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.