[Tilecache] help with openlayers+tilecache?

Christopher Schmidt crschmidt at metacarta.com
Wed Feb 11 17:45:41 EST 2009


On Wed, Feb 11, 2009 at 12:24:31PM -0800, Gregor at HostGIS wrote:
> Christopher Schmidt wrote:
> >These are the numbers used throughout all the OpenLayers Spherical
> >Mercator documentation:
> >  http://docs.openlayers.org/library/spherical_mercator
> 
> Hey, they hid it in the examples! :) 

Hm? "This map has a set of assumptions about the maxResolution of the
map. Specifically, most spherical mercator maps use an extent of the
world from -180 to 180 longitude, and from -85.0511 to 85.0511 latitude.
Because the mercator projection stretches to infinity as you approach
the poles, a cutoff in the north-south direction is required, and this
particular cutoff results in a perfect square of projected meters. As
you can see from the maxExtent parameter sent in the constructor of the
layer, the coordinates stretch from -20037508.34 to 20037508.34 in each
direction."

I'm not sure how that's 'hiding'; can you propose more clear text to
help the situation? (A patch would be nice if you can pull one off;
prose is fine if you can't.) 

Regards,
-- 
Christopher Schmidt
MetaCarta



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