[Qgis-developer] Transparency: group versus layer transparency/opacity

Andreas Neumann a.neumann at carto.net
Wed Aug 26 03:21:33 EDT 2009

Hi QGIS developers,

For QGIS 1.3 (or whatever the successor is called) I would like to discuss
whether we can add group transparency in addition to the regular layer

This is a concept available in SVG. The difference is that with group
opacity/transparency, the layers in the group are rendered first
individually (with or without opacity) and then the transparency is added
on the intermediate rendering result of the group as a whole.

The difference is clearly seen if you have layers in a group where
polygons of different layers overlap. You don't want opacity on the
individual layers (since this would change colors), but you want to be
able to set the opacity on the parent group, for being able to have a
background base map shine through.

Here are two links on the topic:

Maybe something to discuss at the Vienna meeting?

Should I file a feature request?


Andreas Neumann

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