Hello!
I've been trying to figure this out for a while and this would be my first
time asking a question here.
How do I load a 3-band tiff into a virtual dataset, add a band (alpha
layer), warp the virtual dataset, then write it out to a TIFF again
(different, path, different name)?
I'm loading a 3-band tiff into a virtual dataset using C# and then
attempting to add an alpha layer using this code:
// Load image dataset
using (OSGeo.GDAL.Dataset imageDs = OSGeo.GDAL.Gdal.Open(devPath,
OSGeo.GDAL.Access.GA_ReadOnly))
{
// Copy dataset data into a virtual dataset
virtDs = OSGeo.GDAL.Gdal.GetDriverByName("VRT").CreateCopy("", imageDs,
0, null, null, null);
// If addAlpha true, add an alpha layer band
if (addAlpha)
{
virtDs.AddBand(OSGeo.GDAL.DataType.GDT_Byte, null);
virtDs.GetRasterBand(4).SetColorInterpretation(OSGeo.GDAL.ColorInterp.GCI_AlphaBand);
}
imageDs.Dispose();
GC.Collect();
}
I then attempt to warp the virtual dataset and write it back out to a TIFF
again (with the option "ALPHA=YES"). I feel like I'm missing something and
I'm not sure what. Every time I attempt to view the new TIFF, it ends up
transparent.
The only way I seem to get it to work in a viewable manner is to manually
copy each raster band to a new dataset and filling in the alpha band (band
4) with 255.
Any help is appreciated, thanks in advance!
-Alex
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