Hi...<br><br>I've been unable to find a mailing list dedicated to TileCache (<a href="http://labs.metacarta.com/wms-c/">http://labs.metacarta.com/wms-c/</a>) but I've noticed other people posting questions about it here as well so I hope no one minds.
<br><br>I'm trying to get a system working with an OpenLayers front end, GeoServer on the backend with a tile cache in the middle. I chose TileCache because of its nifty meta-tiling feature which makes labelled layers look *much* better (by turning the 256x256px OpenLayers tile requests into larger requests).
<br><br>OpenLayers and GeoServer work just fine together but once I add TileCache to the equation things get nutty:<br><br>a) My first issue is that some of the tiles outside the normal bbox of my layer are rendered strangely. The first tile to the left of the bbox of the layer appears to be a duplicate of the one to the right. The tiles below the normal bbx of the layer appear to be duplicates (for the most part) of the tiles above. This behavior persists with metaTiling on or off. Everything looks fine without TileCache.
<br><br>b) The second issue is that with metaTile=true I start seeing broken images. Some tiles render fine (though with the same problem above when outside the bbox boundary) but others are broken. The error that TileCache reports for the broken images is:
<br><br><pre>An error occurred: Zero length data returned from layer.<br> File "/stuff/tilecache-1.3/TileCache/Service.py", line 399, in modPythonHandler<br> host )<br><br> File "/stuff/tilecache-1.3/TileCache/Service.py", line 384, in dispatchRequest
<br> return self.renderTile(tile, params.has_key('FORCE'))<br><br> File "/stuff/tilecache-1.3/TileCache/Service.py", line 363, in renderTile<br> else: raise Exception("Zero length data returned from layer.")
</pre>I added some debug statements to the TileCache code in order to determine the actual map request it was making to GeoServer. When I make the same request to GeoServer it returns the image just fine so I'm not sure what the actual problem is.
<br><br>The URLs being generated by TileCache with metatiling turned on weren't quite what I was expecting. Specifically the width and height are strange values. I'm using 256x256px tiles and using the default meta* options in TileCache and it's turning my 256x256px tile requests into requests of 1300x532px size. Can anyone explain that to me?
<br><br>Here's the tilecache.cfg file I'm using (note the custom resolutions due to me using a maxResolution setting of 0.5625 in openlayers):<br><br>[cache]<br>type=DiskCache<br>base=/tmp/tilecache<br><br>[basemap]
<br>type=WMSLayer<br>url=<a href="http://maphost:8081/geoserver/wms?BGCOLOR=0x7391AD">http://maphost:8081/geoserver/wms?BGCOLOR=0x7391AD</a><br>extension=gif<br>resolutions=0.5625,0.28125,0.140625,0.0703125,0.03515625,0.017578125
,0.008789062,0.004394531,0.002197266,0.001098633,0.000549316,0.000274658,0.000137329<br>metaTile=true<br>
<br><br>Any help would be much appreciated.<br><br>Regards,<br>Corey<br>