[mapserver-users] Background transparency vs feature (polygon) transparency.

[Basques, Bob (CI-StPaul)]

Ok,

I thought of an easier way to ask my question about a capability being removed in recent Mapserver.

How can a Pick a RGB color and use that as a TRANSPARENT piexel value across the whole image, doesn't matter if the color is the background color, or a feature color.  I just want to make a particular color transparent.

It doesn't look like I can set transparent to TRUE without the background going transparent.  What I'm after is drawing a feature layer (polygon) as transparent.  Is there  a way of setting a layer element transparent??

Bobb



From: mapserver-users-bounces at lists.osgeo.org [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of Basques, Bob (CI-StPaul)
Sent: Monday, April 20, 2015 4:10 PM
To: mapserver-users at lists.osgeo.org
Subject: [mapserver-users] Background transparency vs feature (polygon) transparency.

All,

So I used to be able (MS6.1 and older?) to just define a color and then set transparency to ON, and that color would be transparent.  It didn't matter if it was the background or a feature that was drawn in that color, it just turned transparent.

I have a slightly different use case than most users as.  I want to maintain a background color for the image, but filter out polygons (parcels) to be transparent in color (not opaque) as an overlay.  This is to represent all Public right-of-way areas, or rather, areas that are NOT parcels.

I've been trying for a couple of days now on and off to make the new methods replicate this capability, to little effect.  All the new tools assume a transparency is going to be applied across the whole image background.  I need to be able to only poke holes in the background where there is a parcel polygon.

Is there a way to make this work like in the good old days (I mean good old versions ??  :c) of Mapsever??

One suggestion I did find that would likely work, was the use a mask, but then I need a larger bounding area to contain the mask (Is there a way of defining an edgeless mask??).  Is this the track I should be persuing?  I could use our City Boundary for this as a possible solution.  Also, what's all the stuff about a COMPOSITE block, looks like this is the future of masking type operations in the future.

Thanks

Bobb


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