That should be relatively straightforward to adapt
GDALResampleChunk_AverageOrRMS_T to do sum. Reuse the average code path,
but just don't divide the sum by dfTotalWeight at lines 1418, 1473,
1688, 1700 and 1712. And error out if applied to a band with a color
table (cf line 4361)
For other a
Can we aspire to translate having the same set of resampling algorithms as
the warper?
I see the warper adds min, max, mod, q1, q3, sum
I especially wanted sum for OVERVIEW_RESAMPLING in COG, and I can see where
it's done and ... can maybe see my way through that ... but the 600 lines
of code i
