[gdal-dev] gdal_translate with -projwin possible bug

[Lauren O'Brien]

Hello all,

I've noticed what I think may be a bug with gdal_translate, just looking
for further information before deciding whether to report it.

In version 1.11.4 and earlier, using the -projwin tag to subset a raster
produces an output whose cell alignment and content matches the source
dataset - it just grabs any cells that intersect the box and writes them to
the output.

In v2.1.0 (at least in a Windows environment), this no longer occurs. The
output raster is distorted to match the exact extent of the -projwin
coordinates. No resampling is involved, but the cell origins shift, and the
cell sizes are either shrunk or stretched slightly to conform to the
projwin box. This is a substantial change in behaviour which doesn't appear
to have been documented.

>From my point of view, its an unwelcome change. I've been using
gdal_translate with -projwin and vsicurl to clip out sections of large
national datasets without having to download the whole file first, and
without needing to know things like the source dataset origin, cellsize etc
in order to ensure output aligns with input. I need each dataset I clip out
to 'stack' properly, and to represent an unaltered subset of the source
data.

Please let me know if this is a true bug or just an undocumented change,
and/or if there's a better alternative command to use.

Regards,
Lauren O'Brien
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