That question is probably for Even, Frank or some the developer of drivers that
support mask band.
I am working on ticket #5621 and trying to adapt it to the RFC 15 but I am not
quite sure that I am getting it right.
In GeoRaster, I can have a bitmap mask band that can be applied to all bands,
similar to the concept of GMF_PER_DATASET, I guess. I can also have one bitmap
mask band per raster band, but that does not correspond to the others mask
flags (GMF_ALL_VALID, GMF_ALHA, GMF_NO_DATA). The data type of my bitmap mask
is 1 bit, and there is no implicit connection with Alpha Channel or No Data in
a binary bitmap mask, of course.
So if I have a dataset with just one bitmap mask shared between all the bands,
I think I can return the flag GMF_PER_DATASET and promote the values to
GDT_BYTE. But if I have bitmap masks for each raster bands, then I don't know
what flag to return. I might just lie and say "GMF_PER_DATASET" and when the
mask is requested I will take care of returning the correct one.
Would that works for others drivers participating on
gdal_translate/CreateCopy()?
Of course, if the output driver support just one mask per dataset, there is
nothing much we can do.
By the way, are there any driver that support overviews of mask band?
Regards,
Ivan
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