[OSM-talk] Mapnik Lowzoom TIles - proof of concept

Christoph Hormann chris_hormann at gmx.de
Sun Jun 30 08:27:32 UTC 2013


On Sunday 30 June 2013, Frederik Ramm wrote:
>
> I have updated these tiles with current data. (I had somehow lost the
> code that produced the tiles and had to reverse engineer my way back
> from the old tiles... the year-old tiles are still available from the
> layer switcher.)

Hello Fred,

what method did you use for resizing the tiles?  It seems to be 
different in the new and the old tiles emphasizing the line features 
now.

Since the tiles darken as you zoom out you are probably resizing in 
gamma corrected color space which is not such a good idea (for example 
Labrador is dissolving into the ocean as you zoom out).

A good starting point for resizing techniques in general is:

http://www.imagemagick.org/Usage/resize/

And when rendering the various area features at z=9 it would probably be 
best to turn off the area patterns like on the glaciers which just 
result in artefacts when scaling down.

Greetings,

-- 
Christoph Hormann
http://www.imagico.de/



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