[gdal-dev] Boundary Artifact with ChunkAndWarpImage

[Michael Aschenbeck]

Hello,

I'm using ChunkAndWarpMulti to warp an image.  The warping is working
nicely, however, at the boundary I seem to be getting some artifacts.

The first artifact i see is a DARK boundary of pixels in some location.  My
guess is that the interpolator is interpolating with blackfill (intensity
zero pixels).  Note that I am using the following setup:
psWarpOptions->padfSrcNoDataReal = (double *)
CPLMalloc(psWarpOptions->nBandCount*sizeof(double));
for (int ii = 0; ii < psWarpOptions->nBandCount; ii++)
{
psWarpOptions->padfSrcNoDataReal[ii] = 0;
}
which i thought was supposed to treat zeros as nodata.  It doesn't seem to
be doing what I think it should.

In some cases, I am also noticing a BRIGHT band strip of pixels adjacent to
the dark boundary pixels.  I don't have any thoughts on where this artifact
is coming from.

Below you can find links to an example.  The orange you see is just the
background color of my viewer.  Zero pixels are set to transparent so you
can see the dark boundary artifact.  (Note that all of the orange region is
covered with zero-intensity pixels, so we haven't reached the boundary of
the file, just the boundary of the non-zero pixels.)  Sorry if that's
confusing.
The before image: https://www.dropbox.com/s/3kmyi8wu0qybsq9/before.JPG?dl=0
The after image with the artifacts:
https://www.dropbox.com/s/fo0m8q95b26s61m/after.JPG?dl=0

Any help would be greatly appreciated!

Thanks!
Mike
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/gdal-dev/attachments/20150416/5768a0fa/attachment.html>