[mapserver-users] Color filled transparent polygons

Fawcett, David David.Fawcett at state.mn.us
Thu Sep 25 09:42:29 EDT 2008


You can increase the opacity at the style level by assigning differing
levels of opacity based on attributes in the data table, but I don't
believe that this is the case that Reinoud is describing.  

I am pretty sure that when two symbols of reduced opacity overlap, the
area covered by both symbols has the same opacity level as the areas
that do not overlap.  

David.

-----Original Message-----
From: mapserver-users-bounces at lists.osgeo.org
[mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of thomas
bonfort
Sent: Thursday, September 25, 2008 4:48 AM
To: Reinoud Bokhorst
Cc: mapserver-users at lists.osgeo.org
Subject: Re: [mapserver-users] Color filled transparent polygons


yes,
from version 5.2 AND with AGG output, you can obtain this by setting the
OPACITY keyword at the STYLE level.

cheers,
thomas

On Thu, Sep 25, 2008 at 11:20, Reinoud Bokhorst <bokhorst at argoss.nl>
wrote:
> Hi,
> I have a PostGIS table with about 12000 polygons scattered around the 
> globe. The polygons outline areas where I have particular model data. 
> To get an impression about the data density, I want to plot the 
> polygons with a fill color and a high transparency value. This would 
> mean that the colour on the map gets darker depending on how many 
> polygons overlap at a particular location because the color values 
> will add up. I can do this for example in QGIS but not in Mapserver. 
> It requires that the polygons themselves are drawn using a 
> transparency value but it seems that mapserver first draws all 
> polygons and them applies the transparency value to the resulting 
> image. Is there a solution for this?
>
> Reinoud Bokhorst
>
>
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