[gdal-dev] GDALWarpOperation.ChunkAndWarpImage slow on large tiffs

[Frank Warmerdam]

On 11-03-09 01:46 PM, Radim Blazek wrote:
> Hi,
>
> GDALWarpOperation.ChunkAndWarpImage was reported to be extremly slow
> on larger geotiff (over 1GB). Is it possible that it is much slower
> with respect to GDALRasterIO()  even without reprojection? Should I
> return to 'manualy' reading data via GDALRasterIO() + fidling with
> data extents and cells alignement? I thought that GDAL
> ChunkAndWarpImage will do it even faster, possibly knowing better (?)
> various formats nature.
>
> Is there way to tune somehow performance? Currently no reprojection
> and GRA_NearestNeighbour.

Radim,

GDALWarpOperation is intended to be a high precision image resampler.
Within the constraints of doing this correctly it attempts to be fast,
but it will generally be quite a bit slower than direct RasterIO calls
and in some situations dramatically slower.  Particularly it is completely
inappropriate to use for radical downsampling.

Best regards,
-- 
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