[OpenLayers-Users] Re: [Users] [Geoserver-users] Geowebcache in openlayers problem:SOLUTION FOUND!

[Matt Priour]

Yep.
The maxExtent is instrumental in setting the grid lattice against which tiles will be requested.
Even if you just have data in a small area, unless you have also defined your cache such that it starts (ie level 0) at that area, then you need to make maxExtent match the maxExtent of the grid system you want.
In this case, you are using the web mercator (EPSG:900913 / EPSG:3857) grid system and the cache itself is not defined as a special subset of that grid system, therefore you need to use the global web mercator grid bounds to hit the cache in any kind of reasonable way.

As you have found the correct solution to limiting users interaction is to use restricted extent.

Matt Priour

From: Robert Buckley 
Sent: Friday, October 28, 2011 6:40 AM
To: geoserver-users at lists.sourceforge.net ; users at openlayers.org ; users at geoext.org 
Subject: Re: [Users] [Geoserver-users] Geowebcache in openlayers problem:SOLUTION FOUND!

Hi,

after taking my application apart and rebuilding line by line testing the results as I went along I found that when I replaced this line

maxExtent: new OpenLayers.Bounds(772338.842959, 6576723.127095, 1567283.936983, 7127069.730649),

..with 


maxExtent: new OpenLayers.Bounds(-20037508, -20037508,20037508, 20037508.34),

...everything lined-up and worked as wanted.



The bounds in the first line where an attempt to restrict my map area to this extent, which were then followed by an restrictedExtent.

Could anyone please explain to me why these bounds had such a devastating affect on the output of my geowebcache layer so that I can understand this better?

yours,

Rob

--------------------------------------------------------------------------------
Von: GeoGEOrge <awmlamp at yahoo.com>
An: geoserver-users at lists.sourceforge.net
Gesendet: 14:55 Donnerstag, 27.Oktober 2011 
Betreff: Re: [Geoserver-users] Geowebcache in openlayers problem

I am trying to do something similar, without much success.
you might see if this is related to your problem:

It is, however, very possible to create an OpenLayers application that
caches tiles; just make sure that the tileorigin aligns with the gridset.
from: http://docs.geoserver.org/latest/en/user/geowebcache/using.html

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