I have a digital elevation model (DEM - geoTIFF) in QGIS 3.2. There is a linear feature (earth bund/wall) in the DEM that I would like to shade/colour based on its elevation above the surrounding ground level on which it is built. I have provided an example output below copied from another project, with the red area representing a gap in the earth bund and the green representing the desired 2m above ground level. I'd like to recreate this example using my DEM.
Shading the whole DEM based on elevation is not an option due to the size and range of elevations present, as well as the varying ground level along the earth bund. I suspect the method involves clipping the relevant bund area from the DEM and some clever work in the Raster Calculator that looks at adjacent values, e.g. Pixel X from within the bund area is compared to Pixel Y located 10m perpendicular to Pixel X, outside of the bund area.