Thanks for your reply. I'm using gdal 1.10.1. I'm using cubic resampling, but i have noticed the dark line artifact with bilinear as well. I unfortunately do not reproduce the problem with a basic gdalwarp with cubic resampling.
I have written this code to do some registration. It's hard to tell in the example, but my transformation actually pushed pixels up a bit. The transformation I use handles interior pixels nicely and extends beyond the image, so there is nothing 'weird' going on with that near the boundary that I can think of. I was hoping there is a warp option i have not yet thought of. Thanks again, Mike On Thu, Apr 16, 2015 at 11:10 AM, Even Rouault <[email protected]> wrote: > Le jeudi 16 avril 2015 19:01:57, Michael Aschenbeck a écrit : > > 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 > > > > Mike, > > Which gdal version ? Which resampling method ? > Do you reproduce with gdalwarp ? > If so, providing input file + full gdalwarp command line would help. > > Even > > -- > Spatialys - Geospatial professional services > http://www.spatialys.com >
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