[Tilecache] resolutions in getcapabilities not accurate

[Steven M. Ottens]

Hi all,

I'm building an application based on SharpMap, .Net based opensource  
GIS lib, which supports TileCache. It uses tilecache's capabilities  
document to get the available tilesets. In the capabilities document  
there's a list of resolutions, for instance:
http://labs.metacarta.com/wms-c/Basic.py? 
LAYERS=sigma&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetCapabilities

contains
<Resolutions>
0.703125000 0.351562500 0.175781250 0.087890625 0.043945312  
0.021972656 0.010986328 0.005493164 0.002746582 0.001373291  
0.000686646 0.000343323 0.000171661 0.000085831 0.000042915  
0.000021458 0.000010729 0.000005364 0.000002682 0.000001341
</Resolutions>
for the boston-freemap-remote-mapserver layer.

However if you would use these values you run into a problem at  
higher zoomlevels (14+ or so), since TileCache it self uses a more  
specific value:
It says 0.000171661 whereas tilecache.py uses actually  
0.000171661376953125
If you would use the advertised value you get an error:
An error occurred: Current x value 4.876447 is too far from tile  
corner x 4.877930
Which doesn't occur if you would use the more specific value.

To me this sounds as a bug and TileCache should either use the  
advertised value or advertise the actual used value. Since right now  
it's not possible to use the capabilities document for WMS-C to  
access a cache properly.

Regards,
Steven
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