Hi Even,

> From: even.roua...@spatialys.com
> To: lucena_i...@hotmail.com
> Subject: Re: [gdal-dev] RFC 15: Band Masks vs #5621
> Date: Wed, 20 Aug 2014 20:39:29 +0200
> CC: gdal-dev@lists.osgeo.org
> 
> > 
> > I am trying to help a developer how wants to use VRTs as an intermediary
> > between a GeoRaster and a PNG, in order to produce thumbnails. In that
> > case, does the VRT needs to describe the mask band so that the PNG's
> > driver will received the filtered image, with the zeroes regions masked
> > out?
> 
> You need to explicitely declare mask bands in the VRT. See the VRT 
> documentation for that. But that will just declare the existence of the mask 
> band, and will not do any processing such as zeroing masked regions.

You are right. GDAL can copy the mask from one dataset to another, depending on 
the driver. 

But there is no way to indicate that you want the result of the masking, not in 
the API, not on command line tools.

Maybe we should add that to the wish list.

Regards,

Ivan
 

                                          
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