Sorry I only have access to DSM data (hills AND man made buildings) instead of DEM data (hills only).
As Hongkong is a heavy mixture of high houses with woven hills, this does not work well if the houses are auto postioned onto these spilled DSM elevation data.
DEM, DSM & DTM: Elevation Models in GIS - GIS Geography
We explore the differences between DEM (bare earth), DSM (natural and built environment) and DTM (vector contours and regularly-spaced points).
gisgeography.com