> in the event that we are provided only 4 bands, but from an 8-band
system, will this still hold? It is what we have to work with,
unfortunately or not.
Yes, obviously, the example generalizes to other number of bands.
So, providing either |band_nums=[1,2,3,4]| along with weights and
extracting bands 1 and 4 after-the-fact, or |band_nums=[1,4] and
||providing the corresponding weights for those bands, in my mind
should produce something similar? I haven't tried it just yet.|
No.
Let's consider the minimum example:
A = 10, weightA = 0.7
B = 20, weightB = 0.3
P = 30
PseudoPanchro = 10 * 0.7 + 20 * 0.3 = 13
then A_pansharpened = A / PseudoPanchro * Panchro = 10. / 13 * 30 = 23.08
and B_pansharpened= B / PseudoPanchro * Panchro = 20. / 13 * 30 = 46.15
If you ignore B, than A_pansharpened = 10. / (10 * 0.7) * 30 = 42.85
And, even if you rebalance the reduced set of weights so its sum is
still 1, which makes much more sense, that still won't work, because
that would in that example just give the value of P.
https://github.com/mapbox/rio-pansharpen/blob/master/docs/pansharpening_methods.rst#brovey
: "It assumes that the spectral range spanned by the panchromatic image
is the same as that covered by the multispectral channels." If you
ignore multispectral channels in the computation of the pseudo panchro
value, then the assumption no longer holds true. Or you need some magic
to generate a reference panchromatic image that only takes into account
the subset of bands you are interested in.
--
http://www.spatialys.com
My software is free, but my time generally not.
Butcher of all kinds of standards, open or closed formats. At the end, this is
just about bytes.
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