Hi,
GDALDataset::RasterIO pass the request off to each band objects
rasterio methods with appropriate arguments
In GDALRasterBand::RasterIO
(http://www.gdal.org/classGDALRasterBand.html#a5497e8d29e743ee9177202cb3f61c3c7)
"Some formats may efficiently implement decimation into a buffer by
reading from lower resolution overview images."
So you don't need to choose the right overview level by yourself.
Usually it selected automatically. You can inspect GDAL sources for how
it chosen. GDAL don't have the special function to find out which
overview level is chosen.
Best regards,
Dmitry
14.12.2012 11:24, HariPrasad ?????:
Thanks Dmitry for your replay.
I did that using IRasterIO(), but non of the IRasterIO() parameters has
which overview its displaying. (i.e overview number). How can i know which
overview it has displayed?
I used GetOverview(int). I was able to get the overview numbers. But when i
zoomed to maximum the base image has to be displayed instead of overview if
i am not wrong, which i am not getting the base image number.
am iam thinking in right direction?
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