[Qgis-user] Rasters alpha channel black instead of transparent

[Pedro Venâncio]

Hello Alister,

Yes, the problem is exactly this. It happens to me on Windows with QGIS 1.7 standalone and 1.8 from osgeo4w. It also happens on Linux 1.7 (not tested in 1.8 master on Linux).

The Transparency band on the Transparency tab is always "Not set". This option will be enabled in the near future?

Thanks!

Best regards,
Pedro




----- Original Message -----
From: Alister Hood 

Hi,
This sounds like http://hub.qgis.org/issues/2491

> Date: Tue, 30 Aug 2011 02:38:30 -0700 (PDT)
> From: Pedro Ven?ncio 
> 
> Hello everyone,
> 
> I was cutting some rasters in the same way I did several times in the
past,
> adding the alpha channel to ensure transparency:
> 
> gdalwarp -of GTiff -r lanczos -dstalpha -cutline shapefile.shp
raster_input.tif
> raster_output.tif
> 
> However, now the area that would appear transparent, is shown in black
on QGIS
> 1.7 (and 1.8 dev), as you can see in the picture attached.
> 
> I've tried other software and it open the image with transparency in
these
> areas.
> Images that I've cut in the past and opened correctly in QGIS, now are
black
> instead of transparent.
> 
> Why is this happening? It is an option that can be changed?
> 
> Thanks!
> 
> Best regards,
> Pedro Venbncio
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