[Tilecache] everyblock use of tilecache & openlayers

[Christopher Schmidt]

On Thu, Jan 24, 2008 at 02:53:09PM +0000, Graham Carlyle wrote:
> interesting to note that Adrian Holovaty's new site EveryBlock uses
> OpenLayers & tilecache.
> 
> http://nyc.everyblock.com/streets/brooklyn/kent-ave/473-493/map/
> 
> wonder why they haven't used the multiple subdomains speedup trick to
> serve the images.
> 
> the images seem quite big as well for the amount of detail they contain,
> wonder if they used mapnik or mapserver to generate them.

They're Mapnik. Mapnik images should be post-processed -- a downsampling
after the initial load would be extremely helpful to anyone using the
images. I'm also still pondering whether we can hook in a generic
'post-process' hook for tiles -- the problem I'm having thus far is the
total inability to write anything to downsample them nicely in Python.
Imagemagick does great, and keeps the same general palette, but
everything else murders the tiles because it doesn't take into account
the pallette of the whole map. I did hack in, at one point, this
functionality, which then wrote the file out to disk, converted it using
imagemagick, then read it back in, but it felt so wrong I deleted the
code and haven't looked back :) I have played with downsampling the
tiles once htey're on disk -- with Mapnik, this has been very effective,
shrinking tile sizes by up to 70%.

Regards,
-- 
Christopher Schmidt
MetaCarta