MapFile TRANSPARENCY parameter and WMS GetMap TRANSPARENT argument

[Frank Warmerdam]

On 9/9/05, Jeff de La Beaujardiere <jeff2005 at svs.gsfc.nasa.gov> wrote:
> The Layer object in a mapfile can have a TRANSPARENCY value to control
> overall opacity without having to modify the alpha channel in the source
> image (GeoTIFF raster in my case). This is very helpful.
> 
> Am I correct that there is no way to tie this to the WMS GetMap argument
> TRANSPARENT={TRUE|FALSE} such that a user request for TRUE (the default)
> would use the opacity percentage specified by TRANSPARENCY whereas a
> request for FALSE would act as if 100% opacity had been specified or
> simply ignore the TRANSPARENCY value in the mapfile?

Jeff, 

I *think* that the WMS TRANSPARENCY flag is used by MapServer
to control whether the resulting image makes the background color
transparent or not.  It does not (to the best of my knowledge) 
interact with layer-level transparency at all.   Nor do I think that
would be appropriate, though I haven't considered it deeply.

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent