[OpenLayers-Users] Used gdal2tiles to create several TMS spec maps for Openlayers, but the Overview Map shows the wrong part of the picture!

[Connor Burke]

I'm a student at the Ohio State University medical school, and am working on a histology website. Basically, I've used gdal2tiles.py to tile a few hundred images (several GB each) taken from microscopes - of cells and other tissue - and display them using OpenLayers. It's been quite an exciting project, and already represents an improvement over the current system, which uses Zoomify (a flash based alternative) for the same thing.

For those who aren't familiar with gdal2tiles, it breaks images up into 256px tiles and stores them in a folder structure in accordance with TMS specifications. You can set a spatial reference system and map projection if you want, but I just tile them with nothing, as plain raster images. It then generates a little HTML file that uses OpenLayers and a tiny bit of its own Javascript to read the tiles off the server you put them on.

Here's the problem - the overview map is inaccurate. It shows the image, but off center - and the extent rectangle that shows where I'm zooming is simply inaccurate. I've spent a while trying to troubleshoot this on my own and am out of ideas.

Here's the site - 
http://histology.osumc.edu/test/tiled1.php

(note how you can zoom to the center of the spinal cord, but the overview map shows that we're zooming into the bottom left)

Any help would be much appreciated - thanks guys.

Connor
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