[Gdal-dev] GDALWarpOperation::WarpRegion

[Frank Warmerdam]

On 9/29/05, Sean Forde <sforde at lizardtech.com> wrote:
>
> The prototype for this function is:
>
> CPLErr WarpRegion(int nDstXOff, int nDstYOff, int nDstXSize, int
> nDstYSize,                      int nSrcXOff=0, int nSrcYOff=0, int
> nSrcXSize=0, int nSrcYSize=0)
>
> Are all these parameters to this function in pixel space? That is, if I
> have spatial coordinates to start with, must I convert them to pixel
> space in order to call this function correctly?

Sean,

The "Dst" values are in pixel space on the destination image, and
the "Src" values are in source image pixel/line coordinates.

Note that normally you would not call WarpRegion(), instead
using ChunkAndWarpImage() which will split the overall region
into more appropriate sized sub-chunks.

If you choose to manage the GDALWarpOperation directly, and
don't want to operate on the whole destination image you will need
to select subwindows in pixel coordinates.

Best regards,
--
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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