[mapserver-dev] Transparency attribute on Layer Object

Steve Lime steve.lime at dnr.state.mn.us
Tue Aug 20 00:57:12 EDT 2002

I'll have to look at the implementation in mapdraw.c and see where the creation of the temporary image is happening. If it's before msDrawRaster then this should already work, if not then I'll have to look at moving it.

The transparency parameter works nicely with vector data. Has anyone simply tried it with raster data? It's there in 3.6+.


Stephen Lime
Data & Applications Manager

Minnesota DNR
500 Lafayette Road
St. Paul, MN 55155
>>> Daniel Morissette <morissette at dmsolutions.ca> 08/19/02 12:36 PM >>>

I never used it myself, but you might want to have a look at the
TRANSPARENCY parameter that was added at the layer level in 3.6:

I'm not sure whether this feature is properly supported with imagery
and/or 24 bits output in 3.7 yet... I'll let Frank/Steve reply on that.


David Graham wrote:
> Developers:
> I would like to know if anyone is working on a project to add transpency
> to Layer Objects that are of type raster data.  If not I am trying to
> size the effort required to add the ability to specify a transparency
> parameter in the layer object (map file) that could indicate % of the
> imagery to blend with existing data at rendering time.  The idea is to
> be able to blend multiple raster layers each overlaying the last.  Since
> the we now have 24bit support this should not be too difficult.
> Currently my requirements are only for Raster data, but it would be
> useful to eventualy extend the functionality to vector polygons filling
> also.  I am less familiar with that side of the code.
> Dave Graham
> --
> David W. Graham
> Director of Geospatial Applications Development
> information integration and imaging, LLC
> 201 Linden St, Third Floor
> Fort Collins, CO 80524
> (970) 482-4400
> dgraham at i3.com
> http://www.i3.com

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