Hot answers tagged transparency
Perhaps dissolve the polygons together. Another option: within symbology you can select "no color" for the border of the polygons.
A blog entitled Help! My ECW has speckled edges! from Hexagon Geospatial covers this topic quite well because knocking out pixels is not a reliable solution. If the ECW was created with an Opacity Band, QGIS would use this as an Alpha band. If you received the rail corridor ECW image from a third-party data supplier, I would go back to them and ask that ...
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