I am using gdal2tiles_parallel.py to generate a tile pyramid from a single geotiff with nodata value set. I have noticed that if I have a small hole in the original geotiff (say single pixel), then I get a single pixel hole in each higher zoom level I generate, so the hole effectively grows in geographic area as you zoom out.
I am using the
average resampling method, and I believe the call which actually downsamples the code to generate each lower zoom level is
gdal.RegenerateOverview; the gdalwarp documentation suggests that average resampling ignores nodata values, but I'm not sure that
RegenerateOverview implements resampling in the same way and can't find any detailed documentation on how it works internally.
Does anyone know if
RegenerateOverview ignores (or should ignore) nodata values, or if there is an alternative method I could substitute to handle nodata properly for resampling?