Option for partial pixel overlap in Zonal Statistics

[jfbourdon]

Feature description.
The current native:zonalstatistics only considers pixels which have their centroïd overlapping the polygons and computes statistics as if all pixels have the same weight. It could be useful if an option was available to consider the proportion of area covered for each pixel as weight for the statistics. The count stats would then be fractional also.

Additional context
I must add that there is currently either a hidden feature or a bug for polygons covering the centroïd of one pixel or none at all. In that case, the tool works as I suggest and uses the fractional area to compute the stats. It seems that there has been a bug about that in past (see #25058).

[root676]

I am currently thinking about reworking the whole vector based zonal statistic algorithms in order to make them executable in a background thread. I would be up to include the requested functionality in exchange for a small funding. If you are interested and this is an option for you, just e-mail me: clemens.raffler@gmail.com

[kgjenkins]

FYI, exactextract provides a more robust zonal statistics calculation that takes partial pixel overlaps into account, and there is currently an experimental QGIS plugin Zonal Exact Extract that uses the exactextract library.