I'm using the Smoothing (gaussian) and Smoothing (mean) tools in the QGIS Orfeo toolbox to blur a hillshade raster I've generated. However, they both come out with a thick black border at the edge of the DEM (essentially at sea level as well as at the edge of the DEM where I clipped it).
What I'd like to know is:
A) Can I prevent this somehow? B) If not, is there a tool I could use to easily remove it?
I've also tried Smoothing (anidif) but it causes a lot of unwanted artifacts within the data - it causes the raster to appear to be divided into slightly discontinuous horizontal strips.
Screenshots: Raw input, and Smoothing (gaussian) output respectively. The black border with smoothing (mean) is a lot thinner, but the results of that are also inferior to the gaussian smoothing.