[gdal-dev] Working with overviews (in python)

[Dusty Phillips]

Hi there,

This is almost certainly an RTFM question, but I need a pointer to
what manual pages I need to read. I'm quite new to gdal and coming to
it backwards. I'm working with python and basically trying to
implement the suggestion Frank makes here in python:

http://lists.osgeo.org/pipermail/gdal-dev/2009-March/020200.html

So I've run gdaladdo on a .vrt file to create a vrt.ovr file; the .vrt
file is processed by another python script later. The problem is that
the overviews are not high enough quality and I'd like to warp the
overviews using cubic spline sampling.

I know a little bit how to work with ReprojectImage as discussed in
the above post. The thing I don't understand is how to get the dataset
handles for a specific overview so I can regenerate it. I'm pretty
sure this is a fundamental misunderstanding of how overviews are
generated and handled in gdal, but I can't find any documentation to
enlighten me.

Frank says in the above post:
"For instance, this C entry point could likely be used with hSrcDS
being the base datset, and hDstDS being the dataset for the
overviews."

My understanding is that I will have to reproject each individual zoom
level into the overview file using a different SetGeoTransform, so I
need somehow to reference a dataset in the overview at an individual
zoom level. Am I misunderstanding?

Thanks for any links or additional information,

Dusty