Le mercredi 15 octobre 2014 16:30:19, M Lewis a écrit : > I have searched and found lots of similar queries but nothing that quite > gives me the answer that I am looking for (as they all appear to be related > to gdal_translate rather than the C++ API.) > > We have a set of strips of grey scale satellite imagery that are rotated. > > I use AutoCreateWarpedVRT to generate a 'north-up' image that is converted > to a bitmap and displayed to the user. > When displayed the image has a black area surrounding it which tends to > mask other images that tile alongside. > > From searching around I assume it is to do with the GDALWarpOptions that > can be passed to the AutoCreateWarpedVRT function but the 'no-data' value > of the dataset when queried fails and just returns a default of -10000.0. > Therefore I am unsure of what to set in the padfDstNoDataReal etc > variables to mask out the areas where there is no data. > > The image is grey scale, the 'non-data' areas come out as black once the > image is returned from the RasterIO call so it makes it difficult to > post-process the image data. > > Anybody got any tips on the way to do this and maybe set up the > GDALWarpOptions to pass to the AutoCreateWarpedVRT function? > Is it even possible on a grey-scale dataset with no 'no-data' value?
You can try assigning 0 in padfDstNoDataReal AND assigning 0 as nodata value to the dataset returned by AutoCreateWarpedVRT() with ds.GetRasterBand(1).SetNoDataValue(0) > > Thanks > > Martin > > > > > -- > View this message in context: > http://osgeo-org.1560.x6.nabble.com/Remove-Black-Areas-From-Rotated-Images > -tp5167665.html Sent from the GDAL - Dev mailing list archive at > Nabble.com. > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
