A hillshade is a grayscale 3D representation of the surface, with the sun's relative position taken into account for shading the image. This function uses the altitude and azimuth properties to specify the sun's position.

This dataset is the hillshade used as a background of the basemap on geoportail.lu

It is a rendering of a smoothed version of the 2013 Height model (DHM).

This tool has been used to generate the hillshade: http://desktop.arcgis.com/en/arcmap/10.3/manage-data/raster-and-images/hillshade-function.htm