[OpenLayers-Users] Problems with OpenLayers overview map

[David Herbert]

(Apologies for posting to both lists - not sure which one it belongs
in!).

I have Tilecache 1.9rc3 running as a CGI, and have had trouble getting
my OpenLayers overview map to display anything since.  If I look in
Firefox at pageinfo->media, I find that the tiles which should have
displayed my overview map are zero length, and if I type one such URL
e.g:

http://10.48.1.76:8084/?LAYERS=Coastline%20and%20bathymetry&STYLES=sggis_bathymetry_polygon%2Csggis_coastline&FORMAT=image%2Fpng&TRANSPARENT=off&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&EXCEPTIONS=application%2Fvnd.ogc.se_inimage&SRS=EPSG%3A2007056&BBOX=-1616%2C61560%2C-1104%2C62072&WIDTH=256&HEIGHT=256

into the browser, I get the following error:

An error occurred: can't find resolution index for 2.000000. Available
resolutions are: 
[200.37037000000001, 100.185185, 50.092592500000002,
25.046296250000001, 12.523148125000001, 6.2615740625000003,
3.1307870312500001, 1.5653935156250001, 0.78269675781250003,
0.39134837890625002, 0.19567418945312501, 0.097837094726562504,
0.048918547363281252, 0.024459273681640626, 0.012229636840820313,
0.0061148184204101565, 0.0030574092102050783, 0.0015287046051025391,
0.00076435230255126956, 0.00038217615127563478]

The overview map is given the following options:

var sgOverviewOpts = {
    'maxExtent' : new OpenLayers.Bounds(-82000,7800,80000,116000),     
 
    'maxResolution' : 200.370370,     
    'minResolution' : 0.5,
    'units' : 'm',
    'projection' : EPSG:2007056   
};

var overview = new OpenLayers.Control.OverviewMap(sgOverviewOpts);
map.addControl(overview);

which are the same as I give my Coastline/bathymetry base layer. My
tilecache.cfg contains the following for the same layer:

[Coastline and bathymetry]
type=WMSLayer
url=http://10.48.1.76:8080/geoserver/wms?transparent=off
layers=sggis:bathy_poly,sggis:coast_polygon
extension=png
bbox=-82000,7800,80000,116000
maxResolution=200.370370
srs=EPSG:2007056

Regular tiles for the map appear fine.  It's just when tiles are
fetched for the overview map that the problems arise.  Any idea how I
get round this?  

Thanks for any help,

David Herbert
British Antarctic Survey.

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