On Thu, Nov 22, 2007 at 10:00:19AM +0000, David Herbert wrote: > Apologies for cross-posting this - not sure quite where it belongs. > > While using Firebug (Firefox 2.0.0.9 WinXP) to look at performance and > client-side memory usage of my OpenLayers 2.5 app (which uses Tilecache > 1.9 in standalone server mode with a seeded cache of WMS layer images), > I noticed a large number (50+) failed 404 responses for images 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=-82000,-43494.81471999999,-30705.185279999998,7800.000000000015&WIDTH=256&HEIGHT=256 > > Now the BBOX values being asked for in this request are way outside the > bounds I have specified in tilecache.cfg - here is the extract for the > above layer: > > [Coastline and bathymetry] > type=WMSLayer > url=http://10.48.1.76:8080/geoserver/wms?transparent=off > layers=sggis:bathy_poly,sggis:coastline2007 > extension=png > #extent_type=loose > bbox=-82000,7800,80000,116000 > maxResolution=200.370370 > srs=EPSG:2007056 > metaTile=true > > (The coordinates are a metre projection for South Georgia in the > Southern Ocean). Tilecache correctly reports this with the following > error: > > An error occurred: Lower left corner (-82000.000000, -43494.814720) is > outside layer bounds [-82000.0, 7800.0, 80000.0, 116000.0]. > To remove this condition, set extent_type=loose in your configuration.
What is the maxextent of your OpenLayers Map? OpenLayers shouldn't request tiles outside your maxExtent: If it is, I would suggest rounding off your maxResolution (in TC and OpenLayers) -- floating point errors can cause OL to request tiles it shouldn't. (I'm hoping you're not using 'displayOutsideMaxExtent'.) I think you've hit a couple things: the bug in TileCache, below, and what sounds to me like a configuration change needed in your OpenLayers setup. I'd recommend we omit the latter for now -- it's annoying, but *shouldn't* be affecting you -- and concentrate on how to fix your OL configuration issue -- which means followups should go to OL-Users. > An HTTP 404 response is generated. If I do as the error suggests and > set extent_type=loose (uncomment the line above) then I notice a marked > drop in performance - one layer takes half a minute to load from the > cache for some reason. There are also 20-30 HTTP 500 responses which > generate the error: Right. This is a bug in Tilecache that I haven't fixed: metaTiling results in requests outside the bounding box failing, so each tile is requested, others wait to get the lock, then they're requested, etc. in sequential order. Regards, -- Christopher Schmidt MetaCarta _______________________________________________ Users mailing list [email protected] http://openlayers.org/mailman/listinfo/users
