[Tilecache] Why are MapServer layers not transparent and yet the same layer via a MapServer WMS are?

[Christopher Schmidt]

On Thu, Jun 05, 2008 at 11:16:38AM -0600, Greg Cocks wrote:
> Hello,
> 
> I am setting up an OpenLayers map, reasonably new to this - and can't
> get the vector data via MapServer directly to be transparent if linked
> directly - but CAN if go using the MapServer as a WMS?? (note that both
> methods do show the layer in the web map.)

When using TileCache, the parameters you send in the request -- like
transparency, projection, width, height -- have no effect on the output
tiles. Only the bounding box is used in determining the tile to
generate: everything else is pulled from the config.

This likely means that your TileCache cofig is not set up to request
transparent tiles.

If you're attempting to use a WMS layer, you can fix this by just
appending ?transparent=true to the end of the URL in your config.

Regards,
-- 
Christopher Schmidt
MetaCarta