[OSM-dev] "Retina" tiles - best way to support them?

[Frederik Ramm]

Hi,

On 26.06.2012 23:05, Frederik Ramm wrote:
> 3. Modify style as per 1., double size of meta tiles to 4096x4096, and
> double size of tiles to 512x512. This avoids the increase in font
> nastiness *and* it has the nice effect that one "Retina" tile at a
> certain zoom level shows exactly the same content as a normal tile, just
> on 512x512 instead of 256x256 and therefore at twice the resolution. It
> would, however, require clients (OpenLayers et al.) to work with the
> larger tile size.

I just tried this out and found that, on a standard non-mobile Firefox 
browser, OpenLayers displays the new 512x512 tile just fine, it scales 
it to 256x256 in the browser. I can then use the browser's "zoom" 
function to blow up the OpenLayers display and while everything becomes 
jaggy when I do this with normal tiles, the map still looks nice when 
using the double resolution tiles. Does this mean that it would be an 
acceptable viewing experience for mobile users as well?

mod_tile does not require modifications to work with 512x512 tiles; 
Tirex requires a couple. Also, I'm running this on the standard OSM 
style and Mapnik 2.0 using the AGG renderer's "scale factor" parameter 
and it doesn't scale shields or bitmap icons; I'll see if that's any 
better with 2.1 - else I'll have to do the old style "take xml and 
double all the sizes" route.

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"