Hi,
to briefly answer your question, for the methods bilinear, cubic,
cubicspline and lanczos who have nominal kernel radius of respective
values 1, 2, 2 and 3 (and thus a diameter double that size), the radius
is extended by a factor source_size / dest_size to take into account the
downsampling ( Cf lines 1188-1195 in alg/gdalwarpkernel.cpp), and the
weights of the resampling kernel are evaluated with a scale factor too
(cf lines 3713-3715 / 3741-3743)
Even
Le 24/05/2023 à 16:29, Ramiro Espada Guerrero a écrit :
Hi,
I would like to know if gdalwarp does any "average" regriding when the
source grid is denser than the target grid regardless of the chosen
method for the interpolation. And if there is any document where I can
follow exactly the calculations. I tried to follow the code on github
but it is pretty difficult to follow.
I've programmed my own bilinear interpolation function in fortran and
I got smoother results when I applied -r bilinear with gdalwarp. So i
wonder if there is a pre-average regriding subroutine that is not in
the documentation page.
Thanks!
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