Thanks Gabriel,

In our JWS-rich client we use a mix of GeoServer/GWC map tiles for easily 
cacheable background static "base map" data for roads, lakes, etc., and vectors 
for active communications data (what the tool is used for). We find 22 levels 
of zoom to be reasonably adequate for this type of data, and simply stop 
requesting additional levels at 22 and just "blur zoom" them for tighter views. 
Although a single world-wide tool (USAF), we track items such as inner-ducts as 
small as about 1cm, with multiple fiber optic cable sheaths entering them. Our 
effective resolution goes down to about 0.001 meters (about the limit of Oracle 
spatial filters in a geodetic coordinate system). So we are close to you singe 
(worldwide) GIS dataset - only being off back a factor of 10. Yes - we really 
have pushed the limits ;-)

I agree that more than a level 24 would be pretty odd, unless the user had a 
very small geographic area with some very high precision data they wanted to 
tile for some reason. I would think that 24 would be a sane default limit, with 
a documentation note on how to up that "just in case". 

Yes we only have one main map tile layer in use, which uses multiple style 
hints for the 40 or so vector layers which go into making it up. >From a 
continental view showing things like interstate highways as lines and oceans, 
down to a state view showing city points and urban areas with state highways 
and large roads of various widths and colors, to neighborhood views with local 
streets and parking lots as polygons, etc.

Regards,

Bryan


-----Original Message-----
From: Gabriel Roldan [mailto:[email protected]] 
Sent: Wednesday, April 18, 2012 5:20 PM
To: Hall, Bryan D Civ USAF AFSPC 38 OSS/OSM
Cc: [email protected]
Subject: Re: [Geoserver-users] GeoServer 2.1.3 and GWC Tile Zoom Limit

Hi Bryan,

glad you figured it out.
For the record, GWC's 900913 gridset used to come with 31 zoom levels.
That means up to 0.0001m pixel resolution, which also means a full
coverage of 1000 billions x 1000 billions tiles at the higher zoom
level. Which, if my math is correct, means a fully seeded layer with a
rather small average tile size of 4KB would take more than 3.7 billion
terabytes. Besides I don't think there's a single GIS dataset with a
spatial resolution of 1x10-4m.
The WMTS spec defines it up to zoom level 18. That proved to be too
low for some users, so on trunk we restored back the gridset
definition to its original shape. But I still think it wouldn't make
sense for zoom level > 24 (i.e. almost 1mm spatial resolution), which
is still 33.5M x 33.5M tiles at full world coverage. Which still would
be 4 billion terabytes for the highest zoom level with 4KB tiles.
Hopefully you define your layers with a restricted number of zoom
levels. But it'd make sense to have something saner as a default
value, hence the idea on limiting the number for pre-defined zoom
levels, although you can extend them if you want.

Cheers,
Gabriel

On Wed, Apr 18, 2012 at 5:41 PM, Hall, Bryan D Civ USAF AFSPC 38
OSS/OSM <[email protected]> wrote:
> That figures… after I give up and write that email, I find the answer:
>
>
>
> http://osgeo-org.1560.n6.nabble.com/GeoServer-tiles-generation-issue-above-zoom-level-18-in-Google-Maps-td4356763.html
>
>
>
> I just had to extend it to level 22, and it works fine now. After the server
> upgrade, I’ll write something up on this.
>
>
>
> Regards,
>
>
>
> Bryan Hall
>
>
>
>
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-- 
Gabriel Roldan
OpenGeo - http://opengeo.org
Expert service straight from the developers.

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