and interrogated
separately.  They wont change very much so having them updated once a week
wouldn't be a big problem.

By the way, how are place=country names treated today?






--
>   Lars Aronsson (lars at aronsson.se)
>   Aronsson Datateknik - http://aronsson.se
>
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