Using Mapserver to generate google like tiles

[Frank Warmerdam]

On 5/5/05, Paul Ramsey <pramsey at refractions.net> wrote:
> I think there is a more elegant solution to the "google maps speedup"
> problem:
> 
> - The reason google maps is "fast" is because (a) they restrict
> themselves to fixes scales in their UI and (b) they load in the map in
> parallel chunks of 128x128 size.
> 
> So the answer:
> 
> - Write a google maps style client that forces a limited number of fixed
> scales, and always generates tiled WMS requests using the same
> coordinates for each tile.
> - Place a caching proxy between your Mapserver and the world, and tell
> your client to always make requests to the caching proxy.
> 
> Most of the work is doing the fancy google maps style javascript client.

Paul, 

I like the idea of just using a conventional http proxy caching system. 
However, I don't think your approach fully addresses the concern of
continuity between tiles.  Due to the label placement logic of MapServer
it is very hard to be sure that multiple "tile" requests by WMS will have
compatible label placement which results in chopped off labels, and
other anomolies from a straightforward use of mapserver for generating
the tiles. I think the idea of generating a much bigger region and either
just cutting out the center, or cutting up bigger regions would give much
better continuity between tiles. 

Forgive me if I am stating the obvious. 

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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