AW: [UMN_MAPSERVER-USERS] Transparent raster layer

[Frank Warmerdam]

Pleyer, Walter wrote:
>  
> Thanks, Flavio!
> 
> The TRANSPARENCY Parameter worked - kind of.
> Now when I set the TRANSPARENCY parameter of the layer object to varying
> values, the resulting image gets paler or less pale, but unfortunately
> not transparent in the sense, that I see the underlying image through.
> Do you have any ideas, hints?

Walter,

Are you wanting to return an image from mapserver where the final
image includes alpha type transparency?  What is your output format?

I suspect you will need custom OUTPUTFORMAT declaration indicating a
32bit RGBA PNG output format if you want partial raster transparency.
I'd encourage you to read up on the OUTPUTFORMAT declaration, but something
like this at the MAP level might work.

IMAGETYPE png32

OUTPUTFORMAT
   NAME png32
   DRIVER "GDAL/PNG"
   IMAGEMODE RGBA
   TRANSPARENT ON
END

Good luck,


>> Example:
>>
>> 	LAYER
>> 		NAME "Switzerland Relief"
>> 		MINSCALE 100000
>> 		TYPE RASTER
>>                 TRANSPARENCY 50
>> 		STATUS ON
>> 		DATA "Relief.tif"
>> 		PROCESSING "RESAMPLE=AVERAGE"
>> 		PROJECTION
>> 		 "init=world:CH1903"
>> 		END
>> 	END
> 
> 


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