[Tilecache] TC called if OL maxextent bigger than a particular layer's ?

[christopher.schmidt at nokia.com]

On Jun 22, 2010, at 3:42 PM, ext Marco Nijdam wrote:

> Hi Yves,
> 
> Not too sure about the OpenLayers implementation, but I would expect
> that the Layer's maxExtent could be different from the Map's maxExtent.
> I see the there is even a property in Layer whether to request tiles
> outside the Layer's maxExtent.
> 
> So why not set the Map's maxExtent to whatever you need, and keep the
> Layer.TileCache maxExtent to what you already have?

Only works if your layer is not a baselayer; otherwise, you're out of 
luck.

Some layers also have a tileExtent and layerExtent seperated;
I don't know which ones off the top fo my head.

-- Chris

> Kind regards,
> --
> -- Marco Nijdam
> --
> 
> As quoted from Yves Moisan:
>> Hi All,
>> 
>> We have a case where the maxExtent of our map needs to be larger than
>> the area for which we have air photos (the layers we are tilecaching).
>> Up to now, we have set both OL's maxExtent and tilecache.cfg's bbox
>> element of the layers in question to the same value, which is to say we
>> are deliberately restricting the map extent to the area covered by the
>> tilecached layer.  However we need to use a larger mapExtent than that
>> of the image layers, so the question is do we need to align the TC'ed
>> layers bbox with the new maxExtent ?  According to the docs
>> (http://tilecache.org/readme.html) there's no way around that.
>> 
>> We would of course like to avoid doing that because the series of images
>> we have is only a thin diagonal line in a huge bbox and we already have
>> way too many blank tiles already so making the maxExtent larger would
>> only generate more blank tiles.  Speaking of blank tiles, is there
>> another way than to specify a bunch of bboxes to separate
>> tilecache_seed.py calls to render only areas that have valuable info at
>> very high zoom levels ?  The idea is that in the very unlikely event
>> someone zooms in to level 10 in an area where ther is no image, the WMS
>> server will be called to render blank images and that should not be too
>> costly.  The most likely event of course is that people will zoom in
>> where there are visible images and that would be taken care of by a
>> series of bbox seeds.  How do people cope with OL.mapExtent > TC.bbox ?
>> 
>> TIA,
>> 
>> Yves
>> _______________________________________________
>> Tilecache mailing list
>> Tilecache at lists.osgeo.org
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>> 
> 
> 
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Regards,
-- 
Christopher Schmidt
Nokia