[mapserver-users] Mapserver 5.6, WMS client does not keep layer opacity

[Francesco D'Alesio]

Hi all,
I created a "merge" service for mapserver that, given some WMS getmap 
requests, builds a geotiff merging together WMS getmap responses.
It creates an "on-the-fly" mapfile, with a LAYER CONNECTIONTYPE WMS for 
each layer.

Everything works, except layers with OPACITY:
while the getmap response (agg png 8bit) is correctly opaque (features 
are semi-trasparent), in the geotiff image they are not opaque anymore.
Trasparency is kept (where there's no features, I can see layers under), 
but opacity is not (features are no more semi-trasparent and they cover 
layers under).

Also, if I try to merge getmap responses using PHP/GD, features remain 
correctly opaque.

Have you got any idea about why mapserver is modifying opacity while 
merging?
Is there a way to avoid this?


Thank you

Regards


Francesco

--