Just in case someone else wants to see this for themselves, here are the steps needed to replicate the condition I'm seeing.<br><br>Step 1. Create a large rectangular image of Size 14400 x 7200.<br>
<br>
Step 2. Assign georeferencing to the image:<br>
gdal_translate -a_ullr -180 90 180 -90 -a_srs "EPSG:4326" big_black.tif wgs84_big_black.tif<br>
<br>
Step 3. Load this image into some sort of WMS rendering system and assign a background color value of red to it.<br>
<br>
Step 4. Make sure you have the spherical mercator projection defined in your epsg file.<br>
<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 <><br>
<br>
Step 5. Make a WMS request for a tile that replicates one that TileCache makes:<br>
<a href="http://localhost/cgi-bin/mapserv?map=/var/www/mapfiles/test/test.map">http://localhost/cgi-bin/mapserv?map=/var/www/mapfiles/test/test.map</a><br>
&layers=imagery<br>
&srs=EPSG%3A900913<br>
&version=1.1.1<br>
&bbox=-20037508.34%2C-20037508.34%2C-10018754.1704%2C-10018754.1704<br>
&service=WMS<br>
&width=256<br>
&styles=<br>
&format=image%2Fpng<br>
&request=GetMap<br>
&height=256<br>
<br>
Step 6. Admire the red line at the bottom of the image which indicates no data.<br>--<br><br><br><div class="gmail_quote">On Mon, Oct 20, 2008 at 10:38 AM, Roger André <span dir="ltr"><<a href="mailto:randre@gmail.com">randre@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Ok, I think I've narrowed this down to being a reprojection problem. My source data is actually unprojected lat/lon raster data, with pixels that are .025 x ,025 degrees in size. I've set this to be EPSG:4326 in my MapServer LAYER, and am specifying a spherical mercator reprojection to EPSG:900913 via TileCache. I figure I have either a problem in my source projection, or in my output projection, with a slight suspicion that I might be wrong in assigning EPSG:4326 to the source data.<br>
<br>Does this sound reasonable, and if so, can I define lat/lon geographic without specifying an ellipsoid?<br><font color="#888888">--</font><div><div></div><div class="Wj3C7c"><br><br><div><span class="gmail_quote">On 10/18/08, <b class="gmail_sendername">Roger André</b> <<a href="mailto:randre@gmail.com" target="_blank">randre@gmail.com</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div dir="ltr">Hi Everyone,<br><br>I've encountered something new that is perplexing me. I'm seeding my cache and finding that certain tiles have a row of pixels missing at the bottom of the tile which is being filled with the background color I've set in my MAPFILE. It looks suspiciously like TileCache is having to "split" my seed image in order to fit it into the Google Maps frame, which would indicate something wrong with my georeferencing - or extents setup, but I can't figure out what. Is this a symptom that rings a bell with anyone?<br>
<br>Thanks,<br><br>Roger<br>--<br></div>
</blockquote></div><br>
</div></div></blockquote></div><br>