Selon Belaid MOA <[email protected]>: Belaid,
First, the VRTKernelFilteredSource will only recognize the nodata value if you set it on the VRTRasterBand (it will not fetch it directly from the <SourceFilename>) When a nodata value is set and found in one of the values in a NxN square, the value will be ignored. The effect of this depends whether normalized="1" is set on <Kernel> or not. If normalized=1, the sum of the coefficients is not incremented for that nodata value, so the normalization will operate only on valid pixel values. If normalized=0, the nodata value is just ignored As far as what happens in the borders is concerned, the code says that : "Fill in missing areas. Note that we replicate the edge valid values out. We don't using "mirroring" which might be more suitable for some times of filters. We also don't mark these pixels as "nodata" though perhaps we should." Best regards, Even > > Hi everyone, > I am using VRT KernelFilteredSource to implement an average filter as > done in the VRT tutorial. However, I am still unclear on how it handles the > NoDataValue pixels. Are they too averaged or does it leave them as they are? > If they are masked, does do an adjustment for the kernel coefficients to > compensate for their absence? Another related question, is how does it handle > the pixels on the borders and the kernel coefficients for those pixels? > > Thank you very very much in advance for any help on these issues. > > With best regards. > ~Belaid. > > _________________________________________________________________ > Stay on top of things, check email from other accounts! > http://go.microsoft.com/?linkid=9671355 _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
