[gdal-dev] update to overview resampling methods?

[Etienne Tourigny]

Hi list,

I would like to know if the overview resampling methods listed on help
pages are really up-to-date, because I found some discrepancies in the
docs and code:


- gdaladdo utility page / http://www.gdal.org/gdaladdo.html

nearest,average,gauss,cubic,average_mp,average_magphase,mode


- GDALDataset::BuildOverviews /
http://www.gdal.org/classGDALDataset.html#a2aa6f88b3bbc840a5696236af11dde15

"NEAREST", "GAUSS", "CUBIC", "AVERAGE", "MODE", "AVERAGE_MAGPHASE" or "NONE"


- searching the code I found the following undocumented resampling
methods (there may be others)

AVERAGE_BIT2GRAYSCALE, AVERAGE_BIT2GRAYSCALE_MINISWHITE, AVERAGE_BIT2,
AVERAGE_BIT2GR, NO_REGEN


- gtiff overviews (in frmts/gtiff/gt_overviews.cpp)

only mentions the following, does it also support all others?
AVERAGE_BIT2, NEAR, AVERAGE, GAUSS


So I have a few questions:

1) why are some methods not listed in GDALDataset::BuildOverviews and
gdaladdo docs
average_mp, AVERAGE_BIT2*, NO_REGEN  (there may be others)

2) are there some methods which are not supported in specific drivers,
such as e.g. CUBIC in the gtiff driver?

3) why is AVERAGE_MP considered unfit for use in the gdaladdo docs?
and why is it still available?

4) AVERAGE_MAGPHASE has been reported as buggy by some QGIS users,
could someone comment?
see http://hub.qgis.org/issues/284

5) should the docs be updated and harmonized, including any
driver-specific options, or are they too obscure to worry about?


regards,
Etienne