Hi everyone,
I’d like to ask if some of you would be willing to test something for me? I’d like to narrow down a problem that I’m seeing with tiles generated by TileCache from MapServer. All it takes is for you to load a large artificial image into GeoServer, and then make a WMS request with very specific bbox extents. I’m not sure at the moment if the problem is the result of the renderer, or is a projection problem. Having the test done with another renderer would be very useful.
Below are the steps needed to do the test.
Step 1. Create a large rectangular image of Size 14400 x 7200 pixels.
Step 2. Assign georeferencing to the image:
gdal_translate -a_ullr -180 90 180 -90 -a_srs “EPSG:4326” big_black.tif wgs84_big_black.tif
Step 3. Load this image into some sort of WMS rendering system.
Step 4. Make sure you have the spherical mercator projection defined in your epsg file.
<900913> +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs <>
Step 5. Make a WMS request for a tile that replicates one that TileCache makes:
http://localhost/cgi-bin/mapserv?map=/var/www/mapfiles/test/test.map
&layers=imagery
&srs=EPSG%3A900913
&version=1.1.1
&bbox=-20037508.34%2C-
20037508.34%2C-10018754.1704%2C-10018754.1704
&service=WMS
&width=256
&styles=
&format=image%2Fpng
&request=GetMap
&height=256
Step 6. Save the image and inspect it to see if there is data from top to bottom (using a contrasting background color is useful).
Thanks very much,