Transparency behind rendered vectors

[Doug Nebert]

This is close, but not quite. I am rendering line data from a 
shapefile, but through mapserver it is sent as an opaque GIF. I need
the background to be a transparent GIF.  Can the invocation of GD be 
tweaked to make this work from a setting in the map file?

Doug.

owner-mapserver-users at lists.gis.umn.edu wrote:
> 
> Doug,
> 
>   Transparency for raster layers is defined with the
> OFFSITE keyword.  The value is the color number
> the image's palette.
> 
> e.g.
> LAYER
>   NAME ortho
>   TYPE RASTER
>   STATUS DEFAULT
>   DATA "83P_01s_10TM.tif"
>   OFFSITE 2
> END
> 
> means the third color (since there is a color index 0)
> in the image's pallete for this layer is to be considered
> transparent when reading the tif file and writing the
> pixels into the target GIF (i.e tif pixels with color index 3
> are not written into the GIF).
> 
> Funny thing is, this is from old mapserver 3.2
> documentation (and email).  I couldn't find it in the 3.3
> doc.
> 
> Hope this helps...
> 
> Brent Fraser
> 
> bfraser at geoanalytic.com
> GeoAnalytic Inc.
> #300 , 700 - 4th Avenue SW Calgary, AB
> Canada T2P 3J4
> Tel:  (403)213-2700 Fax:  (403)213-2707
> www.geoanalytic.com
> 
> ----- Original Message -----
> From: "Doug Nebert" <ddnebert at fgdc.gov>
> To: "Mapserver Users" <mapserver-users at lists.gis.umn.edu>
> Sent: Friday, July 21, 2000 1:20 PM
> Subject: Transparency
> 
> > All:
> >
> > I would like to manufacture certain layers as being transparent outside
> > of the opaque features so they can be overlain on similar maps from
> > other servers. I want roads opaque, background transparent.
> >
> > Is there a correct way to specify the transparent color bin to use,
> > through mapfile or other setting?  I am using mapserv with the old
> > gd that supports GIF format. I understand that the PNG files use a
> > different method for transparency, but would hope that this is
> > defined in a single way via map file. Is it defined at all?
> >
> > Doug.
> >
> > --
> > Douglas D. Nebert
> > Geospatial Data Clearinghouse Coordinator
> > FGDC Secretariat Phone: +1 703 648 4151 Fax: +1 703 648-5755
> > Pager Messaging: http://clearinghouse3.fgdc.gov/dougmsg.html

-- 
Douglas D. Nebert
Geospatial Data Clearinghouse Coordinator 
FGDC Secretariat	Phone: +1 703 648 4151	Fax: +1 703 648-5755	
Pager Messaging: 	http://clearinghouse3.fgdc.gov/dougmsg.html