In Simeo-Edito, it is possible to use a DTM at initialization time.
New Project > Edito
Choose the terrain size and a heightMap file to be mapped on it, set the min and max altitudes.
Tune the DTM renderer in the Rendering tab, in particular the mesh size in meters : try values like 1 meter or 5 meters to see the terrain with an appropriate detail level according to its size.