[Qgis-user] RE: Qgis-user] openlayers layers without properties is it possible to alter brightness/contrast

[Richard Duivenvoorde]

On 02/28/2012 09:46 AM, M.E.Dodd wrote:

> Have downloaded the .qml files but now not sure how to proceed. I have osm via openlayers but that does not have properties so ...

If you are using OpenStreetmap as a background via the OpenLayers 
Plugin, then you are stuck with the coloring of the layer provider 
(either OSM, Yahoo or Google).

But what you can do is set the opacity of the OpenLayers Layer in the 
html that is used by the plugin. This plugin is actually a html-page 
showing up in QGIS.

To change the opacity of the layer, go to the plugin directory:

~/.qgis/python/plugins/openlayers
(or in windows it is in your Documents and Settings....)

there is a directory 'html' in which some html files reside which are 
used by the OpenLayers plugin.
Currently my OSM layers seems broken, but if I open the file 
google_streets.html in a text editor, and find the lines:

             var gmap = new OpenLayers.Layer.Google(
                 "Google Streets", // the default
                 { numZoomLevels: 20}

             );

and add opacity to the layer props by making it this:

             var gmap = new OpenLayers.Layer.Google(
                 "Google Streets", // the default
                 { numZoomLevels: 20, opacity:0.5 }

             );

Now when you use the OpenLayers plugin, you will have a much softer 
background...
You can change opacity to any number between 0 and 1
See also: http://openlayers.org/dev/examples/layer-opacity.html

Hope this is usefull,

Regards,

Richard Duivenvoorde