[Gdal-dev] Empty Tiles in GeoTIFFs

[Tugrul Galatali]

	I've recently been working on a high resolution but sparse dataset that
I've been storing in tiled GeoTIFFs. The bulk of the tiles are blank,
and in my own software I just don't write these tiles to the file, and
assume an error in reading one means it was blank to begin with. Which
works great until I attempt to use a third party tool, including GDAL.

	Is what I'm doing a cheap hack I should never expect support for, and
is there a raster format that does have explicit support for missing
tiles?

	Also, after looking at a GeoTIFF generated by GDAL, and skimming the
source and this list, it looks like TIFFTAG_GDAL_NODATA is a string of a
single double, despite -src/dstnodata taking a value per band in
gdalwarp. Is this the set definition for that tag, or is it bound to
change in the future for multiple band support?

-- 
Tugrul Galatali <tugrul at galatali.com>